Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s...

124
Wireless Magazine :: DECEMBER, 1929 :: CONTENTS Valves to use in your set 448 GRAMO-RADIO SECTION Wavelengths of the European stations 452 Notable Dance Records for Christmas 509 In tune with the trade 454 How to Choose a Gramophone 510 A chat with Clapham and Dwyer 459 Realism from your Records 512 The 1930 five valve receiver 461 New Records Listed and Reviewed for your Choice 514 Inside your loudspeaker 466 ----------------------------------------------------------------------- Everybody’s guide to loudspeakers for 1930 470 “Henry V” as a Radio Play! – Verse 519 Under my aerial , By Halyard 477 An Improved Linen Loudspeaker 520 Munich’s Radio House , By Dr.Alfred Gradenwitz 480 The New Q Three 523 The Concentrator – a high-frequency amplifying unit 482 Which is the Best Volume Control? 532 Listener’s Log, By Jay Coote 486 Broadcast Music of the Month 538 We test before you buy: S.G.Brown Three-valve Screened-grid Receiver 487 Some Famous “W.M.” Sets – Readers’ Letters 542 Gecophone Three-valve Short-wave Set 488 Molly’s Radio Education – A Story, By Jay Coote 550 Lewcos Three-valve Chassis 489 Use a Mains-Operated Set Plugged into a Light Socket 552 Regentone Mains units for A.C. and D.C. 490 The New Q Coils, By J.H.Reyner 556 Ekco-Lectric SGP3 (D.C.) 491 The Instruments of the Orchestra 558 Radio evolution – Future commercial designs 493 Our Tests 0f New Apparatus 566 On Unknown Wavelengths! – Humour 495 Reference Sheets 568 Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set Buyers Guide to over 170 sets 504 Televisor Secrets, By H.J.Barton Chapple 506

Transcript of Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s...

Page 1: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine :: DECEMBER, 1929 ::

CONTENTS

Valves to use in your set 448 GRAMO-RADIO SECTION

Wavelengths of the European stations 452 Notable Dance Records for Christmas 509

In tune with the trade 454 How to Choose a Gramophone 510

A chat with Clapham and Dwyer 459 Realism from your Records 512

The 1930 five valve receiver 461 New Records Listed and Reviewed for your Choice 514

Inside your loudspeaker 466 -----------------------------------------------------------------------

Everybody’s guide to loudspeakers for 1930 470 “Henry V” as a Radio Play! – Verse 519

Under my aerial , By Halyard 477 An Improved Linen Loudspeaker 520

Munich’s Radio House , By Dr.Alfred Gradenwitz 480 The New Q Three 523

The Concentrator – a high-frequency amplifying unit 482 Which is the Best Volume Control? 532

Listener’s Log, By Jay Coote 486 Broadcast Music of the Month 538

We test before you buy:

S.G.Brown Three-valve Screened-grid Receiver 487 Some Famous “W.M.” Sets – Readers’ Letters 542

Gecophone Three-valve Short-wave Set 488 Molly’s Radio Education – A Story, By Jay Coote 550

Lewcos Three-valve Chassis 489 Use a Mains-Operated Set Plugged into a Light Socket 552

Regentone Mains units for A.C. and D.C. 490 The New Q Coils, By J.H.Reyner 556

Ekco-Lectric SGP3 (D.C.) 491 The Instruments of the Orchestra 558

Radio evolution – Future commercial designs 493 Our Tests 0f New Apparatus 566

On Unknown Wavelengths! – Humour 495 Reference Sheets 568

Why Signals Fade, By J.H.Reyner 496

The Brookman’s Push-Pull Three 498

Are Radio Critics Justified? By Andrew Soutar 503

“W.M.” Set Buyers Guide to over 170 sets 504

Televisor Secrets, By H.J.Barton Chapple 506

Page 2: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set
Page 3: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. December 1929

4111toogrammesin an oursh

olin astonishing TACT,OU can get over 40 different stations on the wonderful BrownI Receiver! That is not a vain boast; it is a statement of sober

fact-backed by the reputation of the oldest loud speakerfirm in the country.

It has been done many times, and on Tuesday, October 1st, 41stations were obtained at full loud speaker strength in less than anhour -33 on the short and eight on the long wave band.

The reason for such amazing performance is the careful balanceof the circuit and the use of the finest components that money canbuy -a 3d/- Brown Transformer, high precision Polar VariableCondensers, the world-famous T.C.C. Fixed Condensers and thehighly efficient Brown Dual -wave Coils.

If you paid £100, you could not get a better 3 -valve Set than theBrown Screened Grid Receiver. Good things always cost morethan poor ones, but it is well worth the extra cost. Prove this foryourself at any Wireless Dealers' !

3 -Valve Screened GridRECEIVER

In 4 Modelsfor battery or electricmains operation.

Prices from :

£9 to £20All obtainable oneasy payments.

Also supplied ready builtand tested at slightly

higher prices.

FREE!Write for Free Illustrated

Folder to Dept. HS. G. Brown, Ltd., WesternAve., N. Acton, London, W.3

Page 4: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine, December 1929

a ves to seTWO -VOLT VALVES TWO -VOLT VALVES : Pentodes -Five -electrode

(Continued)Amp. I Anode Fil.Make I Type

I

Impedance IIFactor' Volt. Cur. Make Type Impedance Amp. Anode Fil.Factor Volt. Cur.

Three -electrode Dario ... Pent. 100 120 .3

Dario ...Mazda ...Lissen ...Six

Resist.H2 10H2 I o

60,00059,00058,000

3o4735

15015015o

.1

.1.1

Marconi ...Osram ...Cossor ...Mazda ...

PT24oPT24o23oPT23oPen

F 55,000

20,000

909040--

150150

180150

.4-4

.3

.3-Sixty

Mullard ...2 IORCPM i A

55,50051,000

3936

150150

.11

.I FOUR-VOLT VALVESCossor ...Marconi ...

210RCH210 1 50,000

3635

150150

.1

.1 Three-electrodeOsram ...Triotron ...Six -SixtyMarconi ...Osram ...Milliard ...Dario ...Lissen ...Mazda ...Cossor ...Triotron ...Triotron ...Six -SixtyCossor ...Marconi ...Mullard ...Osram ...Triotron ..-TD2Six -SixtyMullard ...Dario ...Lissen ...Mazda ...Triotron ...Marconi ...Osram ...Six -SixtyLissen ...Dario ...Mullard ...Cossor ...Triotron ...Mazda ...Six -SixtyDario ...Mullard ...Marconi ...

H2 1 oWD2

2IoHFHLzioH1.21020PM i HF

Super HFH L210HL2 i o210HF

TioHD2

21oLF210LFL210

PM i LFL2 1 o

225DPM2D X

Univ.L210L210SD2P215P215220PP220SP

PM2220PU D2P220230SPHyperPM252P24o

46,00025,00o

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1- 23,000

22,500

1- 21,000.

1- 20,000

12,500

12,000

11,400II,00010,700

moo()}

6,250

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410 RCResist.H410H4 i o

4o75RCPM3AWD4

SuperHF4 1 o HF

PM3AD4

4o75 HFUniv.RD4

4 t oLFL410L4ioS D4

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4152PPM 25442oSPP425

1 60,000

i

58,00055,00046,00021,00020,000

t 13,000

12,5001,00o09,000

8,50o

7,7007,5007,25o

5,000

4,5004,4504,20o4,0003,7502,7oo2,500

1. 2 500,

2,200

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1,950

403040403738462520141313.510

915151515.51514.5

7.57.5987.786

5

.4.54-5

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Osram ...Cossor ...

P24o230 XP

j.

2,00044

15015°

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Screened -grid-Four -electrodeMullard ...Six -SixtyCossor ...

PM i 44o75HF4 i 0SG

230,000220,000

200190200

150150150

.075

.075

.1

Dario ...Mullard ...Six

SGPMI2

250,000230,000

25o200

15o150

.15

.15

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S4,oS4 TO

4 1 oSG.

200,000

-180180-

150150150

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Cossor ...Marconi

215SG220SGS215

220,0001

190200

150150

.15

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Osram...Mazda ...

S2 I 5215SG

200,000

400,00o

17017o400

150150150

.15

.15

.15Dario ...Mullard ...Marconi

Pent.PM24APT425

55,00o53,000

10083

120300

.15

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Pentodes -Five -electrode...

Osram ...Mullard ...Six -Sixty

PT425PM24

5 0000,

28,00027,000

100200

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.25

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Mullard ... PM22 62,50o 82 150 .3 (Continued on page 450)

443

Page 5: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

In two types tCos or 230 P.T. (2 volts, .3 amp.)and 415 P.T. (4 volts, .15 amp.) Am-

fication Factor 40.Impedance 20,000Anode Volts 100 - 180.

31/FilirPrice (either type) . -

t C. Couor Ltd, Higkisery Grove, London. N.5

Wireless Magazine. December! 1929'

INTERLOCKED

TOOInterlocked Constructionnow incorporated in theN E W Cossor Pentode.Shock -proof Because its elements are

rigidly braced top andbottom the wonderful NEW CossorPentode has exceptional strength Iteasily withstands the hardest shockNothing short of complete destructioncan upset its remarkable performance.

Noise -proof Because of the rock -likerigidity of its construction

the NEW Cossor Pento e is definitelynommicrophonic. Its elements cannotvibrate. Int rlocked construction com-pletely eliminates parasitic noises.

Break -proof Because of its strengthand rigidity the NEW

Cessor Pentode it pi actica ly break -proof. As a result it has an exception-ally long life. No other Pentodecompares with it for strength, forpower or for long service.

ClesNsEworPentode

THE ONLY PENTODE VALVEWITH INTERLOCKED CONSTRUCTION

01900

Mention of the " Wireless Magazine " will ensure prompt attention

449

Page 6: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. December 19*

Valves to Use in Your Set-ContinuedSIX -VOLT VALVES SIX -VOLT VALVES: Screened -grid -Four -electrode

Make 1 Typc 1 ImpedanceAmp.

FactorIA Anode

Volt.Fil.Cur. Make 1 Type Impedance IFacor

Amp. AnodeVolt.

FilCur.

Three -electrodeCossor ...Mullard ...Marconi

oioSGPM i6S61

l 200,000

200200

150150

.1

.075

Mazda ...Cossor ...Marconi ...

H6o76IoRCH6io }

90,000

60,000

405o40

150150150

.071I

...Osram ...Marconi ...Osram ...

oSoloS625S625

1.

i

175,000

210210Ho110

150150180180

.1

.1

.25

.25Osram ...Six -Sixty

H6io6o75RC 58,000

4042

15015o

.1

.075 Pentodes-Five -electrodeMullard ...Marconi ...

PM5BHL6io

33,000i

k

4030

150150

.075

.1 Mullard ... I PM26 I 25,00o I 5o I 15o I .17Marconi ...Osram ...

DE5BHL6I0

i ...10*000 203o

150150

.25

.1 MAINS VALVESMarconi ...Cossor ...

LS5B6i oHF i

25,000

20,000

2020

400150

.8

.I .8 Volt .8 AmpereMazda ...Six -SixtyMullard ...Six -SixtyMullard ...Cossor ...Marconi ...Osram ...Marconi ...Marconi ...Osram ...

HL6o7 i.

6o 7 5HFPM5 XD610PM6D6ToLFL61 oLoioDE5LS5LS5

15,20014,7009,25o9,000

7,500

7,00o

1 6,000

201717.518.518151515

755

15015o15015o150150150150140400400

.07

.075

.075

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Marconi ...Osram ...Marconi ...Osram ...Marconi ...Osram ...Marconi ...Osram ...Marconi ...Osram ...

S.8S.8H.8H.8D.8D.8

HL.8HL.8P.8P.8

l 200,000

}00055,

1.

21,000

i1r 7, 000

Ir 6,000

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66

15015015o15o150150150150150150

.8

.8

.8

.81.61.6

.8

.8

.8

.8Six -SixtyMarconi ...

610PDE5A 4,000

7.23.5

100120

.1

.25 4 Volt 1 AmperzMullard ...Cossor ...Marconi ...Osram ...Marconi ...Mazda ...Marconi ...Osram ...Cossor ...Mullard ...Six -SixtyMazda ...Marconi ...Mazda ...Osram ...Marconi ...Osram ...

PM6610PP6io}

DEP6ioLS5AP625BP625P625

6IoXPP5I256625SPP650

P625AP625AP625ALS6ALS6A

3,550

3,500

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1,600

I300),

r

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Mullard ...Mazda ...Cossor ...Cossor ...Six -SixtyCossor ...Mullard ...Mazda ...Cossor ...Six -SixtyMullard ...Cossor ...Six -SixtyMullard ...Mazda ...Cossor ...Mazda ...

S4VAC/SGMSG4IM41RCSS4GPM41E-IF

354VAC/HL

M4 1 LFSS4Det

164VM4iPSS4PIo4VAC/P

M41 XPAC/Pr

1,330,000600,000200,00020,00014,500

t,

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) 0002C

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jIII

The above list of valves will enable listeners to see at A total of forty-eight six -volt valves n.:ludes forty-onea glance what types are available that will meet the three -electrode and six screened -grid , but only oneneeds of their own receivers. pentode.

Mains valves, the filaments of which are run direct onThere is a choice of no fewer than sixty-two two -volt low -voltage A.C., are now divided into two classes, the

valves, forty-seven three -electrode type, seven screened- first (directly heated) type numbering ten and the secondgrids, and eight pentodes. (indirectly heated) type totalling seventeen.

Of the fifty-one four-volters there are only thirty-six It should be noted that the old B.T.H., Cosmos, andthree -electrode valves, but there are again seven screened- Ediswan valves are now made under the one type -grids and eight pentodes. Mazda.

Puts newlife intoold sets -

?fie NEWossor

A. C. Cossor Ltd., Highbury Grove, London, N.5

-it's awonderful

valve!

950 gcl

450

A

Page 7: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

THEPERFECTEDELIMINATOR

11

Wireless Magazine. Decern`a: 1929

AMODERN -TO -THE -MINUTE

XMAS PRESENT.

A Met -Vick Eliminator makes an ideal presentfor your radio friend. It cuts out the L.T. andH.T. batteries and the attendant bother andexpense of replacing or recharging at frequentintervals. First cost will be last cost if you get aMet -Vick Eliminator.

In the wide range of Met -Vick Eliminators thereis one to suit every need-there's the model " D "for the man with the big power valves and movingcoil loudspeakers and there is the model "B.S"for the listener with a modest 3-valver.

Order from your radio dealer who has full particulars of thecomplete range of Battery Eliminators, Chargers and PowerComponents, or write to us for the Ediswan Blue Book.

JET-VICK MODEL "BS"ELIMINATOR for A .0Mains Operation (Com-bined L.T., H.T., G.B., and3.G.V. Eliminator, A . CType). Price -40/1.00 cycleModel, £13 (complete withvalve); 25 cycle Model,

10 (complete withvalve).

MET-VICK MODEL "C"ELIMINATOR MEDIUMPOWER TYPE for A.G.Maine Operation (Combined

H.T., G.B., andS.G.V. Eliminator). Price -40/100 cycles, 10 10.(complete with valves; 25cycle Model, 11 ss(complete with valves).

MET-VICK MODEL "D'ALL -ELECTRIC ROWE!,ELIMINATOR HIGH VOLT-AGE TYPE. Price £21(including valves).

D 1 SWANRADIO PRODUCTSTHE EDISON SWAN ELECTRIC CO., LTD.,

HEAD OFFICE & SHOWROOMS EDISON RADIO DIVISION:la, NEWMAN STREET, OXFORD STREET, W.1.

('Phone: MUSEUM 9801)..49.sigreierckyorloig_or.x4pAgozimmecoimetiigokuriimw/if_ifq,4440:..,alm

Advertisers take more interest when you mention " Wireless ivlagazzne

451

Page 8: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine, Docemben 1929

WAVELENGTI1SoF theEUROPEAN STATIONSUnder the Prague Plan

A photograph of Prague, reproduced by courtesy of the Czechoslovak Travel Bureau

Wavelength Name 01 Totem Country

25.5331.4200221225227231234238239242

246

251253255257

26295268

270

274276279281

28.1

288.5

2922932942983013043053093103133143t6319322

325329330335331342349351352356

Chelmsford (5SW) ..Eindhoven (PCJ)Leeds (zLS)HelsingforsCork (IFS)Cologne ..MalmoMuenster ,.Bordeaux (Sud-OuestNurnberg ..Belfast (2BE)KielCasselAlmeria (EAJI8)GleiwitzToulouse (PTTI .

Hoerby .. .

Leipzig .. .

Lille (PTT) ..Strasbourg .Kaiserslautern .

Trollhatten .. .

TurinKoenigsbergBratislava ..Copenhagen ..StettinBerlinSwansea (5SX)Stoke-on-Trent it,ST,Sheffield (6LF)Plymouth (SPYLiverpool (6LV)Hull (6KH)Edinburgh (2EH)Dundee (zDE) ..Bournemouth (6B31)Bradford (2LS) ..Newcastle (5NO)Radio Lyons..KosiceLiegeHilversumAberdeen (2I3D)Bordeaux (PTT)AgenRadio Vitus, Paris .

Cardiff (5WA)Cracow ,

OviedoMarseilles (PTT)Bremen ..GoeteborgFal unBreslauGrenoble (PTT'NaplesPosenPetit ParisienBrunnBarcelona (EAJI)Leningrad ..GrazBrookman's Park

Great BritainHolland ..Great BritainFinland ..Irish Free State .

Germany ..Sweden .Germany ..France ..GermanyIrelandGermanyGermanySpainGermanyFranceSwedenGermanyFranceFranceGermanySwedenItaly ..GermanyCzecho-SlovakiaDenmark ..Germany ..Germany ..Great Britain

tO 91

If 1/

PI P9

s, f

1/1 19

IP P9

PP 9 P

f I PP

FranceCzecho-SlovakiaBelgium ..HollandGreat BritainFrance ..France ..France ..Great BritainPolandSpainFrance ..GermanySweden ..Sweden ..Germany ..France ..ItalyPoland ..France ..Czecho-SlovakiaSpainRussia ..AustriaGreat Britain

DialReading

Wavelength Vame of Town

360

368

372377381

385

390394399

403408413418426427436441447

45345645946546847347948749350150951752553354255osno

680760770825

1,0001,0101,0701,0711,1531,200

1,3041,3481,41,1,4581,5541,6351,7961,7251,8751,9352,1002,290

Stuttgart ..Seville (EA J5) ..Radio LL (Paris)Hamburg ..Manchester (2ZY,Radio Toulouse ..Genoa (1GE)WilnoFrankfurtBucharest ..Glasgow (5SC)San Sebastian (EA 18)BerneKattowitzDublin (2RN)BerlinMadrid (EA 17) Kharkov (NK01StockolmRomeParis (Ecole Sup.

PTT)Bolzano (113Z)Salamanca (EA J22)Aachen ..ZurichBarcelona (EAJ13)Lyons (P I 1)LangenbergDaventry (5GB) ..Prague ..OsloMilanBrusselsViennaRiga ..MunichSundsvallBuda -Pest HanoverFreiburgLausanneGenevaOstersundMoscow (PTT)Leningrad ..Basle .

Scheveningen -HavenHilversum ..KalundborgReykjavik ..RodenKharkov ..MotalaWarsaw ..Eiffel Tower, Paris ..Daventry (5XXZeesenLahtiRadio ParisH uizenKovnoNorddeichNorddeich

CountryDual

Reading

Germany ..SpainFrance ..Germany ..Great BritainFrance ..ItalyPoland ..GermanyRoumania ..Great BritainSpainSwitzerlandPolandIrish Free StateGermany ..SpainRussia ..Sweden ..Italy

FranceItalySpainGermany ..Swi tzerl andSpainFrance ..Germany ..Great Britain ..Czecho-SlovakiaNorway ..ItalyBelgiumAustriaLatviaGermany ..Sweden ..HungaryGermany ..Germany ..SwitzerlandSwitzerlandSweden ..Russia ..Russia ..Switzer] andHolland ..Holland ..Denmark ..IcelandSweden ..Russia ..Sweden ..Poland ..France ..Great BritainGermany ..Finland ..France ..Hol land ..Lithuania ..Germany ..Germany .

452

Page 9: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

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Wireless Magazine, Dezember: 1929

11N TUN E THETRA,DEFETTER

New H.T. BatteriesLANE'S Review of Catalogues and Pamphlets

A COMPARATIVE newcomer to the/A ranks of H.T. batteries is the Obeta,the sole agent for the United Kingdombeing F. L. Lesingham, of 13 VictoriaStreet, S.W.'. The Obeta has a newmethod of construction which, it isclaimed, gives it an exceptionally longlife, and increases its recuperativeproperties.

I have just received a folder givingdetails and prices of the Obeta range, andcontaining a graph which is mostinteresting, because it shows the actuallife of a 6o -volt Obeta battery during themost important period, namely the firsttwo or three hundred hours of its life.

This chart is very convincing, and allinterested in a new battery for the newyear should get the folder. 71

A Five Years' GuaroWeeMO the best or my knowledge there are

I only four cars on the market, Ameri-can, British or European, which aresupplied with a five -years' guarantee.Such a guarantee is, of course, equivalentto about a 25.per cent. increase in value,and incidentally equal to about ioo percent. greater confidence in the manu-facturefacturers' product.

Therefore, when the Cyldon folk sentme a folder, giving details of the whole oftheir range, I enthused tremendously onseeing that all Cyldon condensers,irrespective of price or type, are individu-ally tested before dispatch and areguaranteed for five years.

The new Junilog condensers interestedme very much, in view of the restrictionsas to space in many modern sets. Thereis, also, a new Synchratune range, whichconsists of dual sets of thumb -controlJunilog condensers.

Yes, I think the Synchratune andJ unilog ranges are well worth going into,and if you, too, are of the same mind,then write to Sydney S. Bird & Sons,Ltd., of Cyldon Works, Sarnesfield Road,Enfield Town, Middlesex, for this fiveyears' guarantee leaflet. 72A Truthful BookC USPECTING that there is a certain3 amount of prevarication in radio,the Igranic Electric Co., Ltd., have comeout with a booklet entitled "27 TruthsAbout the Truth Collector "-being theconsidered opinion of twenty-seven well-known people on the Igranic Neutro-sonic Seven.

If you are considering getting a reallygood set in which performance has beenput before everything else, and whichis meeting with wide approval inthe open market, then it is worth yourwhile getting this book. Not only to seewhat other people think about it, but alsoto form your own opinion, so that after

judgment you may try-and thenapprove, yourself.

You can have a demonstration of theNeutrosonic Seven at your own home, orat the nearest Igranic branch, and a formof application for such a demonstrationis enclosed with each "27 TruthsBooklet." I should advise you to makeapplication direct to the Sales Manager,Mr. J. T. Mould, Igranic Electric Co.,Ltd., of 149 Queen Victoria Street, E.C.4.

73An Ediswan Batch

MI:good friend,the publicity managerof Edison Swan Electric Co., Ltd.,

of 123-5 Queen Victoria Street, E.C.4.,has just sent me a batch of cataloguesand, slipping off the rubber band, I findthat they deal with the following :-

H.T. and L.T. batteries, complete sets,cone speakers, coils, transformers, andother constructive tit -bits, and, finally, acomprehensive catalogue dealing withthe new Mazda valves. These newMazdas, of course, are the product of thecombined research and manufacturingexperiences of the Ediswan, B.T.H. andCosmos organisations. The new series ismost interesting and one can spend adeal of useful time delving into thecharacteristic curves given.

Write to Ediswans for any of the otherbooks that interest you, no matterwhether you are in need of a grid leak,or an electric gramophone, but don'toverlook the Mazda valve book. 74

The Edison Bell RingsWHENEVER I receive a catalogue

dealing with complete sets and com-ponents, it is always my habit to turn to

SEND TO US FOR THESECATALOGUES!

As a keen wireless enthusiast younaturally want to keep abreast of all thelatest developments and this specialfeature will enable you to do so with I heminimum of trouble and the cost of onlyId. for postage.

Here we review the newest bookletsand folders issued by seven well-known firms. If you want copies of an'or all of them just cut out this couponand send it to us. We will see that yo..get all the literature you desire.

Just indicate the numbers (seen atthe end of each paragraph) of the eat.logues you want below :-

My name and address are :-

Sena tnis coupon in an unsealed en -velope, bearing id, stamp, to "CatalogueService," WIRELESS MAGAZINE.

8 61 Fetter Lane, E.C.4. Valid till .Dee. 31

454

the back pages first of all, and readingthrough the details of components beforeturning to the complete sets, one canoften judge the quality of a componentby looking at it, whereas a complete setis, frequently, a mystery box.

I (lid the same with a recently -received Edison Bell catalogue, althoughthere really wasn't much need to do so,because the quality of the whole EdisonBell range rings clear and is well-known.

This new Edison Bell catalogue is wellworth having, and it would be impossiblein this small space to precis the wholerange, so let it suffice if I advise you towrite direct to Edison Bell, Ltd., ofGlengall Road, S.E.r5. 75Varley's Section CatalogueIF you could see the file which your1 " Fetter" is slowly accumulating inconnection with his catalogue service,you would appreciate the smile whichgrew on his face when he received fromOliver Pell Control (Varley), Ltd., ofKingsway House, 103 Kingsway, W.C.2,a catalogue which does not necessitateyour having it all at once.

This new Varley book is issues insections. There are five of them, andthey deal each with some phase ofVarley production. F'rinstance. Thefirst deals with sets and electricgramophones and the Varley pick-upand auto arm. The second deals withcoils and H.F. components, and thewhole range of resistances for which theOliver Pell people have earned such ajustly famous name.

In like manner, each of the othersections deals with some range of com-ponents likely to be of use to the con-structor. Aussi, what I particularly likeabout these Varley cz Llogues is that theygive plenty of real technical dope, sothat one is not in the dark when makinga choice.

The Climax

76

I HE name Climax is coming rapidlyI to the fore, backed up by many good

components and a new complete receiver.The Chelloset Climax mains unitsinterest me in particular, and a widerange is available, both for A.C. andD.C. The A.C. models fellow the bestfashion and employ the Westinghousemetal rectifier.

I have just received a leaflet givingdetails of all the Climax components,including such old favourites as theClimax low -frequency transformer, asspecified for the Mullard Master ThreeStar receiver. The Climax slogan is : " AYear Ahead," and careful perusal of thisfolder shows that the slogan is fullycarried out in practice.

The address is Climax Radio Electric,Ltd., of Haverstock Works, ParkhillRoad, Hampstead, N.W.3. 77

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! Wireless Magazine. December 1929

A high tension battery eliminatorsuitable for any of the popular receiving setsrequiring a maximum of 20 milliamperes, is mostconveniently built up round a

STINGHOUSEVALL METAL RECTIFIER

TYPE H.T.3It has no moving parts orfragile filaments, and itslife is not limited bychemical action such asoccurs in wet or dry elec-

trolytic rectifiers.Send 2d. stamp for our 32 pagebook " The All Metal Way, 1930"containing details of this andother circuits for all types of

A.C. mains Unit.

VIVAVABNAMIK,16.

05.00000A.c.,00 115:140

PRICE ONLY 21 /-A tested and recommended circuit.

STYLE HT.3

2nro.EL -0+

S

Obtainable through any dealer

The Westinghouse Brake & Saxby Signal Co., Ltd., 82, YorkLoRnd(ii;r1K,irri%igis Cross,

Do you use a pick-up?

THE NOVOTONE.

McLachlan Tone Compensator. Patents Pending...-NOVOTONE PLACED FIRST

by Public ballot in the "Wireless World"Olympia Show Competition. (Classification

7.)Gambrell All -Electric Receivers.Leaflets Free.

Every user of an electrical pick-up should immediately writefor the "Novotone " Booklet.

The Novotone Tone Compensator invented by Dr. N. W.McLachlan, not only compensates for the inherent losses inpick-ups, but also for the even greater losses in recording.

Read this extract From "The Wireless World," August 21st, 1929, Page 177."In ordinary records it is necessary to restrict the amplitudeof notes below about 250 cycles, in order that the vibrationsmay be contained within the standard pitch of the groove. -

TURN LOSSES INTO GAINS WITH THE NOVOTONE.

THE NOVOTONE PUTS IN BASS WITHOUT BOOM.

THE NOVOTONE IMPROVES REPRODUCTION BEYONDOVER THE WHOLE MUSICAL SCALE

REALISM FROM RECORDS CAN ONLY BE ACHIEVED BYTHE NOVOTONE.

Write now for the 8 -page explanatory BookletSee the Diagram illustrating the effect of the Gam-brel!Novotone on electrically reproduced records.

BELIEF

USING

(N.1.)

GAMBRELL RADIO LTD.,6, Buckingham Street. Strand, London, W.C.2.

Teleplume . reinpie liar 3213

It helps us if you mention " Wireless Magazine "

455

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I.Wireless Magazine. December, 1929.

a codtp2/6 teip ham4etc041

EVER READY Batteries provide clear, strong power thatmake wireless reception a delight. They were the first

batteries made for wireless, and are still unapproached forconsistent quality and guaranteed service.

There is news in the " Wireless Magazine " advertisements

456

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Wireless Magazine. December, 1929

THE name Ormond is a suretythat not only the parts seenbut in all those hidden details,

however small, there is the same per-fection of construction and design asshown in the beautifully finishedexterior.

The new Ormond Loud -speakeris no exception to the rule. Itsexterior design is original and mostattractive, whilst the finish is perfect

The handsome Oak or Mahoganycabinet is fitted with the famousOrmond 4 Pole Adjustable Unit andspecially designed " wonder " conewith the result that the tone andvolume is of exceptional excellence." Blare " is absent and the repro-duction, whilst powerful, is verymellow.

The low price affords no criterion of the highquality of this new Ormond Speaker-it is butanother example of amazing Ormond value.

Supplied in either Oak orMahogany Cabinet Price 29/6

THE ORMOND ENGINEERING Co., Ltd.ORN1OND HOUSE, ROSEBERY AV., LONDON, E.C.1

Telephone: Clerkenwell 5334-5-6Telegrams: "Ormondengi, Smith"

You will get prompt replies by mentioning " Wireless Magazine '

457

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Wireless Magazine. December. 1929

Revolutionary new Lissen Pick-upMAKES EVERY RECORD A PICTURE TRUE IN TONE COLOUR

LNew Needle -Armatureso light that response

is perfect at allfrequencies

" Better than Talking ' Picture reproduction "-that iswhat everybody says who hears a gramophone recordplayed by this new Lissen Pick-up. And actually the re-production is better than the film experts have achieved-more natural, nearer to reality, because no longer are thehigh notes thinned out or the lower bass notes lost. TheLissen Pick-up is so responsive that even the perfect elec-trical recordings of to -day can hardly do it justice. Itresponds to the most minute indentation on the record-the needle armature is so light that the needle -point actuallyfeels its way along the record groove.And you'll find your records almost everlasting when youuse this new Lissen Pick-up, because the needle followsthe groove and does not plough its way along.

If you want every single record to sound much better thanthose you hear at demonstrations-if you want radio -gramophone reproduction that comes so near to reality thatin a darkened room you would suspect the presence of theartist-get this new Lissen Pick-up and learn what perfectionmeans. Any Lissen radio dealer will demonstrate it for you.

N,

44,

ads 1 Gt. MIN .63

The Significance of the Curve!Look at Curve 1. A particularly fine response for part of its curve, butnotice the peaks and depressions and the very serious falling off in outputafter z,800 cycles-after zoo cycles it would not remain on the record. Incurves z and 3 the same deficiencies exist. NOW LOOK AT THELISSEN CURVE. It is the only even curve. These are actual testsunder ordinary conditions. The real significance of the Lissen curve is thatyou get true musical values from one end of the scale to the other.

NEEDLE -ARMATURE PICK-UP

304Complete with moulded tone arm 37 6

LISSEN LIMITEDWORPLE ROAD, ISLEWORTH, MIDDLESEX

Factories also at Richmond and Edmonton

(Managing Director: Thos. N. Cole)

458

ita

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[Wireless Magazine. December 19294 c20/

CLAPHAWNDDWYERri-`0 tell you the truth I am uncle'

the impression that Dwyer-he'sthe fat one-would always be per-fectly happy were it not for Clapham,the silly ass with the monocle. Dwyer,you see, is serious, or would like tobe, and I feel convinced that if hewere only allowed to give us hislecturettes in peace we could learnquite a lot from them.

Dwyer's Helpful Talks!He chooses topics of general

interest-well, in most instances;sometimes he tries to tell us somethingof the intricacies of lifeinsurance, endowmentpolicies, or how to fillup an income-tax formtruthfully-a difficulttask, this - and hewould get away with itwere it not for theidio tic interruptionsmade by his partner.How and wl-,y he putsup with a em beats me

It is not that Claphamdoes not know better,for he does, or at leasthe should do, but youwill agree that he neverseems to understandanything, and so manyperfectly simple wordsfloor him.

He makes many jaw-breaking attempts atpronouncing them and then-forhe's clever that way-to hide hisconfusion rapidly changes the sub-ject, and draws a red herring acrossthe trail by asking some silly conun-drum or riddle, two words, by theway, which he has not mastered tothis day.

Listeners' ExpectancyThe whole thing is ridiculous pre-

posterous, too idiotic for words, yeton hearing this pair you cannot helppunctuating their dialogue with loudguffaws. If you switch on the wirelessset as they arrive in the studio and

-J. GODCHAUXABRA HAMS

Meets the FamousEntertainers

tell the family "Oh, it's Clapham andDwyer " there immediately spreadsover the room an atmosphere ofexpectancy.

There may be silence for a momentor two, but in anticipation somemember of the audience is bound togiggle.

And therein, I think, lies the secret

be used once in its actual form and forthis reason alone is always topical.Some of Clapham's most humorousfunniosities are given out on the spurof the moment.

What Pleases UsTaking these various factors into

consideration, you will readily under-stand that a written dialogue wouldbe impossible; it's the spontaneityand topicality of the act that pleases,and of these two qualities the artistshave made a fine art.

Both, as it happens, are blessed

Can You Guess Who is Who ?Let us introduce you to two ofthe most popular radio ( n er-tainers. You can see thrt heyare getting ready for another

"spot of bother !"

01 Clapham and Dwyer's success.They spring surprises on you, forapart from advertising their "spot ofbother, the announcer cannot describethenk in any other way. As a matterof fact, he does not know what theyare going to do; neither does theB.B.C., and for the matter of that, upto the' moment of facing the micro-phone; apart from the rough outlinesof their act, I doubt whether the twohumorists have quite settled in theirminds what it is all to be about.

Possibly ninety per cent. or more ofthe cross -talk is spontaneous; it isimprovised for the occasion, can only

459

with good microphonic voices; Dwyerin particular possesses an excellentdelivery, and it is seldom you willmiss any of Clapham's nonsensicalobservations unless, unfortunately,they are drowned by the laughter ofthe studio audience.

Studio Audience JustifiedThe presence of a small crowd in

the studio is justified on suchoccasions; in fact, it is a necessitywith all humorous turns. It mightnot be impossible to raise a laughamongst outside listeners when stand-ing before the " mike " in an empty

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fWireless Magazine. December, 1929

A Chat with Clapham and Dwyer Continued

Clapham and Dwyer face the microphonewith-is it Cissie ?

studio, but I should imagine it to beno easy task; it must be a very dis-heartening one, whereas, on the otherhand, a few chuckles from apprecia-tive onlookers act as a spur, and anencouragement to develop a vein ofhumour.

When I met Clapham and Dwyerfor the first time, I think that bothcame up to my expectations, inas-much as from their voices I hadvisualised them fairly correctly.

Mental PicturesI suppose we all do this sort of

thing, and endeavour to make amental picture of the people we hearthrough the headphones or loud-speaker. In some instances, we maybe hopelessly wrong, whilst in others-well, in my case I was right.

Dwyer is seriously inclined, butthere lies a dangerous twinkle in hiseye, which gives you to understandthat he does not wish to be to ken thatway; as to Clapham, he is just Clap-ham, and as amusing as he is beforethe mike.

He was not destined either for thestage or concert platform, and someyears ago had no thought of appear-

ing in public. He was educatedfor the law, a career which, nodoubt, could never have givenany scope for his talents.

As a relaxation, theatricalsappealed to him, and he joinedan amateur dramatic society,and as an amateur was chosenby the Brighton and HoveOperatic Society in 1922 to playat the Theatre Royal, Brighton,the part created by GeorgeGraves in V eronique. This washis first appearance on any stage,and his success was such that hewas persuaded to throw awayhis law books and to enter thefield of entertainment.

In Clapham either the Bar orthe Bench may have lost acelebrity; I do not pretend toknow, but one fact is certain,when he decided to forsake lawthe British public gained a radiostar.

I tackled both partners regard-ing their views on microfright, asubject which was dealt with ina recent issue of the WIRELESSMAGAZINE.

"We do not suffer from it," wasthe reply. " At least not to the extentof hampering our efforts to entertain.It's true that there is somethingawesome about the mike, if at anymoment one happens to think thatit is conveying a joke or a song tomany hundred thousand homes.

"The thought alone that the ' turn 'is being heard by so many differentclasses of the community, by so manylisteners, in such varying moods,

460

would tend to promote nervousnesson the part of the performer in thestudio."

"And that," added Clapham, "iswhere I think the studio visitors arehelpful; they bring the outsideaudience nearer to the artist, and thuscreate a more intimate atmosphere.Personally,I have always endeavouredto visualise a very small number oflisteners, say, just a few friends towhom I am telling a funny story."

Familiarity with the Mike" Familiarity with the mike," inter-

rupted Dwyer-" Breeds contempt ? " I suggested."No, certainly not," he retorted,

"but it nerves one to face this unres-ponsive and awe-inspiring instru-ment."

"But what about Cissie? 1

queried.Frankly, I am interested in Cissie

because Clapham has told us somuch about her. He is so fond ofretailing trivial incidents in that pet'slife that I felt he would be only toopleased to give me more details ofher past.

Dropped A BrickApparently, when I mentioned her

name, I dropped a brick ; Cissie seemsto be a bone of contention betweenthe two partners, for since shejoined them Dwyer has had all hiswom k cut out to prevent Claphamfrom drifting over to his favouritetopic. Just as Uncle Dick could notkeep the head of King Charles the

(Continued on page 468)

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'Wireless Magazine. December 1922j

VVVYVVVV777777VTYYVVVVVYVYV7VVVYVVTIVVVVYVVYYYTTYVYVVYVV7VVVVYVYVVYYTYVVVYYVVY

EVER sinceits inception,

the WIRELESSMAGAZINE hasbeen famous-itis no exaggera-tion to say,literally, all overthe world-for itsfive- valvedesigns. Startingwith the famousold 1927 Five, theWIRELESS MAGA-ZINE TechnicalStaff has pro-duced equallywell- knownreceivers as the1928 Five, Exhi-bition Five, andEmpire Five.

Now we areable to give readers details of a newset-the 193o Five.

Similar Successful CircuitsThe circuit combination of all these

five-valvers has been the same, in asfar as each has incorporated twostages of high -frequency amplifica-tion, detector and two stages of low -frequency amplification. All, exceptfor the Empire Five which usedscreened -grid valves, have employedordinary three -electrode valves forhigh -frequency amplification, and the1930 Five followsthe same practice.

This new five-valver is in-tended speciallyfor those whowant a reallypowerful set thatdoes not usescreened- gridvalves for high -frequency ampli-fication. Manylisteners will beable to convertexisting five-valvers into 193o Fiveswith the addition of a few parts atcomparatively low cost.

Dual -range Coils-Single SwitchEvery modern improvement has

been incorporated in the set. Dual -range coils cover both upper andmedium broadcast bands by themanipulation of a single switch.Stabilisation in working is assured bythe inclusion of an anode -filter systemassociated with the detector valve.

Not only is the193o Five a powerful andsatisfactory radio receiver, it is alsoan efficient amplifier for the electricalreproduction of gramophone records.Provision is made for keeping a pick-up permanently connected to the setand putting it in use when requiredby means of a single switch, whichswitches off the valves that are notused.

Some readers may wonder why

For years now the WIRELESS MAGAZINE has been known the

filament switchessimple push-pull on -off switch, con-trols the two high -frequency valves,only.

Use of Three Valves OnlyTwo aerial terminals are provided.

The first is used when all five valves,are needed. For the reception of verypowerful broadcasters, when three

valves (detectorand two low-fre-

world over for its successful five -valve designs, and this set is aworthy successor to such famous sets as the 1927 Five, 1928 Five,Exhibition Five, and Empire Five.

Three -electrode valves have been used throughout to attain thegreatest mechanical reliability. Dual -range coils are used (controlledby a single switch), and provision is made for cutting out two valvesfor the reception of very powerful stations.

Another switch puts the whole receiver on or off and also puts anelectromagnetic pick-up in circuit, when it is desired to reproducerecords electrically. A useful volume control is also incorporated.

gang control has not been incor-porated. The experience of theWIRELESS MAGAZINE Technical Staffin this regard is that while gangingundoubtedly simplifies the operationof a set it is always at the cost ofsome efficiency. Maximum powerwas required from the 193o Five and,therefore, each circuit is tunedseparately.

The dual -range coils are a new typerecently produced by one of the best-known coil manufacturers. These

461

The secondtype, having three poles and threepositions. When the knob is turnedto the central position, the wholereceiver is switched off.

coils are con-nected togetherby special coup-lings, and all threeswitches areactuated by asingle knob onthe panel, througha special leverfixed to the base-board.

It is obviousthat a receiver ofthis description isfar too powerfulfor the receptionof nearby stationsat comfortablestrength. Aspecial switchingsystem has, there-fore, been incor-porated toensure the eco-nomical operationof the set.

Actually, twoare used. One, a

quency stages) areenough, the twohigh- frequencyvalves areswitched right offand the aerial leadconnected to thesecond aerialterminal, which,in turn, is con-nected to the coilassociated withthe detector.

switch is of the rotary

All Five Valves in OperationAs soon as the knob is turned to'

the left, however, all the filamentcircuits are completed, and all fivevalves are in operation, provided theauxiliary switch controlling the high -frequency valves is already on.

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Wireless Magazine, December 1929

The 193o Five ContinuedDual -range coilsare used in the

1930 Five

Flexib'e leads are provided forall battery connections

Turning the main switch to the tions are available,right, on the other hand, switches off No. 4, the formerthe first threevalves (two high -frequency anddetector), andleaves only thetwo low -fre-quency valves incircuit for ampli-fying currentsprovided by theelectromagneticpick-up, which isalso switched intocircuit auto-matically at thesame time.

NeutralisedValves

Both high -fre-quency- valvesare, of course,neutralized; thisis done on the split -primary principle,as will be evident from the circuitdiagram.

Of course, any listener who hasordinary six -contact split -primarycoils covering only one waveband canuse them without any alteration inthe connections.

How to NeutraliseNeutralisation of the high -fre-

quency valves is best carried out forfirst one valve and then the other.The method is to switch off the firstvalve (by disconnecting the spade tagon lead No. 9) and turn the knob ofthe first neutrali ing condenser untila powerful station which has beenpreviously tuned in becomes quiteinaudible.

The spade tagis then replaced,and the secondvalve neutral-ised in a similarway, after re-moving the tagon lead No. rofrom the term-inal on thescreen.

The aerial coilis of the semi-aperiodic type,with a tunedsecondary. Twoaerial connec-

to point No. 3 orbeing the more

often L000 miles away; they, there-fore, need the maximum sensitivitythat can be obtained-and thegreatest mechanical reliability, whichis one reason why screened -gridvalves have not been used for high -frequency amplification.

Minimum DampingThe values of 3 megohms and

.0002 microfarad for the grid leak andcondenser respectively give theminimum damping and the maxi-mum sensitivity.

Resistance -capacity coupling isused between the detector and firstlow -frequency valve, the resistancebeing roo,000 ohms for normal pur-poses, with a .005-microfarad coup-

ling condenser.Associated alsc

with the detector -anode circuit is afilter system, pro-vided to obviateany tendency tolow- frequencyinstability, suchas often occurswith modernvalves and super-efficient trans-formers. The filterresistance is50,000 ohms, andthe by-pass con-denser to L.T.-is 2 microfarads.

REACTION 2nd..11.F. AERIALCONDENSER CONDENSER CONDENSER CONDENSER

DETECT()VALVE

Ist.L.F.VALVE

POWERVALVE

L.F. OUTPUT 2nd.H.F. 2nd.H.F.TRANSFORMER CHOKE COIL VALVE

3_NEUTRAL---' 1 V 4- ISING;CONDENSERS

AERIALCOIL

isIIIFVALVE

1st. H.F.COI L

This plan view of the 1930 Five shows how the parts are arranged on the baseboard

selective of the two tappings.Reaction is applied on the detector

valve by a.000r -micro -farad condenser.

Rectificationis arranged onthe leaky -gridprinciple, as thisis the most sensi-tive method.Experience hasproved thatWIRELESSMAGAZINE fly -valvers are builtby many over-seas readers,whose localstations are

RecordReproduction

The perform-ance of the set as a gramo-radioamplifier wry largely depends upon

Note the neatlayout of the

1930 Five

Choke -capacity output isincorporated

462

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Wireless Magazine. December! 1929

A Powerful Set with Three -electrode Valvesthe choice of a good low -frequencytransformer, which is the form ofcoupling between the first and secondlow -frequency valves.

A number of people who have seenthe 193o Five have asked whether twovalves give sufficient amplification tomake the electrical reproduction ofrecords worth while. But they needhave no fear on that score.

Volume AvailableThe amplification is sufficient to

drive the linen loud -speaker describedon page 520 of this issue at suchvolume that it can be heard clearly allover the WIRELESS MAGAZINElaboratory.

Indeed, with some records, thevolume is too great and for thisreason a volume control has been pro-vided. This takes the form of ar-megohm variable resistance, used asgrid leak with the first low -frequencyvalve; it can be used for either radioor gramophone control, of course.

As a further safeguard against insta-bility, as well as for the protection ofthe loud -speaker, a choke -capacityoutput is provided. In spite of its

Three - elec -trade Valvesare usedthroughout.

All three dual -range coils inthe 1930 Five are controlled

by a single switch

small size, the choke used in theoriginal set was found to give quitesatisfactory results.

Connected between H.T.- andL.T.- is a special type of fuse toprotect the valves from damage, incase of an accidental short-circuitof the high-tension supply throughthe low-tension circuit.

In spite of its size, the 1930 Five isnot difficult to construct; it will cer-tainly present no difficulties to thosewho built one or other of its forerun-ners, and who now feel the need for

This layout and wiring diagram of the 1930 Five can beobtained as a full-size blueprint for half-price (that is, 9d.,post free), if the coupon on page iii of the cover is used byDecember 31. Ask for No. WM171. Wire up in numerical order

a more up-to-date circuit,especially withdual -rangetuning coils.

For thosewho desire it,a full-sizeblueprint ofthe set hasbeen pre-pared. This isavailable forhalf-price

(that is, 9d., post free), if the couponon page iii of the cover is used byDecember 31; an extension of timewill be made in the case of overseasreaders.

Ask for blueprint No. WMI7I; andaddress 'our inquiry to BlueprintDept., WIRELESS MAGAZINE, 58-61Fetter Lane, London, E.C.4.

A blueprint is not, of course, abso-lutely essential, although its use meansa great saving of time and trouble; allthe essential details are reproduced ona reduced scale in these pages.

463

There is little that need be saidabout the actual construction of thereceiver. The method of fixing thelever for the wave -change switch willbe evident.

One point may cause confUsionunless it is explained, however. Onone side of the central screen isscrewed a small pre-set condenser inseries with the second aerial terminal,already referred to.

Detail DrawingThis condenser has two terminals,

one of which is above the other on thescreen. Lead No. 58 is connected tothe top terminal, and lead No. 35 tothe lower one; this is made clear bythe detail drawing at the bottomleft-hand corner of the blueprint, andthe reduced reproduction whichappears above.

As is the case with all WIRELESSMAGAZINE sets, the leads should beplaced in position in the numericalorder indicated. In this way the wir-ing is built up from the baseboard inthe most convenient way.

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Wireless Magazine. December 1929

The 193o Five ContinuedFor the sake of convenience,

battery terminals have been dis-pensed with. Rubber -covered flex isused, and this can be cut to anysuitable length, so that the batteriescan be placed out of sight on thefloor under a table if desired. Careshould be taken to slip the appropriateivorine indicating tag on each lead asit is connected,otherwise there isa very real dangerof accidents in thesubsequent con-necting up.

Arrangementof Controls

The actualarrangement ofthe controls onthe front panel isas follows : In linealong the top partare the threelarge main tuningdials for theaerial and twohigh -frequencytransformers,respectively (see heading photo).

With all five valves in use, thethree dials must be tuned; this is nota difficult matter for the readings ofthe second and third will be the samewithin a degree or two.

If, however, the aerial is connectedto A2 and only three valves are in use,then only the third dial will have tobe operated.

In line with the three large dials,at the right end of the panel, are asmall dial and a knob; these are forthe reaction condenser and "on -offgramo-radio " switch respectively.

Immediately under these, at thebottom of the panel, and side by sideare the wave -change switch (in forlong waves and out for medium

A back view of the 1930 Five, with valves in position

waves), on the right of this is thevolume -control knob (turn to rightfor maximum volume).

The small knob under the largecentre dial is the on -off switch for thetwo high -frequency valves only.

Those who have not operated apowerful set of this type before shouldnot expect magnificent results rightat the start. When there are three

tuned circuits to manipulate in a setit takes a little 'experience to get thebest out of them. A little patiencewill be amply rewarded.

One of the most important thingsis to neutralise the high -frequencyvalves properly, as already explained.It will be found after a little manipu-lation that these controls can be

advanced so thatthe set is almoston the verge ofoscillation - astage at whichsignal . strengthwill be consider-ably increasedowing to theminimisation ofdamping.

Cutting OutInterference

If any interfer-ence from unwanted stationsis experienced-this will happenonly in a fewexceptional cases

-remember that the application of asmall amount of reaction will makethe tuning much sharper. When thereaction control is advanced for thispurpose the three main tuning con-densers should also be readjusted.

In conclusion, let us repeat themain object in designing the 193o Fivewas to produce a reliable and power-ful set that would give good results.

flerk/ toSor3 ValleS

43

Renal

gChoke

'0002

50000

-0117+.1

0/f7Y

L.S.

87 -FUSE

/.7-17+

Pick-up

G.B.+ 08-1 08-2

464

The combinationused in the 1930Five is two high -frequency stages,detector, and twolow -frequencystages. Three -electrode valves areused throughout.The coils are coup-led together and canbe adjusted simul-taneously by a singleswitch to covereither wavelength

band

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Wireless Magazine. December 1929

Dual -range Coils Switch for Pick-upCOMPONENTS REQUIRED FOR THE 1930 FIVE

Choke, high -frequency

xr-Keystone,_type SG, 5/- (or

Bulgin, Wearite).Choke, Low -frequency

i-Climax Capital, 8/6 (or Wat-mel, Ormond).

Coils

O3-Lewcos dual binoculars, one

DBA and two DBP's, 52/6;special Lewcos switching, 3/-.

Condensers, Fixed.0002-mjcrilf2racir

7, type 620, 2/6 (or Graham-' Farish, Trix).

1-Dubilier .005-microfarad, type62o, 3/- (or Graham-Farish,Watmel).

2-Dttbiliex-s-raicralarail...4pe7"BB, 7/- (or Ferranti, Hydra)

Condensers, Variable3-Jackson .00c5 - microfara

livitr-SIow-motion device, 491(or Ormond, Dubilier).

I --Burton .000i-microfarad, 4/6(or Bowyer -Lowe, CyldonBebe).

neutralising con

Bulgin).x--Formodenser, .0003- to

.00025-microfarad, type J, 2/ -(or Igranic).

EboniteI--13( COI, 21 in. by 7 in., 8/4 (or

ReSis2 in.

and 21/2 in. by 2 in.

Holders, Valve5-Lotus anti-microphonic,

red* Marconiphorre;BenjaminPlugs

3-Eelex shrouded socket plugs,black and 2 red, (or Clix,

Belling -Lee).4-Eelex plugs with sockets,

2 black and 2 red, (or ClixBelling -Lee).

2-Clix spade tags, black and red,(or Eelex, Belling -Lee).

7-Clix plugs, 3 black and 4 red,(or Belling -Lee, Eelex).

Potentiometer)s 1--Igranic Megostat, 6/- (or

Dubilier).

Resistances, Fixedy I-Ready Radio, 50,000 ohms,

with holder, 6/6 (or Dubilier,Igranic).

siC I-Ready Radio, ioo,000 ohms,with holder, 8/6 (or Dubilier,Igranic).

I-Dubilier_kmegohm grid leak,2/6 (or KeysTahe;-Lisseri). l[%fL,

Screensz-Ready Radio, 7 in. by 6 in.,

4/- (or Peto-Scott, Raymond).SundriesZi-Pair Magnum panel bracket

(or Bulgin, Igranic).Glazite for connecting up.xo yds. Lewcos rubber -covered

flex.i-Microfuse to carry pp° milli-

amperes. 2/-.

1-Packet Cortab ivorine tags,9d.

SwitchesT-Pioneer on -off, 1/6 (or Bulgin,/r-- Keystone).

I-Wearite three -pole change-over,r., 4/-.

Transformer. Low -frequencyi_paawn type 32L. jaiks

'5( Igranic, Marconiphone).

ACCESSORIESBatteries

x-Ever Ready izo-volt high -capacity high-tension, 42/6(or Columbia, Grosvenor).

1-Ever Ready 16 -volt grid -bias,3/6 (or Ediswan, Grosvenor).

I-Exide z -volt accumulator,type ICZ6, 17/6 (or Marconi -phone, Ediswan).

Cabineti-Clarion, with ro-in baseboard,,V

(or Pickett, Ready Radio).Loud -speaker

1-Brown Duplex (or Gecophone,'"NAmplion).

Valves2-Lissen 111.2 10, 21/- (or Osram

HLz I°, Cossor zroHF).I--Lissen H21o, io/6 (or Osram

H21o, Cossor 2 IORC).I-Lissen L21o, 1o/6 (or Osram

L21o, Cossor 2 IOLF).I-Osram P24o, 12/6 (or Cbssor

z3oXP, Mazda Pz4o).The prices mentioned are those for the parts used in tie original set; the prices of alternatives as indicated in the brackets may be either higher or lower

Getting a Laugh Out of Radio !ASCOT purchased a radio set on

the instalment system, and afew days later returned to the dealerto lodge a complaint.

"What is it?" asked the dealer."Well, it's aw right to listen to,"

he replied, " but those valves are naegood to read by. They're too dull."

The police found a thief's finger-prints on the receiving set of the househe entered. Those thumb controls again.

.It is claimed in many parts of

Scotland that the inventor of mainssupply for receiving sets was aScotsman.

Quite credible. For who but aScots radio fan would think of mak-ing his wife pay the radio bill as wellas the lighting.

Wife, at Cardiff Police Court :"He is a radio fool. Being my secondhusband, I put up with a good dealfrom him."

A wireless dealer.

"What are you doing ? " asked thenurse of John and Mary.

" We're playing a wireless studio,"replied John.

"But y3u should not whisper in astudio," admonished nurse.

"Oh, we're the announcers," saidMary.

A Scotsman entered a fine-lookingwireless shop to see some receivingsets.

"This," said the dealer, showing alarge gramo-radio set, "is worthgo." The Scotsman nodded.

"That is much smaller and is only

465

worth 4o." The Scotsman stillnodded.

"This, here, is smaller again, butit has no gramo section," continuedthe dealer. "It's only voorth 2o."

" Your prices are all right," saidthe Scotsman, "but your sets are notsmall enough."

.4 critic assures us that glass -hellaccumulators are best.

That explains the crackling noises.

Two men had been quarrellingover a receiving set. They appearedat Tottenham Police Court.

Said the defendant : " You couldnot call it a fight. This fellow washitting the air. I fell and hit theground."

The aerial and earth contacts.

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Wireless Magazine, 'December! 1929

In this article W. JAMES ex-plains in simple language thedifferences between the varioustypes of driving unit employed

in modern loud -speakers.

THE ordinary reed type of loud-speaker movement looks a very

simple piece of electrical apparatus.It comprises a permanent magnet, apole or poles fitted with coils and anarmature or reed. To this reed a

---

COIL

Fig. la.-Normalposition of arma-

ture.

FROMSET

Fig. lb.- Armaturereleased by oppos-ing magnetic force.

Fig. lc.-Armature attracted bymagnetic force.

driving rod is fitted. A means isusually also provided for adjustingthe normal position of the reed withrespect to the pole.

Thus there is nothing very muchin the ordinary reed movement,although I am bound to add that thedesign of the parts demands skill andexperience.

Grasping Essential PointsMost amateurs know how such a

unit drives a cone or diaphragm, andanyone who examines a unit willgrasp the essential points. Thereare really three things to note.

First, that normally there is a shortair gap between the end of the poleand the reed shown in Fig. r. Inthis position, we will assume thedriving rod to be upright. The reed

D -SPEAKER

is held in position by two forces; oneis its own stiffness and the other is themagnetic pull produced by the mag-netic lines of force passing throughthe reed, pole piece, and magnet.

In the top illustration, two linesof force only are indicated. Thesecond point to note is that when acurrent passes through the coil of theunit from the receiver to which it isjoined, in the direction indicated, themagnetic field is weakened. Thereforethe pull exerted is reduced and thereed moves away from the pole.

This is because the current fromthe receiver is in such a direction thatthe coil tends to create a magneticfield which opposes that of the per-manent magnet, thus reducing thestrength of the field in the air gap.

This fact is represented by thesingle line of force in the secondsketch; as the reed is fixed at one end,the driving rod cannot move in astraight line passing through itsfirst position, but tends to tilt over asindicated.

The third point is that when thecurrent from the receiver flows in thereverse direction from that shown inthe second sketch the field is strength-ened. Therefore the reed is pulledtowards the pole.

If the current is a relatively heavyone, corresponding to a strong signal,the reed may be pulled down againstthe pole, when a click will be heard,or a buzzing sound should the reedbe vibrating or chattering as theresult of a strong signal.

Such a movement obviously haswave defects. It cannot reproducewithout distortion. Much dependsupon the characteristics of the cone,of course-its size, shape, weight,tiffness, and method of fixing, but the

unit itself distorts and is prone tochatter unless precautions are taken.This type of unit is, therefore, not sosuitable for driving a free -edge coneas other types.

The amount of the movement is notproportional to the current flowing

466

Do you know what type of driv-ing unit is used in your loud-speaker? Read this article andfind out how your own instru-

ment works.

through the coil or its frequencyTherefore, harmonics are introduced,a form of rectification being set up asthe movement one way usuallyexceeds that in the opposite directionfor currents of equal strength.

The sensitivity is only fair. Thesounds heard are proportional to themovement of the cone and will,therefore, be greatest when a weakcurrent causes the maximum move-ment of the reed.

Points for SensitivityFor :.crisitivity, the air gap should

be short, the magnetic field strong,the reed of suitable proportions andthe winding of such a shape andnumber of turns that the maximumchange in the number of magneticlines of force is produced by a givencurrent.

It is not possible to use a verynarrow air gap with such a movementas the reed tends to fall on to the pole ;therefore the sensitivity is not sogreat as in other types, where theconstruction is such that a shorterair gap may be used.

The actual to-and-fro movementof the reed as the result of the varyingcurrents passing through the coilis very small and the air gap could,

Fig. 2. - Arrangement of simplestreed unit.

therefore, be reduced from this pointof view but unfortunately, if the gapis made too fine, chattering results.

In practice, one adjusts the positionof the reed with respect to the air

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Wireless Magazine. December. 1929

gap whilst receiving, setting themovement for the best quality of thereproduction and the loudest signals.

A typical unit is sketched in Fig. 2.It has a permanent magnet A and asupport B to which one end of thereed E is firmly fixed. At the oppositeend of the magnet is a pole c fittedwith a coil D. The driving rod G isfixed to the reed by nuts as shown,this fixing also holding in position abent piece of metal F. A screwed rod

C

POLE

POLE

POLE

Fig. 3.-Showing how moving forcechanges with position of armature.

having a knob t is provided for thepurpose of adjusting the position ofthe reed.

Typical ConstructionAs the knob is turned, the flexible

piece F is released or pressed, thusallowing the reed to take up a positionnearer the pole or further from it.This is a simple form of constructionquite typical of the cheaper move-ments. The reed vibrates, of course,according to the changes in the pullprovided by the magnetic field whichis created by the magnet and thecurrent passing through the coil fromthe receiver.

Those who are interested may careto fit reeds of different widths andthicknesses and note the results. Itwill be found that as the reed is madethinner, the working air gap must beincreased. There is also the effectof the natural period of the reed tobe noted. Very often, an inexpensivemovement may be greatly improvedby a little fitting.

Defects OvercomeThe defects of the ordinary reed

movement as described have beenovercome in the Lion type 1 ysetting the reed at an angle with thepoles. This may be explained byreferring to Fig. 3, where sketchesA and B show an ordinary unit as it isnormally and when pulled down by asignal, and c and n a Lion move-ment under the same conditions. Thediagrams are exaggerated for clear -

ness, of course, but show the prin-ciples involved.

In the Lion movement theleverage is decreased as the reedmoves towards the pole and, therefore,a signal which strengthens the magnetand so increases the magnetic pullproduces the same movement of thedriving rod as a decrease in the currentdoes. Thus the air gap may be setvery finely and the quality andsensitivity are much better.

A further interesting reed move-ment is to be seen in the Brown Veeunit. This is shown diagrammaticallyin Fig. 4, where A is the armature andB the reed of non-magnetic material.The reed obviously travels up anddown without moving sideways andtherefore provides a more uniformresponse than is possible with theordinary reed movement fastened atone end.

A different type of unit, havingwhat is termed a balanced armature,is widely used at the present time andwe will therefore see how this typefunctions and why it may be usedwith fixed and free -edge cones withsuccess.

A typical unit is illustrated in Fig.5. There is a powerful permanentof cobalt steel and a pair of stalloypole pieces, with an armature

ADJUST MG Kt1OBjl

MAGNETPOLE

S

ORIVIrfc ROD

B

r5

MAGNETPOLE

115 C

Fig. 5A.-Normal rosition of ba'an edarmature. Figs. 5B and C.-Operating

positions of balanced armature.

467

PRODFkiViNG

SUPPORT

POLLS:

Fig. 4.-Special arrangement of polesin Brown Vee unit.

of soft iron. The armature is balancedon a knife edge n and is therefore freeto vibrate between the poles, and in sodoing carries the cone driving rodbackwards and forwards.

Magnetic BalanceNormally the armature is set in the

centre of the poles and is thereforemagnetically balanced. The magneticfields are as represented in Fig. 5Awhen no signal is being dealt with.But when a current flows through thecoils, as in Fig 5B, the armature ismagnetised as shown, one end havinga north and the other a south pole.It therefore moves to the positionindicated.

When, now, a current in the oppositedirection passes through the coilsfrom the set, the armature is mag-netised in the reverse direction, as inFig. 5c, and moves to the positionindicated. Thus a backwards andforwards motion is imparted to thecone driving rod.

A movement of this type is ob-viously more sensitive than the simpletype of Fig. r because the workingforces created by the current aregreater, but the quality of the repro-duction is not necessarily as good aswith the corrected movement em-ployed in the Lion unit.

Rectification EffectClearly the reed has a sideways

movement, although this can beminimised by careful design andmanufacture. At the same time themovement is not quite proportionalto the current, and therefore therectification effect occurs.

This form of balanced -armaturemovement may usually. be employedto handle strong signals withoutchattering, but much depends uponthe length of the air gaps and thestiffness of the moving parts. Asimple adjustment for setting thearmature in its best position may befitted by extending the driving rodas shown.

The unit sketched is a Watmel andis a good one of its class. Thesensitivity is good because of the

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rWireless Magazine. Pecember. 1929

Inside Your Loud-speaker-Continuedforces which act to drive the rod.Both ends of the armature are actedupon instead of the single end withthe type of Fig. r, and there areactually four poles.

The sketches show how the unitoperates, but they are exaggeratedfor clearness. Although only a fewmodels have been described, theprinciples are applicable to most ofthose marketed.

How Sensitivity Is AffectedAt is easy to see how one type may

be more sensitive than another, asthe movement of the armature orreed produced by a given current isproportional to an extent upon thestrength of the permanent magneticfield as well as that created by theignal current passing thrcugh the

coil of the instrument. Usually, themore powerful the magnet the greaterthe sensitivity and as a strong magnetassociated with a movement of nor-mal size must be large, the size of themagnet is some indication of thesem it ivity.

The best magnetic materials mustbe used. Thus the poles are oftenlaminated in order to reduce losses

and they may be of special iron inorder that the magnetic effect pro-duced by the current passing throughthe coil shall be the maximum.

The quality of the reproduction

The Gecophone loud -speaker unit hasbee-i used in conjure ion with de linenloud -speaker described on page 520 and

gives excellent results.

actually obtained is, of course,greatly dependent upon the con-struction of the cone, its mountingand the baffle effect provided, but itmust be admitted that the actual

design of the unit and its constructionis all important.

Rattling, buzzing, and distortionmay be produced by fitting an un-suitable cone, perhaps one that is tooheavy, and there must be a mostsuitable type of cone for a particularunit.

Matters for ExperimentThese are all matters for experi-

ment, however, but it is hardlyfair to judge a unit by fitting it toa cone that happens to be handy.Much better results may be obtainedby constructing a cone to suit theunit.

A balanced -armature unit is usuallyto be preferred for driving a linen -diaphragm type of double cone asthe movement is restricted, but evenhere care is necessary when settingup or buzzing will be produced owingto a one-sided pull on the armature.

The quality of the reproduction tobe obtained from a good unit and asuitable cone is such as to beaccept-able to most listeners and, indeed,there are those who prefer a first-classinstrument of this description toone of the moving -coil type.

ontinued fA Chat with Clapham and Dwyer (Cpage 46o)rom

First out of the Memorial, so Claphamwill in ist on dragging Ci,,sie in.

I was told very little about her,for it was a sore subject but Igathered that she had come .to thepicture one day at Burford Bridge,and that Clapham had forthwithadopted her. Up to the present,Dwyer appears to have been success-ful in preventing his partner fromleading her up to the studio-al-thc ugh, I will not vouch for this fact,-the former has made sundryattempts to do so.

A Shower of PresentsThat Cissie, still modestly remain-

ing in the background, has directly,appealed to the radio public is provedby the fact that presents have beenshowered upon her. Even well-knownfirms hearing a casual remark madeconcerning her health, have postedpatent remedies and other veterinaryprescriptions to the studio; samplesof choice cattle foods have been

lavishly submitted, and in fact, Ithink everything has been done totempt her into the c pen.

Once, at Woolwich, Dwyer agreedupon a compromise, namely, thatalthough Cissie was not to appear inpublic, in flesh and blood, so tospeak, he would agree to present aproperty facsimile of her. On thatunique occasion, the audience wasdisappointed, and the c xper imentwill never again be repeated. CiAieis to remain a myth, and her hornswill be used to hang. jc k s upon.

Do ycu know, I failed even toascertain whether she was a Short-horn, a Fi i ian, or a dainty Jersey.

There still remains Mr. Spiegel andthere, I fancy, Dwyer is liable tomeet with trouble. Mr. Spiegel istaboo; he is, I gather, a disreputablefriend of Clapham's, whose veryname arouses Dwyer's ire. Note howmany times an attempt has beenmade to introduce some story abouthim into the dialogue, and on every

468

occasion Dwyer, with brutal frank-ness, has refused to listen to a word.

Perhaps the less said about Spiegelthe better, although it is tantali ingnot to know more about him. How-ever, on one of these evenings, theirrepressible Clapham will let thecat cut of the bag and then-

Well, it is the unexpected thatpleases in humorous turns and in thatrespect he will not disappoint us.

Brightening the ProgrammesClapham and Dwyer have created

a peculiar formal microphone humourwhich has deservedly brought themsuccess; it is wholesome fun, franklyspontaneous, and does much tobrighten the average wireless pro-gramme.

Laugh, and the world laughs withyou;

Weep, and you weep alone;For this brave old Earth must borrow

its mirth,It has troubles enough of its own.

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Wireless Magazine. December. 1929

AWORD ABOUT

FULL-SIZE BLUEPRINTSdir Do you realise that, except for one or two in a range of nearly 200, all " Wire--11 less Magazine " blueprints are full-scale drawings? They are not small-

scale drawings which, as you know, are useless as patterns and templates.Do you appreciate the fact that they save much time and trouble in construc-tion, as they can be used as panel and baseboard templates for marking thecentres for drilling holes and laying out components?

du Further than this, do you know that all the connecting wires are numbered71 separately, so that they can be assembled in the easiest way quite

automatically?dr Remember, also, that a blueprint of any set constructionally described in'91 the " Wireless Magazine " can be obtained for half-price during the currency

of the issue by using the coupon always to be found on page iii of the cover.

SOME MODERN SETS THAT CAN BE SPECIALLYRECOMMENDED TO CO\STRUCTORS

ONE -VALVE SETTHE Al. Simple set for beginners,

with dual -range coil which can beeither made at home or bought. Fulldescription on page 29 of Augustissue. Cost of construction very low.Blueprint No. WM153, price Is.,post free.

TWO -VALVE SETSBROOKMAN'S TWO, designed by

W. James. Detector and trans-former -coupled low -frequency stage,with 1930 Binowave coil coveringboth wavebands. Cost of construc-tion approximately £6. Full des-cription on page 340 of Novemberissue. Blueprint No. WM168,price ls., post free.

F,THER RANGER. Will coverevery wavelength from zo to 2,000(with only a few breaks) by the useof four interchangeable coils. De-tector and transformer -coupled low -frequency stage. Cost approximately£7. Spare coils and all batteries areaccommodated in cabinet. See page121 of September issue. BlueprintNo. WM156, price ls., post free.

THREE -VALVE SETSCOMMUNITY THREE. Detectoi

and two low -frequency stages, thefirst resistance coupled and thesecond transformer coupled. All -wave tuner incorporated and switch-

ing provided for use of pick-up. Costapproximately £5. Described onpage 355 of November issue. Blue-print No. WM164, price is., postfree.

BROOKMAN'S THREE, designedby W. James. The star set of theRadio Exhibition. Uses the famous193o Binowave coils, which givegreat selectivity and volume.Screened -grid stage, detector, andtransformer -coupled low -frequencyamplifier. Cost approximately soguineas. Constructional article onpage 259 of October issue. Blue-print No. WM161, price ls., postfree.

FANFARE THREE. Very simpleto construct: uses dual -range tunerand can be used for record reproduc-tion. Detector and two transformer -coupled low -frequency valves. Alldetails on page 107 of Septemberissue. Blueprint No. WM157,price Is., post free.

FOUR -VALVE SETS

1930 MONO -DIAL, designed byJ. H. Reyner, B.Sc., A.M.I.E.E.Uses two screened -grid high -fre-quency amplifiers, detector andtransformer -coupled low -frequencystage. Dual -range coils controlled bysingle knob and ganged condensers.Details on page 213 of October issue.

Blueprint No. WM158, pricels. 6d., post free.

ELECTRIC FOUR, designed by J .

Sieger and D. Sisson Relph. Usesindirectly -heated A.C. mains valves.Screened -grid high -frequency ampli-fier, detector, resistance -coupled andtransformer -coupled low -frequencystages. Needs only a grid -biasbattery. Cost, as complete radiogramophone in console -type cabinet,approximately X34. Described onpage 285 of October issue. Blue-print No. WM162, price ls. 6d..post free.

1929 CHUMMY, designed by W.James. A most successful dual -range portable, using a screened -grid valve. Transformer -coupled andresistance -coupled low -frequencystages. Cost approximately los.Fully described on page 411 of Juneissue. Blueprint No. WM145,price ls. 6d., post fred.

FIVE -VALVE SETSENCHANTER.-An efficient five -

valve portable set, using ordinarythree -electrode valves. One -knobtuning and specially large high-tension battery for reliable per-formance. Completely self-con-tained with loud -speaker. Des-cribed on page 38 of August issue.Blueprint No. WM150, priceIs. 6d., post free.

Applications for back copies of the " Wireless Magazine " should be made direct to the Publisher, BernardJones Publications, Ltd., 58/81 Fetter Lane, London, E.C.4. All copies are 1 s. 3d. each, post free. Applica-tions for blueprints should be addressed to the Blueprint Department. Postage stamps should not be sentas remittances. Note that blueprints of the sets listed above cannot be obtained under the half-price scheme.

469

Page 26: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine, December, 1929

I VERYBODYS GUIDE TOMoving -coil and Cone Loud -speakers, Loud -speaker Units

Now that almost every listener uses at least one loud-speaker, and sometimes two or more in different rooms ofa house, it is a matter of importance to be able to makea choice easily. This is possible by reference to the lists

MOVING -COIL LOUD -SPEAKERSResist-

Nams {rue Dimensionsin inches

Excitation ence inohms

Price

Chassis Kit - 6-v. acc. or - A.C. £4/410(Lodestone) D.C. mains D.C. £4/14/0

Grawor Chassis .. Battery or - £4/10/0D.C. mains

Hegra Chassis .. - 6.v. acc. or - £4110/0D.C. mains

Epoch Cabinet .. 17 high .05 to 6 amp. High Oak £4/15/0or Low to £10/7/6

Grossman .. Chassis .. - 6-v.; A.C. 2.400 6-v. and D.C.and D.C. £4117/6

A.C. £13/5/0Goodman .. Invincible - 6-v. 4 amp. Low £4/19/6

ChassisZampa Chassis .. 11x1lx 9 6-v..65 amp. Low £5/5/0Goodman .. Invincible - D.C. and Low D.C. £5/9/6

A.C. and D.C. A.C. A.C. £7114/6Webson Chassis .. 13 high D.C. or 6-v.

acc.- £5/10/0

Zampa Chassis Ilx 11X 9 D.C. mains Low £5/10/0.1 amp.

Baker Chassis 12x 12x 9 6-v.; A.C. High 6-v. £5/15/0or D.C. or Low A.C. £9/0/0

D.C. £61010Lissen Cabinet D.C. mains Low Oak £5/15/0

Mah. £610/0Epoch Oak Cabinet 17 high Permanent

MagnetHigh

or Low£6/2/6

Baker Chassis 12 x 12 x 9 PermanentMagnet

Highor Low

£6/5/0

Ferranti Chassis - A.G. or D.C. 20 A.C. £101010Mains D.C. £6/1010

Epoch Chassis - PermanentMagnet

Highor Low

£6/15/0

Marconiphone Cabinet .. 6-v..6 amp. Low £710/0B.T.H. R.K. Chassis 13 high 6-v. acc. and 10-15 £7/7/0

D.C. MainsMarconiphone Cabinet .. - A.C. or D.C. Low D.C. £7/10:0

Mains A.C. £12/12,0Zampa Chassis .. 11 x 11 x 9 A.G. Mains Low £7/10/0

9-v I amp.Magnavox .. Chassis .. 10} cone D.C. or A.G. D.C. £8/5/0

Mains A.C.£.11/0/0Lissen Cabinet .. - Permanent Low Oak £9/10/0

Magnet Mah. £9/15/0Ferranti .. Table .. I8x I6x 12 A.C. Mains Low Chassis

£10/0/0With Cabinet

£18/18/0B.T.H. R.K. Chassis 14 high A.C. Mains 10-15 £11/10/0Brown Cabinet A .. - Permanent - £1511510

Magnet or6-v. acc.

Cabinet .. Permanent - £15/15/0Magnet

Philips Type 2011 29 high Permanent - £15/15/0Pedestal Magnet

Brown Cabinets - D.C. or A.C. D.C. £16110/0B and C Mains A.C.E21/010

Ferranti .. Pedestal .. 48 A.C. or D.C. Low A.C. £18/18/0Mains D.C. £14/18/0

Celeation Cabinet 404x 24x 14 i-v. 1 amp. High Oak £24/0/0Mah. £25/0/0

Celestion Cabinet 401 x 24x 14 D.C. and High Oak £24/12/6A.C. Mah. £2511216

Burndept Cabinet 111 high 6-v.; A.C. Not yetand D.C. available

Kolster KBI51 181 x 231 x II ' i-v..63 amp. Low Not yetBrander fixed

CONE LOUD -SPEAKERS

Name

Lissen

Type

Open Cone

Dimensionsin inches

DrivingUnit

Resist-ance inohms

AdjustableReed

2,000

Price(Mahogany or

Oak)

19/6

printed below, which embrace no less than thirty-threemoving -coil types and seventy-six ordinary cone loud-speakers. Every effort has been made to make this featurerepresentative and all loud -speakers of importance are listed.

CONE LOUD -SPEAKERS- -ContinuedResist- Price

Name Type Dimensions Driving an in (Mahogany orin inches Unit :hems Oak)

Amplion .. Guinea Cone 131 dia. Adjustable 1,000 £1/1/0Reed

Dr. Nester.. Parabol Horn 15 high Adjustable High £1/5/0Diaphragm

M.P.A. .. Popular - - - £1/5/0Plaque

Ridged -Cone Plaque .. 131 high Reed 2,000 £1/5/0

Amplion .. Swan Neck 20 high Adjustable 2,000 £1/7/6Diaphragm

Lissen .. Horn .. 211 high Adjustable 2.000 £1/7/6Diaphragm

Ormond .. Cabinet .. 12 X 12 x 61 Adjustable High £1/9/6Reed

Marconiphone Plaque .. 14 high Adjustable 2,00C £1/10/0Reed

Dr. Nester.. Dragon .. 171 high Adjustable High £1/12/6Diaphragm

G.E.C. .. Plaque .. 15 high AdjustableReed

Me-dium

£1/12/6

Grawor .. Melodia 134 high Adjustable - £1/12/6Cabinet Reed

Puravox .. Open Cone 174 high Adjustable 2,000 £1/12/6Reed

Brown .. Duckling .. 91 high Adjustable 2,000 £1/15/0Reed

Dr. Nesper .. Horn .. 25 high £1/16/0Diaphragm

Amplion .. Standard 161 dia. Reed Unit 1,000 £1/19/6Open Cone

Climax .. Cabinet .. 12 high Adjustable 2,000 £1/19/6Reed

Dibben .. Table .. 12 high Two -pole High Mah. £2/7/6Oak £2/2/0

W.B. Cone .. - Adjustable - £2/2/0Reed

B.T.H. .. Horn .. 23 high Adjustable - £2/5/0Diaphragm

Loewe .. Cabinet .. 13x 13 x 5i Adjustable 2,000 £2/5/0Two pole

M.P.A. .. Popular - - - Mah. £2/7/6Cabinet Oak £2/5/0

Puravox .. Cabinet Cone 151 x 154 x 7 Adjustable 2.000 £2/7/6Oak Reed

Burndept .. Table .. 14x 15 x 5 Adjustable High Mah. £2/10,/0Reed Oak £211010

G.E.C. .. Plaque .. 17 high Adjustable 2,500 £2/10/0Armature

Ormond .. Cabinet .. 134 x 134 x 64 Adjustable 2,000 £2/10/0Reed

Philips .. Plaque .. 121 x 13 x 4i Balanced 2000 £2/10/0Armature

Amplion .. Dragon .. 194 high Adjustable 2,000 £2/12/6Diaphragm

Trix .. Cabinet .. 14/ x 141 x 61 Adjustable High Mah. £.313/0Reed Oak £2/12/6

Grawor .. Orchestra 17 high Adjustable - £2/15/0Cabinet Four -pole

Lamplugh .. Cabinet .. 131 x 131 x 6 Adjustable 2,000 £2/15/0Reed

Watmel .. Table 14 x 14 x 8 Balanced 2,000 £2/15/0Cabinet Differential

UnitPuravox .. Cabinet,

Mahogany14x 144 x 7 Adjustable

Reed2.000 £2/17/6

Amplion .. Cabinct Cone 13 high Adjustable 1,000 Mah. £3/3/0Reed Oak £3/0/0

B.T.H. .. Cone .. 15 dia Balanced - £31010Armature

Marconiphone Cabinet - Adjustable 2,000 £3/0/0M.60 Reed

Puravox .. Cabinc t,Oak 151x 15x 1E4 Adjustable 2,000 £3/2/6Reed

Brown .. HQ Horn .. 20 high Adjustable 2,000 £3/3/0Diaphragm

Grawor .. Choralion 16 high Adjustable -- £315/0Cabinet Reed

...-- -...i

470

Page 27: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

I. Wireless Magazine. December: 1929 ,kW-SPEAKERS Akqand Chassis Arranged on Convenient Price Basis

Many amateurs nowadays prefer to make their owninstruments with a suitable unit and chassis, rather thanbuy a complete loud -speaker. Twenty-two different unitsare here listed, as well as nineteen types of chassis. If any

CONE LOUD-SPEAKERS-Continued

further particulars are required readers are recommended toget in touch with manufacturers. Should any difficulty arisewrite to: -"Loud -speaker Guide," WIRELESSS MAGAZINE,58 6i Fetter Lane, London, E. C.4. See also advertisements

CONE LOUD-SPEAKERS-Continued

Name Type Dimensionsin inches

DrivingUnit

Resist-anceohms in

Price(MahOogany or

ak)

Lamplugh .. Plaque 20 deep Balanced 2,000 £3/15/0Armature

NotAdjustable

Amplion .. Dragon .. 201 high Adjustable 2,000 Mah. £3/12/6Diaphragm Oak £3/8/6

Brown .. Mascot .. 13 high Adjustable 2,000 £3110/0Reed

Celestion .. Cabinet CIO 12x 12x 5 AdjustableReed

2,000 IVOlaat.f..i3/1146t

Dibben .. Table .. 18 high Four -pole High £371-g/0BalancedArmature

Kolster Cabinet. 13x 101 x 71 Four -pole 1,500 Mah.£3/17/6Brandes Ellipticon Reed Type Oak £3/17/6

G.E.C. .. Standard 211 X 168 Balanced High £4/0/0Cabinet Armature

Blue Spot .. Cabinet .. 111 X171 x 5 66K 1,500 £4/4/0Bumdept .. Minstrel .. 14 high Balanced High £414/0

ArmatureGnawer Sectral A. 151 high Special Unit 2,000 £41410

CabinetPuravox Cabinet Cone 15 x 151 X 8 Adjustable 2,000 £41510

Mahogany ReedWates Cabinet .. 14x 14 x 8/ Star Unit 500 Mah. £4/15/0

Oak £4/10/0Amplion .. Cabinet Cone 14 high Balanced 500, Mah. £4/17/6

Armature 700 & Oak £4/10/01,250

Lamplugh .. Cabinet . 20 x 19 x 6 Balanced 2,000 £4/15/0Armature

NotAdjustable

G.E.C. .. Screen Model 321 x 25 X 9 Balanced High £51010Armature

Donotone .. Cabinet .. 12 dia. Balanced - £5/5/0Armature

Kolster K.B.72 171x 15 % x 88 Balanced 760 Mah. £6/6/0Brandes Cabinet or Pivoted Oak £5/5/0

ArmaturePhilips .. Double Cone 19 x 18 x 41 Balanced 2,000 £5/5/0

ArmatureBrown .. V.10 Duplex 138 high Adjustable

reed1,500 £5/10/0

G.E.C. .. Cabinet .. 161x 131 x 74 Balanced High Mah., £5/10/0Armature Oak, £5/10/0

Celestion .. Cabinet C.I2 14x 14 x 6 Adjustable 2,000 Mah., £5/17/6Reed Oak, £5/12/6

Amplion .. Standard 171 high Adkstlble 650 £6/0/0Lion Chassis

Blue Spot .. Cabinet .. 181 x 17 x 91 66K 1,500 £6/6/0Dibben .. Floor type.. 294 high Four -pole High £6/6/0

BalancedArmature

Grawor .. Sectorphone 181 Special 2,000 £7/7/0Model A Four -poleCabinet

Kolster K.B.I35 181x 231x I11 Balanced 760 Mah., £8/8/0Brandes Cabinet or Pivoted Oak, £7/7/0

ArmatureBrown .. V.I2 Duplex 16 high Adjustable 1,500 £7/10/0

ReedCelestion .. Cabinet Z.20 191X 18 x 88 Adjustable 750 Mah., £8/5/0

Reed Oak, £7/15/0Amplion .. Lion Cabinet 18% high Adjustable 650 Mah., £8/15 0

Reed Oak, £8/0/0Amplion .. Power Lion 211 high Adjustable 650 £8/0/0

ReedAmplion . Lion 291 high Adjustable 650 Mah., £9/15/0

Pedestal Reed Oak, £9/0/0Burndept .. Console .. 18 high Balanced High Mah., £9/9/0

Armature Oak. £9/0/0Celestion .. Cabinet C.14 201 X 201 x 91 Adjustable 750 Mah., £11/7/6

Reed Oak, £1110/0Brown .. V.15 Duplex 19 high Balanced 1,500 £12/10/0

ArmatureAmplion . Lion Con- 40 high Adjustable 650 Mah., £16/0/0

cert Cabinet Reed Oak, £15/0/0Celestion .. Cabinet Z.25 24 x 24x 111 Adjustable 150 Mah., £15115/0

Reed Oak, £15/0/0

Name Type Dimensionsin inches

DrivingUnit

Resist-anceohms in

750

Price(Mahogany or

Oalc)

Celestion .. Cabinet C.24 30 x 47 x 18 AdjustableReed

Mah., £21/0/0Oak, £20/0/0

LOUD -SPEAKER UNITS

Name of Unit Type of Drive Price

Lissen .. Four -pole .. .. 12/6M.P.A. .. .. Adjustable Reed . . .. .. 12/6Ormond .. .. Four -pole Adjustable Reed .. .. 12/6W.B. .. .. Four -pole Balanced Armature .. 12/6Grawor .. .. Reed . .. . ..

'Armature13/6 and 16/6

Hegra .. .. Balanced .. .. 3/6Loewe .. .. Two -pole .. .. .. .. 3/6Dr. Nesper . Adjustable Reed .. .. .. 4/0Ediswan .. .. Balanced Armature .. .. .. 5/0G.E.C. .. .. Adjustable Reed .. .. .. 5/0Puravox .. Adjustable Reed .. .. 5/0Symphony Balanced Reed .. .. . .. 5/0Watmel .. .. Balanced Armature .. .. .. 8/6Watmel .. .. Four -pole Balanced Armature 8/6Glassman .. .. Four -pole Balanced Armature .. 9/6G.E.C. .. .. Adjustable Armature .. .. £1/1/0Grawor .. .. Four -pole Balanced Armature £1/1/0Six Sixty .. .. Adjustable Reed .. .. .. £1/216Blue Spot .. .. Four -pole .. .. .. £1/5/0Brown .. .. Adjustable Reed .. .. £1/5/0Goodman . Balanced Armature .. £1/7/6Wates Four -pole .. . £1/16/0

LOUD -SPEAKER CHASSISMax. Dia- Max.

Name meter of Depth of Suitable Units PriceCone

Ormond .. 9 in. 27/a in. Most Units 7/6- Most 0/6Zempa .. 6 in. 3 in. All Types 016H igra .. 9 in. - Most 1/6Wates .. 14 in. 41 in. All Cone Units 2/0Blue Spot I I in. 28 in. Blue Spot 66K 2/6Ediswan .. 121 in. 3 in. Most 2/6Grawor 12 in. 3 in. All Grawor Cone Units 2/6Watmel 10 in. 31 in. All Units 2/6White Spot .. In in. 41 in. Most 2/6Baker .. 9 in. 3 in. All Types 4/0Blue Spot .. 148 in. 7 in. Blue Spot 66K 5/0Squire .. 91 in. - All 5/0Goodman .. - - Moat E. /12/6Zampa .. 131 in. 28 and All Types £ /12/6

11 in.Kolster Brandes 91 in. 318 in. Complete Chassis £2110/0Celestion .. 10 in. 3 in. Unit Incorporated £3/5/0Celestion .. 12 in. 38 in. Unit Incorporated £4/10/0Celestien .. 14 in. 41 in. Unit Incorporated £5/17/6

471

IN, THE FOLLOWING PAGES WILL BE FOUNDILLUSTRATIONS OF SEVENTY -ODD LOUD-SPEAKERS, UNITS AND CHASSIS, MANY OFWHICH ARE ACCOMPANIED BY REPORTS ONTESTS ACTUALLY MADE IN THE " WIRELESS

MAGAZINE" LABORATORIES.

Page 28: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

I Wireless Magazine. December 1929 LOUD-SFEARE_? GUIDE

LAMPLUGH

This Qualkon loud -speakeris of the usual cabinet type.Embodied in the cabinet,which is of good appear-ance, is a standard cone unit,claimed to be both sensitiveand powerful. Accordingto the listener's require-ments, this loud -speakercan be supplied in oak ormahogany, for £4 15s.

MARCONIPHONE

Embodying the improvedMarconiphone reed system,this model 60 Marconi -phone loud -speaker isclaimed to be sufficientlysensitive to operate a simpletwo -valve set. The adjust-ment of the knob at theback enables this speaker tohandle the full output of apowerful four- or five -valveset. Its price is £3.

For listeners who prefer thehorn type of loud -speaker,the Amplion Dragon shownhere can be recommended.The patented construction,it is stated, eliminates metal-lic resonance. This all -metal model, type AR19, is£2 12s. 6d.

AMPLIONThe Amplion Lion wasfound to be well Ealanced.It needs plenty of power towork well. It has a goodeven response, the bassnotes being particularlynatural. This chassis is £6for the standard type, L14,and £8 for the power type,LI8P.

AMPLIONFor those desiring a low-priced cabinet cone loud-speaker of simple designand pleasing appearance,there is the Amplion Juniorcabinet cone. Withoutunduly emphasising eitherthe bass or high notes, thismodel is claimed as a re-producer of a wide range offrequencies. In oak, it is£3, and in mahogany,3 guineas.

MARCONIPHONEThe new Marconiphonemoving -coil loud -speakerchassis has a built-in step-down transformer. It isavailable in three types.With a 6 -volt accumulatorit passes .6 ampere. ForD.C. mains, between 100and 250 volts, the consump-tion is 60 milliamperes.There is also an A.C. modelfor 200- to 250 -volt mains.The prices range from £7 to12 guineas.

MARCONIPHONEImprovements in both sen-sitivity and tone are em-bodied in the new Marconi -phone Octagon loud -spea-ker. Its price has beenreduced to 30s. Two modelsare available, one with thefamiliar flower design andthe other with a differentfret. Both types can beeither hung from the wallor rested on a table.

BAKERThis Super Power 1930 modelmoving -coil loud -speaker can beworked from either A.G. or D.C.mains. For those without mains, a6 -volt model can be run from anaccumulator. All models embodya new centering device and a newlight -weight moving coil. Thefinish is in gun-metal and polishedaluminium. Prices vary from£5 15s. for 6 -volt model to £9 for9 -volt 2 -ampere model.

PHILIPS *-A new and ornate moving -coilloud -speaker we have tested andfound extremely good. It handlesa large amount of power andhas an extremely even response.The price with step-down trans-former is 15 guineas (8 guineasfor unit only without step-downtransformer). It is important tonote that no external power is re-quired to work this moving -coilloud -speaker, which has a cobalt -steel permanent magnet.

GECOPHONE *-A high-class cabinet cone loud-speaker which is claimed to giveexcellent quality reproduction. Theprice in mahogany or oak is £510s.The appearance is good, harmonis-ing with the average surroundingsof the home. We have found thismodel to be quite sensitive whenused with a low -power receiver;the reproduction is a trifle low-pitched.

BAKERClaimed to give a combination oftonal purity and volume, the Baker1950 Super model moving -coilloud -speaker is a slightly cheaperloud -speaker than the Super Powermodels already mentioned. Formains and accumulator working,this speaker is designed to givegood results at a moderate price.The cost is £5 for the 6 -volt type,rising to £8 7s. 6d. for the 9 -volt2 -ampere model.

A star (*) indicates that the loud -speaker has actually been tested in the "W.M." labora.ories.

472

Page 29: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

LOUD -SPEAKER GUIDE Wireless Magazine. December 1929

1 ZAMPA *Another moving -coil loud-speaker that can be used witheither mains or an accumulator,the Zampa varies in price from5 guineas to £7 10s. accordingto type. It has an adjustablecentering device, which wefound quite effective in ourtest of the model submitted.Reproduction we found to begood over the entire range ofmusical frequencies. W .M " Pilot

GRAWORThis loud -speaker has plentyof bass, and the general tone iscrisp and pleasing. The modeltested was housed in a polishedwalnut cabinet, price £3 5s.The adjustable unit is quitesensitive, giving good volumeon a two -valve set. It doesnot easily overload when extravolume is put through it.

AMPLIONA de -luxe loud -speaker, the AmplionLion Concert Cabinet Model is a

handsome model that is claimed to dofull justice to the good qualities of theLion mechanism. This loud -speakerembodies the power chassis alreadymentioned (see or p site r age),In oak itis £15, and in mahogany, £16. Thisloud -speaker is incorporated in a largeconsole -type cabinet.

WATESIn our test of the Wates cone loud-speaker we found it fairly sensitive.It gave clean-cut reproduction; thefour coils in the unit justify them-selves. It is a good all-round loud-speaker and its price of £4 10s. isreasonable in view of the performance.This loud -speaker is interesting be-cause it has a double construction forthe magnet system. The dual adjustment works well.

AMPLIONA handsome piece of furniture isthe Amplion Lion Pedestal cabinetmodel. It has the same movementand cone as the table cabinetmodel, but as the baffle boardeffect is greater, bass notes aremore pronounced. The price inoak is £9, and in mahogany,£9 15s. As may be expected, thevolume of sound available is con-siderable.

GECOPHONEAn entirely new movementis employed in this Storkloud -speaker, which is ofthe cone -plaque type. A support is provided so that thespeaker can be used as atable model if desired. Theprice of this Senior plaqueis only £2 10s.

AMPLIONKnown as "a senior speakerat a junior price," theAmplion Swan -Neck typeAR9 at £1 7s. 6d. is usefulfor working low -powersets. It should give quitepleasing reproduction.

STAR *In our test of the Websonmoving -coil loud -speaker,made by the Star Engineer-ing Co., we noted that itwas not easily overloaded. Itis inclined to be high-pitchedfor its type. The reproduc-tion is clear. Its price i,moderate, being £5 10s.

AMPLION

A very popular model, notedfor its mellow tone, is theAmplion Dragon withwooden flare. In oak it is£3 8s. 6d., and inmahogany, £3 12s. 6d..

BAKER

Baker's 1930 permanent -magnet moving -coil loud-speaker has been improvedin design. It is claimed tgive nearly 40 per cent, in-creased efficiency. It has thecharacteristic quality of amoving -coil loud -speaker,but requires no externalexcitation. Price £6 5s.

GECOPHONE

Specially designed to givea high standard of repro-duction when the input issmall, the Gecophone Ju-nior plaque loud -speaker at£1 12s. 6d. is good valuefor money. The circularframe and cone are finishedin a rich old bronze colour.

A star (*) indicates that the loud -speaker has actually been tested in the W.M." laboratories.

473

Page 30: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. December 1929 LOUD -SPEAKER GUIDE

AMPLION *Another Amplion in the widerange available is the Standardcabinet cone. Alternative valuesof impedance are available. Theattractively designed cabinet isbeautifully finished. The balanced -armature unit is noted for itssensitivity. The price in oak is£4 10s., and £4 17s. 6d. in

mahogany.Photo

Photo

SQUIRE *An extremely flexible loud -speakerchassis is the Squire model, whichwe tested in conjunction with aBlue Spot unit. The result wasvery pleasing, but on the high-pitched side. The combinationgives a performance which, forthe outlay involved, is quite re-markable. The price of the chassisvaries according to the size, from10s. 6d. to 39s. 6d.

WATMELA loud -speaker which, whenassembled, provides a good all-round reproducer, is offered byWatmel. We found the assemblyvery sensitive to weak signals. Itgave a pleasant all-round reproduc-tion when tried with a standardreceiver. It embodies a four -polebalanced - armature unit, price18s. 6d. The loud -speaker chassiscan be had for 12s. 6d.

Photo

Pha,

J.R. WIRELESS .We utilised the J.R. cone assembly inconjunction with a Watmel unit andobtained quite satisfactory results.The cone assembly lends itself to avariety of units. With the unit usedthe cone appeared to do it justice.This assembly is of special interest tothose keen on assembling their ownloud -speakers at a minimum cost.This cone need not be supported allround the periphery as is usual withsuch assemblies.

CLIMAXOne of the most inexpen-sive cabinet cone loud-speakers available is theClimax Chello. As a resultof our tests we can say thatit is good value for 39s. 6d.The tone is rather low-pitched, but the absence of"boominess" rules out anyobjection to the accentua-tion of the low notes. It isa good all-round speaker ofaverage sensitivity.

KOLSTER BRANDESHoused in an attractivecabinet this Kolster BrandesKB72 loud -speaker isclaimed to give results asgood as those from amoving coil. The KB72is available in a chassismodel ready fot mountingeither in a cabinet or on abaffle board. In oak thecabinet loud -speaker is 5

guineas and in mahogany orwalnut 6 guineas. Thechassis is £2 10s.

TRIXA low-priced cabinet coneloud -speaker, the Trix modelgives pleasing reproductionof bass notes. The sensi-tivity is moderate. Thereis a cut-off on the very highnotes. The general repro-duction is good for theprice. In oak, the price is£2 12s. 6d., and in maho-gany or walnut, 3 guineas.

AMPLIONFor listeners who require alow-priced reproducer ofgood tone the AmplionGuinea cone is almostunique. It is designed forhanging from a wall, forwhich purpose a heavy silkcord is provided.

PHILIPS *

In the Philips type 2007loud -speaker is fitted a largemovement which, as ourtests showed, enables it tohandle a large amount ofpower without overloading.The switch giving threedifferent impedance valuesis useful. The price, 5

guineas, is justified.

CELESTION

One of the best-knownloud -speakers, the Celestionmodel C14 incorporates aspecial magnetic systemwith a cobalt -steel magnetand a 14 -inch diaphragm.The resistance is 750 ohms.In walnut the price is £12,in mahogany £11 7s. 6d.,and in oak £11.

KOLSTER BRANDES

Claimed to introduce newprinciples in winding andarmature mounting, theKolster Brandes KB135cone loud -speaker is a good-looking model of robustconstruction. It embodiesan input transformer. Theprice in oak is 7 guineas.

A star (*) indicates that the loud -speaker has actually been tested in the "W.M." laboratories.

474

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LOUD -SPEAKER GUIDE Wireless Magazine, December, 19291

AMPLIONOne of the best Amplioncone loud -speakers for gene-ral use is the Amplion tablecabinet model, made ofpolished oak in a simplebut distinctive design. Inthis model is incorporatedthe standard Lion chassis,comprising a 14 -inch conediaphragm and a Lion unit.The price is £8.

GECOPHONEIntroduced this season, theGecophone cabinet modelof the Stork cone loud-speaker strikes a new notein design. The front ofthe loud -speaker is slopedand exposes an ornamentalfret backed by an artisticfabric of blue and gold. Inmahogany the price is £4,and in oak, £3 15s.

GECOPHONE

An unusual design for aloud -speaker is the Geco-phone screen type. Thecone is fitted into a walnut -finished fire screen whichacts as a baffle. The priceis 5 guineas.

SQUIRE

The Squire double -alumini-um cradle frame is admir-ably suited for a Blue Spotunit. The price is 39s. 6d.

AMPLIONAnother of the standardAmplion Lion loud -speak-ers is the LC41, which, inits cabinet of polishedmahogany, is good value formoney at £8 15s. It in-corporates the standardLion chassis, comprising a14 -inch cone diaphragm anda Lion unit.

PAREX

A novel type of loud-speaker is the Parex dual-purpose loud -speaker clock.A " self -fed " electfie clockis combined with a standardcone loud -speaker assembly,in a cabinet of either oakor mahogany. The priceis seven guineas.

KOLSTER BRANDESA Kolster-Brandes moving -coilloud -speaker embodying a step-down transformer is modelKB151. This is run from a6 -volt accumulator and notfrom the mains. Its price hasnot yet been fixed. Furtherdetails will be announced whenthey are available. Interestedreaders can, of course, applydirect to the manufacturers.

AMPLIONAn easel type loud -speaker, whichmay also be hung from a picturerail if desired, is the AmplionStandard open cone. The cone istinted to harmonise with the brownbakelite rim. It is especially use-ful with low -power sets. Its price,Ll 19s. 6d., should make a popularappeal to many listeners of onlymoderate means.

ZAMPAConstructed on unusual prin-ciples, the Zampa twin -conespeaker unit is of principalinterest to constructors. Thetwin cone is housed in anoxidised or pewter finishedcircular shell (which forms thecabinet) standing on four ballfeet. The price is 35s. Cotton -wool damping is placed roundthe edges of the cones to pre-vent metallic resonance. Photo

GECOPHONEThe Gecophone standard coneloud -speaker is finished in a richcoin bronze. It has an adjustablesloping cone, which gives goodquality reproduction when usedwith the average set. The priceis £4.

SIX SIXTYOf interest to those who likeconstructing their own loud-speakers is the Six -Sixty reed -type loud -speaker unit, whichis available complete with coneand felt pad for 22s. 6d. Theresistance of the unit is 2,000ohms and it is claimed to givegood results when the cone issuitably suspended. With aproperly designed cabinet thisassembly completes whatshould be a useful, effective andinexpensive loud -speaker.

A oar (*) indicates that the loud -speaker has actually been tested in the ^ W.M." laborato

475

es.

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Wireless Magazine, December 192y

PHILIPS

An inexpensive Philipsloud -speaker that can behung on the wall or stoodon a table. A dual -toneswitch is a useful refine-ment. Price £2 10s.

M.P.A.

In the M.P.A. range ofloud -speakers is a moving -coil model having a per-manent magnet. The pricecomplete is 15 guineas.The unit can be boughtseparately for 12 guineas.

GOODMAN

Known as the dual -conechassis assembly, the Good-man combined baffle sys-tem, price 32s. 6d., has beendeveloped to give perfectlybalanced reproduction.

GOODMANThe Goodman loud -speakerunit is specially good inconjunction with the linen -diaphragm type of loud-speaker. The armature ispermanently balanced be-tween four laminated poles.The magnets, pole pieces,armature holder, and bob-bins are held in position bya strong die-casting. Itsprice is 29s. 6d.

LOUD -SPEAKER GUIDE

BURNDEPTThe Burndept Console loud-speaker is a handsome piece offurniture. It can be obtained inoak for £9, or in mahogany for9 guineas. The driving unit is abalanced armature of high resis-tance. It is adjustable. This loud-speaker incorporates the Minstreldouble diaphragm.

LOEWEA good inexpensive loud-speaker is the Loewe, price45s. On test, we found thetone clean-cut and pleasing.The reproduction tended to behigh-pitched, but this was notobjectionable. The name ontop of the cabinet is ratherprominent and would be lessoffensive if placed elsewhere orremoved entirely.

BLUE SPOT ikThe Blue Spot Goliath loud-speaker impressed us on test.It is sensitive to weak signalsand jnclined to be high-pitched.It will take considerable powerwithout rattling. The adjust-able unit is critical in its settingfor best results. The Goliath isan excellent loud -speaker. Usedwith several different outputs,the results were uniformly satis-factory. The price is 6 guineas.

GOODMANThe Goodman Invin-cib'e moving -coil loud-speaker chassis is de-signed to give thehighest possible stan-dard of reproductionat a low price. Thereis a 6 -volt model at£4 19s. 6d., and modelsfor D.C. and A.C.mains, priced respective-ly at £5 9s. 6d. and£7 14s. 6d.

A star NO indicates that the loud -speaker has actually been tested in the " W.M." laboratories.

476

PAREX

An inexpensive model of thenew Parex combined electricclock and loud -speaker is avail-able, price £2 10s. This is ina mahogany or oak cabinet.The claims made for this uniqueinstrument are that the doeis perfectly silent in action anwill run for many months with-out attention.

READY RADIO -*

In our test of the ReadyRadio moving -coil loud-speaker chassis we obtainedexcellent reproduction wellup to the standard to beexpected from this type ofreproducer. At £6, thechassis can be recommendedto listeners as an inexpensiveproposition.

M.P.A.

For constructors of loud-speakers, the M.P A MarkIV unit, price 12s. 6d.,should prove attractive.The unit is claimed to bevery sensitive and to com-bine brilliance of tone witheven response. A chassisor the unit, with a 14 -in.baffle and a 9 -in. cone, canbe had for 10s.

Continued on page 546,

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Wireless Magazine, &corbel: 1929

HALYARD'S CHAT ONMONTH'S TOPICS

11 ILLUSTRATED BY GLO

you see E. L. Rice, the well-known American experimenter, with a newtype of loud -speaker. There are six loud -speakers altogether, as indicated by

the arrows.

The Height of the SeasonGRANTED that there is a wireless

listening season during thewinter, when would you say thatseason reaches its height? Youknow how the holiday season reachesits peak in August. Is there anycorresponding month in the winterwhen the wireless season may be saidto reach its highest point of activity?

We have a very well -marked be-ginning of our winter period ofwireless activity. There are the wire-less exhibitions at Olympia andManchester, and there is the changefrom summer time to winter time.After these events, the winter wire-less season goes on placidly, and thereappears to be nothing of moment tomark the season's climax.

still, I should like to pursue the

Well -marked beginning

idea of there being a height to ourwinter wireless season. Can you helpme? If you are a short-wave en-thusiast, you would be easily able tofix on your height of the wirelessseason. It would be the period whenshort-wave stations come tumblingin at astounding strength.

Some of us might be inclined tojudge the season according to theway in which the American medium -wave stations come in. These stations begin to make themselves heardmore or less itf 'October, and they getbetter and 138.tter until they reachtheir best-when? At the height ofthe wireless season?

Moorside EdgeDo you remember all the pother

there was about the pronunciation ofDaventry when station 5XX wasopened? The local pronunciationwas Daintree, but the B.B.C. de-cided to pronounce the word accord-ing to its spelling, and so Day -en -tryhas become one of the most familiarplace-names in the English language.

It seems rather strange that the

477

B.B.C. should have run up against asimilar peck of trouble regarding thePennine regional station's name.Slaithwaite is the nearest town tothe site of the new station, andSlaithwaite had every reason to hopefor great wireless fame.

As in the case of Daventry, theB.B.C. could not reconcile itself to

Not suitable for broadcastingthe local pronunciation of the place -name. I, for one, am not surprisedat this, for Slewit is not in the least,comparable with the rejected Dain-tree, which is rather a pretty word.

Very much to the disappointmentof Slaithwaite, the B.B.C. has cometo the conclusion that the wordSlaithwaite, pronounced accordingto its spelling, is not suitable forbroadcasting, and so the new stationis to be known as Moorside Edge.

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fie

Wireless Magazine. December 1929

Under My Aerial-ContinuedI have been wondering if this choice

was partly determined because of thethree syllables contained in thedouble word. Daventry, Brookman'sPark, Moorside Edge, 5XX, 5GB,2L0-there are three syllables in each.

Perhaps the B.B.C. prefers a three -syllable call -name or call -sign.

CasualtiesHas there been an aerial casualty

in your neighbourhood yet thiswinter? There has been one suchcasualty in my road, and we are nothalf -way through November. Theworst of it is that the aerial which isdown belongs to me.

Funny, isn't it? I've been givingadvice for years as to the need for ageneral overhauling of an aerial in

My aerial this morninglate summer, and here I am with myaerial down because I forgot to actaccording to my own advice.

You can imagine what my feelingswere when I saw my aerial thismorning. There was no need to goout and conduct a post-mortem onthe spot. It was all too evident thatthe rope on the aerial mast hadsnapped near the pulley.

My aerial ast, as you know, isfixed in a tree. To put my aerial wireup again I shall have to climb intothe tree, let the mast down to theground, and then let it fall from avertical position to a horizontal posi-tion.

Then I shall have to put a newrope through the pulley, and thenget the mast back into the tree.

I have done all this before, and Ilike the work; but the trouble is thatthe weather is so unsettled and Imay have to wait days before thereis a dry day suitable for climbing trees.

What a lot better it is to carry outthe overhauling and repair of anaerial during the warm, dry weatherof summer.

The C.B.C.Isn't it a great piece of news that

Canada is to have a broadcasting

OFFICES

Loyalty to the Old Country

service modelled on our own B.B.C.?I am delighted with the recommenda-tions made by the Rc yal Commissionwhich has just concluded an investi-gation into Canada's wireless prob-lems, and I'll tell you why.

Several years ago I paid anextended visit to Canada. My stayin the Dominion lasted over twelvemonths, and I travelled across thewhole Dominion, Atlantic Coast toPacific Coast, and back. One of theimpressions I retained of Canadawas that the "old country" waslooked upon as a back number inmany things.

Loyalty to the old country wasthere all right, but it seemed to meas if Canadians were rather prone tolook upon us with good-humouredtolerance. Hence it is that it is suchexcellent news to me that Canadahas decided to copy the old countryin the matter of broadcasting.

There is to be a C.B.C. on the linesof our B.B.C. The money to run theC.B.C. is to be raised by licence feesand from advertisers who broadcastprogrammes of their own. A chainof seven 50 -kilowatt broadcastingstations is to be established acrossthe Dominion.

Considering the vast size of theDominion, seven seems a smallenough number, but no doubt thenumber will be added to as Canada'spopulation increases.

;Frame Aerials

What is your candid opinion ofthe frame aerial ? You must havehad some experience of this collectorof wireless energy either in conjunc-tion with your ordinary receiving

One ought to marvel

478

set or in a portable set with aerialenclosed.

I cannot make up my mind whatto think about the frame aerial. Onerecent writer tells us that frameaerials are better than indoor aerials.Another recent writer tells us justthe opposite. So where are we ?

Usually I have felt a little dis-appointed with the results I haveobtained with my frame aerials, butthat must be because I have ex-pected too much. When you cometo look at it, a frame aerial is a smallaffair, and one ought to marvel,perhaps, that it gives any resultsat all.

The curious thing about a frameaerial is that it doesn't seem tomatter very much how you alter itssize or shape within certain limits.The great game is to get as manyturns of wire as possible on the frame.Spacing the turns makes a littledifference.

My mathematical friend was rathersevere with me over my frame aerialthe other evening. He said I wasexpecting too much and, after alittle calculation, he told me that myframe aerial was about equivalent toa vertical aerial one foot high, plusan earth connection. Which, to mymind, was equivalent to telling methat my frame aerial was as good asan earth, and that's all.

American MethodsIt sometimes seems to me very

strange that methods of wireless con-struction in America should so oftendiffer from our methods of construc-tion. Take the important matter ofscreening, as we know it to -day, forexample.

Our usual practice is to employvertical screens to separate the coilsor parts which are liable to interactand so cause trouble. Occasionallywe use screening boxes to enclose andisolate complete amplifying stages.

In America it is apparently com-mon practice to screen the coils in awireless set and to leave the rest ofthe parts unscreened. Thus you willfind a receiver with a number of coilseach in its own circular screeningbox, and the valves all in a neat rowat the back of the baseboard with noscreening at all. If the variable con-densers are screened, they arescreened separately.

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Wireless Magazine. December 1929

Halyard's Chat on the Month's Topics

Liable to interact

To mention another point, I do notremember ever seeing an Americanreceiver, or a description of anAmerican receiver, in which thescreened -grid valve was placedthrough a hole in a vertical screen.We are most familiar with thi ,arrangement of the screened -gridvalve, even in commercial receivers.

Of course, I realise that conditionsin America are vastly different fromconditions here in our country, butI should have thought that the bestmethod of screening in a wireless setwould have been the same for bothcountries.

The Change -over"Well, George, and what is the

latest news regarding the receptionof the new regional station atBrockman's Park ? " I asked mytechnical adviser.

"Nothing very exciting," he re-plied. " Several friends of mine wholive in Surrey tell me reception isdecidedly better from Brookman'sPark than it was from Oxford Street."

" What part of Surrey, George ? ""Oh, just Surrey I""One of my wireless friends who

lives Wimbledon way is of theopinion that reception has beenweaker since the change -over."

"Perhaps he needs a new high-tension battery."

"Have you heard any reports fromfurther afield, George ? "

"Several correspondents reportgreatly improved reception from thewest and the north-west. If you wantfurther information, you had betterask the WIRELESS MAGAZINE readersabout it. They will know."

cj

4' .,4.=.... ,v ,

- --:-.4

OK, "Vi'l re, IImo

Recep(on has been weaker

" I am sure they will, George."" I know of one man in the Mid-

lands who is getting ten times asmuch strength from Brookman'sPark as he did from the old 2L0."

"Ten times as much, George IHow did he-"

" Simple. He has added an H.F.valve since the change -over."

"What do your many friends innorth London think of the change,George ? "

"I haven't dared to ask them.""Perhaps it is just as well not to

rub salt in their wireless wounds.By the way, George, have you anyidea what they are going to do withthe old aerial in Oxford Street?"

"Send it down to the bargainbasement, I suppose."

Die HardsThe high -frequency amplifying

valve, ordinary type with threeelectrodes, is the latest wireless partto be doomed by the prophets.Funny, though, isn't it, how thesethings whose doom is so confidentlyforetold refuse to pass into wirelessoblivion ?

First there was the crystal set,then there was the outdoor aerial,then the accumulator, and then thedry battery. Now it is the familiar

Much less than it used to be

H.F. valve which is to vanish fromamongst our wireless midst.

Well, the crystal set, the outdooraerial, the accumulator, and the drybattery are all with us yet ! I grantthe prophets that the number ofcrystal sets is much less than it usedto be, but the same cannot be saidof the outdoor aerial, the accumulatoror the dry battery.

When the outdoor aerial was sup-posedly doomed, the portable set wasgiven as the cause of the doom. Nowit is prophesied that the S.G. valvewill cause the decease of the poor,little, ordinary H.F. valve with threeelectrodes.

I don't believe this valve is

479

doomed at all. Nothing that hasbeen doomed yet in wireless haspassed out of use completely. Cer-tain types are superseded by moreefficient types, that's all that hap-pens. Wireless possesses the grandestset of die-hards in any branch ofscientific industi y.

Needs MustSome years ago it became quite

the thing in this neighbourhood tostring a lot of corks on your aerialwire in order to prevent the birdsfrom flying into the wire. You canguess the kind of joke which wasperpetrated about those corks. More

Buying the bottles

than one cork -aerialist was accusedof buying the bottles so as to get thecorks for his aerial.

I have been continuing my workon high -frequency amplification and,in order to obtain the screening boxesI required, I have had to do some-thing very similar to what the cork -aerialist was accused of doing yearsago.

In fact, I have had to buy a num-ber of a certain kind of tin of bis-cuits to get my screening boxes. Ofcourse, the biscuits in the tins havenot been wasted. They have beenplaced in other tins and put awayfor future use.

It is not only on the grounds ofexpense that I use one particularkind of biscuit tin for screening pur-poses. The chief reason is that thisparticular tin happens to be just theright size for my work. Anotherreason is that the tin has a lid whichfits tightly and which can be easilytaken off. A third reason is that thetin is thin enough for me to makeholes through it without trouble.

Perhaps I should do better withthe regulation screening box of themanufacturer, but I have neverfound my dealer with screeningboxes in stock, and I have neverwanted to wait for him to get them.You see, when I am engaged on awireless problem delay is dangerous.

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Wireless Magazine. December: 1929

The large studio at Munich, equipped withan electro-pneumatic organ

In this article our special Germancorrespond"nt, Dr. ALFRED GRA-DENW ITZ, describes the layout ofthe Munich station, which wasarranged by Prof. G. Baumgartner

THE headquarters of the BavarianBroadcasting Company have

been removed to a new building ofbeautiful architecture, accommodat-ing the whole of the amplifyingplant, all the offices and studios, andembodying all that is best in modernradio engineering practice.

Three Main StudiosThe main offices and rehearsing

rooms are located in a four -storeyfront wing. The rear part of thebuilding comprises two courtyardsseparated by the transmitter house.Of the three main studios, the twolargest are destined for musical anddramatic transmissions. The thirdstudio is used for talks. All arearranged around a courtyard.

The machinery plant of the mainamplifiers, the transformer station,where the three-phase current sup-plied by the municipal electricityworks is stepped down from 5,000volts to the operating tension of zzovolts, and sundry other accessoryrooms, have been housed in the base-ment.

Acoustic InsulationA special feature of the new radio

house is the exceptionally efficientarrangement for securing an acousticinsulation of the sensitive studios,and mutual insulation of the vari-ous rooms.

It should be borne in mind that ininstalling an up-to-date studio for

Munich'sRadio House

One of the reception rooms at the Munich station

broadcast transmission, four acousticphenomena, namely echo, inter-ference, "after -sounds," and reso-nance, have to be accounted for.While any echo and interferenceshould be disposed of completely," after -sounds " should be allowedwithin certain limits of intensity, aswell as resonance phenomena incertain musical ranges.

Inasmuch as there is no audienceabsorbing sounds in the studios,special provision for this effect hadto be made. After comprehensivecalculations and preliminary tests onsmall models of the hall and ceiling,the best solution was found to bebased on a thorough sectionalisationof the walls and ceiling.

Moreover, the floor was coveredwith sound -absorbing insulators andfabric. This is how any echo orinterference is done away with, while"after -sounds" are reduced to ashortened period of vibration. Inorder, in spite of these damping

480

devices, to securethe required acous-tic resonance ofthe room, the vari-ous parts of thewood panellingwere tuned todifferent funda-mental notes.

"Tuning" theCeiling

Thus the lowernotes are rein-forced in themicrophone.There is also ameans of regulat-ing both "after -sounds" and reso-nance by alteringthe removable in-sulation of, andload on, thewooden ceiling,thus controllingwithin wide limitsits vibratingcapacity.

The large studiois insulated from street noises in thefollowing manner : Street noises areeliminated by providing double win-dows of very substantial glass. Thisis quite sufficient, the main studiobeing insulated from the street by themain building and two inner court-yards.

Noises in BuildingPreventing the passage of noises

from other parts of the buildingproved a much more difficult task,particularly because of water, heatingand ventilating pipes and ducts,traversing the whole of the house.

All water and heating pipes,engines, blowers, lifts and othermechanical installations were furtherinsulated from the studios by meansof ducts and sound -damping devices.A sound -damping layer on the floor(cork -linoleum and rubber) in therooms adjoining the studios, as wellas in all corridors and on all stairs,serve the same purpose.

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The guiding principle in connectionwith all these schemes was anattempt to localise or reduce anynoises at their origin.

Small Studio LiningsIn the case of the smaller studios

no thorough sectionalisation of thewalls and ceilings could be effected.Lining these rooms with sound -absorbing material (special corkplates and cork tapestry) and sec-tioning the ceilings were the principalmeans by which insulation andadequate " after -sound " and reso-nance effects could be produced.

The amplifier plant is subdividedinto two groups, the first of whichcomprises the input amplifiers. Thesecond group raises microphonecurrents to their full intensity, dis-tributing them to the various lines ofconductors.

On the ground -floor (at the level ofthe studios), there is located theswitch -room, whence a sound -proofcabin with largewindows affords agood view of the rlarge studio. An-other sound -proofwindow enables thesecond studio to beinspected. Theswitch -room con-tains the centralswitching cabinet,controlling thewhole of the ampli-fier plant and en-abling all micro-phones to be fed andregulated.

This cabinet issubdivided into fourpanels, of which thetwo central ones arereceiving, leavingroom for a table accommodatingseveral switches. The first panelcomprises fifteen microphone ampli-fiers, fourteen of which are usedpermanently. The whole of the build-ing includes about twenty-five con-nections for microphones and threefor gramophones. Three microphonescan be installed and operated simul-taneously both in Studio I andStudio II, the latter being con-nected to an adjustable echo room.

Duplicate AmplifiersFifteen input amplifiers have been

accommodated on the second panel ofthe switching cabinet, pressure on alever being sufficient to insert eachmicrophone and input amplifier in

-Wireless Magazine. December 1929

circuit. A duplicate amplifier can befitted at a moment's notice in theevent of any one of the amplifiersbeing disabled.

The third panel carries the acousticand mixing devices behind the inputamplifier. These enable the per-formances in any one of four studiosto be combined with one another.Another switch enables an instan-taneous change -over from one studioto any other to be made. A controllinginstrument clearly shows the degree ofmodulation of the amplifiers.

On the fourth panel, there areswitches for actuating the startingsignal and pause signal in each studioand for lighting the danger signs ineach room. There are also in theswitch -room a microphone for theannouncer and a loud -speaker forlistening to performances. As theannouncer's microphone is switchedin, the loud -speaker is thrown out of

Studio III at Munich is tastefully furnished

circuit automatically.The amplifier room proper

is in the basement, andcomprises, on a frame, twomain amplifiers (each of sixline amplifiers which can bechanged over by means of afew easy manipulations);and a further two " listen-ing" amplifiers, each ofwhich can be connected upto twenty or thirty loud-speakers in various parts ofthe house. Moreover, thereis a special amplifier for theloud -speaker in the echo -room, and another ampli-fier for two loud -speakersused during rehearsals to

481

give orders from the sound-proollistening -in cabin to the large studio.

On one of the walls of the amplifierroom there is the switchboard for thecurrent supply of amplifiers, which issub -divided into eight panels con-trolling all the machines and batteries,as well as the amplifier feeds. Theswitchboard also comprises an auto-matic switch which, in the event ofany breakdown of the three-phasecurrent supply, switches in anemergency supply, so that there isnever a break in transmitting.

Check ReceiverIn the amplifier room there is

installed a set for listening -in throughthe ether, a chronometer, arrange-ments for broadcasting meteoro-logical reports, and the starting timesignal.

Current required for the amplifiersis derived from batteries provided induplicate. Voltages of 6, 20, 30o and600 volts are required. A special

room has been pro-vided for thesebatteries. Machinetransformers are usedto charge the batteries.Each of the larger sets(for 20 -volt batteries)has an input of twenty-five horse -power.

TURN TO PACE 486for JAY COOTE'S"LEAVES FROMA LISTENER'S

LOG"

Modern German decoration is well illustratedby this staircase in Munich's new radio station

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Wireless Magazine. Deem/v/7 1929

CONCENTRATORA unit that will give in-creased selectivity with-out loss of strength asis experienced withordinary w av e tr ap s.Simple to build and

easy to operate

A production of the' W. M." Technical

Staff

ADDED TO YOUR SET WILL GIVEBETTER SELECTIVITY, RANGE

\011411I111111/00"ANDVOLUME

Neat in appearanceand simple to

AT this time of the year many listeners think seriouslyof rebuilding their old sets into something more

up to date; but in many cases it is quite sufficient tooverhaul the old receiver and carry out only slight altera-tions to make it conform with modern standards ofperformance.

For the benefit of readers whose sets are satisfactorybut not quite good enough to cope with modern con-ditions, the WIRELESS MAGAZINEoffers details of a simple unitcalled the Concentrator, whichwill increase the range andselectivity of any set to which itis attached.

Amplifying UnitSo that there may be no mis-

understanding, it can be statedat once that the Concentrator isnothing more than a simplehigh -frequency amplifying unit-nothing more, but enough totransform an old and none -too -efficient set into one that willmeet the most exacting demands.

It is often assumed by lis-teners with only a slight tech-nical knowledge that the morevalves a set has the moreunselective it must be because ofits greater "power."

This is by no means true, forin the case of high -frequency

Use is made of an ordinarythree -electrode Valve. Manyamateurs will be able to buildthis unit with parts already in

their possession

operate

valves, every additional stage means (normally) an extratuning circuit. The more tuning circuits there are in aset the more selective it is

The greatest benefit of the Concentrator as regardsselectivity will be experienced with sets that have nohigh -frequency amplification incorporated. The singletuning circuit associated with the detector valve maynot be very selective, and the range will be more or less

restricted.

EF-600011

orwr

L

0005

UNITOUT I

Circuit of theConcentrator, ahigh -frequency

amplifying unit

0

HT.+

TO AERIALTERMINAL0003 ON SID

482

The addition of the Concen-trator to such a receiver willgreatly improve the selectivity,although the tuning will be alittle more complicated until themanipulation of the two circuitsis mastered.

Added RangeUnlike all forms of wavetrap,

which always decrease signalstrength slightly, the Concen-trator will add range. It shouldbe noted that distant stationswill, in effect, be amplified to agreater extent than "local"transmissions.

The unit has been deliberatelydesigned to make use of suchparts as the constructor of a two -or three -year -old set might beexpected to have on hand. Asimilar unit using a screened -grid valve was described in the

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WIRELESS MAGAZINE for March, 1929, under the title of" The Signal Booster."

The Concentrator uses an ordinary three -electrode valvefor high -frequency amplification, such as large numbers oflisteners already have in their possession. In such casesthe cost of construction will be low, especially if thereader also has a few plug-in coils, fixed and variablecondensers, etc.

Those who can read a circuit diagram will be interested inthat on page 482, which shows the theoretical arrangement ofthe unit. In the aerial circuit is a double -pole change -over switch. In oneposition this con-nects the Concen-trator to the mainset and switches onthe high -frequencyamplifying valve. Inthe other positionthe unit is switchedoff and the aerial isconnected direct tothe main receiver.

L.T. CoilAcross the grid

and anode of thevalve is connected atuning coil, the centretapping of this beingtaken to the valve fila-ment. The whole coil istuned with a .0005 -micro -farad variable condenser,while a neutralising condenseris connected between the valve anodeone end of the coil.

and

Anode Circuit ComponentsIn the anode circuit of the valve there is

also a high -frequency choke and a couplingcondenser of .0003-microfarad capacity.There are five terminals to be connected up,one for the aerial and two each for hightension and low tension respectively.

There is one important point about theuse of theConcentra-tor thatmust not beoverlooked.As H.T.-i s con-nected to

inthe

Anotherview of theConcentrator

Wireless Magazine. December. 1_92VI

SLOW-MOTION TUNINGDIAL CONDENSER

-

CHOKE

COUPLINCONDENSER

H.EVALVE HOLDER

AERIALSERIES

CONDENSER

OILHOLDER

NEUTRALISINGCONDENSER

This plan view of the Concentrator dearly shows thearrangements of the parts

Very little paneldrilling is necessary

when building the Concentrator

unit, these connections must also bethe same in the main receiver. IfH.T. - is connected to L.T. in themain set and the Concentrator is thenconnected to the latter, the low-tension supply will be short-circuited.

Before Connecting UpMake certain before connecting up

the Concentrator to a set that H.T. - isconnected to L.T.- in both cases.

The construction of theunit is within the capa-bilities of any listener whohas a few simple tools athis disposal. All theessential details will befound in these pages, butthose who desire one canobtain a full-size blue-print for half price, thatis, 6d., post free, if thecoupon on page iii of thecover is used by Decem-

4

tir 6"CoraV"o

PANEL 06 :6 O

BLUEPRINT II*9,1169

BASEBOARD 9"'06

O

1E9TRIPRMMAL

G" X 2

000,

7TAP

OM COM

-2,7tVEra`

tgRgt1/2.- 1-1T+ ETT LT- A

This layout and wiring diagram can be obtainedas a full-size blueprint for half-price (that is,6d., post free), if the coupon on page iii of thecover is used by December 31. Ask for No.

W.M.169

463

ber 31.

Where to SendAddress your inquiry to

Blueprint Department,WIRELESS MAGAZINE, 58-6I Fetter Lane, E.C.4,and ask for blueprint No.W.M.16p.

An extension of time forobtaining half-price blue-prints will be made in thecase of overseas readers.

The photographs repro-duced in these pages, con-sulted in conjunction withthe blueprint or the re-duced reproduction along-side, will show clearlythe construction of the

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The Concentratorwired up all readyfor use, with valveand coil in position

units and the positions of all thecomponent parts.

In the construction of the unitalmost any parts of equivalent valuesto those used in the original unit canbe used and satisfactory resultsobtained. Many readers will alreadyhave in their possession a number ofsuitable two -pin plug-in coils; itwill be noticed that these must heprovided with a centre tapping.

Wiring SimplicityWhen all the parts have been

firmly fixed in position, the wiring upcan be undertaken. No difficulty atall will be experienced if the wiringdiagram is used. It will be seen thaton this every wire is numberedseparately in order of assembly.

Thus, to wire up, first place wireNo. r in position and connect up bothends; then cross through this numberon the diagram. Carry on with wireNo. 2, and so on to No. 18, which isa short length of flex for connectionto the centre -tap of the coil.

Choice of Suitable ValveThe choice of a suitable valve for

use in the Concentrator is not a diffi-cult matter. It should be what isknown generally as the "H.F." type,with an impedance between 20,000and about 40,000 ohms. A number ofsuitable types will be found in thelist at the beginning of this issue.

It will normally be the most con-venient practice to use a valve witha filament of the same voltage asthose used in the main receiver,

Wireless Magazine. December. 19291

The Concentrator Continuedalthough, of course, thisis not absolutely essen-tial.

To connect up the Con-centrator, remove theaerial lead from the mainset and take it to theaerial terminal on theextreme right of the unit(from the back). Then

connect the secondaerial terminal onthe unit, at the ex-treme left on theterminal strip, tothe aerial terminalof the main set.

To the L.T. ter-minals connect anaccumulator of theappropriate voltage

for the valve to be used; this can bethe same accumulator as used forthe main set, provided a valverequiring the same filament voltageis used.

The best high-tension voltage willvary with different types of valve,but 8o volts should be tried atfirst.

When the unit is not needed,the knob of the switch on thepanel should be kept in, whenthe aerial will be connectedstraight through to the mainset.

To operate the unit, tune inthe local station on the mainset. Then pull out the knob

of the switch on the Concentrator.Use a No. 6o centre -tapped coil formedium waves and a No. 200 or 25ocentre -tapped coil for long waves.

It may happen that the signal com-pletely disappears. If so, retune themain set until it is heard and thenadjust the condenser on the unituntil the greatest volume is obtained.

Better Range and SelectivityAfter a little practice no difficulty

will be found in manipulating thecontrols of the main set and the Con-centrator in unison; a great. increasein range will be noted and the wholeinstallation will be very much moreselective than it was previously.

Another view of theConcentrator com-pletely connected up

COMPONENTS REQUIREDChoke, High -frequency

i-Ormond type R/15o, 7/6 (orReady Radio, Wearite).

Coils2-Atlas Nos. 6o and 25o, centre -

tapped, 4/3 and 6/6 (orIgranic, Lewcos).

Condensers, FixedI-Lissen .000i-microfarad, z/ -

(or Ormond, T.C.C.).I-Lissen .0003-microfarad,

(or Ormond, T.C.C.).Condlinsers, Variable

r-Formo .0005-microfaxad, 4/6(or Lotus, Ormond).

1-Jackson neutralising condens-er, 3/6 (or Peto-Scott, Bulgin).

Dial, Slow-motion1-Brownie, 2/6 (or Formo,

Lissen).Ebonite

I-Raymond panel, gin. by6 in., 2/6 (or Parfait, Pilot).

FOR THE CONCENTRATORi-Raymond terminal strip, 6 in.

by 2 in., I!,Holder, Coil

I-Magnum, baseboard type, r/6(or Wearite, Edison -Bell).

Holder, ValveI-Trix Bob -brown, IF (or Mar-

coniphone, Magnum).Switch

1-Lotus jack type No. 8, 3/6.Terminals

6-Eelex, marked : Aerial (2),L.T.+, L.T.-, H T.+,H.T.-, 2/3 (or Burton, Bell-ing -Lee).

RECOMMENDEDACCESSORIES

Cabinet7-Pickett (or Camco, Ready

Radio).Valve

x-Cossor HF2io, zo/6 (or Mazda2IoHF, Marconi HL2Io).

The prices mentioned are those for the parts used in the original set; the prices of alternativesas indicated in the brackets may be either higher or lower

484

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Wireless Magazine. occembir: 1929

TOO HELL -O!

EFRN

DISTANT VOICE : "Alf, whatever's the matter with young Bill ?

ALF : " 'Sorlrite, Mum, we're playin' broadcastin' an' Bill's listenin'-in."

485

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Wireless Magazine. December. 1929

LEAVES ,5fLISTEN ER'S LOGEACH month appears to bring

with it at least one additionaltransmitter to the broadcast band,and if comparison be made with thesame period a year ago, it will befound that Europe's stations haveincreased both in number andstrength.

The latest additions to date areLuxemburg and Algiers, two citieswhich up to the present have beenbeyond our horizon. For some timenow, the little Grand Duchy which iswedged in between Germany andBelgium has been playing with aprivately -operated toy broadcastingstation which failed to give satisfac-tion to even strictly local listeners.

A Big EffortTired of being compelled to turn

to Germany or France for their wire-less fare, the Luxembourgeois havemade a big effort ; they have raised theE.um of three million francs, createdthe Compagnie Nationale de Radio -diffusion, and installed a slap -bangup-to-date 3 -kilowatt transmitter onthe summit of the Kohlenberg, ahill in the vicinity of Cesange-Luxemburg. From October r, thebroadcasts on 223 metres have beenof daily occurrence, and graduallythe programmes are being extended.

Now, the Grand Duchy is one ofthese little frontier or buffer Statesblessed-or cursed i-with two differ-ent languages, and a popular dialect,and the male announcer who offici-ates in the studio is compelled to givethe call in all three. You will hearhim regularly in both French andGerman, and from time to time inLuxemburgisch.

Alarm -clock SignalAs an interval signal between

items, I have heard a sound whichmight emanate from an alarm clock;the ticking is not quite that of theordinary metronome. When closingdown the National Anthem is played,a patriotic song bearing the dialecttitle of OnsHeemecht (Our Fatherland).

The power of the signals is suchthat there should be no difficulty inpicking them up in any part of theUnited Kingdom. Give y..ur con-denser a slight twirl away fromCologne, and you should tune in

By JAY COOTERadio Luxemburg without inter-ference, for the transmitter is verystable on its wavelength.

To all appearances 1930 is to pro-vide a further crop of high -powerbroadcasters and gradually, it seems,the small stations will be thrown intothe background.

If the schemes put forward by thedifferent broadcasting authorities arestudied, you will find that the averagelistener within the next month or sowill possess a log of much smallerdimensions than at present, but thatas a compensation it will be possibleto rely nightly on a choice selectionof foreign programmes, more easilycaptured and no doubt held withoutdifficulty.

From Belgium, for instance, ifBrussels is not'always available, wehave as an alternative Radio Lou-vain, broadcasting with at least 8kilowatts in the aerial, whoseinitiative should furnish many novel-ties in the way of entertainment.

New Radio BillAs regards France, possibly-

although there still remains a strongdoubt-the new Radio Bill may be-come law, in which case some con-siderable reorganisation of the wholesystem will take place, and in thatquarter we may expect to see somehefty developments.

In the meantime, however, Stras-burg will be endowed with a 12 -kilowatt transmitter, and simul-taneously programmes from EcoleSuperieure, Paris, should be cap-tured at greater volume.

As regards the fate of such privatestations as Petit Parisien, Radio LL,Vitus, and other numerous " one-horse " installations, it is not easyto forecast what will actually happen.

Such threats as the closing downof Nice-Juan-les-Pins, as a protestagainst the continual breaking ofpromises made by the state authori-ties to give this region an effectiveservice, are to be withdrawn, for nowI am given to understand that after aresting period of some three monthsJuan-les-Pins is to blossom out as aworth -while transmitter.

486

With the number of stations in itsbroadcasting net, France may experi-ence considerable difficulty in allot-ting the wavelengths given to her,and for some time to come she maystill prove a disturbing factor in thegeneral European scheme.

Most Continentalstates areanxiousto possess super -installations, andamongst the probables are Spain,with Madrid (2o kilowatts), and Bar-celona (to kilowatts). Italy contem-plates a 50 -kilowatt transmitter forRome, another of 20 kilowatts forMilan; and an increase in the powerof Naples.A 60 -kilowatt Station

The new Czecho-Slovakian pro-gramme also comprises a 6o -kilowatttransmitter for the capital Prague,and the raising of Brunn to 35 kilo-watts; Sweden, as is well known, has agiant under construction and Norwaywith its Oslo transmitter should bynow be giving a regular programme.

But this is not all, as the Polishbroadcasting organisation is to beentirely remodelled on the B. itishB.B.C. plan with a view to providingalternative entertainments over agreater portion of the country. Thescheme calls for one 120 -kilowatttransmitter, and two high -powerregional stations at Lemberg andVilna, of at least 16 kilowatts aerialinput; mention is also made of somethree or four local relays to work ona common wavelength. The newsuper transmitter will be operated inaddition to the station now working,which is already heard over a greatpart of Europe.

Added to these we must bear inmind that Switzerland shortly in-tends to cany out sweeping changes,and Russia with its 1930-32 pro-gramme cannot be ignored.Less Time in Searching

If we take these various plans intoconsideration, I think we are safe insaying that in the very near future weshall not, as we have done up to thepresent, spend so much of our timein searching for weak distant trans-missions emanating from the Euro-pean continent, for most of the pro-grammes of any note are bound to bebroadcast through the high -powerstations.

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Wireless Magazine. December. 192J

A.AAA.A.A.AAAAAAAAAAAAAAAAAAkkAAAAAkAAAAAAAAAAA.A.AAAAAAAAAAAAA/AAAAAAAAAAAAAAAA

156 ANY faroifki fefsBROWN THREE -

VALVE KIT SET

Name of Set : Type A Brown Three -valveScreened -grid Receiver.

Maker : S. G. Brown, Ltd.Price :.£r2. (Other types and prices on

application.)Valve Combination : Screened -grid high -

frequency amplifier, detector, andlow -frequency amplifier.

WITH the introduction of theBrown models, the ever-increasing

range of kit sets has been notablyaugmented. This new kit set is made infour models; the A and AM modelsinclude a Brown loud -speaker, built intothe cabinet of the receiver; the B andBM models do not.

Battery or Mains OperationBoth distinct models are available for

either battery or mains operation. TheBrown kit set, therefore, has a wideapplication of uses, which should appealto all classes of listener.

We

The Brownthree -valve set with

self-contained loud-speaker

have recently completed theassembly of a Brown type A kit set,which has also been put through ourroutine laboratory tests as a completebroadcast receiver. We are able to saythat the kit completely fulfils the firstrequirement of its species, in beingextremely simple to assemble.

Favourable ComparisonIn its completed form the Brown kit

set compares favourably with factory -built sets employing a similar combina-tion of valves.

The instruction sheets are well pro-duced. They are almost an inducementto build the set, so carefully are theyarranged. The makers seem to haveprofited by the combined experience of

A SPECIAL Assembly of the Brown

FEATURE FOR three -valve set almostcompleted

SET BUYERS

other kit -setproducers.A separate

instruction sheetis arranged for

each definite stagein the assembly. In Stage i, for example,all the necessary instructions are givenfor the mounting of the components onthe baseboard. We found this part ofthe assembly perfectly simple andabsolutely above criticism.

Confusion is avoided at this stage bythe thoughtful provision of a baseboardaccurately stencilled with the shapes ofthe baseboard components. This goodidea appealed to us very much, for itshows that the makers are not relyingon the constructor's theoretical know-ledge to augment their instructions.

Even the screws for the componentsare carefully packeted and marked, so asto avoid the confusion that mightpossibly arise from one box of assortednuts, bolts, and screws.

In Stage 2, the constructor is shownhow to connect together the componentshe has mounted on the baseboard. Thepicture of these first seventeen wires is soclear that this part of the assemblycould be carried out without reference tothe wiring key. The length of each wireis given in this key and each wire has asimple reference number.

Referring to our notes, we see thatsome of the wire lengths were on thelong side, but this is preferable to beingtoo short.

Stage 3, the assembly of the front panel,and the connection of three furtherwires, brings the constructor to a mostinteresting stage. All the previous seven-teen wires now "take a back seat " bybeing printed in red instead of black asbefore. Now only the next three wiresare shown in black, and, as a result ofthis clever idea, the constructor at wire18 is no more confused than he was atwire number one.

The fixing of the variable condensersto the panel and their connection withthe rest of the receiver constitutes Stage4, and, more or less, completes theassembly.

In Stage 5, the whole of the actual setwiring is printed in red, but around eachterminal to which a battery lead has tobe connected are placed lettered blackrings. This idea of making the con-nections to be done stand out in contrast

487

to those alreadyfinished is highlycommendable.

The completed set cannow be described. It is athree-valver employing one screened -grid valve for high -frequency amplifica-tion, a detector valve, and a transformer -coupled power valve for low -frequencyamplification. The main controls are thetuning condensers, for aerial tuning andscreened -grid valve tuning.

Distortionless Volume ControlSubsidiary controls are the reaction

condenser, the volume control and theon -off switch. Volume is varied byadjusting the filament voltage of thescreened -grid valve. It is therefore apre -detector control and introduces nodistortion in its variation.

Although they were not embodied inthe original models, all -wave tuning coilsare now fitted as standard in the Brownkit sets. Our first tests were made with

SETS WE CANRECOMMEND

from personal experience underboth normal operating and speciallaboratory conditions only arereviewed in these pages. Thismonth we report on the followingcomplete receivers, kit sets andmains units :-

PAGEBrown Three -valve Kit Set 487

Cecophone Short-wave Set(Three-valver) - - 488

Lewcos Three -valve Chassis 489

Regentone Mains Units forA.C. and D.C.

Ekco-Lectric SGP3 (D.C.) - 491

490

Also, on page 504, there is a listof more than 170 sets arranged inconvenient price groups and anarticle on " Choosing A Setfrom the W.M.' Buyers' Guide."

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Wireless Magazine. December 1929

Tests of the New Season's Best Sets Continued

Every set of which a report appears inthis regular feature has reached acertain standard of efficiency in ournew testing laboratory. No reports willbe given on receivers that do not reachthis standard; it will be understood,though, that only a limited numberof the good sets actually tested can be

discussed in each issue.

the medium -wave coils originally pro-duced and we were able to make aninteresting comparison.

These coils are somewhat bulky: thealteration of wavelength range is broughtabout by means of a small rotary switchconveniently mounted on each coil. Thelid of the set has to be lifted to changewavelength bands.

Pleas ant SurpriseThese all -wave coils do not appreciably

reduce efficiency when compared withthe old coils. This was rather a pleasantsurprise for us. Themakers were wise, wethink, in alteringtheir coils, for theconvenience of all -wave coils is nowdemanded by almostevery listener.

The tuning dialsare pleasantlysmooth in operation,the slow-motiondevice being good.We found thevolume controleffective in reducingthe strength of sta-tions received at Gecophonegreat intensity. Re-action is rather fierce and is inclined toparalyse the action of the set unlesscarefully applied. As a fact, we did notoften have to use much reaction, becausethe set is really sensitive.

As might be expected from the Brownlow -frequency transformer and theBrown loud -speaker chassis, quality ofreproduction is of a high order. There isplenty of base, but no "boominess." Apentode output valve, which was notstipulated by the makers, imparts apleasing crispness to the tone.

Great SelectivityBrookman's Park was in the designers'

eyes before the Brown sets were pro-duced; as a result of their foresight, theBrown sets have a degree of selectivitythat, although not at present universal,will soon have to be when regional trans-missions make unselective sets useless.

Selectivity in the set tested was of thekind that makes it quite difficult to findeven the local stations until the correctdial readings are obtained. We are,therefore, glad to see that approximate

dial readings forthe principal Euro-pean stations areincluded in the in-struction sheet.

When completed,the Brown A typekit set is a self-contained radioinstallation,requiring only theaddition of an aerialand earth. Amplespace is availablebehind the loud-

/speaker for bothhigh-tension and

low-tension batteries.The convenience of this type of set,

which does away with untidy batteryleads, is becoming more and moregenerally appreciated by discriminatinglisteners.

THOSE OF YOUR FRIENDSWHO ARE THINKING OFBUYING NEW SETS BEFORECHRISTMAS WILL BE GLADTO KNOW OF THESE SPECIAL

" W.M." REPORTS

short-wave three -valuer connected up ready for use

GECOPHONESHORT-WAVE SET j

Name of Set: Gecophone Screened -gridShort-wave Receiver.

Maker : The General Electric Co., Ltd.Price: Which includes valves,Valve Combination: Screened -grid high -

frequency amplifier, detector, andtransformer -coupled low -frequencyamplifier.

TO don a pair of headphones and,holding one's very breath for fear of

interruption, wrestle with dials that onlyjust hold the faintest whisper of a soundborne through ro,000 miles of the etherof space-that might well have been afrequent experience of a short-wave fanof a few years ago.

But, to -day, the more sophisticatedbroadcast listener insists upon somethingmore tangible-if less glamorous-beforehe will forsake the familiar broadcasting

488

wavelengths between zoo and 2,000metres.

If we take it that the only argument infavour of short-wave reception likely toinfluence the broadcast listener is awidening of his present reception facili-ties, we are on much surer ground nowthan we were a few years ago.

A glance through a list of short-wavestations will show what the short waveshave to offer; New York can be heardevery night, and quite frequentlyAustralia; Kenya, Java, and Madeira-the list covers almost every pointon the globe.

Unique PossibilitiesWe are trying to show that here, in

this country, short-wave reception isalmost as worth while as, presumably,it is in the Dominions; the sale of short-wave sets in this country, for home use,would be considerably increased, wethink, if the manufacturers concernedwere to make more of the uniquereception possibilities of such sets.

The General Electric Co., Ltd., as oneof the "big noises" in the electricalindustry of this country, quite naturallythinks in terms of Empire when design-ing radio sets for sale throughout its far-

flung organisation; andin the production of theGecoph one short-waveset we have anothergratifying example of afirm that is, at last,really getting down tothe business of establish-ing a British pre-emi-nence in radio that someof us believe is possible.

We have had theGecophone short-waveset, which has just beenintroduced by theG.E.C., on test for severalweeks past, and ourvaried experience of itenables us to recom-

mend it with a whole-heartedness that isnot always possible without reservation.

One of the most interesting receptionfeats of which the set is capable was thedaily tuning -in of Australia. On about 29metres we received loud speech from anamateur of some importance, whofrequently got into touch with theEnglish relations of settlers in Australia.We tuned in 2 XAF, the American broad-casting station on 31 metres, as a matterof course.

Astonishing RangesThe variety of languages to be heard

during an evening at the dials of theGecophone short-wave set would astonishthose with quite powerful broadcastreceivers. The extraordinary range oflow -power amateur telephony stationsprovides some unexpected surprises tothe newcomer to short waves.

We- heard an amateur in Elsinorecalling as clearly as we heard one insouthern Italy, and neither were appreci-ably less strong than a local amateurin London.

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Wireless Magazine. December; 1929

Complete Three -valve Sets, Kit and ChassisThe Gecophone short -waver is a

three -valve set completely enclosed in acompact metal box Removal of the lidby undoing four screws reveals asimplicity of layout characteristic ofshort-wave sets. The three valve holdersare arranged in a row at the back of thebox, with the coil holder convenientlymounted between the screened -gridvalve holder and the detector -valveholder.

Ease of ControlWith the valves and coils in position,

ample space is left for the variablereaction and tuning condensers. These,together with the potentiometer, aremounted on the metal panel, which formsone side of the box. Both variable con-densers have widely spaced vanes; takenin conjunction with the well-knownGecophone slow-motion device, thisrobust construction assists in the ease ofcontrol of the set.

Some may object at having to undofour screws to remove the lid every timeone of the plug-in coils needs to bechanged. But we do not think this is avery fair criticism, since one of threeavailable coils will be in use more thanthe other two in any given locality; weare thinking of the world now and not ofa district in England !

One little thing we do not quite under-stand has to do with the battery cordwhich we note only provides connectionsfor the high-tension and low-tensionbatteries; for the grid -bias battery con-nections separate leads have to beprovided-whyRobust Low -loss Coils

The coils are typical short-waveinductances, robustly constructed onlow -loss principles. Tuning and reactionwindings are brought out to four pinsmounted on a strip of insulating materialunderneath each coil.

The operation of the Gecophone short-wave set is interesting. It should beexplained that the screened -grid valveincorporated in this set is as much astabiliser of tuning and reaction as it isan effective amplifier.

A screened -grid valve eliminates a lotof the hazard in short-wave tuning. Ithas the additional advantage that easyoscillation of the detector valve isrendered possible right down to the

Another view of theGecophone short-wave set showingthe neat layout and

- wiring

low wavelength ofr9 metres, evenwhen the aerial is aninefficient one.Down to about25 metres,tuning is notat all "knife-edge

Reactionis delight-fully smoothwith this set, pro-vided that a logicaluse is made of the potentio-meter control. As it is notexpounded at length in the instruc-tion book, we take it upon ourselves topoint out that the potentiometer is analmost indispensable adjunct to thereaction control. At first, the knob of thepotentiometer should be turned to itsmaximum position, in a clockwisedirection. So placed, reaction will befound so smooth that, when the detectorvalve begins to oscillate, it will hardly benoticed.

Having tuned in a station and reducedreaction to a point just below oscillation,the potentiometer knob should be turnedin an anti -clockwise direction, until anappreciable increase in volume is noted.An increase in reaction will then, in allprobability, produce an unpleasant"plop."

It is the operator's task to effect acompromise between the adjustment ofthe " pot" control and the reactioncontrol. More especially on signals ofweak intensity, it is advisable to increasethe strength by reaction, rather than bythe potentiometer. So with weak signalsthe rule should be to keep the potentio-meter in such a position that reallysmooth reaction is maintained.

Of the three coils provided, themiddle-sized one was found most useful,since it covers a wavelength range ofapproximately 32 to 65 metres. Thesmallest coil tuned right down to about19 metres and up to 4o metres, and it waswith this coil that the 31 -metre Americanbroadcasting station was tuned in. Thelargest coil goes right up to 105 metresand is quite useful for the reception oflocal amateurs.

We understand that a coil can beobtained covering approximately 12 to19 metres. Those who consider a short-

wave set somewhatof a luxury canreceive the local sta-tion on the broad-cast band with stillanother coil covering.270 to 550 metres.These are " extras "that normally are notrequired.

We found the con-denser -dial calibra-tions for the threecoils extremely use-ful and quite accu-rate when comparedwith our standardshort-wave wave -

489

The Lewcos three -valvechassis with coils for both

wavebands

meter. These calibrations, when used inconjunction with the list of short-wavestations also included in the instructionbook, make it perfectly easy for thenovice to "find" himself on the shortwaves.

Good Loud -speaker StrengthFor most of our tests with this set we

used headphones, but for those whoseonly interest is in loud -speaker reception,it is interesting to record that, on anindoor aerial, the American broadcastingstation was received at good loud-spe.kerstrength.

LEWCOS THREE-

VALVE CHASSIS

Name of Set: Lewcos Chassis.Maker : London Electric Wire Co., I tdPrice : 7.

Valve Combination : Screened -gridhigh -frequency amplifier, detector,transformer -coupled low -frequencyamplifier.

WE have recently been experimentingwith an unorthodox piece of radio

apparatus, which for want of a moreaccurate definition, we may call theLewcos three -valve " chassis." Asimplied, this Lewcos product forms thebasis of a complete three -valve set. It isa three -valve set, except for variablecondensers, reaction condenser, on -offswitch, panel and cabinet.

Efficient ComponentsLewcos coils of all types are well known

to WIRELESS MAGAZINE readers, as isthe Lewcos high -frequency choke. Thesewell -tried accessories, in conjunctionwith a new Lewcos product, the Lewcoslow -frequency transformer, can form thebasis of an efficient three -valve set.

AS FAR AS POSSIBLE WE SHALLENDEAVOUR TO GIVE REPORTSON SETS WHICH PARTICULARLYINTEREST OUR READERS-SO

JUST DROP US A LINE

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'Wireless Magazine. December: 1929

Tests of the New Season's Best Sets Continued

It is there-fore quite logical that the

makers should have assembledtheir high - and low -frequency couplingdevices on a baseboard which also accom-modates three valve holders and thenecessary terminals for batteries andexternal components.

External ConnectionsBefore we could test the chassis, it was

necessary to connect up to appropriateterminals two .0005-microfarad variablecondensers and a .0002-microfarad reac-tion condenser, as well as a simple on -offswitch. The photograph shows howthese simple additions were made.

On the side of the unit near the aerialand earth terminals is a small metal linkwhich, according to its position left orright of a central contact, makes the setsuitable for directly- or indirectly -heatedfilament valves. The makers had inmind the fact that when A.C. valves withindirectly -heated filaments are employedin an all -mains set, the filament circuitis a modification of that invol,,eri ina normal battery -operated set. Thethoughtful provision of this filament linkis commendable.

There are four Lewcos coil unitsincluded in the Lewcos chassis, two pairsbeing placed one on each side of a smallvertical screen separating the screened -grid valve from the detector valve.

The aerial coils are the normal BAC5and BAC2o types, and those for thescreened -grid valves are the morerecently -introduced BSG5 and BSG2otransformers. The use of these trans-formers enables the screening to bereduced to a minimum and goodamplification to be obtained from thescreened -grid valve. Each pair of coilsis movable on a special base controlledby knobs fitted to the end of spindlesprojecting from the bases.

Wave -Change DeviceBy this push-pull action, a dual range

of wavelengths is available; by pullingthe knobs away from the panel, themedium wavelength coils are put intocircuit and by pushing these knobstowards the panel the almost equallyuseful long waves are available.

Connected up with a batch of Osramvalves and the usual Ito -volt battery forhigh tension, the Lewcos chassis behavedwell. There was no trace of instability on

Tuning con-densers con-nected ex-ternally tothe Lewcos

chassis

either longor shortwaves a n dthe amplifi-cation ofweak signalswas good.

As part ofan all -electricset, the Lew -cos chassisalso gave a

good account ofitself. It was necessary

to use a detector valve with a fairlylow impedance, such as the Mullard type354 mains valve, in this connection. Inpassing, readers may care to know thatthe makers are now developing a powerunit which will convert the Lewcos chassisto a complete all -mains receiver.

In noting the quality of reproduction,we were particularly interested to seehow the new Lewcos low -frequencytransformer worked. This couplingdevice is sturdily built and appears tohave plenty of wire and iron in it.Anyway, it gave extra good qualitywith an " H.L. " type of valve as detec-tor. We think it is a good transformer.

DO NOT OVERLOOK THE LISTOF SETS-ARRANGED ON APRICE BASIS-WHICH APPEARSON PAGE 504 OF THIS ISSUE.

This Regentone WICmains Unit gives hightension of 120 volts at

20 milliamperes

HOW OLD READERSCAN HELP US.

This new feature is of par-ticular value to listeners whonormally have no particularneed far a radio paper ofany kind. Old readerswill be doing their friendsa service by bringiug it totheir notice-and the morereaders we have the betterwe shall be able to cater for

all radio interests.

490

For A.C. mains only

REGENTONEMAINS UNITS

Name of CimIs : Regentone De -LuxeD.C. Model; Regentone WiC A.C.Model.

Maker : Regent Radio Supply Co.Pric?..s : 3 18s. for D.C. Model; i3 15s.

for A.G. Model.FROM the wide range of Regentone

mains units we have selected two ofthe most useful for test in theWIRELESS MAGAZINE laboratory. Togain a general idea of the Regentoneunits, we have tried one for A.C., and an-other for D.C. supply.

Both units tested are, in our opinion,very reasonably priced, and should meetthe needs of the listener with an averagethree -valve set.Voltage Allowance

The first unit tested was the WiC,which was connected to a 205 -volt A.C.supply. In connecting up, we notedthat near the flexible lead coming fromthe mains unit is an insulated block,having two sockets to make allowancefor the wide variations in A.C. voltagesof supply. One socket is for zoo- to220 -volt mains and the other for 230- to250 -volt mains.

To take an average condition, weconnected the unit to a three -valve setemploying a

screened -grid valve,a detector, and asmall power valve.The common high-tension positiveterminal of the setwas taken to theterminal marked "P"on the unit. Thescreened -gridterminal from theset was taken to theunit terminal marked" Var." A leadbetween the high-tension negativeterminals of the unitand set completed

the connections. The valves used in theset were Marconi types S215, HL2io,and DEP215.

As a preliminary test, we noted thatabsolutely no hum was audible, evenwhen listening a few inches from theloud -speaker. No appreciable hum wasnoted when the oscillation point wasapproached. This is usually a good testof the smoothing of a mains unit, whichin this one appears to be excellent.Loud, clear-cut signals, characteristic ofa mains -operated set, were readilyobtainable.

No Crackling NoisesThe best position of the knob varying

the screened -grid voltage was easily_found. During the rotation of this knobno crackling noises developed. The Ile \\

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! Wireless Magazine. December 19291

Short-wave Set : D.C. & A.C. Mains H.T. UnitsRegentstat voltage -adjuster controlledby this knob on the unit works verysilently.

The measurements taken with Fer-ranti meters gave a useful index to thegeneral utility of the unit. With ananode -current consumption of 14 milli-amperes, the maximum voltage atterminal " P" of the unit was found to be125 volts. The voltage variation atterminal "Var" was from zero to 115volts. This is a useful variation for ascreened -grid valve set.

With a super -power valve in place ofthe small power valve, the anode -current

OUR FREE SERVICE OFADVICE TO SET BUYERSTo take advantage of thisservice it is necessary only tomention (1) the maximumprice and whether this is fora complete installation or thebare set ; (2) where the setwill be used ; (3) what par-ticular stations are desired ;(4) whether a self-containedset (with or without aerial),or an ordinary set withexternal accessories is pre-ferred ; and (5) in the caseof mains -driven sets, whetherthe mains are A.C. or D.C.A stamped addressedenvelope for reply is the only

expense

consumption increased to 20 milli-amperes; but the maximum voltagederived from the unit was as before.

The makers rating for the WIC unit is120 volts at 18 milliamperes. Our testsshow that this rating is, if anything,conservative. We can safely say that upto a load of zo milliamperes the maximumvoltage will certainly not be less than120 volts.

Well -finished CaseIn its general construction, the unit is

excellent. It is well protected by apleasingly -finished metal case. It isquite compact, being only 8y2 in. by6 in. by 2% in. We note that, in com-mon with other makers of mains units,the Regent Radio Supply Co., fit theirflexible leads with lamp -socket plugs.Personally, we should imagine that thereis more demand for a two -pin plug, butwe understand that this firm will, ifrequested, make the alteration withoutextra charge.

Although it is not a serious fault, wethink the terminals on the unit are placedrather too close together and too close tothe knob of the Regentstat.

A big advantage in this type of unit isthe inclusion of a Westinghouse metalrectifier, which should be almost ever-lasting. The makers have had a wideexperience of this type of rectifier and,as our tests of this unit show, that

experience is clearlyevident in the excel-lence of its per-formance.

A rather largerunit is the RegentoneDe -Luxe D.C. model,which is providedwith two variablehigh-tension tap-pings, as well as amaximum -voltagepower -supply tap.This unit was con-nected to a three -valve set employingfour -volt screened -grid, detector, andpentode valves. Thetotal anode -current consumption was 3omilliamperes.

The voltage at terminal "Power" wasfound to be 155 volts. Voltage variationpossible at "Var" was between to and140 volts. Voltage variation possible atterminal "Screen" was similar.

These readings compare quite favour-ably with the maker's rating, which is,160 volts at 5o milliamperes, withvariations between zero and 140 volts forthe other supplies. A low -melting pointfuse is a thoughtful inclusion in theflexible lead from the unit to the mainsplug. When using such a D.C. unit it is,of course, necessary to connect the earthwire to the set through a large fixedcondenser.

To those with a D.C. supply and a bigset requiring several different high-tension voltages, we can heartily recom-mend the Regentone De -Luxe model,which is not only well made, but has itsknobs and terminals convenientlyarranged.

EKCO-LECTRIC I

SGP3 (D.C.) I

Name of Set Ekco-Lectric SGP3.Maker : E. K. Cole, Ltd.Price : £21.Valve Combination: Screened -grid high -

frequency amplifier, detector, andpentode (five -electrode) output valve.

AS we said lastmonth, the large

proportion of D.C.-mains supplies in thiscountry appears to havebeen neglected bysome makers of all -mains sets. In fact, theconcentration on all-A.C. sets has been oneof the few concertedactions on the part ofradio manufacturers.

As a result the com-paratively few firmsoffering reliable D.C.-mains sets are nowexperiencing a big de-mand for their pro- Underneath view of the Ekco-Lectric SGP3, showing theducts. E. K. Cole,

This Regentone De LuxeD.C. unit gives 160 volts

at 40 milliamperes

For D.C.Mains

Limited, as pioneers of D.C.- and A.C.-mains units, have, we understand, foundit difficult to cope with orders for theirSGP3 sets, which are made foreither A.G. or D.C. supplies. Wehave only recently been able to test thelatter.

Housed in a distinctive cabinet,designed on modernistic lines, the EkcoSGP3 is an interesting example of anall-D.C.-mains set. From an examina-tion of its exterior, the set certainly doesnot lack in variety of controls. To oneside of the escutcheon plate is whatmight be termed the main control, thisbeing the knob that rotates the gangcondenser and dial.

To the left and right of this are twosubsidiary control knobs. That on theleft is a "compensator" for the maintuning and has not always to be operated.The reaction knob on the right is morefrequently used, especially when theincoming signals are weak. Beneath theescutcheon plate is a fourth knob, butas this is for changing the wavelengthband, here, again, it is not a real com-plication.

On the left of the cabinet is fitted asturdy make -and -break switch, which isused for connecting or disconnecting themains supply. Close to this is stillanother knob, which serves the dual,purpose of controlling the volume andselectivity obtained from the set.

In considering the control of theSGP3, it is obvious that the makershave not sacrificed efficiency by eliminat-

491

horizontal mounting of the valves

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Wireless Magazine. December 1929

BEFORE BUYINGA SET OR MAINS

UNITread through the WIRELESSMAGAZINE reports of new sets,which are quite unbiased,authoritative and based onactual operating experience.

* * *Now that there are so many

receivers from which to chooseit is more than ever necessaryfor the prospective buyer tohave an impartial opinionbefore making a purchase.

* * *Up to the present the follow-

ing sets have passed through theWIRELESS MAGAZINE labora-tories and can be recommendedfrom every point of view :-

OCTOBER

Pye No. 360 Receiver(Three-valver)

Lissen Radio Gramophone

Ferranti Screen -grid Three

Oldham Auto Power Units(H.T. and L.T.)

NOVEMBER

Philips Model 2511(Four-valver)

Aero Short-wave Converter

Marconiphone Model 44(Four-valver)

Kolster Brandes Portable

Gecophone A.C. Three

Gambrell All -electricThree

Climax D.C. MainsH.T. Unit* * *

A limited number of copiesof these issues is available atIs. 3d. each, post free, onapplication to the Publisher,WIRELESS MAGAZINE, 58-61Fetter Lane, E.C.4.

Tests of the New Season'sBest Sets Continued

ing controls that are really desirable.They have given the listener what ispractically one -dial tuning; but becauseaerials differ so greatly, the additionalcompensating control of tuning has beenfitted. Sensitivity should be equallygood on all aerials. As this is only athree -valve set, reaction, even thoughthe valves are extraordinarily sensitive,is still a necessity. And no set withoutdual -range -wavelength facilities can beconsidered complete to -day.Important Asset

The advent of Brookman's Park andthe near possibility of further regionalstations makes selectivity an importantasset of a set. We are, therefore, glad tosee that the makers have made provisionfor increasing the selectivity, should it benecessary.

The bottom of the set can be removedin a second or so to expose part of theneat layout. The three valve holders areconveniently placed in this sub -sectionof the set. The makers recommend abatch of three Mullard valves, thesebeing the PMI4 screened -grid valve,PM4D X detector valve, and PMz4pentode valve. All these are 4-volters. Ininserting these valves into the valveholders flexible leads for the screened -grid and pentode valves have also to beconnected to the auxiliary terminals.

A plug and socket arrange-ment provides for a wide varia-tion in the D.C.-supply voltage.The three tappings are marked" zoo/2ro," "220/230, and"240/250." As our voltage ofsupply is 205 volts, we in-serted the wander -plug in thefirst socket. Next to thissocket arrangement is a similarone, whereby three alternativesmoothing connections may bemade, according to the charac-teristics of the mains used.

In our tests, using the specifiedvalves, we could not detect anydifference in performance wheneach of these alternative smooth-ing connections were tried inturn. Rotation of the maintuning knob soon brought in Brookman'sPark and 5GB. We were impressed withthe good quality of reproduction, as de-livered by a number of our standard testloud -speakers. No background of humwas audible, except when the oscillationpoint was approached, when a slight, butnot objectionable, noise developed. Theset appears to be extremely sensitive, andin the evening a number of stations werebrought in at good loud -speaker strength,with a minimum of tuning difficulty. Wefound the tuning compensator, whencarefully adjusted, brought up thestrength of some of the distant stationsvery appreciably.

Reaction was not required for themore powerful stations. Its smoothnessmade it a pleasure to use on the weakerstations, the strength of which it greatlyincreased.

492

These remarks apply to both wave-length bands. The performance appearsto be about equal on both.Good Selectivity Control

The selectivity control on the side ofthe receiver was tried with interest. Wefound that by first tuning in a fairlyweak station at its maximum volume, wecould reduce the interference fromBrookman's Park without altering thetuning. A slight diminution in thesignal strength of the distant station wasthen noted. We are of opinion that thisselectivity control will prove valuable tothose residing within the " wipe-out "areas of regional stations. As a volumecontrol we are not so impressed with theknob at the side of the set. We found itbetter to reduce reaction to a minimumand slightly to detune with the com-pensator.

Provision is made for the use of agramophone pick-up. The leads fromthe pick-up, when plugged into twoclearly -marked sockets, are connected tothe last two valves of the receiver. Theelectrical reproduction of gramophonerecords in this way was good. Anexternal volume control must be usedwith the pick-up. The volume of soundwithout this additional control is toogreat. As when used as a radio set, thequality of the reproduction when the

Note the neat caseof the Ekco-Lectric

SGP3.

SGP3 is a gramophone amplifier is verygood.

Apart from very infrequent renewals ofvalves, the maintenance of this set is notlikely to be troublesome. The makersgive some interesting figures for thepower consumption of their set. Therunning cost for I,000 hours at, say, six-pence per unit, works out at 2os. Inview of the convenience and efficiency ofmains operation, this cannot be con-sidered excessive.

A.C. Model AlsoThe SGP3 is also 'available for A.C.

mains at the same price; in the nearfuture we hope to be able to review it.Meanwhile, to those with D.C. mains, weheartily recommend the D.C. model,which has given a good account of itselfin our tests.

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Wireless Magazine. December. 1929

VYVvirvvTT-IVYTT7V7r1VITYY7YYVITIIMYVVY7TVVvVYVvvvyVyvvvvyyvyyvyyvvyyyTyyyyvv

RadioEvolution

In this article QUEUE explainshow members of the " W.M."Technical Staff sometimes"discuss" advance commercialdesigns with manufacturers !

STALE news, I am told, is neverwanted. And yet I have a piece

of news, the origin of which datesback to last Show time, which Ithink will interest readers. In par-ticular it will interest a small groupof manufacturers who . . . but I ambeginning at the wrong end of thestory.

The story began, as I have said,last Show time. I was pushing myway through the crowd and seeingwhat I could when I felt a friendlythump on the back. It was the Manu-facturer.

"Queue, old man," he said, "Iknow you are keen on portables.Come over to my stand and have achat about a really good set 1"

I went." Queue," he said, " I am bringing

out a new portable. The technicaldepartment have made up seven setsfor trial, but I don't like any of them.I am afraid our technical people aretoo technical. You are an averageman. If you wanted a good portablewhat would you do ? "

Buy A Super X Five!"I should go to the X stand over

there," I said, `and buy a Super XFive."

" Fool," said the manufacturer. " Ican't buy up the entire stock of myrival's portables. Besides, I wantsomething bigger, and better-"

He waxed eloquent. The hour grewlate, so we postponed the discussionuntil the next day.

At a reasonable hour of the morn-ing I met him again in the large airydrawing office, which had seen thebirth of a number of famous com-ponents, and at least two well -

A manufacturer's "mystery" portable undergoing tests by amember of the "W.M." Staff

known "threes." Here there was nofriendly Show atmosphere.

"You see, Queue," he explained,"my sales manager tells me that ifwe make a portable of any kind,bearing our own name, we are boundto sell at least-. But, as you know,there is a golden opportunity if onlywe could bring out something unusual.And I want you to suggest something."

Five -Valuer for £10 ?" Why not make a good set down

to a price and sell a five-valver, com-plete for £r°? " I suggested tenta-tively.

"No," he said, "I admit that wecould make a workable set for acouple of fivers, but . . . well, justlook for yourself.

"The price is ito, you say. If wetake off the cost of royalties thatleaves about LB ins. Now assumethat I can get a Continental importerto let me have a contract for the valvesat 4s. a piece, that brings the pricedown to £7 15s. My own profit on aset of that selling price is 3os., andif you add to that the factors' profit,the price comes down with a flopto about £4 Los.

" Now what have we to provideout of that? Accumulator and H.T.battery? Yes, about would beright for those two articles, assuminga very cut price. That brings us downto £3 los. This sum has to provideall the other parts, the case, frame,aerial, loud -speaker, transformer forR.C. units, condensers, dials, switchesand so on.

" And on top of that is the cost ofassembly and wiring, an easy twohours' work. Assembling and wiringwould cost at least los., so all the

493

afore -mentioned gadgets would haveto be bought for £3. I know whereto buy at the right price, but-thequality . I ask you No, mydear Queue, the ten -pounder won'tdo."

" But," I said, " if you want toput the set out at a cut price, surelyyour margin of profit of 3os. isexcessive ? "

" No," he said, " you must remem-ber that from this figure of profit hasto be deducted all the overheadexpenses, which are big in my littlefactory. I have to pay, too, foradvertising, packing, despatch, andaccounts work. Probably only afew pence of that 3os. actually goesinto the pockets of my fellow workingdirectors. And even directors mustlive."

" Well," I replied, "as you haveopened your heart to me and toldme just what these things do cost,I suggest that you tack the otherway, put the price up to £15 and sella good -quality four-valver. Surelyyou can do that ? "

Specimen Sets for Tests"Come and see what our technical

brains have done," he retorted. Amember of the drawing -office searchedthrough drawers for circuit diagramsand blueprints, and, taking these, wewent over to a bench on which weredisplayed seven separate sets, allmade up in rough cabinets andapparently ready to work.

" These sets," explained the manu-facturer, "are rough hook-ups andnot made in every case with theactual type of component we shoulduse if the set were put on the market.For instance, this five-valver would

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Wireless Magazine. December 19291

Radio Evolution Continued

have to be sold with a slightly lessexpensive accumulator, H.T. batteryor set of valves than this three-valverhere, provided the retail price werethe same. ' '

I examined the sets closely. Twowere three-valvers, three were four-valvers and two were five-valvers.

I went into details a little and pickedout what to my mind were the mostinteresting and most " possible " sets.One of the three had one S.G. stage,a detector and a transformer -coupledL.F stage. The other had two trans-former -coupled L.F. stages only.

A Motley GroupThe " fours " were a motley group.

One had two S.G. stages and onetransformer -coupled L.F. stage, onewas very much the same, but had apentode in the output stage; thethird embodies my favourite circuit,namely one S.G. stage, and oneR.C. and one transformer L.F stage.

One of the five-valvers had twoaperiodic H.F. valves, and the otherhad two screened -grid valves andtwo transformer L.F. valves. I sawthe circuits of all these sets and satis-fied myself .regarding their technicaldetails.

" How do the prices run of allthese sets ? " I enquired.

" Well," replied the manufacturer," both the three-valvers are cheaperto manufacture than the four-valvers,but the five-valver with the aperiodicstages costs about the same as thefour-valver with the one S.G. stageand what you call the `R.C. trans.-

I took another look."If," pressed the manufacturer,

"you did not know anything aboutthe behind -the -scene cost of thesesets which would you pick ? "

My Own Choice" As a matter of fact," I said, " I

would pick the two sets you havementioned, namely, the four-valverwith one S.G. stage, and the aperiodicH.F. five-valver. I don't knowwhich I like the better. Without atest I don't think anyone could say."

" A test? My dear Queue, that'sjust what I want you to do. Takeyour pick, take 'em both, fora niceweek -end trip and let me know whichyou, my friendly Average Man,think my reputable firm ought tomanufacture 1"

So the week -end saw me with theset packed at the back of the car,making a trip down in the heart ofSussex.

To convince the manufacturerthat I had made my test as fully aspossible I took a couple of snapshotsof the two "mystery" sets in use,and you will see one of them on thepreceding page.

Neither of the sets proved to beideal for use in the car, but I blamethis more on the car than on the setsbecause of its metal body. I gaveboth sets a preliminary trial at acafé in a centre very well known tomotorists, but which, I suppose, Ihad better keep anonymous.

Here I blessed the five-valver,because of its ease of operation (therewas only one tuning dial, for bothH.F. stages were aperiodic) andmildly cursed the four-valver, be-cause its H.F. adjustment was rathertricky. I made a pencil note to theeffect that if the four-valver werefinally chosen the reaction controlwould have to be improved.

Strength from London and 5GBseemed to be about the same, butwhen we subsequently tried bothsets at our hotel at Angmering, andthe mileage had been increased byabout 25, the four-valver with itsscreened -grid stage certainly seemedto have greater powers for reachingout.

As Captain Kettle says, " whenseen make note of." And I dutifullydid make a careful note of the factthat as one got farther from the localstation the aperiodic H.F. set becametrickier to adjust if one wanted thesame volume as that given by thefour-valver.

I had gone rather carefully into thetwo circuits concerned, and, I wasnot quite convinced that the " R.C.-trans" arrangement was the bestto follow the detector of the four-valver, and I had taken a small trans-former in case the test should showthat it was needed.

After working the set for one night,right down at the South Coast, mydoubts increased to such a point thatI took out the R.C. unit and substi-tuted the transformer This madequite a difference to reception but,of course, the valve was not wellmatched (though I found out after-wards that the makers of this trans -

494

former do specify an R.C. valve of a'certain type to work with it as adetector).

The five-valver had two trans-formers and I changed the valvesabout in an endeavour to produce abetter matching of detector valve andtransformer in the four-valver. Atits best the four worked better thanthe five.

Without InterferenceThat is to say it brought in

London, 5XX and 5GB fairly freefrom interference (except spark,which is the bête -noire of the coastdweller) and at a strength greatenough to dance to in a closed room.The results on foteign stations werevariable, but there were four or fivealways at really good loud -speakerstrength-pleasant to listen to, butnot quite good enough for dancing.

The five-valver, on the other hand,brought in the three main stationsat about the same strength as thefour. Obviously the two aperiodicH.F. valves were working fairly well,though I doubted this at the time.Together, however, they had onlythe punch of the one screened -gridstage of the four -valve set.

I tried both sets with a shortexternal aerial, using the frame asthe tuning coil. This made quite adifference to the performance of thefive-valver, but the only differencenoticeable in the case of the four-valver was that the tuning wasaltered and broadened. Normally,the tuning of the four was very sharp.

There were snags in both cases.Monday morning saw me back againat the manufacturer's.

Which Shall. We Make?Well," said that worthy, ' which

are we going to push on with ? ""Neither," said I unkindly, ' if

you are wise, you'll stick to either thefour- or the five-valver, but they bothwant rebuilding."

"Rebuilding ! Why, mygood Queue,I've got to have the final planspassed within three days from now.What's wrong, anyway ? "

I brought out my pencilled list :Four-valver wants two transformersand anti -motor -boating device, re-action control is tricky and tuningcould be ganged if a small neutralisingcondenser were fitted as a balancer.

(Continued on page 507)

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Wireless Magazine, Decembel; 1929

011linknownPvelengthsiIS it true that a white lobster,

caught at Littlehampton, Sussex,was offered the B.B.C. for broad-casting purposes ?

L Obster.

A man who was summonsed forkeeping a receiving set without alicence said : "I sold it a year ago.The day before the detective called thebuyer brought it back for repairs."

The Inspector :" The common excuse,sir."

Woman at Marylebone PoliceCourt : "I don't object to my neigh-bour's wireless, because my daughter'syoung man likes it when he visits us."

Tom: "They claim to be connectedwith some of the best people."

Bill: "Yes, by wireless."

It was 6.3o p.m and the news hadjust been read from 2LO. A womanlistener who wanted to phone thebutcher and 2L0 got rather muddled

The Adventures of Alec Trode

A shop hand left an accumulatoron charge for six days.

Result : Discharge.

Husband and wife were discussingthe merits and demerits of women asbroadcasters. The woman had theworst of the argument.

She : "In the battle of tongues awoman can hold her own."

He : "Then why doesn't she ?"

with the numbers2L0 asked :

" Will you have any brains to-morrow?"

"It is not a long step from the gramo-phone to radio."

A foxtrot does it nicely.

Man (at Willesden) : "He wouldhave struck me, but he saw that I had

and when she

495

got

an H.T. battery in my hand, and heunderstood what was going on in mymind."

TheMagistrate : "And what didyou intend doing with the H.T. bat-tery? "

Man : "I had not quite made upmy mind about it."

A Welsh milkman has discovered acondenser that will revolutionise radio.Evidently his long experience withcondensed milk.

American SOS announcement :"Elizabeth is nineteen years old andsigns her name Queen."

That's why she never marriedprobably.

Clerk at Tottenham : " Does yourhouse join the house of the defendant?"

Witness : "No, there is an aerialbetween."

Marjorie : "Lucy has been tryingto learn how to manipulate her newradio set for a fortnight."

Tom : " Is the wireless engineerstupid ? "

Marjorie : "No, handsome."

A schoolboy howler : "Oscillation iswhat they do to your arm to stop youhaving small -pox."

Burglars broke into a house inDevon and stole a portable wirelessset shaped like a portmanteau, whichthey knew contained money.

They must have heard the notes.

There is a new radio gadget which isdescribed as "silent as the Sphinx."Sounds like an H.T. battery after ayear's use.

Diner : " What pudding was thatyou gave me ? "

Waiter : "Our latest radio pud-ding, madam."

Diner : "I suppose the bits ofglass were valves."

Willesden Wife :" We had a separa-tion order some months ago. Then hegave me a wireless set, so we livedtogether again and it squashed it."

Wireless bursts.

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Wireless Magazine, Decembent929

*Nis PakYrJ.H4yNER,B.sc.A.m,EE

" When one first encounters this problem. one usually makes a hurrieddive for the receiver and begins to fiddle with everything possible."

THIS is the time of year when thepeculiar phenomenon known as

"fading" becomes particularlytroublesome. Everyone will haveexperienced the gradual falling awayof a signal until it is a mere whisper,or perhaps may have disappearedaltogether.

Fiddling With EverythingIndeed, when one first encounters

this problem, one usually makes ahurried dive for the receiver andbegins to fiddle with everythingpossible, it being incrediblethat the transmitting sta-tion itself could have variedin power so enormously.

Yet if this course of actionhas been taken, one is doomedto disappointment, for noamount of readjustment ofthe receiver will make anydifference to the results. Thesignal has faded out and thatis all there is to it.

When we get a little moreexperience, we put on adignified and, we hope, knowingexpression and say airily : " Ah,don't you worry; it will come backagain in a minute or two." Sureenough, without any alteration to thereceiver, the signal comes back, oftenwith renewed vigour, so that it isgreater than it was before.

Just "Fading "We speak to our friends, who are

supposed to know these things,having read the WIRELESS MAGAZINEregularly, and they say : "Oh, yes,of course, that is just fading."

" But what," you say, " do youmean by that? Has the sun got atthe works of the receiver and causedthe condensers to fade, or what ? "

Whereat they laugh scornfully, butare, nevertheless, unable to give usmuch assistance.

Fading is certainly a puzzlingphenomenon. It is quite beyond thecontrol of listeners, at any rate as longas they confine themselves to theuse of one aerial and one receiver and,therefore, it is an evil with which wemust be content.

The town -dweller who listens to hislocal programme is not troubled withfading until he attempts to receiveforeign stations, and then he will find

This article explains insimple language that canbe understood by everylistener why signals vary

in strength

air are always in a state of more orless intense ionisation. This meansthat some of the electrons of whichthe atoms are composed are free andare shooting about without beingdefinitely attached to their parentatoms so that the molecules of gaswhich are left are electrified orionised.

Ultra -violet LightUltra -violet light, such as is pro-

vided by the sun, has a considerableeffect upon the extent to which this

ionisation is present while, in

N.

// 0.0 THIS INDIRECT/ ,e1 ..;Y*%"" tp.40, ARRIVES AT

"8" BY REFLECTION/ FROM MEAVI5IDE

LAYEREARTH

TI115 RAY NEVERGETS TO "B"

Fig. 1.-How wireless waves travel between two points

that what are often his best pro-grammes are the most liable to beinterrupted by this annoying fluctua-tion of signal strength.

The unfortunate dweller in thecountry, however, is liable to experi-ence fading even on his local pro-gramme. He may live a matter of 5oto roo miles away and fading at suchdistances is not only possible, butextremely probable. What, then,causes this variation in strength ?

In explaining this phenomenon, wemust have recourse once more to ourold favourite the Heaviside layer. Afew brief words of explanation aboutthis will be desirable before weproceed further.

The atoms of the gas which we call

496

addition, the pressure of theatmosphere exerts its in-fluence, for gases may bemore easily ionised at reducedpressure. Therefore, as we gofarther and farther awayfrom the earth, there is agreater tendency towardsionisation.

The whole of the time,however, the free electronsare re -combining with theiratoms so that the ionisation

tends to disappear unless it is main-tained by some suitable means.During the daylight, the influence ofthe sun is very powerful, as a result ofwhich the atmosphere at relativelylow altitudes is in a state of fairlyheavy ionisation.

A Sticky MediumWe thus have the atmosphere

electrified as a whole, and the effectof this is that wireless waves whichare radiated from a transmitter, onordinary broadcast wavelengths atany rate, have to force their waythrough a very sticky medium.

If we have a wireless wave passingthrough a heavily -electrified atmos-phere, all the electrons tend to

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Wireless Magazine, December 1929

oscillate in conformity with thewireless vibrations and this absorbsenergy so that wireless waves trans-mitted up into the atmosphere arerapidly absorbed and get nowhere.

At night-time, the influence of thesun's rays has disappeared and there-fore the ionisation near the grounddisappears also. As we increase theheight above the earth, however, thepressure gets less until a point isreached where the ionisation is alwaysmaintained without any externalinfluence. Moreover, it is found thatthis point of transition from electri-fied to unelectrified atmosphere isfairly sharp.

At Night-timeLet us consider what happens to a

wireless wave, therefore, at night-time. It leaves the transmitter in aslightly upward direction and travelspractically unhindered for some con-siderable distance, for there is now noelectrification of the atmosphere toabsorb energy. After a time, howeverit reaches this, more or less, well-defined layer of electrified atmosphereand this is exactly the same as a lightwave striking a mirror.

The wireless wave is reflected downto the earth again, some of the energybeing lost in the process, but thefact remains that it no* comes downto earth distanceaway from its starting point.

In Straight LinesThis explains the fact that many

signals are received at night-timewhich cannot be heard during theday. For example, consider twopoints on the circumference of theearth, as shown in Fig. 1. Wirelesswaves travel in straight lines, there-fore a wave radiated from A can neverget to the point B except through theearth, which it will not do.

If the waves radiated from A in anupward direction, however, are capa-ble of being reflected from an upperlayer of electrified atmosphere, thenit is clearly possible to receive at the

point B transmissions radiated fromA. This, indeed, is the only means bywhich B can receive transmissionsfrom A at all.

Let us now turn to the question offading. This phenomenon is onlyexperienced on such transmissions asdo come from the upper atmospherein the manner just described. Thereis nothing in what has so far beensaid, however,which supplies areason for a periodicvariation in thesignal strength.

We can, however,devise explanationsby making suitableassumptions. Letus suppose, for ex-ample, that theHeaviside layer isnot uniform, but isundulating incharacter. Then it is possible to con-ceive a state of affairs somewhatsimilar to that shown in Fig. 2, wherethe point B will receive waves fromtwo different directions, due to thefact that the layer of ionised gas is notuniform, but has a different curva-ture at two adjacent points. Thesignal strength received at B will thenbe the resultant effect of these twoindividual waves.

Even will not cause anyvariation, but suppose we assumethat the Heaviside layer is in a stateof fluctuation whereby its formationis changing, more or less rapidly.Then it is conceivable that the par-ticular arrangement shown in Fig. 2may only last for a few seconds, beingsubsequently replaced by an entirelydifferent arrangement.

In fact, the signals at Is may bereceived instantaneously from onepoint or from two or three points,and may conceivably never be thesame from one second to the next. Insuch circumstances, the signalstrength will fluctuate violently.

What is more, the waves receivedfrom one part of the Heaviside layer

may be in theopposite phase, ordirection, to thosereceived from anadjacent part, sothat, instead of thetwo signals addingup, they cancel out.We can, therefore,receive a number ofvarying signalstrengths betweennothing at all and a

PEER

Fig. 2.-Waves

signal several times as strong as thenormal.

Here, therefore, we have a validexplanation of fading. Fluctuationsof signal strength on this basis wouldprobably be somewhat rapid incharacter and actually this class offading occurs around sunset (andsunrise), and is usually known as"sunset fading."

arriving at B by two different reflections

Fig. 3.-Twisting of waves. The arrows represent the direc-tions of the electric fields

497

When the sun's rays are withdrawnfrom the particular portion of theearth over which the transmissionstake place, the ionisation near theearth rapidly disappears and, whilethe Heaviside layer is settling down,there is a very violent agitationtaking place so that reflections anddepressions take place in all sorts offashions, and signals vary gr. atly.

Layer More UniformLater on at night the evidence

tends to show that the Heavisidelayer is much more uniform and thatthere are not rapid variations takingplace. In such circumstances, ourtheory of fading is not tenable, andwe must look elsewhere to obtain asatisfactory explanation.

This is forthcoming, as a result of adiscovery recently made that theHeaviside layer does not reflect thewaves exactly as it receives them.It upsets what is known as thepolarisation of the wave. In order tounderstand this, a simple experimentis desirable.

Mechanical AnalogyTake a length of about To feet of

fairly heavy cord-a clothes line willdo very well-and attach the far endto a suitable fixed point. The nearend could be held in the hand and ifthe hand is jerked rapidly up anddown a ripple will travel along therope to the far end. This ripple is agood mechanical analogy of a wire-less wave which is only a similarripple produced in an imaginary ropiwhich we call the ether.

(Continued on page 502)

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Wireless Magazine. December.1929

This photograph shows the sz,000-volt direct -current generators used at Brookman's Park for supplying the valve anodes

A Successor to thePopular Brookman'sThree and Brookman'sTwo, which Were De-signed by W . JAMES

AFTER the Brookman'sThree and Brookman's

Two-noW the Brookman'sPush-pull Three Pheno-menal is the only word todescribe the interest that has beentaken in these new sets by W. James,Research Consultant of WIRELESSMAGAZINE.

AERIAL -TUNING MILLIAMMETER ANODE TUNINGCONDENSER CONDENSER

AVE- 'HANGSON -OFFWITCH

Solving the Problem

Just at the time when everybodywas realising that the advent ofBrookman's Park meant the need ofsuper -selective and sensitive sets-and wondering where they were tocome from-the WIRELESS MAGA-ZINE was able to solve the problemby giving readers details of W.James' Brookman's Three in theOctober issue.

Of this set the designer, who isknown by all home -constructors to bemost conservative in the claims hemakes, said :

The set is sensitive. More thantwenty stations have been received ina few minutes with ease. And thequality of reproduction is good.It is a three -valve receiver which

REACTIONWAVE- CONDENSER

li . ON -Oft CHANGE VOLUMERHEOSTAT SWITCH SWITCH CONTROL

Although the controls look complicated, the set is not difficultto operate, as never more than one or two knobs need be used

at the same time

will set a new standard, particularlyin regard to selectivity.Those claims have been more than

upheld in practice and the set hascreated a furore in radio circles. Thedemand for blueprints has beenenormous and shows no signs offalling off yet. Many listeners whohave been in a state of indecision-wondering whether some other setor kit would give them better satis-faction-have now come to the in-evitable conclusion that the Brook -man's Three is the best all-roundreceiver that has yet been put beforethe home constructor.

Far in AdvanceOf course, the secret of success of

the Brookman's Three and Brook -man's Two (described in the Novem-ber WIRELESS MAGAZINE) lies inW. James' 193o Binowave coils,which are far in advance of anyother type of dual -range coil yetproduced.

498

This Set Has BeenAdapted from theBrookman's Three bythe " Wireless Maga-zine" Technical Staff

This is neither the timenor the place to go intodetails of the coils, the con-struction of which was fullydescribed by W. James

himself in the previous issue.Now, having reminded old readers

of the supremacy of the " Brook -man's" series of receivers and intro-duced them to new readers, let usexplain why we have produced theBrookman's Push-pull Three-whichactually uses four valves.

Greater OutputThe valve combination of the

original Brookman's Three was ascreened -grid high -frequency ampli-fier, detector, and transformer -coupled low -frequency amplifier. Thenew set is almost identical with theoriginal except that a pair of posh -pull amplifying valves is used inplace of the single stage utilisedbefore; this arrangement gives greateroutput and even greater purity ofreproduction.

Another feature of the new designis that it is adaptable at the turn ofa switch for reproducing gramophonerecords electrically through the

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medium of a pick-up in place of thesoundbox on any machine. This is apoint that will make an immediateappeal to a large number of listeners.

It should be particularly noted thatthe components required with thisset are almost identical with thosefor the Brookman's Three, exceptfor the pair of push-pull transformerswhich is needed instead of a singleordinary type of transformer.

" By Request "The new set has been designed in

response to numerous requests fromreaders who feel that one low -fre-quency stage is hardly enough fortheir requirements.

A glance at the photograph form-ing part of the heading to this articlewill reveal the arrangement of thecontrols. There are so many knobsthat the inexperi-enced might sup-pose that the setis very difficult tooperate, but thisis by no meansthe case, for nevermore than one ortwo need be mani-pulated at thesame time.

For instance,whenradio signals,there is no needto touch the pick-up switch or theknob marked"Volume Control."If the volumehappens to be toogreat, as itundoubtedly willbe in many cases,it is reduced by

Wireless Magazine. December /929

turning back the high -frequency rheostat. Thisincreases the impedanceof the screened -gridvalve and, incident-ally, increases theselectivity of thewhole set.

On theother hand,whengramophonerecords arebeing repro-duced, theonly knob to touchis that marked " VolumeControl," for different kinds ofmusic often sound better when thestrength is specially adjusted.

It should be understood thatalthough two valves are used in the

Brookman'sPush-pull Threeall ready for use

REACTION ANODE ANODE MILLIAMMETER 'ALRIACONDENSER CONDENSER TUNER CONDENSER,

PUSI1PULOUTPUT

TRANSFORM

\16.

PUSH-PULLVALVES

PUSH-PULLINPUT

TRANSFORMER

DETECTORVALVE

GRID LEAKCONDENSER

GRID -BIASCELL

AERIALTUNER

AERIALSERIES

CONDENSER

S.GNALVEHOLDER

This plan view of the Brookman's Push-pull Three dearly shows how all the partsare arranged on panel and baseboard

push-pull stage, no greateramplification is actually ob-tained. The effect is simply

that the input to thelow -frequency sectioncan be greater without

4,ny distortionraising.

This will be bet-ter un der

stood, per -h a ps , bydiscussing

some arbitraryfigures. Suppose

that a single power valveis used with a grid swing of

so volts. Then, if the signal comingfrom the detector valve is 12 volts,the power valve will be overloadedand distortion will result.

499

In the case ofpush - pull, whereidentical valvesmust be used, theavailable gridswing is doubled.Thus two powervalves, each witha grid swing ofso volts, used ina push-pull ar-rangement willresult in a totalgrid swing of zovolts.

In this way thefullest advantageis taken of strongsignals from thehigh -frequencyand detectorstages, and no dis-tortion is experi-enced.

There are a number of interestingpoints to note about a push-pull cir-cuit. The most important is thattwo normal types of power valvewith a low anode voltage will giveresults equivalent to a large powervalve with 5oo or 400 volts on itsanode.

Total Impedance of CircuitIt should also be noted that the

total impedance of a push-pullarrangement is equal to the additionof both valve impedances. Thus, iftwo 3,00o -ohm valves are used thetotal impedance will be 6,000 ohms.For this reason identical valves oflow impedance should be employed.

The method of arranging the push-pull stage will be clear from thecircuit diagram on page boo. It will

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Wireless Magazine. December. 1929

The. Brookman's Push-pull Three Continued

CIRCUIT OF THEBROOKMAN'S PULL -PUSH

THREE

The high -frequency a n ddetector portionof this circuit isidentical withthat of the orig-inal Brookman'sThree and almostidentical com-ponents are used.

A very highdegree of ampli- Sfication is ob-tained from W.James' 1930 Bin-owave Coils,which are usedfor tuning theaerial and anodecircuits.

Es

The milliammeter on thepanel is a refinement that can

be omitted, if desired,without affecting theoperation of the set.It is useful in so far as

it gives a readycheck on the

presence ofdistortion.

If thereproduc-tion is per-fect themilliam-

Note the grid -biasmeter will

battery on the baseboard asteadyreading of the combined anode cur-rents of the two power valves. If itflickers at all, then overloading is

Some readers may question theadvisability of running a push-pullamplifier direct from a detector valvewithout any intermediate amplifyingstage. The strength obtained fromthe high -frequency stage, however, isso great that the signal available atthe detector is ample for direct inputto the push-pull transformer.

" Detector " as AmplifierIn the case of gramophone -record

reproduction, the movement of theswitch that brings the pick-up intoplay automatically converts the" detector " into an amplifier, pro-vided with grid bias.

The actual layout of the set neednot be discussed, as it will be quiteclear from the details reproduced inthese pages. If desired, a full-size

X/D.

0005ME

be noticed that the secondaryof the input transformer is pro-vided with two grid -bias terminals inplace of the usual centre -tap.

This has been done with the ideaof matching up two slightly dissimilarvalves by an alteration in the gridbias so that both give the same anodecurrent. We have shown connectionsby which advantage can be taken ofthis scheme if desired.

Use of Matched ValvesWe recommend, however, that the

two grid -bias terminals be connecteddirectly together so that the samebias is applied to both valves, whichshould be obtained specially matched.

.0007Jock switch (I,for Pick-up

C

0002

toa000,-Ohms

Pick-up

RT. G.

A

5.8.Bott

0-50

occurring, and oneor both volumecontrols should bebrought into play.

The milliam-meter can also beused to check upthe push-pullvalves. Removeone and note thereading; then putthat valve backand take out theother, again not-ing the reading. If the readings arenot within a very few milliamperes,then the valves are not matched, andone of them should be changed.

500

WHEN YOU HAVE BUILTONE OF THE "BROOK -MAN'S " SERIES OF SETSLET US KNOW WHAT YOUTHINK OF IT-AND RE-MEMBER THAT WE OFFER10/6 FOR EVERY PHOTO-GRAPH PUBLISHED OF A

W.M." SET BUILT BY AREADER

blueprint can beobtained for half-price (that is, 9d.,post free) if thecoupon on page iiiof the cover isused by Decem-ber 3i.

Just addressyour inquiry toBlueprint Dept.,WIRELESS MAGA-ZINE, 58-61 FetterLane, London,

E.C.4, and a copy will be sent byreturn. Ask for No. WMr7o.

Although there4 are nearly sixtywires in the set, no difficulty will be

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Wireless Magazine, December 1929

Fine Quality from Radio or Recordsexperienced in connecting up if use ismade of the blueprint or the reducedreproduction of it c n page 502.

Each wire is nu.nbered in order ofassembly, so that the whole wiring iscarried out from the baseboardupwards in the most convenient way.

Choice of ValvesThe choice of valves for the set

will present no difficulty if the list ofrecommended components and acces-sories is consulted. This appears atthe foot of this page. Although tworo5-volt high-tension batteries arerecommended, two -6o-volt typeswould give satisfactory results.

Once all the knobs on the panelhave been memorised, no difficultywill be experienced in operating theset; a fact that has already beenemphasised.

For radio repro-duction pull outthe knob of thepick-up switch anddo not touch thevolume -controlknob. Turn bothswitches asso-ciated with theBinowave coilseither to the right

-1/ IN GREAT MEASURETHE INCREASING POP-ULARITY OF "W.M."SETS IS DUE TO THECLARITY OF THE FULL-SIZE BLUEPRINTSWHICH ARE PART OFOUR SERVICE TO THELEADER-GET ONE OFTHIS SET FOR 9d., POST

FREE.

(long waves) or left (shortwaves). The left-handswitch, associated withthe aerial coil, also actsas a filament switch; theset is switched off whenthis switch is in itscentral position.

Normally thehigh -frequencyrheostatshould bekept fullyturned on;that is, theknob shouldbe turned asfar as pos- The screened -grid valvesib 1 e in a is mounted horizontally

clockwise direction. If the volumeon radio is too great turn the knob

back.Then the only

knobs which needbe manipulatedare the two vari-able con denserdials tuning theaerial and anodecircuits, and thereaction con-denser, at the bot-tom right-hand0

cornerof the set.

The readings oftuning dials will be nearly the sameas those given by W. James for theBrookman's Three in his article"Results with the ' Brookman's'Sets," which appeared in the previousissue Of WIRELESS MAGAZINE.

the two main

Reaction CondenserIt is important to note, by the way,

that the reaction condenser must beof .0003-microfarad capacity. Many

COMPONENTS REQUIRED FOR THECoils

i-Pair Wearite 193o Binowavecoils, types A and B, 34/-.

Condensers, Fixed2-T.C.C. .000r-rnicrofarad, 3/8

(or Igranic, Marconiphone).I-T.C.C. .0002-microfarad, type

SP, 2/4.2-T.C.C. r-microfarad, 5/8 (or

Dubilier, Ferranti).Condensers, Variable

2-Cyldon Junilog .0005 -micro -farad, 17/6 (or Polar, Key-stone).

r-Cyldon Bebe .0003 -micro -farad, 8/- (or Utility, Bowyer -Lowe).

Dials, Slow-motion2-Burndept, 12/- (or Bowyer -

Lowe, Harlie).Ebonite

I-Becol, 18 in. by 7 in., 7/7 (orRipault, Redfern's).

2-Becol strips, ioy2 in. by 2 in.and 3 in. by 2 in.

Holders, Valve3-Benjamin Vibroholders, 4/6

(or Lotus, W.B.).r-Parex screened -grid, single

type, 2/- (or Colvern, Key-stone).

BROOKMAN'S PUSH-PULL THREEMeter

r-Sifam 0-50 milliammeter, 25/-.Plugs

5-Belling-Lee wander plugs(marked : G.B.+, G.B.G.B.- r, G.B. - 2, G.B. - 2),I/3.

PotentiometerI-Centralab roo,000-ohm po-

tentiometer, type Proo, 8/6.Resistance, Fixed

i-Ediswan 3-megohm, 2/6 (orLoewe, Dubilier).

Resistance, Variablei-Lissen I5 -ohm, panel type,

2/6 (or Benjamin, Burton).Screen

r-Parex vertical screen, ro in.by 6 in., 2/9 (or Ready Radio,Peto-Scott).

Sundriesi-Pair Pair panel brackets

(Ready Radio).Glazite for connecting up.

SwitchI-Lotus jack, type No. 8, 3/6.

Terminals12-Belling-Lee, type M (marked :

Aerial, Earth, Pick-up (2),L.T.+, L.T.-, H.T.+3,

H.T.-F 2, H.T.+1, H.T.-,L.S. L.S.-), 4/6 (or Eelex):

Transformers, Low -frequencyr-Pair Varley push-pull trans-

formers, 46/- (or Ferranti).ACCESSORIES

Batteries2-0beta 105 -volt, power type,

33/- (or Siemens, Ever Ready).[-Siemens r r/ -volt grid cell, 1/6

(or Ever Ready).-Siemens r6 -volt battery (orEver Ready).

[-C.A.V. 2 -volt 6o -ampere -houraccumulator, type 2AG r 1,15/6 (or Tudor, Lissen).

Cabineti-Pickett, with io-in. baseboard,

35/- (or Lock, Cameo).Loud- speaker

I-Celestion, type Cro cone,3/I5/- (or Ediswan, Blue

Spot).Valves

I-Cossor zzoSG, 22/6 (or Mazda213SG, Marconi S2r5).

i-Cossor 2 I oHF, ro/6 (or MazdaFIL2 10, Marconi HL2 ro).

2-Cossor 23oXP, 25/- (or MazdaP24o, Marconi, P24o).

The prices mentioned are those for the parts used in the original set; the prices of alternatives as indicatx1 in the brackets may be either higher or lower

501

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Wireless Magazine, December, 1929

The Brookman's Push-pull Three Continued

This layout and wiring diagram can be obtained as a full-size blueprint for half-price(that is, 9d., post free), if the coupon on page iii of the cover is used by December 31.

Ask for No. W.M.170.

listeners seem to think that the arbitary and that .000r or .0002value of this component is quite microfarad could be used with equal

satisfaction. This is not the case.To use the set for the reproduction

of gramophone records connect apick-up to the terminals providedand push in the knob of the pick-upswitch. Volume is then controlledby the knob marked " VolumeControl."

When the pick-up is switched intocircuit the screened -grid valve isautomatically switched off and the"detector" is biased for amplifying.

Grid -bias TappingsActually three grid -bias negative

tappings are provided, one G.B.-and two G.B.- 2. The latter, as pre-viously explained, are to enable theoperator to match up two slightlydissimilar power valves in the push-pull stage by giving one more or lessbias than the other, so that the anodecurrent from each is the same.

The makers' recommendations re-garding anode voltage and grid biasshould be adhered to rigidly if thebest results are to be obtained.

Other Articles to ReadProspective constructors of the

Brookman's Push-pull Three will findit worth their while to read thefollowing articles, which have ap-peared in the previous issue of WIRE-LESS MAGAZINE :-

" Results with the ' Brookman's'Sets," by W. James (November).

"Making the 1930 BinowaveCoils," by W. James (November).

Why Signals Fade-Continued from page 497The ripple is actually produced by

a movement of each part of the ropeup and down in a direction at rightangles to the general direction of therope itself or, in other words, thedirection of motion of the wave. Ifthe hand is moved up and downvertically, this motion of the rope isalways in a vertical plane.

It is possible to produce an exactlysimilar phenomenon by shaking thehand horizontally or at some otherangle. If we do this we produce awave similar to the previous one, buthaving a different "plane of polar-isation."

If we fix some device at the far endwhich would only respond when therope is jerked vertically, then anyhorizontal impulse will not affect the

device although the phenomenonproducing the ripple is of exactly thesame character as before.

The same thing happens in awireless receiver. Wireless waves arenormally vertically polarised, and weerect vertical aerials in order toreceive the waves. If we place theaerial horizontally it will receivenothing and conversely if we try toreceive a horizontally polarised waveon a vertical aerial we also receivenothing.

Probably, by now, the explanationof fading has begun to be clear. Thereflection of the wireless waves fromthe Heaviside layer twists the planeof polarisation so that they are notreceived as well as they should be onan aerial system intended for a truly

502

vertically polarised wave. The extentof the reception depends upon theamount of twist in the wave, and ifthe wave has become so twisted thatit reaches the earth horizontallypolarised, then no signals at all willbe received.

Now the evidence goes to show thatwhat actually happens is that, as aresult of the reflection from theHeaviside layer, the wireless wavesare given a gradual twist. That is tosay, as they approach the earth theygradually change their plane ofpolarisation from vertical to hori-zontal and back again.

The effect of this on a wirelessreceiver is that the signal strengthgradually falls from normal tonothing and then grows again. Thistakes place in a more or less well-defined interval.

Page 59: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

L_I Wireless Magazine. Aremben 1929

Are Radio CriticsJustified?

In this article ANDREW SOUTAR, the well-knownnovelist, confesses that he was converted to radio onlytwo years ago and makes a sly suggestion to account

for the activities of captious broadcast critics !

"GROUSING " is a prerogative of

the Englishman, and if hehasn't anything to grouse about, hegrouses about the lack of a grievance.Grousing is a characteristic of the racethat is cherished by those, who arefond of talking of tradition : theymake of grousing a virtue and say, ineffect : "We take nothing lyingdown."

Off His FoodI have known a hard -grained,

mahogany -headed man to go off hisfood because he couldn't think ofsomething that merited his damna-tion. Broadcasting was a godsend tothat fellow 1

I read the newspapers assiduously-it is part of my job-because I amsupposed to keep in touch with any-thing that is going on. Frequently,they depress me; I feel the bottom ofthe world falling out and the rooffalling in and hope and ideals stiflingin the mud.

But, in my heart, there is a sparkof optimism that will never allowitself to be quenched. One of thesedays, I tell myself, I am going to reada perfectly honest eulogy of theB.B.C. and the radio. Someone isgoing to write :

"There was a perfect programmebroadcast last night from SavoyHill. We had no asthmatic oldgentlemen squeaking their waythrough an essay on moles, nor anytin -voiced sopranos to make the glassand cutlery dance on the dining -roomtable with the terrible vibrations ofa misunderstood gift.

" There was no nerve-racking waitbetween the announcement of theweather forecast and the winner ofthe first race at Kempton Park. Noneof that torture to a racing man thatfollows 'sport '-cricket and footballresults, lawn tennis in Labrador,

billiards in Melbourne, shove -ha'-penny in Somerset. That awful soul -tiring enumeration of sports andgames that do not interest.

" No, sir. The announcer knewinstinctively that our mind wasfrayed with anxiety. Straightway,after that one word `sport' came'results.' And when we had heardthem we turned off the radio so thatwe might calculate our winnings inpeace.

"We had music that was music,singing that elevated, light, crispanecdotes from the stage; we had nopolitical speeches-thank God; nocriticisms of anything-thank God,again. We had what we wished-anevening of pure entertainment.

"And, in atonement for all thebrutal things we have said about theB.B.C., we ask Savoy Hill to acceptthis, our sincere apology, for hurtingthe feelings of the officials. Werealise that now they do know whatthe public desire most."

I don't envy the programmeselectors their job, although I wouldgive more than I can afford to beallowed to broadcast for one hourwith no restrictions on what I mightfeel inclined to say.

It would be the finest advertise-ment the radio could ever hope togain, for publicity, in itself, is adver-tisement. I might get into gaolbecause of what I had said but, on thewhole, I think it would be worth it.

Change in Our LifeIt has wrought a great change in

our life, this broadcasting to thepeople. Looking back, it is almostincredible that the late Lord North-cliffe, the greatest journalist that thisor any other country has ever known,had to keep on hammering at theGovernment for weeks and monthsbefore the people were allowed to

503

Andrew Soutar, the well-known novelist,who was converted to radio only two

years ago

enjoy similar privileges to thosewhich America had been enjoying fora couple of years.

To -day, there is scarcely a cottagein the country that hasn't some formof wireless. Newspapers carry pagesof advertisements of various types ofinstruments. Wonderful instruments !Wonderful prices I Instruments thatyou may carry about in a motor -car,keep in the cellar, in the drawing -room, or hang up in a tree.

In A Cottage PantryOne may give any fancy price and

yet the one that I always admire isthe collection of accumulators andwires and gadgets arrayed on a dealplank in the pantry of a cottage bythe eldest son or the boy of the familywho has got his nose into wireless asfirmly as a rat gets into a trap.

How he does it, I cannot say, butfor an expenditure of about thirtyshillings he can give me the joy oflistening to a sand -dance down inAlabama when my dignified expen-sive contraption does no more thangrind itself to death in impotent rage.

' Here is a phase of listening that hasnothing whatever to do with theforegoing. I wonder if others aresimilarly affected? I cannot toleratethe radio if I am alone in the house !What is it that makes the "loneli-ness" lonelier still? There is nothingsepulchral about it, nothing eerie : itis just that inexplicable feeling thatsolitude has been emphasised.

And when there is company(Continued on page 508)

Page 60: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. ,December, 1929

°Set13ugers GUideA LIST OF UP-TO-DATE SETS ARRANGED CONVENIENTLY IN PRICE GROUPS

The 170 -odd sets listed below are new models for 1930,and are representative of modern types and prices. Readerswill be able to see at a glance average prices of any particulartype of set. For portables refer to the May issue.

In the " Name of Set " column, a star ( * ) indicates thatprovision is made for connecting a pick-up if desired so thatgramophone records can be reproduced electrically.

Where, under " Power Supply," no mention of " Bat." ismade, the set must be worked from the mains.

NOT EXCEEDING £10Maker Name of Set Price Power Supply Combination

Loewe .. .. *Type 0.E.333 £3/3/0 Bat. Multiplevalve

Edison Bell .. Bijou .. .. £3/12/6 Bat. D., L.F.Lamplugh .. .. Chassirad .. £3115/0 Bat.Lamplugh .. .. Popular 2 . £4/2/6 Bat.Castagnoli.. .. Castaphone E2 £4/10/0 S.C. Bat. D., L.F.Lamplugh .. .. Chassirad .. £4/15/0 Bat. D., L.F.Lamplugh .. .. Popular 3 .. £517/6 Bat. D., 2L.F.Eagle Engin. Warwick 2 .. £5/9/9 Bat. D., L.F.Automobile Acc. . *Melody 3 .. £5/10/0 Bat. D., 2L.F.Automobile Ace... *Melodia 3 .. £5/12/6 Bat. S.G., D., Pen.E. J. Batt' ....Baty 2 .. £5/15/0 S.C. Bat. H.F., D.Castagnoli.. C,astaphone

ES5£5/15/0 S.C. Bat. D., 2L.F.

Lamplugh .. Standard .. £5/17/6 Bat.Pye .. No. 232 .. £6/010 Bat.E. J. Baty ....*Baty 3 . £6/0/0 Bat. D., 2L.F.Ormond . Two -valve Set £6/3/0 Bat.Edison Bell Homestead 3 £617/6 S.C. Bat. D., 2L.F.Bowyer Low, *Pentovox 2 .. £6/8/0 Bat. D., L.F.Lamplugh.. Standard .. £7/2/6 Bat. D., 2L.F.Marconiphon, Model 37 .. £7/2/6 Bat. D., 2L.F.Marconiphone Model 23 .. £7/5/0 S C. Bat. D., L.F.Edison Bell S.C. Bat. D., 2L.F.Kolster Brandes .. Brandeset 3a.. £7/10/0 Bat. D., 2L.F.Automobile Acc. .. *Self-contained £7/1510 S C. Bat. D., 2L.F.

3

E. J. Baty .. .. *Baty 4 .. £81010 A C., D.C. H.F., D.,2L.F

Lissen .. S.G.3. .. £8/13/0 ...c C. Bat. S.G., D., P.Eagle Engin. *Warwick 2 .. £8/5/0 C. Bat. D., L.F.

PedestalFalk, Stadelmann.. Wolfe .. £8/7/6 Bat. D., 2L.F.Eagle Engin. Junior 3 .. £8/7/9 Bat. D., 2L.F.Burndept .. .. Screened £8/10/0 Bat. S.G., D., Pen.

EthophoneEdison Bell .. *Maison S.G.3 £8/10/0 : C. Bat. S.G., D., PenLamplugh .. .. Chassirad .. £8115/0 Bat. S.G., D., Pen.Ormond . .. Three -valve Set £8/18/6 Bat. D., 2L.F.Ecison Bell *Pedestal 3 .. £9/12/6 S.C. Bat. D., 2L.F.Ed i swan . . Three .. £9/12/6 Bat.Kolster Brand, s .. K.B.102 .. £9/15/0 Bat. S.G., D., Pen.Bowyer Lowe .. Pentovox 3 . £10/010 Bat. S.C., D., Pen.City & General .. *City Super 3 £10/0/0 Bat. S.G., D., Pen.Marconiphone .. Model 23a .. £10/010 S.C. Bat. D., L.F.

BETWEEN £10 AND £20Maker Name of Set Price Poper Supply Combination

Lamplugh .. Screened -grid 3 £10/10/0 Bat.Kol t r Brandes *K.B.163 .. £10/15/0 Bat.Lamplugh .. Standard .. £111010 Bat.Burndept .. Screened £11/8/0 Bat. S.G., D., Pen.

EthaphoneBurndept .. .. Empire .. £11/10/0 Bat. S.G., D., Pen.Marconiphone .. Model 35 .. £12/0/0 Bat. S.G., D., Pen.Pye .. .. No. 275 .. £12/0/0 5 C. Bat.Lamplugh .. .. Standard .. £12/5/0 Bat. D., 2L.F.Philips Lamps .. *2502 Type .. £12/10/0 Bat. S.C., D., Pen.Philips Lamps .. *Type 2515 .. £12/10/0 A.C. D.. Pen.British Rude. *Craigweil .. £12/12/0 5 C. Bat. D., 2L.F.Aeonic .. *Mains 2 .. £12/15'0 A.C.Lamplugh Quality 3 .. £12/1510 S C. Bat. D., 2L.F.Cole, E. K. .. *Ekco Electric £12117'6 D C., A.C. D., Pen.

Falk, Stadelmann.2

Repton .. £12/1776 Bat. S.G., D., L.F.Gambrell . .. All -electric £13/15/0 D.C.

TwoLotus . .. RS70 .. .. £13/15/0 Bat. S.G., D., P.

...

If you want further particulars of any of these sets, writeto us and we will forward your inquiries to the manufacturersconcerned. There is no charge for this service. Just address theenvelope : Set Selection Bureau, WIRELESS MAGAZINE, 58-61 Fetter Lane, London, E.C.4.

Sets which have been actually tested in the " W.M."laboratories and which can be recommended from personalexperience are indicated in bold type. This month's testreports will be found on page 487.

BETWEEN £10 AND £20 (Continued)

Maker Name of Set Price Power Supply Combination

Castagnoli.. .. Castaphone £14/14/0 S.C. Bat. H.F., D., 2L.F.Dual Four

Lamplugh .. .. S.G.3. .. £15/12/6 S.C. Bat. S.G., D., P.Marconiphone .. Model 39 £13/0/0 S.C. Bat. S.C., D., Pen.G.E.C. .. .. Short -waver £15/0/0 Bat. S.G., D., P.G.E.C. .. .. Gecophone .. £15/0/0 A.C. D., P.Ormond .. .. Screened -grid

ree£15/0/0 S.C. Bat. S.C., D., Pen.

Pye .. .. Two-Th valver .. £15/0/0 A.G.Eagle Engin. .. *Warwick 2 .. £55/15/0 A.C.Lamplugh .. .. Trans 5 .. £15/15/0 S.C. Bat. 2H.F., D.,

2L.F.Lamplugh .. .. Straight A.C.2 £15/15/0 A.C. D., L.F.Burne Jones .. *AC/2 Mains . £16/10/0 A.C. D., L.F.E. K. Cole .. *Ekco-electric 3 £1611010 D.C., A.C. D., 2L.F.

ES2Falk Stadelmann Waterloo .. £16/15/0 Bat. S.C., D., Pen.Aeonic .. .. Trans 5 .. £16/16/0 S.C. Bat. 2H.F., D.,

2L.F.Edison Bell .. Console 4 .. £16/16/0 S.C. Bat. H.F., D., 2L.F.Varlet' .. *All -electric .. £16/16/0 A.C., D.C. D., L.F.

*S.G.3.. .. £17/0/0 S.C. Bat. S.G., D., P.Gambrell .. .. All -electric .. £17/10/0 A.C.Kolster Brandes .. *K.B.161 .. £17/10/0 D.C., A.C. S.G., D., Pen.Pye .. .. No. 275M .. £17/10/0 A.C.Burne Jones .. Universal 3 .. £1810/0 Bat. S.G., D., Pen.Trix .. .. *All Mains 3

.

£18/10/0 A.C.Larnplugh.. .. Straight A.C.3 £19/10/0 A.C. D., 2L.F.Burgoyne .. .. Model A .. £18/18/0 S.C. Bat. 2H.F., D.,

2L.F.Burgoyne .. .. Pentod .. £19/19/0 S.C. Bat. 2H.F., D.,

L.F., Pen.McMichael .. *Screened- £19/19/0 S.C. Bat. S.C., D., Pen.

Dimic 3Aeonic .. .. Screened 4 .. £19/9/0 - -Pye .. .. No. 460 .. £19/10/0 S.C. Bat. S.C., D., 2L.F.Bowyer Lowe .. *Vox Populi 3.. £20/0/0 Bat. S.G., D., Pen.City & General .. *City Super Ill £20/0/0 A.C. S.G., D., P.Falk. Stadelmann Waterloo D: £20/010 S.C. Bat. S.C., D., Pen.

Luxe

BETWEEN £20 AND £30Maker Name of Set Price Power Supply Comb nation

Lamplugh.. .. Quality 3 .. £20/5/0 S.C. Bat. D., 2L.F.B.T.H. .. .. 4-valver .. £21/0/0 Bat. H.F., D., 2L.F.E. K. Cole .. *Ekco-lectric £21/0/0 A.C., D.C. S.G., D., Ikn.

S.G.P.3Ediawan .. .. *Mains 3 .. £21/0/0 A.C., D.C. S.G., D., P.Brit. Radio Grain°. *Craigweil £21/15/0 S.C. Bat. 2H.F., D., 2L.F .

PortableLotus .. .. RS80 .. £21/0/0 A.C. S.G., D., P.Gambrell *All -electric £22/1010 D.C. S.G., D., Pen.

ThreeRegent Radio Regentone .. £22/10/0 A.C. S.G., D., P.Marconiphone .. Model 44 .. £2271010 Bat. 2S.G., D., Pen.igranic .. Neutrosonic £2310/0 Bat. S.G., D.

Short -waver L.F., P.Philips Lamps .. *Type 2514 .. £23/0/0 A.C. S.G., D., Pen.Aeonic .. *Mail, 4 .. £23/2/0 AL., D.C.Marconiphone .. Model 34 .. £23/17/6 Bat. D., 2L.F.Bowyer Lowe *Vox Populi 4 £24/0/0 Bat.

L.F., P.Marconiphone .. *Model 47 .. £241010 A.C. S.G., D., 2L.F.Amplion .. *Radio Set .. £25/0/0 Bat. H.F., D., 2L.F.Burndept .. .. *Screened 4 .. £251010 Bat.

L.F., P.Falk, Stadelmann *Waterloo de £25/0/0 A.C. S.G., D., P.

Luxe

504

Page 61: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

BETWEEN £20 AND £40 (Cont nued)

Maker Name of Set Price Power Supply Combination

Ferranti .. A.C. Set .. £25/0/0 A.C. S.G D., P.Gambrel) .. .. *All -electric £25/0/0 A.C. S.G., b., Pen.

ThreeG.E.C. .. .. Mains 3 .. £251010 A.C. S.C., D., P.Pye .. 350A.C. .. £25/0/0 A.C. S.G., D., P.Burgoyne .. .. Screened 4 .. £25/4/0 S.C. Bat. S.G., D.,

L.F., Pen.G.E.C. .. .. Four-valver .. £26/0/0 S.C. Bat. S.C., D., 2L.FLotus .. .. RS51 .. .. £26/5/0 A.C. S.G., D., Pen.M P.A. .. .. *All -electric 3 .. £26/5/0 A.C. H.F. D., Pen.Reproduction .. Rhapsody Twin £26/5/0 S.C. Bat. 2H.F., D., 2L.F.Varley .. .. *All -electric .. £26/5/0 A.C., D.C. S.G., D., L.F.Columbia .. .. 304H .. £27/0/0 S.C. Bat. 3S.G., D., P.Borne Jones .. *AC/3 .. .. £27/10/0 A.C.Lamplugh. .. All Mains 3 .. £27/1010 A.C. S.G.. D. L.F.Marconiphone .. *Model 56 .. £27/10/0 S.C. Bat. 3D.G., D.. Pen.Regent Radio .. Regentone .. £27/10/0 A.C. S.G., D., P.Burndept .. .. Screened 4 .. £27/18/6 Bat. S.C., D., 2L.F.McMichael .. *Screened £28/0/0 A.C.

Dimic 3Universal .. .. *Home Model £291810 S.C. Bat. S.G., D., P.Lissen .. .. *Liasenola Rad.

Gramo.530/010 A.C., D.C.,

Bat.S.G., D., Pen.

Philip .. .. *Type 2802 .. £30/0/0 Bat. S.G., D.,L.F., Pen.

R.I. .. .. *All -electric £3010/0 A.C., D.C. S.G., D., P.Trans 3

BETWEEN £30 AND £50Maker Name of Set Price Power Supply Combination

Cook's ._ .. *Screened -grid 4 £31/10/0 S.C. Bat. S.G., D., 2L.F.A.C., D.C.

Edison Bell .. *Radio Gramo. £31/10/0 S.C. Bat. S.C., D., Pen.Empire Electric .. Metropolis £31/10/0 S.C. Bat. Super -het.

Table GrandColumbia .., . Model 304 .. £33/0/0 A.C., D.C. 35.G.. D., P.Gambrel! .. : . *All -electric £33/0/0 D.C. S.G., D., Pen.

FourBowyer Lowe .. *Screened Vox £33/10/0 A.C. S.G., D., Pen.

Populi 3Lamplugh.. . Radio Gramo. £35/15/0 D.C. D., 2L.F.M.P.A. .. : . *All -electric £36/5/0 A.C. S.G., D., 2L.F.

Trans 4Bet. Radio Gramo. *Craigweil 37.. £37/10/0 S.C. Bat. S.G., D., Pen.Philips .. . *Type 2511 . £37/10/0 A.C. 2S.G., D., Pen.Burndept .. : . *A.C. Screened £37/16/0 A.C. 25.G., D..

7 L.F., P.Lamplugh .. Radio Gramo £38/0/0 A.C. D., 2L.F.Burndept .. . k C. Screened £38/17/0 A.C. 2S.G., D., 3L.F.Gambrel' .. : . *All -electric £39/15/0 A.C. S.C., D., Pen.

FourVarley .. .. Radio Gramo. £40/19/0 A.C., D.C. D., L.F.Lamplugh.. .. Radio Gramo. £41/5/0 D.C. 2H.F., D.,

2L.F.

Wireless Magazine. Decemfien 1929

BETWEEN £30 AND £50 (Continued)

Maker Name of Set Price Power Supply Combination

Brit. Radio Gramo. *Model 42 .. £42/10/0 D.C. S..G, D., P.Lamplugh.. .. Radio Gramo. £43/10/0 A.C. 2H.F., D.,

2L.F.Cook's .. .. *Radio Gramo. £45/0/0 S.C. Bat.,

A.C., D.C.S.G., D., 2L.F.

Ormond .. .. *Pedestal .. £45/0/0 S.C. Bat. D., 2L.F.Brit. Radio Gramo. *Model 45 .. £45/1010 A.C. S.G. D., P.Bumdept .. .. *Ethograrn B .. £461010 A.C. 2S.G., D.,

L.F., P.Lamplugh .. .. All Mains 3 .. £46/010 A.C. D., 2L.F.Trix .. .. Radio Gramo. £47/5/0 A.C.Universal .. .. *Chubby Model £49/7/0 S.C. Bat. S.G., D., P.Amplion .. .. *Mains Set .. £50/0/0 A.C. S.C., D., 2L.F.

City & General .. *Radio Gramo. £50/0/0 AL., D.C. -Amplifier

Ormond .. .. *Console .. £50/0/0 S.C. Bat. D., 2L.F.Universal .. .. *Truvox .. £50/0/0 S.C. Bat. S.G., D., 2L.F.

OVER £50Maker Name of Set Price Power Supply Combination

Marconiphone . Model 61 .. £51/0/0 Bat. 3S.G., D.,2L.F.

Peto Scott.. .. *All British 6 .. £51/5/0 A.C., D.C.,Bat.

3H.F., D.,2L.F.

Marconiphone .. Model 82 .. £57/0/0 Bat. Super -het.Radio Gramo. .. *CraigwAl Elec-

tric Grams.£57/15/0 A.C. D., 3L.F.

Gambrel! .. *All -electric £59/17/0 D.C. S.C., D., Pen.Radio Gramo.

Edison Bell .. *Mains Radio £65/0/0 A.C., D.C. S.C., D., 2L.F.Gramo.

Universal .. .. *Truvox .. £65/0/0 A.C., D.C. S.C., D., P.Gambrel! .. *All -electric £67/4/0 A.C. S.C., D., Pen.

Radio Gramo.Varley .. .. Radio Gramo. £68/5/0 A.C., D.C. S.C., D., L.F.Advance .. .. *Radio Console £75/0/0 A.C.H.M.V. .. .. Radio Gramo. £75/0/0 A.C. S.G., D., 2L.F.M.P.A. .. .. *Radio Gramo. £78/15/0 A.C. S.G., D., 2L.F.Reproduction .. *Chair -Side .. £97/13/0 A.C. D.C. -Pye Radio.. .. Radio Gramo. £9911510 A.C. 2H.F.,D.,2L.F.Reproduction .. *Boudoir .. £99/15,0 A.C., D.C. -City & General .. *Cinema .. £100,0 0 A.C., D.C. -

AmplifierHarlie .. .. Radio Gramo. £110/2/0 to A.C., D.C. H.F., D., 3L.F.

£152/10/0Donophone .. *Radio Gramo. £115/10/0 A.C., D.C. -131 it. Radio Gramo. *CraigweilRadio £1201010 A.C. H.F., D., 2L.F

Gramo.Reproduction .. *Rhapsody Twin £131/5/0 A.C., D.C. -Brit, Radio Gramo. *Craigweil 165 £160/0/0 A.C. 2H.F., D., L.F.M.P.A. .. .. *Ethatrope Radio £178,10/0 A.C. 2S.G., D., 2P.

Exchange

Choosing a Set from the "W.M." Buyers' GuideFFURTHER additions are made this

month to the WIRELESS MAGAZINESet Buyers' Guide which, in its presentcomprehensive form, should give theset buyer a bird's-eye view of the leadingradio sets available. It will be seen thatsets are grouped according to their price.Inexpensive sets, moderate -priced sets,and the more expensive sets are thusconveniently divided.

Concentrated InformationMost set buyers know beforehand, to

a pound or so, how much they want tospend. But, as we wish to show, thisinformation is not quite enough toenable the set buyer to make a goodchoice. In the WIRELESS MAGAZINESet Buyers' Guide, concentrated informa-tion is available which should greatlyassist the set buyer if he understands itsreal meaning.

For example, in the column headed"Combination," the high -frequency andlow -frequency amplifying capabilities ofthe set are disclosed. The simplest com-

bination is "D, L.F." This combinationis associated with local station receivers.Sets using it require an outside aerialfor best results. They can be used witheither batteries or mains supply. TheBowyer -Lowe Pentovox Two is a goodexample of a set making use of thiscombination. It is battery -operated.

The Philips type 2515 employs amodification of this simple combination.As shown in the table, its combination isD, Pen. All that has been done is to usea pentode valve instead of a small powervalve. Where this combination appearsin a set it can be taken that, althoughthe set is not more sensitive to weaksignals than one embodying the combina-tion D, L.F., it will give louder signals.

The next most straightforward com-bination of valves is " SG, D, P." Aslight variation of this is when H.F.takes the place of S.G. Whenever eitherH.F. or S.G. precedes D, it can be takenthat the set embodying the combinationis sensitive to weak signals and that itwill give good results from near -by

505

stations, when using an indoor aerial.A good example of a set employing thiscombination is the Kolster Brandes KB102, which has both screened -grid andpentode valves. Here, a pentode valvegives stronger signals than the ordinarypower valve and the screened -grid valvemakes the set more sensitive than wouldan ordinary high -frequency valve.

Question of Power SupplyAn important part to be considered in

any set is the power supply. The set -buyer must decide whether he is going tomake use of his electric light, if this isavailable, or whether he is going to usebatteries. Many sets are now availablethat run entirely from the mains. If theset -buyer has a choice he would beadvised to choose a mains set in prefer-ence to a battery -operated set. If bat-teries have to be used, or are preferred,they should at least be self-contained.Some sets have not yet developed the self-contained idea to the extent we considerjustified.

Page 62: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. Derems 1929

TYVVVVVVYVYVVTIFVVYTTIFTTYYTVVYV VT YVVVITYTTVITTIITYTTTYVT7TVTYVVYV7V77TYTTYVT7TAround the Scanning Disc

st,

11-

A TELEVISION RECEIVERInside of a large Baird Televisor, complete with moving -coil loud-speaker. The lens. framing mask and neon cowl are seen clearly

on the left

Secretscielevisori

BY H. J. BARTON CHAPPLE,Wh.Sch., B.Sc. (Hons.)

a picture A motor which of itself is steadyor framing running, that is, free from sporadicmask, a tendencies of speed change, throws amagnify- much lighter load on the synchronis-ing lens ing mechanism and will ensure an

SO far we have confined our (optional), a driving motor, and entire absence of any "picture hunt"attention mainly to a considera- synchronising mechanism. under normal working conditions,

tion of transmitting details, although The motor must be of the shunt- and this is very essential.no attempt has been made to delve at wound type, capable of developing aall deeply into the problems. Gener- speed up to about goo revolutions peralities are always best minute. The average A reference to Fig. i will give ato start with, and we running speed is 75o rough idea of the layout of the tele-can particularise after a r e v o 1 u t i o n s per visor. Assuming vertical scanning,working knowledge of minute (121/2 pic- we have a long tubular neon lampthe receiving end has tures per second), with a relatively large flat -platebeen garnered. and, above all, it is electrode which glows when the

Here, of course, it is necessary for this appropriate potential is appliedfairly obvious that we

4motor to be able to between the positive and negative

require a wireless run at a steady speed electrodes.receiving set to con- I for long periods at a The intensity of the plate glow isform to certain stand- stretch. dependent upon the strength of theards and a Baird Tele- According to the signals applied to the grid of the lastvisor. Since the

4

I supply available, the valve in the wireless receiver, thequestion of the wireless electrical power may neon, of course, being connected inreceiver is bound up b e d e r i v e d f r o m the output circuit either directly orvery largely with the accumulators or choke coupled, but of this more later.amplification of a suit- electric -light mains Revolving immediately in front ofable kilocycle sideband, and, in the case of the neon lamp we have the spirallytogether with a the latter, a machine perforated disc, and in front of thisquestion of tuning, of the universal type again, some form of rectangularwhich should be as (that is, one capable framing mask. Depending upon thebroad as possible, compatible with of running from either alternating- type of televisor which is in use, a lensselectivity, we will defer this until current or direct -current mains) has can be mounted in front of this againafter we have examined the televisor advantages which are self -obvious. to enlarge the picture, and in theitself. To my mind,

FLATPLATE.NEONLAMP

REVOLVING DISC

FRAMINGMASK

ENLARGINGLENS

Fig. 1.-General layoutof a Televisor

Leading QuestionsNow of what does a televisor con-

sist, and is it difficult to operate, andcomplicated in construction? Thesethree questions are being put to meregularly and can be disposed ofquite simply.

The essentials are a disc perforatedwith a spiral of holes exactly similar,from a proportional point of view, tothat at the transmitting station, aneon lamp with or without a cowl,

apart from thesynchronisingmechanism, which,of course, is ofparamountimportance, thesecret of a success-ful televisor lies inthe employment ofa high-grade motorand too much at-tention cannot begiven to this detail.

506

FOCUSSINGLENS

A

Layout of a Televisor

DISC

MOTOR

LAMP

OBJECT BEINGTELEVISED

1.--o 0 )

0

0

0

Fig. 2.-Illustrating direction of rotation

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Wireless Magazine. December! 1929

accompanying photograph, whichshows the back of a large model Bairdtelevisor, we can see the neon cowl,framing mask, and lens on the left ofthe picture, together with the disc.

As the disc revolves before theglowing neon plate, and provided thetransmitter and receiver are in syn-chronism, at any one instant aperforation in the disc will enable aspot on the neon to be observed.

Light and ShadeThis spot will correspond to one at

the transmitting end in an exactlysimilar position and, since the neonglow at that instant is directlyproportional to the amount of lightreflected from the spot on the tele-

is scanned vertic-ally from right toleft and frombottom to top.

With a trans-mitter arranged sothat the drivingmotor is on theleft-hand side ofthe light source(see Fig. 2A), andviewing the discfrom the motor Fig. 3. Arrangement of receiver.

end, the spiralwould be as shown in Fig. 2B, and thedirection of rotation clockwise.

The focusing lens on the other sideof the disc will then reverse the lightspot travel, so that it traverses the

11017,

DISC

MOTOR

A Lover Down the AgesIn times that are no more, on Christmas DayA gallant swain, when he lived far away

Would pen a stilted note his Love to greet,Or come by coach if they had planned to meet.

Last year he phoned "just thought I'd give a ringTo wish you luck, so cheerio ! old thing ! "

Or landed on her lawn in flying kit,Vowing his plane was " absolutely ' it' "

If she is wintering abroad to -dayNo doubt he'll greet her in the modern way,

And she will see him too without surpriseBecause, of course, they both will " televise !

LESLIE M. OYLER.

vised object, we shall have a degree oflight or shade of correspondingintensity.

Spot by spot and strip by strip thisprocess of exposure at the trans-mitting end, and re -exposure at thereceiving end takes place. Theresultant effect, therefore, to a personlooking into the televisor at theilluminated portion of the disc is tosee a succession of strips side by side,exactly as scanned by the spotlighttransmitter and picked up by thesensitive photo -electric cells.

Continuous PictureAs in the case of the transmitter,

the rapidity of the process does awaywith the mechanics and the resultantimage appears as a continuous whole,rich in detail.

It is advisable to consider one ortwo important "running" details atthis juncture, as they will explainsome phenomena which, to theuninitiated, appear rather puzzling.

In the transmissions which are nowbeing sent out every morning by theBaird process via the London station,the image, or object, being televised

area as shown in Fig. 2C, that is,starting from the bottom right-handcorner and finishing at the top left-hand corner.

Turning now to the receiver andconsidering the assembly, illustratedin the photograph and indicateddiagrammatically in Fig. 3A, then

NEONLAMP

0

/OBSERVER

0 0 o

13

0

from the observer's end the disc willbe mounted so that its spiral of holesare as shown in Fig. 3B, while thedirection of rotation for the disc isanti -clockwise.

Since we have the glowing neon atthe back of the disc, this will give ascan or exploration of the plate fromthe bottom right-hand corner to thetop left-hand corner, as shown inFig. 3c; and this, of course, gives usan identical condition to that at thetransmitting end.

Now supposing the disc wasmounted so that the spiral was theopposite way round to that of thedisc at the transmitting end, whatwould happen? Why, the imagewould appear from left to right,instead of from right to left. That is,if a person got into position from theright-hand side at the televisionstudio, it would appear to the observerthat he got in from the left-hand side.

Again, the moving printed scriptwhich is invariably transmitted dailyduring the course of the tests, wouldappear to be moving backwards andlook rather uncanny.

Naturally, it is very easy to rectifymatters by reversing the disc.

Radio Evolution-Continued from page 494H.T. consumption 57 milliamperes,with the valves tried.

Five-valver generally not so good,nor so selective. L.F. side O.K., H.T.consumption 24 milliamperes, needsexternal aerial and earth plugs and abetter frame aerial tuning arrange-ment.

General Remarks on Both Sets.-Condensers and valves poor, loud-speaker unit very good, but awkwardto adjust, frame aerial awkward tooperate and ought to be entirely re-designed, battery leads difficult todisentangle, but general accessibilitygood."Queue," he said, "I can't quite

get what you mean by these reports,let's have a talk about the sets."

We talked and talked and then,finally, "Hang it, man, I'll get the

507

four-valver modified to -night andtest it out myself all to -morrow."

So I left it at that.But when I met him three days

afterwards, after he had tried toavoid my eye, he told me that thesales manager had bullied him rightand left because the aperiodic H.F.set was easy to tune, and would sosell more easily. Also, the retailprice of the four, with its refinements,would have to be a guinea more thanthat of the five-valver.

But his own fancy had changed toone of the three-valvers, so I shouldnot be surprised if, next Show time,I find a nine -valve super -het on hisstand !

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Wireless Magazine. December 1929

VIDELESS SUPERSTITIONSWireless is in its infancy

T" phrase shouts at you fromthe columns of your daily paper

so often that you doubtless wonderwhen on earth this Peter Pan ofscience will attain the dignity of, atleast, adolescence.

But, until this happy stage isreached, you must content yourselfwith signs of this infant's growth.And I have recently made the inter-esting discovery that superstition isbecoming rife among the wirelessfraternity. And is not superstitiona sign of age ?

Take Warning!And so, to save you innocently

falling foul of this wireless bogy,and thus suffering casualites whichyou might otherwise have avoided,take warning of several things whichmust never happen, or-.

For instance, the number "thir-teen." In wireless, as in otherdirections, thirteen is decidedly thereverse of fortune. Never have thir-teen H.F. valves in your set-itwon't work if you do. And if thatisn't proof of the potency of thir-teen, I should like to know what is.

Neither must you have thirteen sets-a certain amount of domestic frictionover financial matters is usually theresult of disregarding this.

It is very unlucky to paint thewiring of your set green. Or to splashgreen paint down your loud -speaker.And if the terminals of your L.T.accumulator turn green-well, it's a

No/ NEXT MONTH! Nit

An Efficient Screen-ed -grid Three -valveSet with One -knobTuning Control,Which Any Begin-ner Can Operate

with Ease

sure sign that you'll have to buy anew one. So avoid green.

Never walk under an aerial. Goover it instead. This superstition,by the way, is supposed to have itsorigin in the unhappy fate of theman who erected an aerial to one ofMr. Heath Robinson's designs,and, when it was finished, stood

back to look up at it. He was 39.At all costs avoid allowing the L.T.

and H.T. wiring of your set to cross.This is very unfortunate from yourvalve's point of view.

Superstition, in wireless, reflects inevery way upon the enthusiast'spocket. In other words, if you reck-lessly disregard these omens, you'lleither have the deuce of a row withthe wife, or, if you are still sane, withyour bank manager.

What Not to DoTherefore, if your slogan be "peace

at all costs," never put a new boot onthe diaphragm of your loud -speaker;never spill salt into your variablecondensers (should you do so, thecorrect way to ward off evil is tothrow the set over your left shoulder) ;never light three valves with oneH.T.; never have your hairial-sorry,aerial-cut-pardon, lowered-on aFriday, and, above all, never let aglass accumulator fall. That is mostunlucky-for the accumulator.

In fact, the one way to avoid badluck in wireless is to use your setonly when the moon is green.

W. M. G.

Are Radio Critics Justified ?-Continuedfrom page yo3present, I prefer to use the earphoneswhile they listen to the sound fromthe loud -speaker. In their presence, Iprefer to be isolated from them. Is itmerely a foible of mine? A tempera-mental eccentricity, shall we say?

Only within the last two years haveI taken an interest in wireless. Thefirst time I heard any sound comingthrough the ether was in 1920when I was on board the Mauret-ania, heading into the grey of theAtlantic.

My Brutal SuggestionThe captain very kindly invited me

into his cabin to listen to a concertthat was being broadcast fromColchester. I was brutal enough tosay that it suggested a crackedgramophone record.

But, last year, I was lying ill in aNew York hotel and Big Boy wentout into Broadway and purchased forten dollars (two pounds), a small set

that one could have carried in anattaché case.

The aerial was composed of coatedtape which he laced around the sick-room. It looked like a gangway forflies. But when I had fixed the ear-phones, I was able to lie back on thepillow and listen to concerts andlectures broadcast from several sta-tions. It was better medicine thanany the doctor brought me.

I pride myself on being a tolerantman; yet it was a long while before Iallowed myself to be inveigled intobuying a set. Since then I havejoined the great army of grousers.But a friend of mine, who served inthe same squadron as myself, andcarries into the future with him thereputation for being a champion"moaner," modified my attitudetowards Savoy Hill.

In the flood of his vituperationagainst the daily and nightly pro-grammes, I saw something that

508

enlightened me, tempered my ownharshness and swung my sympathiesaround to the B.B.C. This was aboutthe time I was thinking of having aninstrument of my own installed. Ihad listened to his language for tenminutes, then I asked him a question ;

"Do you have to pay anything forthis listening -in business ? " said I.

He contemplated me with a steel -like eye.

A Sort of Licence!" Naturally," he said. " You have

to pay for a-a-sort of licence."" How much ? " I asked."I don't know," he said; "I have

never had one."And, between you and me, that

explains probably the weakness of thedaily programmes. We do not carewho pays for them so long as theyare good, but, by George, we wantto know what they mean when theprogramme is bad !

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GRAMO-RADIO SECTION Wireless Magazine. December 1929,

I,41111111111%11111014."4,,,, iiiiieinitteettnitrAntlit4114 til(7411Intlet illlitlAtittitt4tuntAtittnt

Wireless MagazineGRAMO -RADIO

SECTIONTHE FIRST SUPPLEMENT OF ITS KIND PUBLISHED BY ANY

RADIO PERIODICAL

Notable Dance Records for ChristmasSelected by H.

DESERVING to be markedwith a big M for the inter-

esting writing in the music, witha big P for the quality of theperformance, a big V for thefine tone volume, a big B forthe balance the recording direc-tor has obtained for the variousinstruments, and a big S for thesweetness (absence of harshness)in the tone, there are just a fewdance records among the many Ihave tried during the last fewmonths that may safely berecommended to those wishingto make up a Christmas pro-gramme.

Better Than a BandI have selected a set all by not-

able performing units and yetdiffering from one another asmuch as possible in style andinstrumental quality in orderthat your friends may acclaimyour reproduction as beingbetter than a band.

How mediocre even a goodband seems to be when one hasbeen listening to it for an houron end I

I have only one STOMP, "Sen-sation" on one side and "White-man " on the other, played byPaul Whiteman (H.M.V., B5577,3s.). It is an exhibition numberin "hot" work, and one side hasgood work for the piano.

Two Jolly RecordsA single ONE-STEP disc," High-

land Medley" and " Rob Roy

T. BARNETT, M.I.E.E.Medley," both Scottish selec-tions and very jolly (Parlo-phone, E6172, 2s. 6d.). EveryHogmanay programme oughtto include this.

YALE BLUES.-" I'm a One-man Girl," played by the Kit-Kat Dance Band, comprises anice piano part (Parlophone,R3o8, 3s.).

SLOW FOX-TROTS. - "Whenthe Lilac Blooms Again" and

FOR GOOD TONE

The well-known Limit Soundboit,recommended by H. T. Barnett in

the article on the next page

"Flower of Love," played byBarnabas von Geczy. These arein the Viennese style and ex-ceptionally rich in tone (Parlo-phone, R33o, 3s.). "Honey,"played by Carolina Club, andcomprising some good banjowork (Parlophone, R400, 3s.).

"There's a Four-leaf Clover,"played by the ManhattanMelodymakers (2s), and " Reach-ing for Someone" (2s.), played

by the same band; both areBroadcast Twelves (long -play),middle distance recordings show-ing a pretty " hall effect."

TANGOS.-I Wish to callespecial attention to thesebecause they are so beautiful;they are useful as exhibitionrecords, as well as for dancingto. "In a Little Café"(Pavilion Lescant) and " Par-don, My Lady" (von Geczy)(Parlophone, R411, 3s.). " Mic-hella " and "Love's BanishmentWaltz" (Radio is. 3d.). "DoYou still Love Me" and "Inthe Twilight" (Radio, Is. 3d.).

Well -sung Refrains.TANGOS (CON CANTO).-

These three are all Parlo-phones, at 3s. each; the vocalrefrains are well sung; the con-stitution of the band and theplaying are such as to take onestraight over to Buenos Airesin a flash. Each " con canto "has a non -vocal number on thereverse. "Plegaria, Noche deReyes," "A Media Suzan" arethe titles of the vocal sides.

SIX-Emifrs.--The first disc Ihave with one of these newdances on each side is H.M.V.,B57o1, 3s.: "Valentine" and"Dites moi ma Mere"(Innocents of Paris), played bythe Rio Grande Band.

Splendid WaltzesWALTZES.-Splendid double -

(Continued on page 511)

It tit iii1C; lllll 4,31111111011.1.1 M11411611011 11111111.81,111111.11111111A11111i1111%111114

4

tin tgAntoittein itlAynte<>

509

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Wireless Magazine. Pecwnber /9291GRAMO-RADIO SECTION

H. T. BARNETT,M.I.E.E.,

Explains forMusic Lovers

T h e Wonderphone,which was fully des-cribed on page 383 of

the previous issue

THERE are four considerationsthat in a general way must be

taken into account when setting outto purchase a new machine; theonly simple case being that of thosewho wish to reproduce language orother spoken records only.

Difficult ConsonantsThis small class may be disposed

of initially by recommending thepurchase of a small to medium-sized portable for the purpose, forthe smaller the amplification of themusic or vowels the more clearlywill the consonants, always recordedwith difficulty, come out.

Two machines of this kind thatI think should be heard (tried, ofcourse, with a spoken record)against others of equal price are theEdison -Bell at £3 5s. and the Pero -phone at £3 17s. 6d.; on both ofthese cheap machines correctitudeis approximated as closely as spacewill allow.

Others who wish to reproducemusic must first think of (1) whatmoney is available, (2) the spaceinto which the machine must go,(3) the class of music to be speciallyfavoured (if any) in reproduction,and (4) the acoustic qualities of themusic -room.

Good Table MachinesUnder the second heading some

people will be driven to the conclu-sion that they must have a tablemodel or a portable. Should it notbe required for use also out of doors,I should much prefer the former tothe latter; and in selecting a tablemachine, if no more money than £6is available, I think the mahogany -finish Edison -Bell model at thatprice should be heard.

Those who can spare £12 should

HOW TOCHOOSE AGRAMOPHONE

IN TIME FOR CHRISTMAS !certainly try the new H.M.V.Model 13o in solid mahogany. Thismachine gives excellent reproduc-tion and also the greatest tonevolume I ever heard from a machineof its size.

The Murdoch Trading Co. havejust produced a large Jussriterecord -filing cabinet on which itstands nicely. For those who wishto have a gramophone and a largenumber of filed records on a smallfloor area this is a useful combinatiOn.

The H.M.V. model139 (top) fits nicelyon top of a Jussritefiling cabinet (bot-

tom)

A portable for reproducing musicshould, in my opinion, always be alarge one; after all, one has to takea lot of heavy records about with it,so that a pound or two extra on theweight of the machine, while itmakes but little difference in thetotal weight to be carried, willgreatly improve the quality of themusic.

Recommended PortablesTwo of these that any dealer will

be able to show are the big H.M.V.and the largest size Decca. Shouldthe tone of the latter seem a littlehard a Limit soundbox may betried on it.

Those who have space availablefor a cabinet pedestal will get thebest reproduction and the greatestfurnishing value for their money,together with the probability ofexactly suiting their own taste inreproduction quality, suiting theclass of records they speciallyfavour and the acoustic charac-teristics of their music -rooms.

Before finally making a purchase,I would say unhesitatingly that ifone has an obliging dealer he shouldbe induced to send in severalmachines for trial side by side in themusic -room, and with the class ofrecords and kind of needles onespecially favours.

Qualities of A RoomIt is astounding what differences

to the reproduction of machines theacoustic qualities of a room willmake; in my own house there isone room in which the pungency ofa Columbia entirely disappears,while in the other even a Peridulceis brilliant.

People's tastes in tone qualityand in reproducing characteristicsvary enormously. A lady came

510

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GRAMO-RADIO SECTION Wireless Magazine. December. 1929]

from Littlehampton the other dayto hear my Perophone (Model 22),and when I pointed out to her theforwardness of the tone, whichmost folk delight in, she went upto the machine and closed thedoors; she preferred the tone inside

the case !I am quite at a loss to know what

to recommend in cases of this kind;some of the cabinet makers' as-semblies sold by cheap furniturestores might exactly suit.

On the score of the kind of recordfavoured, those admirers of feeblerecording by string quartets will

Largest sizeDecca port-able, recom-mended byH. T. Barnett

most likely be able to do with thegreatest possible amplification, evenat the cost of a clanging bass frompiano records and a generallycavernous quality.

Larger MachinesFor those who have just £13 13s.

to spend, one of the Edison -Bellreflex horn cabinets in oak-a newand extraordinary production atthe price-should be included inthe final test. Fortunate people whocan afford more should try one ofthe new Chromogram series Pero -phones (I prefer the 22) againstall -comers, irrespective of price.

For a big room the new hornmachine, the Wonderphone(414 14s., with table), a productionthat defies successfully all our oldtheories, should be tried. In adance -hall it is as good as manyhundred -guinea electrical repro-ducers.

Excellent ResultsIn a drawing -room its appearance

might be objected to, but should itbe possible to place it behind acurtain, and to use a Romanticsoundbox and fine -gauge steel gripneedles with it, I can well believe

" I millellOr-

"Xefirfze,Mtk, MAIATi VA fr

Perophone 22 machine, which the authorprefers " against all -corners." One ofthese machines is in constant use in the

"W.M." laboratories

that in many cases (e.g., roomswhere good tone is difficult toachieve) it might give more satis-factory results than could be gotwith the most expensive cabinet.

Notable Dance Records for Christmas-Continued from p. fogsided discs are " Twelve O'clock "and " Anita " (3867), " Just an OldLove Affair " and " Blue Waters "(5o15), both Brunswicks at 3s. each.Discs having a fox-trot on thereverse are " I'll Always be in Lovewith You " (R389), and " OneKiss " (R359), Parlophones, at 3s.each. "Underneath the RussianMoon" (2513), and " Pagan LoveSong" (2514), are long -play Broad-cast Twelves at 2S. each.

FOX-TROTS.-H.M.V., at 3s. each,axe "Dance of the Paper Dolls,"with " Ragamuffin," played on twopianos (B3o75), "A Love Tale ofAlsace-Lorraine," with " House onthe Hill Top" (B5628) ; "Let's Fallin Love " and " The Banjo " (B5622) ;" Is Izzy Azzy Wozz," with " WhenI met Connie" (B5666). The lastthree pairs are all played by JackHylton ; I like the first pair the best.

An Amusing PairParlophones at 3s. each com-

prise two discs of Sam Lain's " NowI'm in Love," with " The One I

Love Loves Me " (R4oi); also " TheWedding of the Painted Doll,"with "The Toymakers' Dream," amost amusing pair (R276). Reu daCosta has three piano and orchestrapairs : "Glad Rag Doll," with"Old Man Sunshine" (R276)," Laughing Marionette," with " Rag

TELL YOUR FRIENDSABOUT THE "W.M."LISTS AND CRITICISMSOF NEW RECORDS-THIS MONTH ON

PAGE 514

Doll " (R238), and " Fashionette,"with "Dancing Shadows" (R335).If I make up a programme, at leasthalf the numbers have a good partfor the piano.

Electron, the two popular num-bers from Mister Cinders, " EveryLittle Moment," with " Spread aLittle Happiness" (0284, 3s.).

Brunswick (at 3s. each), Red

Nichols (3991) plays " I'm MarchingHome," with "I Used to LoveHer," Jesse Stafford (3966) plays" A Precious Little Thing," with"Lover, Come Back to Me," andHarry Archer (3922) plays "Think-ing of You," with "Up in theClouds."

Broadcast Twelves (long play),at 2s. each. Teddy Brown gives acouple of xylophone solos thatought to be in every programme :" Glad Rag Doll," with " Weddingof the Painted Doll" (25o5). Othercombinations play" Wedding Bells,"with "Here We are " (2512), and" I Want to be Bad," with " Buttonup Your Overcoat" (2518)

Wonderful I s 3d. RecordsRadio.-From among many of

these wonderful one -and -threepenny8 -in. records I mention "Old ManSunshine," with " There's a Rain-bow" (939), and " Po-kee 0-keeOh 1" with "Oh ! Arthur" (913).The last is vocal right through, butin dance time.

511

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Wireless Magazine. December. 1929 GRAMO-RADIO SECTION

N. W. McLACHLAN, D,Sc., M.I.E.E., F.Inst.P., Explains How to Get Better

OgiateattiSL DETAILS OF AN AUTO-

MATIC COMPENSATOR KNOWN AS THE NO VO TONE

SOME time ago I was invited to ademonstration of sound effects

produced from gramophone records.Specially -prepared records of thedesired sounds, for example ex -

Fig. 1.-Shows method of connectingcompensator

haust of motor -car, aeroplane, etc.,were used in conjunction with pick-up, amplifier, and moving -coil loud-speaker.

The results were quite devoid ofrealism. This was due mainly to thegramophone record, although imper-fections existed in the pick-up, etc.The possibility of obtaining realisticeffects from a modern gramophonerecord immediately occurred to me.

Inherent DefectsBefore dealing with the solution

of the problem, let us discuss theinherent defects in the system usedfor reproducing gramophone records.

1. The pick-up does not give aneven response over the entiremusical scale. The response of somepick-ups falls away in the upper andlower registers, whilst others havepronounced resonances which accen-tuate scratch.

2. Although amplifiers which arealmost perfect can be designed, theaverage amplifier is often faulty ateach end of the musical scale.

3. For a given loudness the depthof cut in the walls of a record shouldincrease as the pitch of the sounddecreases; for example, the cut forthe lowest C on the pianoforteshould be four times as deep as formiddle C.

In an actual record the depth ofcut is the same for all notes below

middle C. Hence the bass notes arelost in the reproduced version oforchestras, organs, etc. The reasonsfor limiting the depth of cut are asfollows :

The deeper the cut the thickermust be the Valls of the record be-tween consecutive grooves. Torecord the low tones of orchestras,organs, etc., at their proper strength,would require a disc several feet indiameter. With such records thepick-up would jump out of thegrooves when playing low notes,

SPOWIMC COMPENSATIONINCREASE Ili OUTPUTWITH COMPENSATOR

SNOWING EFFECT OFCOMPLIISATINC FOR LOSSES

NOTE. %WV/MC LOSSO1 ,MICA NOTE.DUE TO RECORD ''./eLoss

PICK -LOP

C C. PIANO SCALE

MoDDLE C

Fig. 2.-Effect of McLachlan tonecompensator on the electrical re-

production of records

owing to the excessive sidewaysmotion.

From the preceding, it is clearthat the main defect to be remediedis the reduction in output belowmiddle C due to the narrow groovesin the record. The output at lowfrequencies falls off according to adefinite law and it is possible todesign apparatus which will givealmost exact compensation.

With such a device the bass regis-ter is reproduced at its properstrength, that is, by electrical meansa record r2 in. in diameter is ren-dered equal to one several feet indiameter.

When the bass register is repro-duced at its proper strength it isoften found that the upper registeris not sufficiently prominent. Thisis partly due to the effect of the lowtones masking the higher tones.

To solve this problem I haveintroduced a tone compensatorknown as the Novotone. As sup-plied by the manufacturers, it isconnected between the pick-up andthe amplifier. It can be designedfor intervalve coupling, but this isnot satisfactory where an amplifieris used for a dual purpose (radio andgramophone), since it puts too muchbeef into the bass of the radio.

For Talking PicturesI should like to make it clear,

however, that the principles em-bodied in the Novotone can beapplied to any apparatus for soundreproduction, for example, talkingpictures, whether film or record.Also, by fitting stud switches, thetone can be controlled over widelimits; the bass or the upperregister, or both, can be reducedfrom full strength to zero by steps.

Fig. I illustrates the method ofconnecting the compensator. Theaction of the compensator can be

Fig. 3.-Method of reducing outputfrom compensator. RI must notbe less than 2 megrAms. R2 can bea variable mega m used as a poten-tiometer or merely a variable resis-tance. The 30 -ohm resistance isused as a scratch contrcl. WhenPU.2 and S.C. are short-circuited

the scratch is a minimum.

512

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GRAM -RADIO SECTION Wireless Magazine. December: 1929

explained by aid of the diagramshown in Fig. 2. Owing to theamplification of the input from thepick-up, care must be exercised toavoid overloading the first valveand subsequent valves of theamplifier.

Volume ControlIt is preferable to have a volume

control in the amplifier, but it ispossible to put one before it. In thelatter case the resistance across theinput to the valve must not be lessthan 3 megohms. The arrangementis shown in Fig. 3.

The upper register (scratch) canbe controlled by putting a variableresistance of about 3o ohms acrossthe terminals S.C. and P.U.2 (Fig. 3).The maximum reduction occurswhen S.C. and P.U.2 are short-circuited. With a B.T.H. pick-up,which has a noticeable resonance at

WOMEN"

F-413i IVIWII01-7°0; 0 lilliqj

.I

L -

lilM110

41WAY CHAPICIE-OVER SWITCH

Fig. 4.-Method of switching Novo -tone for comparative tests.

TO PICK-UP

AMPLIFIER

GB

4,000 cycles, the scratch is pro-nounced, unless the control is used.

Owing to the great sensitivity ofthis pick-up, precautions must betaken to avoid overloading thewhole amplifier. In fact, with themajority of pick-ups the same argu-ment applies and the experimentermust bear this in mind.

CalibrationThe calibration of the Novotone

can be conducted in several ways.Those who have special constant -frequency records can readily testthe voltage step-up by aid of a four-way change -over switch of the formillustrated in Fig. 4.

When using these special recordsat frequencies below 15o cycles orthereabouts, it is usually found thatthe average pick-up will not stayon the record. Personally, using an

ordinary pick-up, I havefound it. im-possible to reg-ister 5o cyclessatisfactorilyon a loud-speaker by thismeans. Ac-cordingly it isnecessary tocalibrate theNovotone byother methods.

A simple cir-cuit suitablefor calibrationpurposes isshown dia-grammaticallyin Fig. 5. Herea sine -wavegeneratorsends a sine -wave cur

2000 PICA -UP

15- s

12COMSTAM VOLTAGE

11 \ FREQUENCYSUPPLY Of VARIABLE

\ COMPENSATOR

9 g

7

s

rit

-

3'2- t

032

THEORETICALCURVE

s4 41_5

Ca CI

27.

19000 mins

20,000 004115

300 V.

CAL; GRATEDAMPLIFIER

256 512 1024

C C' C2CYCLES PER SEC.

2045C3

1

4096C4

V.

22-5

20.0

7.5

15.0

2.5

0

7.5

5.02-50

5192

CS

Fig. 5.-Calibration curves of the Novotone. Curves 1 to 5are with infinity, 50, 30,15 and zero ohms between P.U.2 and S.C.

rent through the pick-up andthe input of the Novotone.* Theoutput terminals of the Novotoneare connected to the grid and fila-ment of the first valve of an ampli-fier, whose performance at allfrequencies is known.

Now the first valve of the ampli-fier has an effect on the Novotone,and' this is included in the cali-bration curve. Accordingly theNovotone is designed to suit thecondition obtained with an averageamplifier.

During calibration a constant vol-tage is main-tained by thegenera torbut its fre- 14

quency is var- 13

ied from 5o to is8,000 cycles.

11

Readings aretaken from the '°output of the 9amplifier at anumber of fre-quencies.

The result ofsuch a test isshown by curve

of Fig. 5.The dottedcurve showsthe theoreticalvalues for therange of 5o to250 cycles. The Novotone isdesigned to suit a2,000 -ohm pick-up

a

'7

5

4

2

0

The actual curve of the Novotonenever departs from this by morethan z decibels (units of sound), andsuch an amount cannot be perceivedby the human ear.

Peak FrequencyThe curve rises to 4,000 cycles in

the upper register and falls awaygradually beyond this. The peakfrequency varies to an extentaccording to the effect of the firstvalve of the amplifier. Duringcalibration the first value was an

(Continued on page 518)

CONSTANT VOLTAGESUPPLY OF VARIABLE

FREQUENCY

CAUBRATEDAMPLIFIER

CONDITIONS FOR CURVE I

ASABOVE cONP 95A,OR

CONDITIONS FOR CURVE

4 1J6 256Ce Ce

CYCLES PER SEC.

22-5

20.0

17.5

5.0

2.5

0.0

7.55-02.50

2646 4096 8192

Ca C4 C5

Fig. 6.-Calibration curves with special output circuits.Tests taken with S.C. free.

513

1

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Wireless Magazine. December 19291 CRAMO- RADIO SECTION

NEW RECORDS LISTED

AliPPNEWMforNidlokBelow will be found a list of the latest releases of the chief record publishing companies (Broadcast, Decca.Dominion, H.M.V., Parlophone, Piccadilly, Radio and Zonophone). It is arranged alphabetically in groups,and readers will be able to see at a glance what recordings are available of any particular item. Both sidesof every record are listed. Criticisms are by C. Whitaker -Wilson, the well-known musician and writer.

VOCALRECORDS

Abide with Me, DominionChoir, with organ, 1/3.

Dom AzooAll going Back, George Form-

by, Lancashire corn., withorch., 1/3. Dom A197

Always the Same Sweet Pal,Bob Fisher Black, singingcorn., with orch., 3/-.

PARLO R442Amor ti Vieta (Giordano)

Guido Volpi, ten, withorch., 1/9. Dom B25

Anvil Chorus (" Il Trovatore ")(Verdi), Grand OperaChorus, with orch.,

BRDCST 5107The band plays excellently

in the opening. The precisionof the chorus shows carefulrehearsal. Get it, for it is Verdiat his best.

Aren't We All? Elsie andDoris Walters, corn., withpiano, 3/-. PARLO R447

Ava Maria (Bach-Gounod)in Latin, Elsie Suddaby,sop., with piano, 4/6.

H.M.V. C1733Bandolero (Stuart), Manuel

Hemingway, bass, withorch., BRDCST 5,08

This song seems to have hadits day. It is, however, soadmirably sung here that it isworth having, even only for amemory of the past. The dic-tion of the singer is exception al.

Bird Songs at Eventide (EricCoates), Norton Collyer,ten., 2/-. DEC F1522

A pleasant ballad. Mr.Collyer's diction is not perfect-but his tone is excellent.

Blarney Roses, Foster Richard-son, bass, with orch., 2/6.

ZoNo 5415Breakaway, Maurice Elwin,

bar., with orch., 2/6.ZoNo 5418

Cast Thy Burden, Tom Burke,ten., with orch., 1/9.

Dom B23Che Gelida Manina (Puccini),

Oreste de Bernardi, ten.with orch., /9.

Dom B24Christ Who once amongst Us ;

There's a Friend for littlechildren ; All things brightand beautiful ; Come, sing withHoly Gladness, Bobby Le-maire, chorister with organ(d.s.) 1/3. BRDCST 457

Cigno Fedel (Wagner), Guido

Volpi, with orch., 1/3.Dom Fla

I recommend this as beingworthy of inclusion in any"Wagner library." Those whohave made a study of Wagnershould not miss it. Ask tohear it and judge for yourself.

Cobbler, Harry Wulson, yodel-ling, with orch., 1/3.

BRDCST 455"Jerre yodel": "tu te yodel":

"il se yodel" should be a pos-sible conjugation, with italicsfor il se yodel. For yodel hecertainly does I

Come in, Mr. Cummin', Clark-son Rose, corn., with orch.,z/6. ZoNo 5429

Come on Baby, Stuart Ross andJoe Sargent, Americanduettists, with orch., 3/-.

PARLO 8445Dai Campi Dai Prati (Boito),

Guido Volpi, with orch.,1/3. Dom Br8

Very well recorded. GuidoVolpi's singing is thoughtfullyphrased, and his voice is fullin tone.

Dear Old Girl, Maurice J.Gunsky, ten., with piano,2/6. ZoNo 5424

Devout Lover (White), NortonCollyer, ten., z/-.

DEC F1522Very well sung : but is Norto.i

Collyer a tenor ? The highe3tnote he sings in this record is F.He is a baritone, surely ?

Don Juan's Serenade (Tchai-kovsky), Roy Henderson,bar., with piano, 2/-.

DEC M69Roy Henderson at his best.

What a voice the man has 1Tchaikovsky at his best, also, itmay be added I

Dream (Massenet) " Manon,"Browning Mummery, ten.,with orch., 3/-.

H.M.V. B3121li Lucevan Le Stelle (Puccini),

Oreste De Bernardi, ten.,with orch., 1/3. Dom Bi6

Sevenpence halfpenny forthis work seems too little.The price of 1/3 for this (and

Non Piangere Lin) with sogreat an artist as Bernardisinging seems to me ridiculous!Of course, get itl

Evening Star, Gwen Henry,with Arthur Rosebery'sDance Band, 3/-.

PARLO R439Excelsior (Balfe), sung by

Browning Mummery andFoster Richardson, withorch., 4/-. ZoNo A368

Powerful and resonant voices;and diction that could be heardin heaven, one would think 1

Faust -Jewel Song (Gounod),Fanny Heldy, sop., withorch. con., by Piero Cop-pola (d.s.), 6/-.

H.M.V. DAro51Genevieve, Barrington Hooper

and Foster Richardson, withorch., 2/6. ZoNo 5417

Grand March (Tannhauser)(Wagner), Grand OperaChorus, with orch., 2/-.

BRDCST 5107The tone of the chorus alone

makes this worthy of inclusionin any Wagner library. I adviseall Wagner -lovers to have thisif they have not already acquireda record of the immortalchorus.

He's a good man to haveAround, Mabel Marks, corn.,with orch., 1/3. BRDCST 450

A voice and not a voice: adiction fierce enough to cutthrough steel: a philosophy per-vades this song which makes itamusing -yet pathetic. It isexceedingly clever.

Hollow of the Hill, NormanBlair, bar., with orch., 2/6.

ZoNo 5419Hollow of a Hill, Phil Arnold,

light ten., with orch., 1/3.Dom A r 98

Home in Maine, Norman Blair,bar., with orch., 2/6.

ZoNo 5419Honey, Mildred Hunt, sop.,

with orch., 3/-.H.M.V. B3 ,4o

Not a good voice, but there issomet ag appealing in the w avshe does this. I must admitto being attracted by the tune.

Abbreviations Used in These Listsacc.bar. ..BRDCSTCorn.con. ..DEC...Dom. ..d.s.f.

AccompanimentBaritone

. . BROADCAST

.. Comedian

.. ContraltoDECCA

.. DOMINION. Both Sides

. Foxtrot

orch. .

PARLO.PIC.RAD. ..s .f.sopten.

ZoNo.

Orchestra.. PA RLOPHONE.. PICCADILLY

RADIOSlow Foxtrot

..Soprano

.. TenorWaltz

ZONOPHONEWIN", a tunas appears in braketo dire lip afterthe title of an iient 0 io that of .e composer.

Hungry Women (Whoopee).Eddie Cantor, corn., withorch., 3/-. H.M.V. B31,16

I'm Doing what I'm doing forLove, Lily Lapidus, jazzgirl with Novelty Orch., 2/-.

PARLO R443in Seventh Heaven,

Johnny Marvin, ten., withorch., 3/-. H.M.V. B3119

I'm the last of the Red HotMammas, Mabel Marks.corn., with orch., 1/3.

BRDCST 450I thought it was a man sing-

ing -but I see it is MabelMarks. She will make her mark;for her diction if not for hervoice. It is an excellent recordof its type.

I Must have a Cup of Tea, withComedy Dance Orch.,

PARLO R44.6Indian Love Call, Tom Bailey,

with orch., g3. BRDCST 452In the Congo, eorge Formby,

Lancashire corn., with orch.,1/3. Dom A197

In the Valley where the Blue-birds, Barrington Hooperand Foster Richardson, withorch., 2/6. ZoNo 5417

I Only Met Her on Sunday,Elsie and Doris Walters,com., with piano, 3/-.

PARLO R447L' Anima Stanca (Cilea), Guido

Volpi, ten., with orch., 1/9.DOM B25

Let me Dream in Your ArmsAgain, Solemn and Gay,with orch., 2/6 ZoNo 5427

Little Pal (from Say it WithSongs), Gene Austin, ten.,with orch., 3/-.

H.M.V. B3113Gracie Fields, corn., withorch., 3/-. H.M.V. B3147Paul Robeson, bass, withorch., 3/-. H.M.V. B3146Tom Bailey, with orch., 1/3.

BRDCST 451Rather like Son of Mine, but

not so strongly atmospheric.Hear it before buying it: youin ty respond to it -or not. I

,nnot presume to say.Lonesome Road, Maurice

Elwin, bar., with orch., 2/6.ZONO 5418

Paul Robeson bass, witharch., 3/-. H.M.V. B3,46

Louise, Solemn and Gay, withorch., 2/6. ZoNo 5428

Love, Your Spell is Every-where (Goulding), GloriaSwanson, sop., with orch.,3/-. H.M.V. B3 t68

I feel the same about thisrecord as I do about theSerenade. Miss Swanson'svoice is in advance of her choice

514

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GRAMO-RADIO SECTIONWireless Magazine. December! 1929

of literature. She should givea little attention to her diction,though.

Lovelight in Your Eyes, Bar-rington Hooper, ten., withorch., 2/6. ZONO 5416

Makin' Whoopee, Stuart Rossand Joe Sargent, Americanduettists, with orch., 34- .

PARLO 445Eddie Cantor, corn., withorch., 3/-. H.M.V. B3116

Mastersingers (Wagner). RoyalChoral Society, con. by Dr.Malcolm Sargent, with orch.,(d.s.), 3/-. H.M.V. B3122

Merry Widow, Vocal Gems,Zono Light Opera Com-pany (d.s.), 4/-.

ZONO A367Old favourites from this

excellent opera, which, by theway, is of German origin,appear here. The voices aresplendid; the enunciation veryfair, but not unassailable. It is agood record from the technicalstandpoint. Altogether, havinglistened attentively to bothsides, I consider it the bestrecord of selections of this workI have heard. The chorus, I -

ought to add, is admirable.Mi Amado, Lupe Velez, con.,

with orch., z/6. ZONO 5425Moon has Raised her Lamp

(Benedict), Browning Mum-mery and Foster Richard-son, with orch., 4/-.

ZoNo A368I seem to have heard this

before I If I had not, I shouldnot mistake a single sylla. 'e;these two singers have a fiercediction about them. It is anexcellent record of an oldfavourite.

Mucking About the Garden,Jack Morrison, corn., withBidgood's Broadcasters, 1/3.

BRDCST 453This is excellent. Its clasti

title is a little startling, but Increcord is splendid.Clarkson Rose, corn., withorch., 2/6. ZONO 542)

My Dear, Mildred Hunt, sop.,with orch., 3/-.

H.M.V. B3140Mildred Hunt is no singe!,

but she "gets there" every time.I confess to listening to tai(and Honey, the other side)with some amount of pleasure.

My Heart is Bluer than yourEyes, Cherie, Franklyn Baur,ten., with arch., 2/6.

ZONO 5426The originator of this title

must have had some medicrlknowledge; he seems verycertain of his discovery, any-how ! It is quite effective.

My - Little Lady, JimmieRodgers, yodeller, withguitar, 2/6. ZONO 5423

My Old Shako (Trotere),Manuel Hemingway, bass.,with orch, 2/-. BRDCST 5108

Admirably sung ! Everyword comes through clearly.The orchestral accompanimentis perfectly balanced. An ex-cellent record.

New Moon (Romberg), LightOpera Company, with orch.,4/6. H.M.V. C1734

This is what one might calla "smart" record. It has theflavour of a real, up-to-dateopera company.

Non Piangere Liu (Puccini),Oreste De Bernardi, ten.,with arch.; 1/3. Dom B16

Bernardi sings with perfecttone in this excellent record.The recording also is admir-able. I sencerely recommendthis record, which would graceany repertory.

No Possible Doubt, Whatever,Dominion Light OperaCompany, with orch., x/3.

Dom A194No, Punchinello, No More

(Leoncavallo) (Pagliacci)Browning Mummery, ten.,with orch., H.M.V.

B3121Nothing in General and Less

in Particular (Clifford),Stainless Stephen, corn., 2/-.

DEC F x 526This is extremely funny.

Stainless Stephen dictates allhis arguments, punctuationincluded.

Oh ! Maggie, What Have YouBeen up To ? Jack Morrisoncam., with Bidgood'sBroadcasters, 1/3.

BRDCST 453Close inquiries into Maggie's

behaviour of late are here goneinto. It is an admirable record.Clarkson Rose, corn., witharch., 2/6. ZONO 5430

Page Song (Verdi) Falstaff,Arthur Fear, bar., withorch., 3/-. H.M.V. B3123

Park yourself Close to Me,Clarkson Rose, cam., witharch., 2/6. ZoNo 5430

Parted, Solemn and Gay, withorch, 2/6. ZONO 5428

Perfect Day, BarringtonHooper, ten., with orch.,z/6. ZONO 5416

Plantation Song Medley,soloists, chorus and danceband, 1/3 (d.s.) BRDCST 454

I thought the day for plan-' t 'don songs was passed long

ago. It may have passed, but ifthere are any gramophoneenthusiasts who feel inclinedto go back to the days of theirfathers -here is the oppor-tunity. The songs are well sung.

Ploddin' Along, The Revellers(male voices), with piano,3/-. H.M.V. B3I56

My friend the bass is hereexcellent. The first tenor hasa tone which would crack agas -globe, but he seems to fitinto the picture.

Rose Marie, Vocal Gems, arch.acc. (d.s.), 1/3. Dom A199Tom Bailey, with arch., 1/3.

BRDCST 452Sarah Jane, North and South

with Comedy Dance Orch.,3/-. PARLO R446

Sea Rapture (Coates), TomBurke, ten., with orch., 5/3.

DOM B15Tom Burke's voice has

"grown" since I first heardhim, when I chanced to play atthe same concert at which heappeared for the first time inEngl old. He sin';s this admir-ably. It is worth having.

Serenade (Toselli), GloriaSwanson, sop., with arch.,3/-. H.M.V. B3 x 68

Miss Swanson's voice is cle itand sympathetic. She coulddo worse thin sing better musicthan this for her records.

Silvery Moon, Harry Wulson,yodelling, with orch., 1/3.

BRDCST 455Harry Wulson's vowel -in-

tonation is founded upon aprinciple with which I am notfamiliar. As for the yodelling

effects, I recommend them tothose who appreciate theirvalue. The gentleman possessesconsiderable technique, I admit.

S'posin', Solemn and Gay,with orch., 2/6. ZONO 5427

Strange Adventure, DominionLight Opera Company, withorch., t/3. Dom A194

Talor dal mio Forziers (Puccini)Oreste de Bernardi, ten.,with arch., 1/9. Dom 824

Tannhauser (Wagner), LauritzMelchior, ten., with LondonSym. Orch., con. by AlbertCoates (d.s.), 6/6.

H.M.V. D,675That's the Good Old Sunny

South, Lou Abelardo, lightten., 1/3. Dom At 98

There is no Death, Torn Burke,ten., with orch., 1/9.

DOM B23There'll Always be Room for

You, Maurice J. Gunsky,ten., with arch., 2/6

ZoNo 5424There's a Girl in Kildare,

Foster Richardson, bass,with arch., 2/6. ZoNo 5415

This is Heaven, Bob Fisher,black singing corn., withorch., 3/-. PARLO R442Tom Bailey, with arch., 1/3.

BRDCST 451A little sentimental for popu-

lar appeal nowadays, but it iswell produced. Perhaps theproduction is worthy a bettersubject.

Though Reviling TonguesAssail Us (Bach), ElsieSuddaby sop., with orch.4/6. H.M.V. C1733

To the Forest (Tchaikovsky),Roy Henderson, bar., withpiano, 2/-. Dec M69

I have never heard it bettersung. What more can I say?

You, Johnny Marvin,ten., with orch.,_ 3/-.

H.M.V. B3119Vesti La Guibba (Leoncavallo),

Tom Burke, ten., withorch,. /-. Dom 815

A fine rendering. This iswell worth getting. Also I hopeI shall have the pleasure of re-viewing more records by thisadmirable singer.

Wake up ! Chillun, Wake up,Revellers (male voices), withpiano, 3/-. H.M.V. B3156

This is an excellent edition ofthis fascinating tune. The voicesare splendid, the bass particu-larly. The precision and dic-tion is another point. It is apleasure to hear men sing . sowell together.

Wanderer's Warning', Bud Bill-ings, ten., with NoveltyTrio, 2/6. ZoNo 5422

Winnie and the Picture Book,Harry Hemsley, child imper-sonator, I/3. Dom A2 01

Winnie is Told a Story, HarryHemsley, child impersona-tor, 1/3. Dom Azoi

When Survey, DominionChoir, with organ, 1/3.

DOM A200When My Dreams come True

(Berlin), Franklyn Baur,ten., with arch., 2/6.

ZONO 5426Franklyn Baur is a tenor,

which is more than can be saidfor some who thus label them-selves. I like the song; it is agood specimen of its type.

When You've Gone, GwenHenry, with Arthur Rose-

bery's Dance Band, 31-.PARLO R439

Where is the Song of Songs forMe? Lupe Velez, con.,with arch., z/6. ZONO 5425

Whoopee, Light Opera Com-pany, with arch., 4/6.

H.M.V. C1734A very smart chorus. This

and The New Moon give theimpression that the chorus hasbeen well drilled. Admirablerecording.

Why Can't I be Like You?Lily Lapidus, jazz girl, withNovelty Orch., 2/-.

PARLO R443Why Can't You ? Gracie

Fields, corn., with arch.,3/-. H.M.V. B3147Gene Austin, ten., witharch., 3/-. H.M.V. B3113

Will the Angels Play theirHarps for Me ? Bud Coll-.ings, ten., with NoveltyTrio, 2/6. ZONO 5422

Woo thou thy Snowflake(Sullivan), " Ivanhoe,"Arthur Fear, bar., witharch., 3/-. H.M.V. 83123

World is Yours and Mine,Morton Downey, ten., withorch., 3/-. H.M.V. B3138

You and My Old Guitar,Jimmie Rodgers, yodeller,with guitar, 2/6. ZONO 5423

You're Just Another Memory,Morton Downey, ten., witharch., 3/-. H.M.V. B3138

You Surprise Me (Clifford)Stainless Stephen, corn.,2/-. Dec F1526

This refers to the other sideof the record. The StainlessOne has a long conversationwith an American. Veryamusing.

ORCHESTRALRECORDS

Artist's Life (Strauss), ViennaPhilharmonic Orch. (d.s.),4/6. H.M.V. C1697

Ballet Egyptien (Luigini), Do-minion Orch. (d.s.), x/3.

Dom A2o2Belle of New York (Kerker),

H.M. Life Guards (d.s.), 2/-.BDCST 5105

If any of my readers make ahabit of collecting records ofthese selections from musicalcomedies I advise them to havethis: it is splendidly played.The recording is fine.

Bitter Sweet, Parlophone SalonOrch., con. Victor Olof(d.s.), 3/-. PARLO R44I

Call of the Angelus (Walton)Zono. Salon Orch., 2/6.

ZONO 54E1A very taking melody, with

music illy and pleasing modu-lations. It is most excellentlyplayed and the recording iseven.

Cavalleria Rusticana (Mas-cagni), Marek Weber andHis Orch., 4/6 (d.s.).

H.M.V. C1736This is a very good selection:

most of the well-known melo-dies appear. The recording isadmirable and the playing allthat can be desired.

Chinese Lullaby, Salon Orch.,3/-. H.M.V. B3539

Cock o' the North (Carrie),

515

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Wireless Magazine. December: 1929GRAMO-RADIO SECTION

New Records Listed and Reviewed ContinuedH.M. Life Guards, 1/3.

BDCST 456There is some admirable

playing here: the tone of thesolo clarinet is practically per-fect. An excellent record.

Fairy Tiptoe (Fredericks),Zono Salon Orch., 2/6.

ZONO 5421Quite delicate in construc-

tion, as befits the title. It iseffectively orchestrated; plea-sant counter -themes appearagainst the main theme -which always pleases me.

Folk Song Suite (Williams)Part I (mch.) Decca MilitaryBand, con. by C. Leggett,2/-. DEC M68

Dr. Vaughan William's deli-cate touch is well brought outin this excellent fantasia onSeventeen come Suitclay.

Part 2 (intermezzo).DEC M67

This is My Bonny Boy.It is most attractive to anyonewho loves English music; thescoring is absolutely fascinating.Part 3 (mch.). DEC M67

This is a delightful record offour Somerset folk -tunes. Thewhole record makes one feelthat one can only be in England.

Grand Vizier (Ansell), DeccaSymphony Orch., con. byJohn Ansell, 2/-. DEC M66

A melodious and pleasantwork, with some careful scoring.It is smartly and clearly played.

Hold Everything (selections),London Orch. (d.s.), 2/6.

ZONO 5414Innisfail (Irish Suite), Decca

Symphony Orch., con. byJohn Ansell, 2/-. Part I.

DEC M65This is very brisk and very

attractive. The orchestralscoring is really admirable.Part 3. -The tone of the fullorchestra here is round and full.The work as a whole is wellworth having.

Introduction and Allegro forStrings (Eiger), John Bar-birolli's Chamber Orch.(d.s.), Parts x and 2, 4/6.

H.M.V. C1694Parts 3 and 4, 4g.

H. .V. C1695Lead, Kindly Light, Creatore's

Band, 4/-. ZoNo A369Londonderry Air, String Orch.

with Organ, 2/-. BDCST 51o6Mignon Overture (Thomas),

Symphony Orch., Berlin(d.s.), 2/-. BDCST 5104

One of the best orchestralrecords I have ever heard. Itcan do no one any harm to getthis record for the sake of thepleasure of listening to the toneof the wood -wind. Practicallya perfect record.

Nation Emblem (Bagley), H.M.Life Guards, 1/3.

BDCST 4556A typical "Life Guards"

production. It is a pleasure tolisten to such precision. Thetone of the trombones attractedmy attention very quickly.

Nearer My God to Thee, Crea-tore's Band, 4/-. ZoNo A369

Old Time Favourites, LondonOrch. (d.s.), 2/6. ZoNo 5413

Onward, Christian Soldiers,

Creatore's Band,ZONO A369

Pagan Love Song_L Salon Orch.,3/-. H.M.V. B3139

Rose Marie, Parts 1 and 2,Bidgood's Symphonic DanceBand, with soloists andchorus, 2/-. BDCST 5109

This is a thoroughly goodrecord. The soloists have goodvoices. An excellent duet is afeature of the second portion ofthe record, which concludeswith some good choral singing.

Rose Marie, Tom Bailey, withOrch., BDCST 452New Mayfair Orch. (d.s.),4/6. H.M.V. C1756

Sacred Hour (Ketelby), StringOrch., with organ, 2/-.

BDCST 5,06Suite No. 2 in B Minor (Bach),

Chicago Symphony Orch.d.s.), H.M.V. D,673

Swan Lake (Tchaikovsky),H.M. Coldstream Guards,con. Capt. R. G. Evans(d.s.), 4/6. H.M.V. C1745

The Coldstream Guards herekeep up their great reputation.It seems that no more need besaid. I thoroughly recommendthe record.

Toccato Marziale (Williams),Decca Military Band, con.by C. Leggett, 2/-.

DEC M68This is an exceedingly clever

work. Admirers of VaughanWilliams will thoroughly enjoyit.

Vocal Gems, from MerryWidow (Lehar), Zono.Light Opera Co. (d.s.),

ZoNo A367

INSTRUMENTALRECORDS

Canzonetta (D'Ambrosio),David Wise, violin, 2/6.

ZoNo 5420David Wise's phrasing is

noteworthy. He plays withfeeling, but not with too muchsentiment. In a work of thiskind that is important. Hisdouble -stopping is clear andwell in tune.

Finale from Violin ConcertoIMendelssohn), Louis God-owsky, violin, with piano,1/9. Dom B27

I'll Always be in Love with You,Alex Taylor, organ fromDavis' Theatre, Croydon,

DEC F,525I'm Still Caring, Leslie Hut-

chinson, piano, 3/-.PARLO 8444

Liebestraume (Liszt), HermanWasserman, piano, 1/9.

Dom B26Molly on the Shore (Grainger)

Herman Wasserman, piano,1/9. DOM B26

Monk's Dream (Holmes),Sandy Macpherson, Wur-litzer organ, 3/-.

H.M.V. B3173My Mother's Eyes, Alex Tay-

lor, organ from Davis'Theatre, Croydon, 2/-.

DEC F1525My Sin, Leslie Hutchinson,

piano, 3/-. PARLO R444Prelude in E Minor (Mendels-

sohn),VladimirdePachrnann,piano, 6/-. H.M.V. DA9z6

There is only one Pachmann !I have heard him play thisbefore actually, I mean -andit brings back memories. Histone is one of the seven wondersof the modern world.

Prelude in B Minor and Preludein G Major (Chopin), Vladi-mir de Pachmann, piano, 6/-.

H.M.V. DA927No one has ever playe

Chopin -probably not evenChopin himself -as Pachmannhas done. Thanks to thegramophones he will live withus always. This is a perfectrecord.

Scottish Pastorale (Saenger),Yehudi Menuhin, violin,with piano, 8/6.

H.M.V. DBI284Siciliana (Mascagni), David

Wise, violin, 2/6.ZoNo 5420

A very good rendering of it.Do you know the Siciliana ofMascagni ? If not, you ought to;and you will not hear it betterplayed than by this same DavidWise

Songs My Mother taught me,Louis Godowsky, violin,with piano, z/9. Dom P27

Starlight (Brownsmith), SandyMacpherson, Wurlitzer or-gan, 3/-. H.M.V. B3173

Tattoo (Grimshaw), EmileGrimshaw's Banjo Quartet,z/-. DEC FI52I

Te Deum, Yehudi Menuhin,violin, with piano, 8/6 (d.s.).

H.M.V. DB x 28The young violinist gives a

good impression of Handel -not always easy to do. Hisplaying is characterised by goodphrasing and even tone.

Vienna Blood (Strauss), Sch-willer Octet, instrumental,

DEC F1527An excellent specimen of the

Viennese type of waltz. Thereis something very distinctiveabout Viennese waltzes.

Wayside Shrine (Sherwood),Schwiller Octet, instrumen-tal, 2/-. DEC F1527

A very well balanced octet.There is a great deal to be saidfor small bands for recordingbands for recording purposes.The music here is quite attrac-tive.

Wedding Music, from St.Margaret's, Westminster,con. by Stanley Roper, 3/-(d.s.). H.M.V. B3 reo

DANCERECORDS

A Little Bungalow (f), HerbertJaeger and Orch., 2/-.

DEC F 1528Am I Blue ? (f.), Arcadians

Dance Orch., z/6,ZONO 5433

Birmingham Bertha (f.), MiffMole and His Molers, 3/-.

PARLO Rt32Bitter Sweet (w.), Barna as

Von Geczy and Orch., 3/-.PARLO R440

Broadway Baby Dolls (f.), JayWilbur and Orch., 1/3.

Dom A189Building a Nest for Mary (f.),

Midnight Merrymakers, 1/3.BDCST 449

This is the second effort Ihave had to face about a nest.Some people successfully fea-thered the last one. This ismerely a building oneration. Iwas distinctly entertained by it.The words are good: so is thetune.

Button Up Your Overcoat (f.,from Follow Through), Dor-sey Bros. and Orch. withvocal refrain, 3/-.

PARLO R385Ambrose and Orch., 2/ -

DEC M76What a rage this tune is !

Everyone seems inclined torecord it. It is quite worthhaving -possibly it will be thesuccess of the season. I shouldnot be surprised.Jack Hylton and His Orch.,3/-. H.M.V. B5703Jay Wilbur and Orch., 1/3.

Dom Ax86There is some excellent

advice in this -beginning withthe injunction contained in thetitle. The advice is worth the1/3 which you would have topay for a patent medicine !Buy it, and obey it when youhave bought it 1Manhattan Melodymakers,2/-. BDCST 2518

I have already commented onthe words of this song. Itis only necessary to say herethat this is an excellent record:the vocal refrain is sung withexcellent diction.

Chinese Twilight (f.), Arca-dians Dance Orch., withvocal refrain, 2/6. ZONO 5432

Come One Baby (f.), RhythmManiacs Dance Orch., withVocal refrain, 2/ -

DEC FI528Brooklyn Broadcasters, 1/3.

Dom A:95Rhythmic Eight, 2/6.

ZONO 5436Come West, Little Girl, Come

West, from "Whoopee" (f.),George Olsen and his Music,3/-. H.M.V. B5683

Dance of the Wooden Dolls (f.),Harry Bidgood and Broad-casters, 1/3. BDCST 447

Dear Little Cafe (f., fromBitter Sweet), Ambrose andOrch., 2/-. DEc-M75

I understand this to be popu-lar. I think it is deservedly soand this is certainly a goodrecord of it.

Dites moi ma mere (six -eight,from Innocents of Paris), RioGrande Band, 3/-.

H.M.V. B57oDown Amoy the Sugar Canes

(f.), Midnight Merrymakers,1/3. BDCST 449

Quite an atmosphere sur-rounds this. It is a good dancerecord.

Dream Mother (f.), Harry Bid -good and Broadcasters, 1/3.

BDC.ST 446A splendid dance -tune,

rhythm clearly marked. It iswell produced in every way.

516

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GRAMO-RADIO SECTIONWireless Magazine, December: 1929

Criticisms by Co Whitaker -WilsonExcuse Me, Lady (f.), (Nich-

holls), Arcadians DanceManhattan Melodymakers,2/-. BDCST 2.517

excellent. It is an attractiverecord in every way.

Some Sweet Day (f.), CarolinaClub Orch., with vocal

Orch., 2/6. ZONO 5431 Another well -scored number. Makin' Whoopee (f., from refrain, 3/-. PARLO R435Fairy on the Clock (f.), Jay The Manhattan Melodymakers, Whoopee), Deauville Dance Manhattan Melodymakers,

Wilbur And Orch., 1/3. I have come to the conclusion, Orch., 1/3. Dom Ax88 2/-. BDCST 2517Dom A192Forget -me -Not (slow f.), Her -and

bert Jaeger and Orch., 2/-.

are quite a safe investment. Ihope they will keep up theirstandard of excellence.

This is quite entertaining,excellent for dance pur-

poses. There is something

There is some effectivescoring here -a fact which al -ways incites me to recommend a

DEC F1524The composer of this attrac-

I'm Just in the Mood To -night(f.), Rhythmic Eight, 2/6.

original about the whole designof the tune.

record of this kind. Poorscoring should be a thing of thepast by now !

tive dance -tune has realisedthat good orchestral effects and

ZONO 5436Indian Love Call (from Rose

George Olsen and Music,3/-- H.M.V. B5683 So the Bluebirds and the Black -

little contrapuntal melodies areexcellent in all music -light or

Marie), Thea Phillips andTom Bailey, with Orch., 2/-.

Ambrose and his Orch., _2/,DEC M71

birds got Together (f.), Man -hattan Melodymakers, 2/-.

otherwise. It is well written. BDCST 452 Arthur Rosebery and Band, BDCST 2516

Forgive Me (f.) (Egen), Herbert Al Benny's Broadway Boys, with vocal refrain, 3/-. I expected the Bluebirds andJaeger and Orch., 2/-. 2/-. BDCST 2515 PARLO R437 the Blackbirds to be drinking

DEC F1524 I Want to be Bad (f., from Jack Hylton and Orch., 3/-. Stephen's Ink, but I was mis-taken. It turns out that it was

There is everything to be Follow Through), Manhattan H.M.V. B57o2 over a question of the weathersaid for this type of fox-trot. I Melodymakers, 2/-. Mean to Me (f.), Arcadians that they got together. I en -admire the thoughtful orches- BDCST 2518 Dance Orch., with vocal joyed this record very muchtration. The other kind -and A certain wildness and aban- refrain, 2/6. ZoNo 5433 indeed: there is somethingunfortunately there are too don characterizes the musi3 My Dream Memory (f.), Jack picturesque about it not easy tomany -I simply intend to here, which, of course, suits the Hylton Orch., describe. It is very appealing.ignore in these columns.

Gotta Feelin' for You (f.),Frankie Trumbauer's Orch.with vocal refrain, 3/-

PARLO R434Heather Moon (w.), Harry Bid-

good and Broadcasters, 1/3.BDCST 446Those who dance to a gramo-Arthur

title. The tone of the bassinstruments in the orchestra isexcellent. I dare not name theinstruments -for heaven onlyknows what one of them is I

Jack Hylton and his Orch.3/-- H.M.V. B5695

It Wasn't Meant to be (f.),Wilbur and Orch.,Jay 1/3

and 3/-.H.M.V. B57o4

My Lucky Star (f., from FollowThrough), Jack Hylton andOrch., 3/-. H.M.V. B5703Arthur Rosebery and Band,with vocal refrain, 3/-.

PARLO R436On Top of the World Alone (f.),

Rosebery and Band,

Spell of the Blues (f.), DorseyBros. and Orch., with vocalrefrain, 3/-. PARLO R385

S'posin' (f.), Carolina ClubOrch with vocal refrain.,

3/-- PARLO R435Spring it in the Summer (f.),

Rhythmic Eight, 2/6.ZoNo 5435

phone ought to have this for thewinter season. Good waltztunes are always in demand.

He's a Good Man to Have

Dom A189For dance purposes this is to

be recommended, but the in-atruments are a little harsh. Ifyou have it, use a soft needle I

with vocal refrain, 3/-.PARLO R438

Pagan Love Song (w.), EdKirkeby Wallace and Orch.,

This is Heaven (f.), Al Benny'sBroadway Boys, 2/-.

BDCST 2514Arcadians Dance Orch., 2/6.

Around (f.), Rhythmic Eight,with vocal refrain, 2/6. Kansas City Kitty (f.), Rhyth- with vocal refrain, 3/-.

PARLO R432ZONO 5431

Brooklyn Broadcasters, '/3.ZONO 5434Almic Eight, 2/6. ZoNo 5437 Benny's Broadway Boys, Dom A195Hitting the Ceiling (f., from

Broadway), Ambrose and Eight

Say the title ten timesquickly ; it is good exercise. The

are what they2/-. BDCST 2514

Very effective, and a goodThou Swell (f.), Johnny John -

son and Statler Penns lean-Orch., 2/-. DEC M70

Our fox-trots are gettingsay they are ! waltz. I am not so sure about

its paganism, though. Ratherians Dance Orch., 3/,

H.M.V. B5706-ultra -modern l This is rhyth-mical to almost a startling point.Admirably recorded I

Arthur Rosebery and Band,with vocal refrain, 3/-.

PARLO R437

conventional, I thought it.Reaching for Someone (f.).

An excellent dance number.It is not so much the tune asthe clear playing which will

I Don't Know How (f.), Jay Little Pal (f., fom Say it with Brooklyn Broadcasters, 5/3Dom A193 make it valuable for dance

Wilbur and Orch., 1/3.DOM A i90

Song), Rhythm ManiacsDance Orch., with vocal Rosa (one-step),. HUITIOTOM

Voca . Midnight Merry-purposes.

Toymaker's Dream (f.), JayI feel at home with You (f.), refrain, 2/-. DEC F1523 makers, 5/3. BDCST 448 Wilbur and Orch., 1/3.

Jay Wilbur and Orch., 1/3.Dom A,90

George Olsen and his MusicDance Orch., 3/-.

A simply constructed tune ofthe greatest value in a danceroom. It is well orchestratedand played cleanly. The vocalrefrain is sung sotto -voce and is

Rosa comes from Italy.Quite amusing. Kisses evident -ly record well: I was ratherinterested in this fact.

DOM AI92Underneath the Russian Moon

(w.), Al Benny's BroadwayBoys, 2/-. BDCST 2513

H.M.V. B5706 quite fascinating. Rose Marie (f.), All Benny's I like this. There is a plea -This is very well played and

is an exceedingly useful dancerecord. As a composition thework suffers from ordinary pro-gressions, but it has, as I say,a value for the ballroom.

I'm Bringing a Red, Red Rose

Al Benny's Broadway Boys,2/-. BDCST 2513

I suggested in the review ofit with Tom Bailey -find it,will you? -that you had betterhear it before buying. Havilgheard it twice in one

Broadway Boys, 2/-.BDCST 2515

San Sebastian (f.), ArthurRosebery and Band, withvocal refrain, 3/-.

PARLO R438Singing in Rain from

by a violin against an equallysant contrapuntal melody played

pleasant voice. It is well scored.Until you get Somebody Else

(f., from Whoopee), GeorgeOlsen and his Music, 3/-.

H.M.V. B5684(f., from Whoopee), Am-

mornirg.I do not know what to suggest

the (f.,Hollywood Revue), Dorsey Valentine (six -eight, from In-

brose and Orch., 2/-.DEC M75

now ILouise (f.), Rhythmic Eight

Bros. and Orch., with vocalRefrain, PARLO R433

nocents of Paris), Rip GrandeBand, 3/-. H.M.V. A57o1

This is interesting and mo-dern in style. There is a good

2/6. ZONO 5437Rhythm is the hall -mark of

3/-.Ambrose and His Orch., 2/-.

DEC M70Wake Up, Chillun' (slow f.),

Brooklyn Broadcasters, 1/3.deal of originality about it.

I'm doing what I'm doing forthis octet, evidently; one can-not imagine them indulging in

This is exceedingly cleverand admirable for dancing

Dom A193Manhattan Melodymakers,

Love (f.), Harry Bidgood and rabato. Excellent for dancing, ofpur-

poses. It has a considerable 2/-. BDCST 2516his Broadcasters, 1/3. course ! amount of originality about it. A good bass voice sings early

BDCST 445 Lovable and Sweet (f.), Jack Jay Wilbur and His Orch. in the record. At the pitchThe title left me wondering Hylton and Orch., 3/-. 1/3. Dom A187 which the gramophone plays

here he delivers himself of awhether he meant without pay-ment or for the sake of affection:it appears he is something of a

lover

H.M.V. B57o4Love Me or Leave Me (f., from

Whoopee), Jack Hylton and

The singer hisses his s's asthough he had holes in his frontteeth ! The tune is a good one,'

few healthy low G flats. Theorchestral effects are novel, also.

atand a goodat the same time. It is quiteeffective.

I'm Feathering a Nest (f),Harry Bidgood and Broad-

Orch., 3/-. H.M.V. B57o2Ambrose and His Orch.,....2/-.

DEC M71Leo Reisman and His Orch.,

H.M.V. B5684

though. He is quite amusing'.(w., fromSleepy Valley Rain-

bow Man), Harry Bidgoodand Broadcasters, 1/3.

We Toddled up the Hill (f.),Ryhthrnic Eight, with vocalrefrain, 2/6. ZoNo 5434

Who Knows? (f.), DeauvilleDance Orch., 5/3.

casters, 1/3. BDCST 445Harry and his Broadcasters

3/--Deauville Dance Orch., 43.

Dom Ai88

BDCST 447A good waltz. It is well

Dom A191Why Can't You ? (f., from Say

feather it well between them. played, and is rhythmical in it with Song), RhythmThese "numbers" are of realvalue for dance purposes. Thevocal refrain is splendid.

The title is rather disarming,and I am not sure whether thepeculiar tapping rhythm makesme want to be loved -or left !

construction.Bamabas Von Geczy andHis Orch., 3/-.

Maniacs Dance Orch., withvocal refrain, 2/-.

DEc FI523I'm Just a Vagabond Lover (f.), The words of the refrain are PARLO R44o (Continued at foot of next page)

517

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Wireless Magazine. December: 1929 GRAMO-RADIO SECTION

Realism from Your Records Continued fromi Pagecl

Inside view of the McLachlan Novotone compensator, whichhas given excellent results in the " W.M." laboratories.

LS5, with ro,000 ohms in its anodecircuit. The valve magnificationwould be about 4. If the magnifica-tion had been 16, the curve wouldprobably have had its peak about3,500 cycles.

Adding BassThe effect of using resistances of

various values across the terminalsP.U.2 and S.C. is shown by curves2, 3, 4, and 5. Obviously the upperregister can be kept under com-plete control by this simple expedi-ent. In fact, if curve 4 is used, theeffect of the Novotone is merely toadd the bass register.

It was shown above how to reducethe output from the Novotone. Theuse of resistances of the grid -leakvariety leads to curve 2 of Fig. 6.The peak of the upper register isnow about 800 cycles higher thanbefore, and is comparatively incon-spicuous. The reduction in tile peakis due to the combined effect of2 megohms in series with the effec-tive valve capacity across r megohm.

Reducing Upper RegisterThe result, in practice, is to

reduce the upper register. To insertthis register in varying degrees, it ismerely necessary to put a con-denser of .0005 to .00r microfaradacross the 2-megohm leak.

By using the .00r-microfaradcondenser across the grid and fila-ment of the valve, the upper registerwill disappear and leave the bass.This is an interesting experiment toconduct. The experimenter will

discover to hissurprise that, al-though powerresides in thebass, it is really" quiet " andconversation canbe carried onwith ease.

Not a fewloud- speakershave resonancesbelow roo cycles.The Novotonemay excite theseinstruments toapparen tlyheroic deedswhich are notalways welcome.

In case it is de ired to curb suchunseemly behaviour, I propose toindicate how the lower register ofthe Novotone can be reduced.

All one does is to substitute a.0005 to .00r-microfarad condenserfor the 2-meoghm leak, as shown inFig. 6, curve r, and this gives an

ordinary resistance -capacity coup-ling. The calibration curve, usinga .00r-microfarad condenser, isshown in curve r. By comparisonwith curve r of Fig. 5, it is evidentthat an appreciable reduction in thelower register has been effected. Toobtain a greater reduction it ismerely necessary to use a condensersmaller than .00r microfarad.

Wonderful TransformationIn tact, i1 this condenser is

reduced to .000r microfarad, thelower register will substantiallydisappear. The upper register willnot be " quiet," rather will it be.irritating. A lack of body, so tospeak, will be apparent. Althoughneither the upper nor the lowerregister is "loud" by itself, a won-derful transformation results whenthe two present a united front.

By combining the schemes setforth above, the experimenter willbe able to secure the tonal balanceand voltage input which best suitshis complete apparatus.

WHEN YOU HAVE APROBLEM TO SOLVE

Which is more than you canunravel for yourself, whetherit be a gramophone or radiomatter, do not hesitate to con-sult the WIRELESS MAGAZINE

Information Bureau.

The rules are simple, butthey must be rigidly observed :(1) Ask not more than twoquestions at a time, (2) writeon one side of the paper only,

(3) send a stamped addressedenvelope for reply, (4) andthe coupon on page iii of thecover, with a fee of 1s.

Address your inquiries to"Information Bureau, WIRE-LESS MAGAZINE, 58/61 Fet-ter Lane, E.C.4." In mostcases you will get a satisfac-tory reply within forty-eighthours.

New RecordsReviewedand Listed

forYour Choice(Continued frompreceding page)

This is quite amusing. Ithink I reviewed it last month(by another publisher).

You Wouldn't Fool me, WouldYou? (f., from FollowThrough), Jay Wilbur andOrch., 1/3. Dom A186

It is an old question as pre-sented here, but it makes anexcellent dance record. Notat all a bad tune.Arthur Rosebery and Dance

Band, with vocal refrain, 3/-.PARLO R436

Jack Hylton and His Orch.,H.M.V. B5695

Your Mother and Mine (f.),Dorsey Bros. and Orch.,with vocal refrain, 3/-.

PARLO R433

You're a Pain in the Heart toMe (f.), Rhythmic Eight,2/6. Zoivo 5435

518

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Wireless Magazine. December 19291

"Henry V" as a Radio PlayIf broadcasting had been in vogue in Shakespeare's time, he mighthave written " Henry V " as a radio play, in which case the famousprologue would doubtless have been modified somewhat after this fashion :

0, for a wireless Muse, that would ascendThe brightest heaven of invention !A kingdom for a stage, princes to act,And monarchs to describe the swelling scene !Then should the warlike Harry, like himself,Assume the microphone, and at his heels,In big armchairs, should all the station staff

Cram within this studio

Await employment. But pardon, gentles all,The flat unraised spirit that hath dar'dFrom this unworthy station to sen forthSo great an object ; can your earphones holdThe vasty fields of France ? or may we cramWithin this studio the very casquesThat did affright the air at Agincourt ?

0, pardon ! since a crooked figure mayAttest in little place a million;And let us, ciphere to this great accompt,On your imaginary forces work.Suppose within the girdle of these wallsAre now confined two mighty monarchies,Whose high upreared and abutting fronts

41.6\161;"ii

'

Within the girdle of these walls are now confined.two mighty monarchies

The perilous narrow ocean parts asunder ;Piece out our imperfections with your thoughts ;Into a thousand parts divide one voice,And make imaginary puissance ;Think, when the "Noise Department" reproducesThe sound of prancing horses, that you see them

Sound of prancing horses . Printing their proud hoofs i' the receiving aerial ;For 'tis your thoughts that now must deck our kings,Carry them here and there ; jumping o'er times,Turning the accomplishment of many yearsInto an hour's broadcast ; for the which supplyAdmit Announcers to this history ;Who, prologue -like, your humble patience pray,Gently to hear, kindly to judge, our play !

W. OLIVER. Admit announcers

519

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Wireless Magazine. December: 19291

7VYVVYVVVYVVVVYVVVYTYVVYVVVVVVVYVVYVVYVYVVVVYVVIIYYVVVVIIVVVIITYVVVVVYYVVVYVVVVVY

An Improved linenLoudspeaker

HOW TO BUILD YOUR OWN INSTRUMENT !AT the beginning of this article, it

will be just as well to remind oldreaders, and inform new readers, thatthe WIRELESS MAGAZINEfirst radio paper in thiscountry to introduce thenow tremendously popu-lar type of linen loud-speaker to listeners.

Success AssuredRight from the publica-

tion of the first details-in the WIRELESS MAGAZINE for September, 1928-the success of the newtype of Icud-speaker wasassured. During the inter-vening months variousmodifications of theoriginal design have ap-peared in our contempor-ary, Amateur Wireless.

HALF -SCALEBLUEPRINT FOR6d., POST FREE

This month we offer readers detailsof a new loud -speaker which ineOrporates all the improvements that a

was the year's constant research have proved

Another view showing how the Blue Spot unit ismounted at the back of the small diaphragm

This photograph shows clearly how the BlueSpot unit is held in position by a brass strip.Other units can, of course, be supported ina similar way, but the mounting must

be rigid

to be best for the averageama' eur.

For the benefit of thosereaders to whom this type ofloud -speaker is quite new,we will briefly explain thefundamental points of itsconstruction.

Two frameworks are pre-pared, one comparativelymuch larger than the other,and across each is tightlystretched a piece of linen.The frameworks are heldapart by any suitable means,but the centres of the twopieces of linen are drawntogether and held in positionso that in effect two shallowconical diaphragms areformed. Any suitable driv-ing unit is then attached tothe centre points of the twopieces of linen. These

520

features will be clear after a glance atthe photographs of the completedloud -speaker.

Reason for Two DiaphragmsThe object of providing

two diaphragms is simplyto get the necessary ten-sion on the linen; there isno method of which weare yet aware by which asingle linen diaphragmcan be satisfactorily"shaped" to give goodreproduction.

Question of SizeIf desired, both frames

could be made of the samesize. The effect of makingone larger than the other,as claimed by the originalAmerican inventor of thesystem, is to give a betterbalance between bass andhigh -note reproduction.

It is assumed that thevibration that takes placein the linen is radial in

character along the diaphragm andthat the linen does not move as awhole, which is the case with anordinary conical diaphragm.

According to the radial theory,therefore, a small diaphragm willgive the best high -note reproduction,and a large diaphragm the best bassreproduction

Superb ResultsIn practice, a well -constructed

linen -diaphragm gives reproductionthat is of a very high quality indeed-provided that a suitable driving unitis used. It is found best to use abalanced -armature unit, such as theBlue Spot, which gives superb results.

A single -pole reed -type unit is notfound to give first-class reproductionas a rule. Nowadays, however, thereis a large number of well -madebalanced -armature units available.

The first linen loud -speaker

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described in the WIRELESS MAGA-ZINE used an octagonal frameworkand this new model is constructed onsimilar lines, except that it is smallerin size, being 28 in. high and 28 in.across.

In this size there is no need toemploy a baffle as the bass is repro-duced at good volume; in fact, the,balance is excellent for all normalpurposes.

Easy StretchingThe large diaphragm is octagonal,

because it is easier to stretch thelinen on this shape than on to asquare or rectangular frame. Thesmaller diaphragm is stretched on asquare frame for simplicity, there islittle trouble in putting it on sucha small frame.

Arrangements have been madewith a number of manufacturers forthe supply of wooden frames for thisloud -speak -,r, but for those whoprefer to make their own, we haveprepared a half -scale blueprint.

This can be obtained for half-price(that is, 0d., post free), if thecoupon on page iii of the cover isused by December 31. Ask for No.WMI72; and address your inquiryto Blueprint Dept., WIRELESSMAGAZINE, 58-61, Fetter Lane,E.C.4.

Fixing JointsOne of the photographs repro-

duced here shows how the jointsof the octagonal and squareframeworks are held withcarpenter's "dogs."

Before beginning the con-struction, the parts detailed on

page 522 should be obtained.The linen actually used for ouroriginal model was branded" Webb's Irish Linen," andwas obtained from Wallis's ofHolborn.

On the face of the octagonalframe is fixed a length of therubber used for keeping draughtsout of windows and doors; themethod of fixing it will be clearfrom the photograph below.The part of circular cross-sectionshould be placed near the inneredge of the frame.

To start the construction, cutout apiece of linen about 5 or 6 in.bigger all round than the mt-

..

Rubber beading, as sold for excluding draughtsfrom doors and windows, placed round the

inner edge of the wooden frameworks

Wireless Magazine. December. 1929

The diaphragms stretched and dopedbefore the fixing of the driving unit

agonal frame. Lay it out on a flatsurface and place the frame on topof it, the rubber beading down-wards, so that the warp and weftof the **envy are at right angles toan owning pair of sides.

Pull the linen up over the backof the frara and fix it with ordi-nary tin tacks ; these should notbe stinted. Now take the linen atthe opposite side, pull it -as tightas possible and nail it to theopposite side. Carry on in this wayuntil the linen is fixed firmly to allsix sides, and is quite evenlystretched.

Next, stretch another piece of

521

The framework is jointed by meansof carpenter's " dogs "

Linen in a similar way over thesmall square frame. After thishas been done the two supportsfor the square frame can bescrewed into position.

Finding CentresThe next step is to find the

centres of each linen diaphragm.This is done by drawing a numberof diagonal lines. Where theselines meet, apply a sharp -pointedinstrument and carefully pullaside the threads of the linen tomake a hole large enough to becarefully buttonhole -stitched (alittle feminine assistance will befound welcome at this stage !).

In carrying out this operation,take care only to pull the threadsapart and not to break any ofthem or the diaphragm will beweakened.

Now place the large frame,(linen downwards) on a tableand put the square frame withits supporting strips (linen up-wards) on top. At the four points

where the supports cross the oct-agonal frame, drill holes, rightthrough the supports and about it in.into the octagonal frame. Theseholes should be large enough to pass aNo. 2B.A. rod.

Joining the CentresNext, place four 4 -in. lengths of

this threaded rod in position, asindicated by the photograph abovewith nuts between the frames.Place the nuts so that the frames arealmost touching. Now take thespecial conical washer with a smallchuck and join the centres of thediaphragms together, so that the

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Wireless Magazine. December 192?]

An Improved Linen Loud-speaker-Continued

THE BEST LOUD -SPEAKER forTHE HOME -CONSTRUCTOR

A front view of the complete " W.M." linen dia-phragm loud -speaker

chuck is on the small square dia-phragm side.

The nuts on the four threaded rodsshould be then screwed up so that theframes are held about I in. apart. Itis now time to apply the first coatingof dope, which should be brushedthoroughly all over the outer surfacesof the linen-out of doors, as thesmell of the collodion is likely tocause trouble in the house !

Stretching the DiaphragmsWhen this coating of dope has

thoroughly dried, the nuts should bescrewed up to stretch the diaphragmsa little more and a second coat ofdope applied.

As soon as the second coat-ing has dried the nuts shouldbe carefully screwed up alittle at a time, until the linenis under maximum tension.

If each nut is screwed upin turn, the linen will not betorn, and a surprising degreeof tension will be attained.Now the third and lastcoating of dope can beapplied.

The fixing of the drivingunit can next be undertaken.This is mounted on a strip ofbrass % in. wide and A- in.thick. The best way is toscrew the threaded rod of thedriving unit into the chuckon the square diaphragmbefore fixing the brass mount.

Note how far the back ofthe unit projects and care-fully bend the brass to thebest shape. This will beclear from the photographs onpage 520. Drill holes in thebrass strip to accommodatethe fixing screws on the unitand fix the whole assemblyin position.

Care should be taken to keepthe linen stretched as tightlyas possible. Unsatisfactory resultshave been traced in a numberof instances to constructors nottautening the linen sufficiently. Thetension should be so great that asharp pinging noise is produced whenthe diaphragms are tapped with thefinger-tip.

The desirability of using a balanced -armature type unit has already beenemphasised.

J. Sieger, the member of theWIRELESS MAGAZINE Technical Staffwho has been responsible for all theexperimental work on linen loud-speakers, has found that the Blue

Spot 66K unit gives the best repro-duction, although there are a numberof other satisfactory units, such asthe Gecophone.

Decorating the LinenReaders with an artistic turn of

mind will be able to decorate theirinstruments by stencilling fancydesigns on the linen. This has beendone very successfully by more thanone constructor and the result is a

PARTS REQUIREDFOR THE IMPROVED LINEN

LOUD -SPEAKER

[-Set of wooden frameworkswith supports and stand(Pickett, Sewell or Cameo).

3/4-yd. Webb's Irish linen,approx. 6/-.

i-Pair conical washers withnut and chuck.

2-I -f t. lengths No. 2B.A.threaded brass rod, with8 nuts and washers.

io-oz. collodion -meth,approx. 3/-, from anychemist.

[ y2-ft. 114 --in. hard brassstrip, 3/4 in. wide.

4-yd. rubber draught -stopper, approx. 6d. peryard (Hookite).

[-Balanced - armature unit(Blue Spot, Gecophone,or Grassman.).

[-Pair panel brackets (Bul-gin, Camco or Raymond).

3/4 lb. 3/4 -in. tin tacks.

loud -speaker that is attractive inappearance, as well as satisfactory inreproduction.

It may be mentioned in conclusionthat a British firm has obtained therights of manufacture in this countryand that complete instruments cannow be bought by those listeners whodo not wish to make their own.

GOOD NEWS FORCONSTRUCTORSABOUT NEXTMONTH'S "W.M."

Order Your Copy Nowand Make Sure of It !

W. JAMES, who has designed for WIRELESS MAGAZINE

such famous sets as the Brookman's Two and Three,

Binowave Three and Four, Touchstone Four and LodestoneThree, will describe the construction of a new four-valver with

two screened -grid high frequency valves, using his famous193o Binowave coils, which have been such a success.

522

Page 79: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Here is a set of un-usual interest. Not onlydoes it use two of thenew Q coils, which havebeen greatly improvedsince last season, but itmakes use of a pentodevalve as a detector.The advantages of thisrevolutionary step willbe seen by referenceto the article itself.

BEFORE the adventof Brookman's Park

it was often suggestedto me that our positionat Elstree was much toofavourable for the test-ing of receivers, owingto the distance from2L0, which gave usquite fictitious ideas ofselectivity.

Tables ReversedThis was admittedly

so to some extent, butthe tables have nowbeen reversed with avengeance, for we aresituated only some sixmiles from Brookman'sPark.

In fact, it is possibleto see the Brookman'sPark masts from the topof the hill on the sideof which the laborator-

By J. H. REYNER,B.Sc. (Hons.) A.M.I.E.E.

The Set suppox ted on a pairof Belling -Lee Radio Legs

lies are situated, so that we now,receive a very considerable signalfrom the local station.

Indeed, the strength here is sogreat as to give quite misleadingresults in the reverse direction, forwipe-out effects are not merely amatter of a slight broadening of thetuning. The strong signal introducesa paralysing effect on the detector,which makes the production of reallysharp tuning a matter of considerabledifficulty.

Saving ExpenseThe present receiver is the outcome

of an attempt to devise a simplethree -valve receiver capable of givingreally selective results with goodsignal strength. One can, of course,tackle the problem by devising veryefficient coils and transformers,screening, de -coupling and using everymodern aid to the production of goodresults, but the resulting receiverwould be expensive and, moreover,would not meet the majority ofrequirements.

This receiver is the next best thing,,giving results which are satisfactory

for the great majority of people with-out undue expense.

The coils in use are the new Qcoils. These have been re -designedsince last season, with a view toimproving the selectivity on theshort-wave band. Moreover, theswitching system has been con-siderably simplified, for despite allthe precautions which were taken, itwas found that difficulties wereexperienced with the switching on theold pattern.

With the new type, the switchinghas been reduced to a simple push-pull arrangement and this is muchless likely to give any trouble. Theconnections have been maintainedexactly the same as before, but forfurther information, reference shouldbe made to the article on anotherpage of this issue.

The present receiver was actuallyconstructed before Brookman's Parkstarted operations. Owing to theastatic properties of the Q coils, itwas felt that relatively simple screen-ing would be all that would be neces-sary, and this proved to be the case.A very simple layout was all that was

523

Wireless Magazine. December 1929

THIS SET HAS BEENSPECIALLY DESIGNEDFOR THE " WIRELESSMAGAZINE " BY THETECHNICAL EDITORAT THE FURZEHILLLABORATORIES ANDIS AN ENTIRELY NEWDEVELOPMENT THATWILL CREATE GREAT

INTEREST .

necessary, and the receiver tuned inthirty or forty stations on the loud-speaker without any difficulty what-ever, and gave evidence of beingparticularly selective.

London (the old 2L0) could betuned in and out at Elstree within3 degrees, which appeared to be avery creditable performance in viewof the use of dual -range coils, whichneed not be changed on going fromthe long to the short wavelengths.

My impression, indeed, was thatthe new Q coils were the most selec-tive dual -range coils with which Ihad come in contact.

Severe Wipe-out EffectsThe receiver was deliberately put

on one side, however, until Brook -man's Park had begun operations,and it was then re -tested. The resultswere distinctly disappointing. Wipe-out effects were so severe that it wasbarely possible to get within ioometres of 2LO's wavelength, althougha detector, using a Q coil, with a wave -trap got within 5o metres.

The tests which had been made onthe coils showed that these coils were

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Wireless Magazine, December 1929

The New Q Three Continued

not the root of thematter and, aftera little investiga-tion, it becameclear that the de-tector stage itselfwas being para-lysed,owing to theamplification re-sulting from theH.F. stage in use.Whether the re-sults were due toan increased de-tector damping,or to some moreobscure actionwas not clear, butit was obviousthat the influence

The Construc-tion of this setis within thecapabilities ofany amateur.

Although this set uses a pentode as detec-tor the anode -current consumption is

very low and economical.

of detectorvalve.

It wasfound that,properlyutilised, thepentod egave ap-proxima t e-ly the sameorder ofsignalstrength asa grid de-tector withthe selec-tivity of theanode- bendarrange-ment. It

the detector-cum-wavetrap set just re-ferred to, with which it had only beenpossible to get 5o metres away fromLondon's wavelength. In all cases,the circuits used were of an averagecharacter, and were not speciallyselective, but it became clear that theuse of a pentode -detector was givingresults distinctly out of the ordinary.

Low Priming -grid VoltageThe use of the pentode as a detector

sounds rather curious, but, in reality,it is quite simple. The valve wasbiased with a negative bias on thegrid in the same way as an anode -bend rectifier. At the same time, thevoltage on the priming grid is reducedto a low value, between 20 and 3ovolts, in order to arrange the working

point on the curve

VVARBLE.

RES.

C3

nosElm v)

00/.0005

6 p DIFFL '08-1 CONDSR

This is the circuit of the New Q Three, a novel set using a pentode as detector

o/7+/077+2

6:8-2 GS+

of a really heavy signal, such as isobtained from the local station atclose range,- was sufficient to renderthe receiver of little use.

Anode -bend RectificationAttention was turned to anode -

bend rectification and, although thisimproved the selectivity, the signalstrength suffered to an extent whichwas considered inadvisable. Con-currently with the tests on thisreceiver, however, some experimentshad been made on the use of a pen-tode valve as a detector and, based onthese tests, an attempt was made touse a pentode in this set.

The results obtained proved veryencouraging, and after a little extraexperimental work, the receiver wasfinally completed, utilising this form

was possi-ble to tune -in a station(with a cer-tain back-gr ou n dfrom 2L0which couldbe heardwhen theforeignstationsceased tom o dulate),at a separ-ation of 3ometresonly.

This isdefinitelybetter than

The grid -biasbattery isclipped onthe base-

board

The voltage on the priminggrid of the pentode...detector

need be only 20 or 30 volts

524

at a suitablepoint.

The valve thenbehaves as ananode -bend recti-fier with the im-portant advant-age that we havea distinctly higheramplificationfactor than ispossible with thecustomary H.F.valve, so that ourrectification effic-iency is corres-pondingly in-creased.

The old(Cont. on page 526)

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THESOUL

OF THESPEAKERFit the new Amplion B.A.2 unitto any chassis and you fit quality,life, sensitivity and volume hand-ling capacity-you put heart andsoul into the speaker. Note thefollowing points:-(1) Strong and robust construction

with neat compact design andworkmanlike appearance.

(2) Designed for normal chassis. Adap- T Hfor plate is supplied for use onother types of chassis.

(3) Sensitivity far above the normal,combined with adequate volumehandling caparity.

(4) Three terminals giving alternativevalues of impedance.

(5) Equally suitable for use with powervalves of low or medium imped-ance or with pentodes.

Your dealer will gladly demonstrate.GRAHAM AMPLION LIMITED, 25/26, SAVILE ROW,

[ Wireless Magazine. Decernfier 1929

11

A

,/ 711,9:5074:00',A poi0/141//// //,/L

A

,/ ..//IllLONDON, W.1.

A

Mention of the " Wireless Magazine " will ensure prompt attention

525

///

WORKS : SLOUGH

Page 82: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. December 1929

The New Q Three ContinuedrClIfZIY..0 5V 5LUVPAOftlr

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This layout and wiring design of the New Q Three can be obtained as a full-sizeblueprint for half-price, that is 6d., post free, if the coupon on page iii of the

cover is used by Dec. 31. Ask for WM 167. Wire up in numerical orderquestion of the increase in A.C.resistance of the valve, due tothe bias on the grid, crops up again.Owing to the negative bias, the A.C.resistance of the valve under workingconditions is about three times asgreat as under ordinary conditions,and this factor must be taken intoaccount when designing the circuitsto follow the detector valve. In thepresent instance, it was desired tofollow the detector with a transformer,but this is clearly not practicable withthe ordinary run of pentode valves.

Transformer CouplingFortunately, however, the new

Cossor pentode (z3oPT) has an anoderesistance of 20,000 ohms only undernormal conditions, so that, under thecorrect biasing conditions for use asa detector, its A.C. resistance is stillonly approximately 6o,000 ohms, andthis is not too high to be followed by atransformer having a high primaryinductance. This has been done in

the present instance, a Ferranti 31/2 to(AF5) transformer being used.This is an essential point in the

working of the receiver. Othermakes of transformer may be used ifdesired,providedthat theprimary im-pedance iswell overroo henries.

The re-mainder o fthe H.F.and detec-tor circuitsare more orless con-ventional. Atransformer-coupl e dH.F. systemis employedwith reac-tion applied

Another view ofJ. H. Reyner's

New Q Three.

around the detector, a differentialcondenser being utilised in this latterconnection. This condenser has twosets of fixed plates, the moving platesbeing arranged to slide in betweenone set of fixed plates as they slideout of the other set.

Constant H.F. By-passThe circuit is so arranged that one

set of plates controls the reaction,while the other is connected as a by-pass from the anode of the detector toearth. Thus the total path for thehigh -frequency 'current to earth,either through the reaction coil ordirect, is always maintained the same,so that the detector is enabled tooperate at its proper efficiency overthe whole scale.

The H.F. choke employed shouldbe a good one, and the use of theLewcos or the new Wearite iron -cored choke is to be recommendedhere. If a poor H.F. choke is em-ployed, there will be a nasty growl asthe circuit goes into oscillation. Thismay be noted on both wavebands, oronly on one, but should this beexperienced, the remedy lies in theuse of a better choke.

Controlling VolumeVolume control is obtained by

means of a variable control of thescreen voltage on the H.F. valve.This is a very convenient method ofobtaining the required control, for itdoes not upset the quality in any way,and enables the volume to be reduced

(Continued on page 528)

Volume is controlled by vary-ing the voltage on the screenof the high -frequency valve.

526

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thatOff

TheOeitictrain

Rotary

SwitchBattery

Wireless Magazine. December. 1929

EXPERIENCE, backed by4,000,000 sales, says .-" TO GET BETTER RESUELTS

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THE BENJAMIN ELECTRIC LTD., BRANTWOOD WORKS, TOTTENHAM, LONDON, N.17Irk ftWhen replying to advertisements, please mention " Wireless Magazine "

527

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Wireless Magazine. Decemfien 1929

The New Q Three Continued

COMPONENTS REQUIRED FOR THE NEW Q THREEChoke, High -frequency

i-Lewcos, 7/9 (or Wearite).Choke, Low -frequency

i-Wearite choke-ouput unit,type P, 21 F.

Coils2-Ready Radio Q Coils, types

QA and QSG, 30/- (or Wearite,Lewcos).

Condensers, Fixed2-T.C.C. .00i-microfarad, 4/8

(or Ormond, Edison Bell).-T.C.C. i-microfarad, 2/10 (or

Dubilier, Lissen).

Condensers, Variable2-Burton .0005-microfarad, 10/6

(or Igranic, Marconiphone).1-Lotus .0002-microfarad dif-

ferential, 7/6 (or Pye).

Dials, Slow-motion2-Brownie, 5/- (or Ormond).

Ebonite1-Parfait, 7 in. by 18 in. (or

Raymond, Ready Radio).2-Terminal strips, 7 in. by 2 in.

and 3 in. by 2 in.Holders, Valve

2-W.B. anti-microphonic, 3/ -

(or Formo, Clix).r-Parex screened -grid, single

type, 2/- (or Keystone,Colvern).

Plugs3-Belling-Lee wander plugs

(marked : G.B.+, G.B.-1,G.B. -2), 9d. (or Clix).

Resistance, VariableI-Volustat, medium resistance,

7/- (or Clarostat, Regentstat).Screen

I-Ready Radio vertical, ro in.by 6 in., 2/- (or Parex, Peto-Scott).

SundriesShort length of Lewoos rubber -

covered flex.Glazite for connecting up.1-Pair Bulgin panel brackets,

x/6 (or Raymond, Cameo).r-Pair Bulgin grid -bias battery

Clips, 6d.Switch

1-Bulgin on -off, i/6 (or Ben-jamin, Pioneer).

Terminals9-Burton (marked : Aerial,

Earth, L.T.+, L.T. - ,

H.T.+2, H.T.-,L.S. , L.S.-), 2/3 (or Eelex,Belling -Lee).

Transformer, Low -frequency1-Ferranti AF5, 30/-.

RECOMMENDEDACCESSORIES

Batteries1-Siemens 12o -volt, brown

label, 20/- for Lissen Marconi -phone).

1-Siemens 9 -volt, 2/- (or Lissen,Ever Ready).

r-Oldham 2 -volt accumulator,type CL64, 13/9 (or Young,Exide).

Cabineti-Camco, with ro-in baseboard,

24/- (or Raymond, Caxton).Loud -speakers

1-M.P.A. cone (or Climax,Celestion).

Valves1-Mazda 2 I 5SG, 22/6 (01

Osram S215, Marconi S2 I 5) .I--Cossor 23oPT, 25/-.r-Lissen P215, 12/6 (or Osram

P215, Marconi P2 I 5) .The prices mentioned are those for the parts used in the original set ; the prices of alternatives as indicated in the brackets may be either higher or lower

before the detector stage, therebyavoiding any overloading of the latter,due to the presence of too strong a

It is possible to tune the receiverfully in to Brookman's Park and yetto reduce the volume by means ofthis control to a pleasant strength of

quite good quality. A medium -resistance Volustat should be usedfor the purpose and this, with mostscreened -grid valves, will be found tobe satisfactory.

In some cases, however, it may notbe found possible to reduce thevolume quite to the required amount,

ANODE -TUNINGCONDENSER

L.F.TRANSFORME

OUTPUTFILTER

POWERVALVE

H.F.PENTODECHOKE DETECTOR

VOLUMECONTROL

AERIAL -TUNINGCONDENSER

H.F. SCREENCOIL

AERIALCOIL

'SCREENED -GRID

VALVEMOLDER

BY-PASSCONDENSER

This plan view clearly shows how all the parts are arranged in the New Q Three

528

and if this proves to be the case, aresistance of 20,000 ohms should beconnected across the screening -gridby-pass condenser, that is to say,between the screening -grid andL.T.-. This resistance need not bewire wound, provided it is reasonablysilent in operation, and its inclusionwill be found to put the volumecontrol in a thoroughly satisfactorycondition. It has been omitted inthe present instance because it is notalways necessary.

Avoiding Battery Feed -backThe only other point of interest

concerning the circuit is the outputstage, in which a choke -output filterhas been employed. This avoids anybattery feed -back which would set upwhistling, when the battery ran down,or might cause the set to " motor-boat" if it were utilised with a mainsunit. Otherwise, the receiver is ofstraightforward construction, andrequires no comment.

To operate the receiver, insert ascreened -grid valve in the H.F. stage,and connect the flexible lead fromterminal No. 3 of the QSG coil to theanode. Insert a low -resistance pen -

(Continued on page 53o)

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BRITISH

III

111111111111111i'

Wireless Magazine, pecemben 19291

THROUGHOUT

Ili1,11 11111111111111111

We Stake OurREPUTATION

on the TRUTH ofthese STATEMENTS

THE new Brown " Vee " Reed principle combined with the newBrown Duplex diaphragm gives results far in advance of any

other kind of loud speaker.Only in the new Brown Duplex Loud Speaker are these revolution-ary principles to be found. They are the patent of Mr. S. G. Brownwho is known throughout the world as the maker of the first wirelessloud speaker.For this reason, no matter how much you have paid for a loudspeaker, you have not heard results that can even be compared tothe reproduction of these new Brown instruments.But a hundred descriptive words are not worth as much to you asone minute's listening. Before you buy a loud speaker, get yourDealer to demonstrate the new Brown Duplex models. You willbe more than impressed and will place your order at once.

In 3 models: VIO, 45 10 0. V12, £7 10 0. V15,412 10 0. All obtainable on easy monthly payments.

41111111111

DUPLEX LOUD SPEAKERS11 11111111111111 1111111111111 1111111111111111 11111111111111111111111111111111111111111111111}111m111 1111111111111111 1111111111111111111111 1111111111111111111111 11111111

Advt.-S. Q. Brown Ltd., Western Ave., N. Acton. W.3.

When you send your order don't forget to say you " saw it in the W.M.'

529

11111111 1111111111111l11111111111ill

906

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Wireless Magazine. ,December. 1929

The New Q Three-Continuedtode havingan A.C. re-sistance of20,000 ohmsor less inthe detectorstage andconnect aflex leadfromto the ter-minal on theside of thecap.

A suitablepower valveshould beincorporatedin the laststage. Ifparticularvolume is required, a pentode valvemay be included, although this willnaturally increase the current con-sumption somewhat. If a pentodevalve is used, however, the chokoutput unit should be obtainedspecially for the purpose.

A normal chck?.-output unit isknown as type P and this is employedfor power valves of the ordinary type,

The New Q Threeall ready wired up

for use.

Tell your friends about thisnew set which uses a pentode

as detector.

while for pentode valves the type PPshould be used as this is providedwith a step-down in order to matchthe loud-speakor better to the valveresistance.

H.T. should be connected toabout zo volts ; G.B.- r, the grid biason the detector should be -3 volts,while the grid bias on the last (power)valve should be chosen in accordance

with the maker's instructions.H.T. +2 may be too or rzo volts, ormore if desired.

At first it is best to screw theVolustat towards its maximum (fullyin) position, as the best operatingpoint will be somewhere rqund thisregion. Both the Q -coil switchesshould either be in (long waves), orout (short waves). Do not have onein and the other out, as they will notoperate satisfactorily. The receiverwill then tune in the ordinarymanner.

Current ConsumptionOne final remark may be made

regarding current consumption.Despite the fact that a pentode isused for the detector, this set does notconsume any more than one using anormal type of detector. The pentodeis biased so that the anode current isnearly zero, in consequence of whichit does not take any appreciablecurrent from the battery.

Provided the power valve in thecircuit does not take too much, there-fore, readers need have no hesitationin using this receiver with amedium -size battery.

"Schools " of Radio ProductionSPECIAL TENDENCIES THAT LISTENERS MAY DISCOVER

ALTHOUGH British broadcastingis several years old, the pro-

gramme -builders are still working inthe experimental stages, and, as Igathered from one of the Savoy Hillstaff some time ago, they are not atall eager to lay down laws as to whatconstitutes the right way and what

.the wrong of broadcasting any par-ticular item.

Encouraging NewsThis is encouraging news since,

whatever its faults, the B.B.C. isdefinitely governed by an artisticrather than commercial impulse, andthis, whether it be "high -brow" or"low -brow," demands time and free-dom to develop.

At Savoy Hill there are men work-ing, as it were, shoulder to shoulder,some producing jolly "radio slap

stick " and others works of a " liter-ary " value. But whatever badinagepasses between the groups, there areartists on both sides putting inspira-tion into the work.

Although there are no hard and fastrules, certain "schools" of thoughtand treatment are developing, and thelistener who cares to do so may de-tect them in the various plays whichare broadcast from time to time.

One of the most outstanding ofthese is whit I might call the"Sievking School." Mr. Sievking,who was responsible for those mile-stones of broadcasting, KaleidoscopeNo. r and No. 2, is a great believer insound effects, and has done somevaluable work on their development.

Those who heard his picture of adrowsy summer day in KaleidoscopeNo. 22-the bees, the mowing

530

machine, and so on-will realise thepossibilities of this school.

The other school of dramatic pro-duction usually takes music as itsbasis for "atmospherics." It wouldrather give a musical background ofsomething slumberous than repro-duce the sound of a mowing machine.It would rather stop its music sud-denly, leaving a striking silence thanbang a door.

Discovering " How It Works "Both schools (and there are others)

have their possibilities.It seems to me the musical

school requires a finer ear and moresusceptibilities to follow, but for thelistener who desires to get the best outof his radio, there is as much fun tobe had in trying to discover the "howit works " side of an item. A. D.

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15

Wireless Magazine, December 1921

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531

Page 88: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine, December 1929

A QUESTION EVERY LISTENER ASKS :

GithileflestVoluse6flifol7AVOLUME control is admittedly

a necessary part of a modernwireless receiver, if only because ofthe local station.

Practically everyone finds that thesignals collected by the aerial whentuned to the local station are sostrong that, unless the magnificationprovided by the set is cut down, thevolume is excessive.

Probably the quality is poor aswell. Anyhow, if the volume when

1

In this article W. JAMESanswers a question thatevery set owner asks atsome time or other, andexplains how volume canbe controlled without

introducing distortion.

Further, when the signals appliedto the detector exceed a certain value

the low -frequencyamplifier will over-load. Consequently,there is every reasonfor including a con-trol in one of thehigh -frequencycircuits.

But sometimes itis equally essentialto employ one in thelow -frequency cir-cuit of the receiver.Thus, when the de -

fully tuned to the local station is not tector is of the anode -bend type, itstoo great, the set is not a powerful input should preferably be keptone and will not reliably

1-1T+1

RE.SISTANCE.

B

Fig. 1.-Resistance in parallel (a) and in series (b) with aerial-tuning coil

receive other stations.Clearly, then, the prime

function of a volume controlis to enable a user to regulatethe volume. But this is notthe only reason for includingsuch a control.

Selectivity and quality ofreproduction must be con-sidered as well. Thus, forexample, the most usedvolume control, reaction fromthe detector to one of thehigh -frequency circuits, un-doubtedly affects selectivity

connected either across the aerial -tuning coil or in series with the coiland condenser, as illustrated inFigs. IA and ra respectively. Theadjustable shunt resistance of Fig.IA may be of 250,000 ohms, whilst asuitable resistance for the circuit ofFig. Is would be of 5o or roo ohms.

These resistances will not greatlyalter the tuning when they are of suit-able pattern. They must be non -inductive and have the miminum ofcapacity in order that they shall notchange the inductance or capacity ofthe circuit. They reduce the input tothe valve by increasing the -dampingof the circuit. Therefore, the selec-tivity is varied as they are adjusted.

Broader TuningAs the resistance of Fig. IA is

reduced, for instance, the signalstrength is cut down, and the tuningof the circuit is made more broad.The resistance of Fig. In must, ofcourse, be increased to reduce signalstrength.

Controls of this type are not oftenused in sets intended for the

POTENTIOMETER

Fig. 2.-Two potentiometer arrangements for screened -gridvalve sets

and the quality.Reaction may be considered an

indirect form of volume control,however, and as it is often included ina set fitted with one of the more directcontrols, will not be discussed here.

Regulating Detector InputA volume control is normally in-

cluded in one of the high -frequencycircuits, in order that the input to thedetector may be regulated. As iswell-known, a detector may be over-loaded by the application of toostrong signals and will then distort.

within limits and then the actualvolume be controlled by adjusting theamount of the low -frequency magni-fication.

In sets withouthigh- frequencyamplification, too, alow -frequency con-trol may be used.

One of the simplestcontrols, suitable fora " local station " typeof set, comprises anadjustable resistance,

reception of distant stations,but they are quite usefulwhen it is suspected that thetuning is normally so sharpthat the quality is poor.

A different type of controlis shown in Fig. 2. Here apotentiometer is used be-tween the aerial circuit andthe grid of the first high -frequency amplifying valve.Two methods are indicated.The first, Fig. 2A, shows apotentiometer with grid biasfitted to a high -frequency

transformer; and the second, Fig. 2B,(Continued on page 534)

532

HT+1

- AFig. 3.-Positions of high -frequency filament resistances

HT+1

L.+

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Wireless Magazine, December: 1929

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533

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Wireless Magazine. December: 1929

Which is the Best Volume Control ?=Continuedshowing how the method may beapplied to a plain aerial circuit.

Tne potentiometer method looksideal, but it is not. In the first place,the control tends to reduce the selec-tivity; and secondly, owing to thecapacity of the valve, there is achc king effect which renders thecontrol non -uniform.

High Grid ResistanceThus, let us suppose the potentio-

meter to have a resistance of 250,000ohms, and that the slider is set aboutits mid -point. Then there is, in effect,a resistance of about 120,000 ohms inseries with the grid of the valve.

The effect of thiswill be understoodwhen it is.rememberedthat we often include aresistance of this valuein the grid circuit of alow -frequency ampli-fying valve in order toprevent H.F. currentspassing through.

Thus, although thepotentiometer is sethalf way (when onemight think half thevoltage of the circuitwas being applied to

RESISTANCE

high, a resistance of this value willnot materially reduce the strength.

a compara-As so often happens,tively cheap and simplemethod may be usedwith better results inmany instances. Thearrangements of Fig. 3will be recognised fromthe number of times Ihave included them insets, the resistancesbeing of the ordinaryfilament types. In Fig.3A the resistance is in-cluded in the negativeside of the filament

circuit; in Fig. 3B in the

POTENTIOMETER

Fig. 4.-Use of potentiometer

LT

Fig. 5.-Circuit with variablescreen resistance

the valve), in actual fact the gridvoltage of the valve is much less thanhalf the full amount.

positive side.The arrangement of

Fig. 3A is the one moreoften used, because anegative bias is pro-vided for the valve.Being in the negativeside of the filament cir-cuit, the grid is biasedby the amcunt of thevoltage dropped.

Thus the effect ofincreasing the amountof the resistance in cir-cuit is twofold. First,

the filament Current is reduced. Thisincreases the impedance of the valve,and therefore lowers the actual

amplification

Fig. 7.-Another method of control withvalves

TONEXTVALVE

A ,C.

01 -ITindirectly -heated

In spite of this serious drawback,however, the method is sometimeswed.

Obviously, the choking effect willbe minimised by employing a low-resistance potentiometer, and a valuethat might be used is roo,000 ohms.When the tuned -grid circuit is heavilydamped, that is, when its losses are

obtained. Secondly,the grid bias is in-creased and this alsoraises the impe-dance.

In the circuit ofFig. 3B the grid biasdoes not changewith adjustment ofthe resistance, andmore resistance istherefore needed toproduce a giveneffect in comparisonwith the arrange-ment of Fig. 3A.

Volume control by alteration of theanode impedance of the H.F. valve isreliable and safe. It introduces notuning complications, and has thefurther advantage that a loose -coupling effect may be obtained.Thus, as the resistance is increased,the tuning becomes more sharp.

A smooth -acting component is, of

534

course, essential as noises are pro-duced when the contact is not good.

A control not much used at presentis shown in Fig. 4. Itcomprises a potentio-meter and grid -biasbattery, and also agrid leak R and con-denser c. Thisarrangement may bepreferred by .some tothose of Fig. 3.

Volume is, of course,controlled by alteringthe H.F. magnifica-tion. Actually, thegrid bias is increased

or reduced by adjustment of thepotentiometer, and this varies theimpedance of the valve. The gridbias is conveniently applied throughthe grid leak, whilst the condenser cprevents the grid battery from dis-charging through the leak.

The values of c and R are notcritical; c can be of.00r microfarad,and R of r megohmor thereabouts.

Control of high -frequency magni-fication may alsobe effected when ashielded valve isused by adjustingthe voltage of theshield. This mayconveniently becarried out by in-cluding an adjustable resistance inthe shield circuit, as in Fig. 5.

The resistance must be of the high -resistance type, as the shield currentis normally a fraction of a milliampereand it should be of a pattern whichdoes not vary during use.

A.C.Fig. 6.-Use ofresistance withindirectly -

heated valve

Danger of Excessive CurrentA compression type is generally

satisfactory when it has a resistanceranging from a few hundreds to say500,000 ohms. A certain amount ofcare must be exercised in adjustingthe resistance, because if it is reducedto too small a value, an excessivecurrent may pass through the valve_

The anode impedance of the valvealters with the shield voltage, withthe reEult that the selectivity of theH.F. coupling may be controlledwithin certain limits.

(Continued on page 536)

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rWireleSs Magazine. December 1929

Which is the Best Volume Control ?-ContinuedThe same principle is used in the

circuit of Fig. 6, which shows anH.F. valve of the indirectly -heatedtype. It is not possible to control avalve of this type by connecting afilament resistance in the filamentcircuit, as there is a considerabletemperature lag.

Fall in VoltageIt is possible to employ the grid -

bias method, however, and a neat wayof including it is shown in Fig. 7.Here a potentiometer R is included inthe cathode circuit. The anodecurrent therefore passes throughresistance R and there is a fall involtage across it. By adjusting thesliding contact, therefore, the gridbias is varied.

This is an excellent control whenthe valve is of the indirectly -heatedtype. The resistance of R may bei,000 ohms approximately. With thisvalue, and an anode current of 2milliamperes, the voltage drop is 2volts, which is adequate. Manyvalves pass a greater current, how-ever, with the result a little lower

resistance may be used in some cases.Methods of adjusting the low -

frequency magnification are well-known. In one well -tried method, anadjustable resistance is used acrossthe primary winding of the firsttransformer in the set, as in Fig. 8A.

Fig. 8.-Use of resistance and potentio.meter

This resistance should be adjustablefrom a few hundreds to, say, roo,000ohms.

In the second method illustrated, apotentiometer is used in the' gridcircuit of a resistance -capacity stage.The grid condenser is marked c, and

the grid leak R. This leak is notneeded when the potentiometer is ofthe continuously variable pattern,but is useful when a stud -type isused. A usual value is from roo,000ohms to 500,000, according to thecapacity of condenser c.

When an anode -bend detector isemployed with H.F. and L.F. magni-fication, two controls may be fitted.One of them may be used to adjustthe H.F. signal strength applied todetector and the second to control theactual low -frequency magnification .

Anode -bend DistortionAn anode -bend detector distorts if

it is supplied with too strong or tooweak signals, and arrangements are,therefore, often provided in the bestsets for the input to be regulated. Aseparate L.F.' volume control is alsofitted, as one does not always needthe full output from the set.

One of the H.F. controls describedmay be fitted to the set, and also acontrol as in Fig. 8A or 8u. They areboth non -distorting and do notcomplicate a set.

How They Anticipated Wireless !The Wireless Play

" The play, I remember,pleased not the million; 'twascaviare to the general."

Shakespeare : Hamlet.

The Announcer's Ideal" Speak the speech, I pray

you, as I pronounced it to you,trippingly on the tongue; butif you mouth it, as many ofyour players do, I had as liefthe town -crier had spoken mylines."-Shakespeare : Hamlet.

The Children's Hour" 'Tis the defect of age to

rail at the pleasures of youth."Mrs. Centlivre : Basset Table.

Tuning -in"Few men can afford to be

angry."-A. Birrell : ObiterDicta.

The Listener" The sincere controversialist

is above all things a good lis-

tener."-G. K. Chesterton :What's Wrong with the World.

Broadcast Debates" Our disputants put me in

mind of a scuttle -fish, thatwhen he is unable to extricatehimself, blackens the waterabout him till he becomes in-visible."-Addison : Spectator.

Oscillation" You have not converted a

man because you have silencedhim."-Lord Morley : On Com-promise.

Television" I don't know where this

here science is to stop, mindyou ; that's what bothers me.-Dickens : Sketches by Boz.

The Average Listener"The English take their

pleasures sadly, according tothe custom of their country."-Sully : Memoirs.

The Burnt -out Valve"An event has happened,

upon which it is difficult tospeak, and impossible to besilent."-Burke : Impeachmentof Warren Hastings.

The New Gadget"Man's nature is greedy of

novelty."-Pliny the Elder.

The Broadcast Critics"No one minds what Jeffrey

says-it is not more than aweek ago that I heard himspeak disrespectfully of theequator." - Sydney Smith :Sayings.

The New Valve"A good man is merciful,

and lendeth."-Prayer Book.

Weather Report"When two Englishmen

meet, their first talk is of theweather."-Johnson : Idler.

536

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Wireless Magazine. December 1929

In a good set each unit, how-ever small, must be perfectlymade. It is because com-ponents are so importantboth to the quality of re-ception and the ease in build-ing, that Lotus componentsare recommended almostuniversally by technical menand the Press. Lotus units aremade in one of the most modernradio factories in this country.They are made to an exceptionallyhigh standard and each one-largeor small-is carefully tested beforeit leaves the works. You can de-pend upon Lotus components.Put them into your next set.The Lotus range includes: Lotus ValveHolders ; Lotus Variable, Differentialand Reaction Condensers ; Lotus AllMains Unit ; Lotus Dual and SingleDrum Dials and Dual Wave Coils ; LotusL.F. intervalve and power transformers;Lotus H.F. and L.F. Chokes ; LotusRemote Control units ; Lotus jacks,switches and plugs and also an ex-ceptionally fine selection of Lotus re-ceiving sets.

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537

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Wireless Magazine. December. 1929

The popular Miami Dance Band which has been broadcasting during the month.

BROADCAST MUSIC THE MONTH

THE month of November is prac-tically the first of the winter

months, and variety is the oneessential for good programmes. Theorchestra has been tolerably wellrepresented by the start of the B.B.C.Symphony Concerts, the choice ofArthur Catterall, the famous Englishviolinist, being eminently awise one.

A concert of foreigninterest was that announcedfrom Belfast on November13, when the vocalist wasCornelius Bronsgeest, theGerman baritone who broad-cast recently from 2L0 also.He is well known on theContinent, and is operaticdirector to the Berlin broad-casting station.

For the greater part ofthe month, best results

GershomParkington

REVIEWED BY STUDIUShave been obtained through the workof the special quartets, outside bands,and instrumentalists. The MiamiDance Band is one of the most popularof dance bands, and heard chieflythrough 5 XX; the bands, too, ofMoschetto and Alphonse du Clos, on ahigher musical plane, are invariably

A. Robson

artists who are appearing in theSymphony series at Queen's Hall, wehave had a good measure of instru-mentalists. -In the concert of Novem-ber 9, conducted by Sir LandonRonald, the two Hungarian sisterviolinists, Adila Fachiris and JellyD'Aranyi, were the stars.

Others have been EduardSteurmann, the brilliantpianist, Adolphe Hallis, andPaul Belinf ante, the vio-linist. A clever young 'cellistalso figured prominently inUrsula Katrovitch, a Rus-sian musician.

Welcome re -appear-ances have also been madeby the Aeolian Players, acombination betweenJoseph Slater, GordonBryam and Rebecca(Continued on page 538)

OlgaHaley

Sandy Rowan, humorist

welcome. Among newcomers havebeen Fred Kitchen at the Astoria,Brixton.

On the classical side, the concertedmusic by Gershom Parkington andhis quartet of players, the John FryQuartet, and a new combination,heard through 5GB, known as theD'Alton Quartet, consisting of fourmembers of a Northampton family,who have previously appeared with

Mario de Pietro and his mandolineand guitar orchestra, were good.

Including the world-famous

538

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Wireless Magazine. December, 1929

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Its realistic reproduction is something tomarvel at. Its appearance will please themost fastidious --and when other gifts aregone and forgotten, Blue Spot will sing,play and talk in its own inimitable style,giving pleasure to all that listen.Choose from the Blue Spot range-Speakers with sil-vern tongues. Remember it is the famous Blue Spotunit driving them -you cannot go wrong with Blue Spot.

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539

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Broadcast Music of the Month--Cont.

Tom Jones

Wireless Magazine. DecemSen 19291

GwynnethEdwards

Clarke, one andall soloists ofmerit.

In the pro-vinces, someartists ofinterest havebeen Alec Sim,the Scottishviolinist heardfrom Aberdeen very fre-quently, and known also forhis fine Beltona records.From Belfast was heard thenew Radio Quartet, and fromEastbourne, Tom Jones andhis Grand Hotel Orchestra.Mr. Jones fills the place ofAlbert Sandler most admirably.

There is naturally a preponderanceof singers in every programme, butunder the new regional system, it isworth noting that there is far moreroom for improvement in dictionthan before. The voice is heard, butthe words are apt to be lost. Whetherthis is a defect that can be overcomeor not, it is hard to say. The bestknown operatic and concert artistshave been heard, but even with these,the change has proved the existence of

this diffi-culty.

MarjorieDixon

Amongst the finest voices, onemust mention Olga Haley, known forher many classical recitals, as well asconcert -hall appearances. From 5XXwere heard Dennis Noble and EdaBennie, late of the B.N.O.C. In theprovinces, also, mention should bemade of Eliot Dobie, the Scottishbaritone, noted as well for his Beltonarecords, and A. Robson, also a well-known Scottish artist.

Artists who have made note-worthy appearances before the micro-

phone includeGwynneth Ed-

wards, ElsieCochrane, andMarjorieDixon.

JulianRose, al-though byno means aperfect im-personator of

ElsieCochrane

StephenWearing

Hebrew characters,still led off the monthby his rather free translation of The Merchantof Venice into They GetsHis. Clapham andDwyer with their new1929 Concert Party," 5GB Calling," made abrave attempt to recallholiday -memories. Ofcapital account, also, was the pro-gramme with Tommy Handley,Yvette Darnac, and Clarice Mayne.

Ronald Frankau could do withstronger material, but his artists,known as the Cabaret Kittens, in thesketch, Up to the Scratch, reached itsthird edition on November 13.

540

Elliot Dobie,bass baritone

Television would have helped therepresentation of a real Russiancabaret from zLO on November 7,but the effects were as strong as couldbe expected. Built on, more or less,familiar lines, the vaudeville pro-gramme of November 8 from 5GB,included Tommy Handley again,with fresh songs at last; HelenAlston, always a popular singer ; andJack Rickards, Winifred Dunk andthe two old favourites, Pitt andMarks.

With plays, we have been a littlemore fortunate this month. Truly,we had inflicted the boresome Shawplay, Captain Brassbound's Conver-

sion, which is not soclever as its authorbelieves, but it wasredeemed by the adap-tation of Joseph Con-rad's Typhoon, andCompton Mackenzie'sCarnival, . the lastadapted tot the micro-

phone byHolt Marvel.

UrsulaKantrovitch,

'cellist

StanleyKaye,pianist

Page 97: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine, December: 1929

VARLEY Resist-ance CapacityCouplers, as a re-sult of intensiveresearch andmany experi-0 ME 1E 0 PORTION OF W K

ments, have beenentirely redesigned. Complete reliabilityand increased efficiency under all conditionsare foremost among the improvements whichhave been made. Look at the curve taken by theNational Physical Laboratory. This curve showsabsolutely uniform amplification throughout thewhole range of musical frequencies-a resultunparalleled by an L.F. intervalve coupling ofany other kind.These Resistance Capacity Couplers are hous-ed in attractive bakelite moulding similar tolast year's model. They are made in threetypes to accomodate various types of valves.Write for Sections B and C of the Varley Catalogue.

PricesType ' H ' 14/-. Type 'M 14/-. Type ' L' 13/ -

Advertisement of Oliver Pell Control Ltd., Kingswav House, 103, Kingaway, London, W.C.2. Telephone. Holborn 6903.

Speedy replies result from mentioning " Wireless Magazine "

541

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Wireless Magazine, December 1929W P Of 001 OM***WI/ n

SOME FAMOUS W)ETSBROOKMAN'S THREE

INDOUBTEDLY the most popular16../ WIRELESS MAGAZINE set since theInceptor Three, W. James' Brookman'sThree (WIRELESS MAGAZINE, October,59291 has created nothing short of a furore.Here are some comments from a Glasgowreader :

To say that the Brookman's Three isthe best set I have ever built is no mereextravagance of words. The results, onan indoor aerial, are briefly as follows :

Long waves : all the stations shownon the tuning chart given on page 344come in at good loud -speaker strength.5XX, strange to say, is the weakest ofthese and Hilversum the strongest.

On the medium waves, the number ofstations on the loud -speaker is toonumerous to detail. Incidentally,Brookman's Park comes in at suchvolume that use of the volume controlis absolutely necessary.

I hope you will pass on my quota ofcheers to the designer.

P.S.-Selectivity excellent.

NOTHER reader at Dover finds theABrookman's Three especially selective

on the long waves :Having last week made up the Brook -

man's Three, I thought you would liketo know my opinion of it.

I may say I have made up many sets,from super-hets, etc., and I find thisset to be one of the best I have heardand, what is most important here, thatit is very selective on the long -wave band,where I find most sets fail.

I can with the Brookman's Threeseparate completely Daventry 5XX,Zeesen, and Eiffel Tower, which is avery good test in this part of the world.

Of course, on the short waves it isalso very selective and I have up todate, in under a week, receivednineteen medium -wave stations andeight long -wavers.

I have used the components youspecify, except for Remler condensersand a Ferranti AF5 transformer.

I may say I use as a loud -speaker thelinen -diaphragm double cone as des-cribed in Amateur Wireless some timeago, which I think is one of the best Ihave heard.

LODESTONE MOVING -COILLOUD -SPEAKER

CPECIALLY designed for the WIRE-LESS MAGAZINE, W. James' Lodestone

Moving -coil Loud -speaker calls forthpraise wherever it is heard. Here ss acomment from a Wembley reader :

I am writing to you to express myappreciation of the wonderful repro-duction obtained from Mr. James'Lodestone Moving -coil Loud -speaker.

I also wish to thank and congratulatethe makers, Whiteley, Boneham & Co.,Ltd., for such perfect production.

I am using the speaker after theDubilier S.G. Four (Toreador).

The letters from readers re-produced here are somethingmore than just praise for theWIRELESS MAGAZINE -theyare a definite help to thelistener who intends to builda new set, showing as they dothe merits of various types ofreceivers in different localities.

Remember that full-size blue-prints of and back copiesdescribing most of these setsare available as indicated onpage 469 of this issue.

Readers are invited to sendus photographs of WIRELESSMAGAZINE receivers theyhave built ; for each oneprinted we shall pay half aguinea. The prints must besharp and clear for repro-duction.

DRUM MAJORA READER at Hornsey has obtained ex-

cellent results with the Drum Major(WIRELESS MAGAZINE, April, 1929). Readwhat he has to say about it :

I am sending you my impressions ofthe Drum Major, which I have made. Imust say that I do not think you wouldrecognize it if you saw it, as it is mostlybuilt with parts from an ancient four -valve set I bought about three years ago,that is, before I built your Nomad Six,which still retains pride of place as afamily entertainer.

From experience gained with the big-ger set, a milliammeter was incorporatedin the Drum Major, as it was primarilybuilt for quality programmes fromLondon and 5GB. These two stations arereally worth listening to on the DrumMajor as the last valve is a super -powertype taking r5 milliamperes at 15o volts.

The Drum Major also has quite auseful log of foreign stations, the chiefbeing Nurnberg, Cologne, Turin, Tou-louse and Brussels, although of coursefor foreign programmes the Nomadcomes into its own, as the great range andterrific volume of this set make theresults comparable to a programme fromthe local station.

The two sets are sharing an aerial andearth between them, either set beingbrought into use by means of switcheson the wall which cut one set right offwhen the other is in use. Both sets arerunning from the mains, and the 2-microfarad earth condensers are mountedin the sets so that the mains units aretreated as ordinary H.T. batteries andthe earth lead from the sets is not broken.

This, I think, is much the best way asthe earth lead can be as short and directas if using batteries and, furthermore,the earth terminal on the set is not

live, so no shock can be felt if anyonetouches it.

The mains unit for the Nomad is anEkco 3V supplying four voltages, thelast at 3o milliamperes and the unit forthe Drum Major was described in theissue for March, 1928, to supply bothH.T. and L.T., so that the Drum Majorhas practically been turned into an all -mains set, but with the advantage thatthe best possible valves for each stagecan be used.

The valves are four -volt Mullards, asused in the Nomad. Thank your staff fortwo really good sets.

CHUMMY FOURAMOST useful report on W. James'

Chummy Four (WIRELESS MAGA-ZINE, June, 1929) has been received froma Birmingham reader, who recently madean extended tour in the North :

You will perhaps be interested in myresults with the Chummy Four.

At first I had some trouble, but yourcorrespondence people did all they couldto help me, and in the end the fault wastraced down to a defective coil. Whenthis was rectified the set became alive,and we took it on a tour with us thisholiday and derived a great amount' ofpleasure and satisfaction, besides somevery interesting data which I think youmight be interested in.

In the Midlands 5XX comes in withenormous volume and 5GB comes inwith great volume. My home does notappear to be a particularly good spot,as I have noticed with other sets, butafter dark several stations-Toulouse,Hamburg and Manchester-sometimescome in with great strength.

The first place we tried the ChummyFour on tour was at Doncaster. Here5XX was very powerful. The nextplace was Hornsey, near Bridlington ;5XX powerful and 5GB very good.This was at 9 o'clock in the evening.Our next call was at Barnard Castle inthe Pennines. 5XX came in here at verynice loud -speaker strength; 5GB wecould not get, but Manchester came inat nice strength.

Stopping for a picnic near GretnaGreen, 5XX came in at a nice loud-speaker strength, but we had to usefull reaction here owing to slight fading.Strangely, at Dumfries, some 3o or 40miles further on, 5XX came in aboutthe same strength, but no fading. Thesame applies to Castle Douglas.

The next day we rode round the Mullof Galloway and at the lighthouse there5XX came in very loud indeed, butManchester one could only just hear;strangely, I could not pick up Belfast.

At Stranraer, 5XX was very good.We next tried the set at Kilmarnock,but here 5XX was very, very weak.Glasgow came in very good indeed,

(Continued on page 544)

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HEAR K -B INYOUR HOME before

BUYINGYour nearest K -B dealer will 6e glad todemonstrate any of these K -B receiversin your own home when convenient toyou. You will 6e under no obligation tohim or to us. Send us the coupon belowfor details, and arrange a demonstration.K -B 161 and 169. The KOLSTER-BRANDES All -Mains Three -Valvescreened -grid Pentode Receivers, designed for operation off A.C.electric supply mains. Including valves and royalty, £17 10s.K -B 163. The highly selective KOLSTER - BRANDES Three - valvescreened -grid Receiver. With Pentode valve, £10 15s. WithPower valve, £10 2s. 6d. including valves and royalty.K -B 103 and 156. The KOLSTER-BRANDES Four -valve PortableReceiver. Including valves, royalty and all accessories £18 18s.BR ANDESET IIIA. A popular three -valve set arranged for onedetector and two low Frequency valves. Including valves androyalty £7 10s.All K -B products costing £5 or more can be obtained on simpleHire Purchase Terms.

BRITISH MADE BY BRITISH LABOUR

Kolster-BrandesScrvie AdvertisinP

r

Wireless Magazine. December: 1929

Brandes Authorised dealer,send the coupon to Kolster-

Brandes, Cray Works, Sidcup, Kent.

For Full particu-o'. lars, and name of

your nearest Kolster-..

NAME

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You will get prompt replies by mentioning " Wireless Magazine "

543

W.M . Dec.1.=

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Wireless Magazine. December, 19291

Some Famous " W.M." Sets-ContinuedAt Sanquher, which is on the Moun-

tain Road about half way betweenGlasgow and the Border, we could notget a trace of 5XX, but Glasgow wasvery good. We also tried the set in theMountain Pass, Dalvein, but we couldonly get 5XX about phone strength,and we could not pick up Glasgow.

Next we stayed at Keswick a fewdays, and here we were right under theshadow of Skiddaw and 5XX came invery, very weak, but we put an outsidetemporary aerial from a tree to the farm,and here the set became immediatelywonderful, and we could get 5XX,Manchester, Glasgow and one foreignervery nicely indeed; this appears to be areal dead spot, because I have heard ofthem not getting very good results withfour valves up there, usually havingto use five.

We also tried the set on the Cotswolds,near Broadway, and 5XX and 5GBcame in like a true orelestra.

I think you will agree with me thatthis is rather a useful test, and provesto me that the set is far above theaverage, and we are, therefore, delightedwith it.

ANOTHER reader, writing from Mun-ich, tells a tale of woe-about getting

his Chummy into Switzerland. He gotgood results once there, however :

As you like hearing what your readersthink of WIRELESS MAGAZINE sets, Ishould like to tell you of my experienceswith the Chummy Four on the Continent.

When, some months ago, I read in theWIRELESS MAGAZINE that Switzerlandmade difficulties about taking portablesets into the country, I was inclined todisagree. I now heartily endorse thatstatement.

Last year with another set I had notrouble at all. I wrote in advance to thepost -office of the town I was going to, andobtained a licence. At the customsexamination at Bale I produced thelicence, the set was weighed, I receiveda yellow form, and paid 8 francs. Onleaving the country I produced myyellow form and received my moneyback. This year I determined to takemy Chummy Four with me. I accordinglywrote and got my licence as before. Itwas a slip of green paper stamped bythe post -office and having written on theback "Concession Radio, 8 Aofit au8 Septembre."

On producing this at Bale, they toldme it was not a licence.

"But," I protested, "it has on it'Concession Radio. " " You might havewritten that yourself," was the reply.

There was a great deal of trouble andat the end of 40 minutes the gentlemanproduced a book of forms-white, red,and yellow. After weighing the set andwriting for about three minutes, hesaid : " What make ?"

I replied that I had made it myself.He repeated his question and I gave thesame reply. He then called anotherofficial, who asked the same question.I replied that I was not ignorant of

French, as the other man seemed to thinkI was, and that I had made it myself.

They then stamped the set with thecustoms seal and demanded 15 francsfor the weight of the set and 20 francsfor not having a licence. I pointed outthat the weight of the set was less thisyear and yet the fee was nearly double,but they merely shrugged their shoulders.

I managed to get back the 20 francs,by much arguing, from the post -office.My advice is : " Don't take a set toSwitzerland."

Once there, the Chummy Fourworked splendidly, and was the envy ofeveryone. Rome, Milan, Turin, Toulouse,Lausanne, and two German stationsbeing available any night at full loud-speaker strength. I was also able toget various other stations, unidentified,but conditions varied. Atmosphericswere very prevalent.

I got the set into Germany withoutany bother whatever. No paying at thefrontier for the weight, and no licenceto buy, although I shall be here for somemonths.

Here I get the local and numerousGerman stations-Toulouse, Turin, andone unidentified station, probably Polish.5GB comes in at weak phone strength,and I cannot get Vienna at all, althoughI can often get it in London. Atmos-pherics are very bad at the moment.

I can certainly say that the ChummyFour is the greatest boon; I am alwayssure of getting several programmes.

TOUCHSTONE FOURASTATION at nearly every degree

of the dial is a Ponders End reader'srecord with the W. James' Touchstone(WIRELESS MAGAZINE, November, 1928),on which he has received thirty-onestations at loud -speaker strength (withoutreaction) :

I am writing to you to express myappreciation of the Touchstone four -valve set. I built up the receiver exactlyas specified, except that I am using aFerranti AF5 transformer. I have alsobuilt up separate from the receiver achoke -filter output. (R.I. filter chokeand 2-microfarad Dubilier condenser.)

The set behaves very well; as forselectivity, it is of the highest order. Ihave often been sceptical when I haveread of sets that get a station nearlyevery degree of the dial but, believe me,I have logged thirty-one stations on theloud -speaker (Celestion C52), all identi-fied.

I am using 4 -volt valves in the follow-ing order : Ediswan HF45o, Cossor45oHF, Cossor 4.5oHF, and MullardPM254. Also Exide 520 -volt type WHaccumulator.

My aerial has an effective height of34 ft.; for an earth I am using the watermain. The total anode -current con-sumption as shown by a Bulgin meter is15 milliamperes.

With best thanks to the WIRELESSMAGAZINE for such a fine set.

544

Prague *London*Daventry Graz*Langenberg BarcelonaLyon BrnoZurich CadizParis (PTT) *GleiwitzRome GotebergMadrid Cardiff

*Berlin AberdeenKatowice HilversumA total of about 6o.Those marked with a * are received

at good loud -speaker strength on threevalves, the remainder on four. I useCossor valves throughout.

[Readers who wish to build this setwill be glad to know that old -typeBinowave coils are still obtainable fromOliver Pell Control, Ltd., the Makers ofVarley Components.-En.]

RESULTS are beyond expectation,"IA is the comment of an East London

reader, who had previously used anotherfour -valve set designed by W. Jamessome years ago :

Re my correspondence with you, anda personal interview, in reference to mydifficulties with the Touchstone.

On your final advice, I tested thereceiver stage by stage, and found thatalthough the filament of the super powervalve was not broken, it failed to amplify.

This has now been replaced, and theresults are beyond expectation. Iobtained splendid results with a four-valver designed by W. James some yearsago, but I consider the Touchstonemuch in advance.

BINOWAVE FOURTHIS fine four-valver (WIRELESS

MAGAZINE, January, 1929) madeuse of the first dual -range coils to bedesigned by W. James. The followingletter from an Eccleshall (Stafford) readergives a good idea of its capabilities :

I constructed the set a week ago, toreplace the Inceptor 3, because I wanteda set to cover both wavelength rangeswithout coil changing. I have made twoslight changes in the design and circuit,(I) an upright panel, and (2) I have in-cluded a jack switch in the plate circuitof the third valve to avow for the use ofthree valves only.

I constructed both the coils myself,in accordance with the directions givenin a previous issue of your paper.

The results obtained are nothing shortof marvellous. I don't think I can dobetter than give a list of stations toshow what the set is capable of :

LONG WAVES*Huizen *Eiffel TowerLathi Motala

*Radio Paris *Kalundborg*Zeesen Hilversum*Daventry Croydon, etc.

SHORT WAVESHanover Glasgow *Stoke

*Budapest *Frankfurt Berlin relayMunich Wilno *BratislavaVienna *Toulouse Konigsberg

*Brussels *Manchester *Turin*Milan *Hamburg BarcelonaOlso *Stuttgart Morayska

OstravaNewcastleLeipzig

*HorbyToulouse

*BreslauBelfast

*NurnbergMunster

*Cologne

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p

0.6611.1

FVUireless Magazine. Decepber 1929

TOThe SCREENED GRID 3The Set that after 12 months is not obsoleteAmid a welter of " improvements "and changes in set design, it is apoint of some significance that theFERRANTI Screened Grid 3, de-signed twelve months ago, is stillpre-eminent as the set for the homeconstructor.

In one respect improvement is nowpossible with this receiver, as with allsets employing only one stage of L.F.amplification. It is desirable to havegreater L.F. amplification than hashitherto been obtainable with one

stage, and to meet this need Ferrantihave introduced the AF6-a trans-former which combines double theamplification with a quality of outputformerly unattainable.Ask your dealer or write direct forfree constructional chart, and buildthe Ferranti Screened Grid Threewith the assurance of superb per-formance.

EASY CONTROL. NO SOLDERING.

NO COIL CHANGING

FERRANTI LTDL LINWOOD

LANCASHIRE

545

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Wireless Magazine. December. 1929

ULTRA *

"W .M." Photo

We have tested the typeF Ultra Air -Chrome loud-speaker and found it topossess all the inherentlygood characteristics of thedouble -diaphragm princi-ple. Brilliant tone andgreat sensitivity are note-worthy. Four chassis areavailable, the prices rang-ing from 42s. to 105s.The smallest of these pricesis admirable for port-.able sets.

CELESTION

For constructors of portable sets and radio gramo-phones, the Celestionloud -speaker shells arerecommended. The type Crange have a back adjust-ment. Prices £3 5s. to£5 17s. 6d. The ZB rangehave a front adjustment;prices as before. Themedium overall sizes ineach range are 13/ by 14by 5 and 144 by 144 by 4 in.

CELESTION

Giving sufficient volume tofill a hall, if necessary, theCelestion model C24 loud-speaker is housed in anextremely ornate and hand-some cabinet. A largediaphragm 24 in. in dia-meter is incorporated. Theprice in walnut is £25 ; ma-hogany, £21 ; and oak, £20.

LOUD -SPEAKER GUIDE-Continued from page 476

CELESTIONAlthough the smallest andlowest price of the many Celes-don niodels, type C10 retainsall the characteristic Celestionfeatures. Extreme sensitivity isclaimed. A 10 -in. reinforceddiaphragm is used. In ma-hogany, the price is £3.17s. 6d.;and in oak, £3 15s.

ORMONDA very inexpensive cabinetcone loud -speaker is theOrmond type R452. It is fittedwith the new Ormond four -pole adjustable unit. An evenresponse, faithfulness of repro-duction, and a capacity forhandling great volume areclaims we found justified. Theprice in oak is 29s. 6d. Weconsider this loud -speaker to bereally excellent value for money. "W .M." Photo

CELESTIONModel C12 is the standardCelestion loud -speaker thathas been so universallypopular since its inception.The diaphragm is 12 in. indiameter, and the resistanceis 2,000 ohms. In walnut itis 6 guineas ; in mahogany,£5 17s. 6d. ; and in oak,£5 12s. 6d.

BLUE SPOTIn our test of the Blue Spotmodel 49Z loud -speaker, price2 guineas, we were agreeablyimpressed with both the sensi-tivity, and the quality of repro-duction. This is on thehigh-pitched side, but quitepleasing. It is of special valuewith small -power sets, such asa simple two-valver.

"W.M." Photo

CELESTIONIn the Celestion modelZ20, the designers antici-pate that this loud -speakerwill become the newstandard Celestion. It incor-porates a sensitive electro-magnetic reed movement,working in conjunctionwith the Celestion rein-forced diaphragm. Theprice in mahogany is £8 5s.;and in oak, £7 15s. Madeto special order, the walnutmodel is £9.

CELESTION

With its specially attacheddiaphragm, the new Celes-tion model Z25 is claimedto be of very advanceddesign. Its appeal is to boththe music -lover and thecabinet connoisseur. Theprice in mahogany is 15guineas, and in oak, £15.

BROWN ik

The new Brown V10 Du-plex loud -speaker pleasedus immensely during arecent test. There is plentyof bass of a natural quality,and the high notes areparticularly well evident.It is sensitive to weaksignals. The price is £510s.

CELESTION

Celestion's first moving -coil loud -speaker is theCelestrola. A 6 -volt D.C.model with speech trans-former and filter is availablefor £25. Other models forA.C. and D.C. mains arealso listed.

A star (*) indicates that the loud -speaker has actually been tinted in the "W.M.",Laboratories.

546

Continued on page 548

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In all the Best SetsEfST8N...-

SUPERCOMPONENTS

Keystone H.F. CouplingUnit-a complete untuned

H.F. Coupling Stage.No. 1. for fast stage 10 6No. 2. for second 10:6

YOU will be wise to includeKeystone Components in your

Radio Set. They have becomeamazingly popular, fully justi-fying all claims made for them.

Keystone products are usedin all the best sets. They aredesigned by qualified engineers,and made from the best materialsby expert workmen.

KEYSTONESTANDARD WAVE TRAP

Suitable for use with any 101/6type or make of receiver .. Li

UNIVERSAL TUNING COILCovers wavelength ranges of 250.600 and1,000-2,000 metres, changing by Push-pin switch supplied with unit.

1.4Price, including six -pin base

"S.G." H.F. CHOKESuitable for all wavelengths from 20 to2,000 meters. Equally effective for Eshort-wave or ordinary broadcast. 0

DRUM DRIVEFits all standard condensers. Slow-motion drive gives reduction of r9 to 1. Drilling templates supplied

The BRITISH RADIO GRAMOPHONE CO., LTD.77 CITY ROAD, LONDON. E.C.1

Telephone : Clerkenwell 5684

CI.

tIcfrtc,Nne.cv N.\, c 6.-%°,,,NL:' ' 1'

,...i 4. L. ,,\... N.

3, ,k, -P.8,00.... \V'0- -V

... 6

,;(0 tI s s?' sr fr

Wireless Magazine, December: 19291

amourthe linendouble diaphragmspeaker

Model

£5.5.0

o,

. . . incorporates theDouble -diaphragmPrinciple... uniformfrequency responsefrom 60 to 10,000cycles ... reproducesthe high and the lownotes faithfully.The Double - dia -phragm principleis a patented de-vice (British PatentNo. 295,625) and isincorporated intothe Ultra AirChrome Speaker,the chassis form ofwhich is suitable

for use in the"Music Lover'sGramo-radio," the"Music Leader"and in all receiversembodying t h clinen double -dia-phragm speakerchassis.

Ultra Chassis Type " F"£4 . 4 . 0

IN CHASSISFORM

Type L12 X "I0"x 3i"

42/ -Type K

T4."xi4"x5152/-"

Type FiVx 23"X 5i"

84/-peTy

24"x 24' X 61"105/-

,

AIR CHROMEUltra Electric Limited, 661-3 Harrow Road, London, N.W .10

Please mention " Wireless Magazine " when corresponding with advertisers

547

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Wireless Magazine, December 1929

SYMPHONYThe Symphony loud-speaker unit is marketedcomplete with packingwashers, cone washers andstrip of felt for cone for thehome -construction of anefficient cone loud -speaker.The price is 15s. ; and ourtests of the unit show that

it is capable ofgood resultswhen properlyassembled. Ithas averagesensitivity.There is noappreciableemphasis ofany particularfrequency.

LOUD -SPEAKER GUIDE-Continued from page 546

EPOCH GRAS SMANT h e Epoch The new Grassmanmodel 66P.M. loud -speaker unit, inmoving -coil spite of a wide gap in theloud -speaker armature movement, isrequires no ex- extremely sensitive. Itternal excitation. has the advantage ofThe permanency being difficult to over -of the magnet is load, so that a large out-guaran teed for put of sound is possibletwo years. The without any trace ofprice of the corn- rattle. The response isplete unit is good for all frequencies.

15s. i Its price is 19s. 6d.

MAGNAVOXIn our test ofthe Magna-vox X coremoving - coilloud- speaker,we concludedthat thismodel is oneof the bestwe have everheard. T h e

bass is exceptionally good. There isno papery effect on the high notes.Prices vary between L8 5s. and (,11for D.C. and A.C. models. Theseloud -speakers are provided with twodifferent sizes of cone, namely 10i and71 in., and for all kinds of supply.

G.E.C.I Extensive test of the Gecophone Stork

loud -speaker unit prove it to be a highlyefficient drive for all types of cones anddiaphragms. Theprice is a guinea; and,in our opinion, thisis justified. The sen-sitivity is good,and theresponseeven.

(*) indicates that the loud has actually tested in " W.M " laborato,ies.

WITH OURCARTO ONIST

in the STUDIOSCaricatures by

LISSENDEN

Above you see erotessor W. G. deBurgh, who has been giving a seriesof talks on " The Meaning of

Ethics" for six weeks

Colonel J. T. C. Moore-Brabazon(seen on the left) has been givinga similar series of talks on motor-

ing

548

Every listener has heard AlbertSammons (seen below). He is aviolinist of unusual merit, and is afrequent broadcaster He was soloviolinist at the popular Queen's Hall

Promenade Concerts

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With PorterCondensersas used in theB own' 3.

valve S.G.Receiver.which bring,in ,oleos han41 Sta Lns.Thanks V.

Polar!

POLAR" IDEAL"

.0005 - 1216.00035 - 12/3.0003 - 12/ -

POLAR CONDENSERSWrite for the Polar Catalogue (M1

WINGROVE R ItillF.RS. Ltd . 1RS-9 strand. W C 2

4, r! flyr,

for ERICIVICV NaldiligImlUrit simplifies all soldering

FLUXITE is sold in tins, SOLDERINGprice 8d., 1 / 4, and 2'8. SET Complete

Another use for F'ar.ite : ardening Toolsand Co.,' Horde -zing

A,It for leaflet cmImproved methods.

FLUX'T4 LTD.iDest. 3321

Rotherhitbe, S.E.16

7/6or LAMPonly

2/6

111

0 00)01DY

Wireless Magazine, December, 19291

SSE111

0.014(fik

ASK your dealer to let you see the WatmeBalanced Armature Unit. Note the heavy

magnet of Cobalt Steel, the pole pieces andArmature of specially selected soft iron. See

how the Armature is balanced between thepole pieces, and how, at any given momentduring working, the Armature is being actedupon by two pole pieces at once.It is this true differential action that makesthe Watmel Unit so famous for its sensitivity.Now ask your Dealer to connect it to a suitableChassis and Cone. If possible, get him to com-pare it for you with any other Unit, irrespectiveof price. Notice particularly the sonorous wayit handles the bass frequencies, and noticealso that it does not " cut off " the upperregisters either. No finer Unit is turned outeither in this or in any other country, andfrom none will you get better reproduction.

(if We shall be glad to send you on request--JJ our Folder No. 102, showing you how tomake up a very fine Loud -speaker from aKit of parts, also Folder and Blueprint forbuilding up a modern 3 -Valve Set.

f

Wireless Co., Ltd.Imperial Works, High St., Edgware, Middlesex.

Telephone : Edgware 0323 P. & T

There is news in the " Wireless Magazine " advertisements549

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F-Ni-C/ireless Magazine. December. 1929

dikpadio gthicaliolliOW you do it beats me !"

Molly, a very attractivecousin of mine, evinces considerableinterest in radio, and "taking pity, "as she terms it, on an old bachelor,periodically invites herself to my fiat,towards the tea -time hour. The realreason of the visit, is, I believe, thefascination experienced in turningthe knobs of my wireless receiver.

On these occasions, I have beenusually dragged from a comfortablearmchair and an interesting book toact as guide and mentor for a touraround Europe, and the innumerablequestions fired at me as to " What'son now ? " have usually left me in astate of utter prostration.

Improving the MindMolly, who will be twenty next

birthday, if I remember rightly, isintent on improving her mind; hereducation, she considers, in thematter of languages, has been sadlyneglected, and because in view of asmattering of foreign tongues I havebeen able to identify the nature of thevarious transmissions captured, I amcalled upon to act as interpreter when-ever she strikes a foreign station.

I had switched off the set followingan announcement to the effect that aDutch lady would now recite somepoem of which I had not clearlyheard the title.

" Quite simple," I remarked, " whenyou know."

"Exactly !" retorted Molly, " andit's just what I want to know. Somany of these stations give courses inItalian, French, German and otherlanguages. I want to learn them all."

" When you were at school . . ."I began.

" When I was at school," said Molly,"I conjugated ad nauseam the verbto love in German, French, and Latin,in every conceivable tense, and youmust admit that this knowledge wouldnot be of much assistance to me inasking for a meal at any foreign hotel."

"Why not practise on me? " I said,"it might all come back to you."

Molly did not deign to reply, butshe gave an audible sniff; it soundedcontemptuous.

" And you propose ? " I queried." To buy a wireless receiver and

A Story with AMoral: By JAY

COOTE

follow the courses regularly from boththe home and foreign stations."

This ambition, I considered, wasone worthy of encouragement, andwe discussed ways and means, finallydeciding on a visit to a West -Endstore, which in due course installedthe necessary apparatus in her home.Both her father and mother werepleased with the arrangement which,personally, I felt was a good oneinasmuch as I fully anticipated, atshort intervals, a series of SOS callsdemanding immediate assistance.

I was doomed, however, to dis-appointment, and not having heardfrom her for nearly ten days, I madean excuse to telephone about sometrivial matter.

" Getting on ? " I asked. " Whatlanguage have you .mastered ? "

"None yet, but I am making goodheadway. I'm taking five courses,"she added, "and you'll soon see whatI can do."

"Stick to it," I enjoined, "andwhen you have time, drop me a linein, say, French or German or Italian.I should like to see what progress youare making," and I rang off.

As a matter of fact, I thought thatshe had undertaken too big a taskand that the simultaneous assimila-tion of some five lessons per day waslikely to cause mental indigestion.That she had undertaken the studyof several languages was demonstratedin a short note received from hersome days later. It read as follows :

A Good Start"Mon caro Vetter Dick." As a

start this was decidedly good; itproved ipso facto that French, Italian,and German were part of the curricu-lum, and the combination was thenearest approach to an internationaltongue that I had ever met. But morewas to follow :

"Si Ich scrivere these quelequeslinien, es est solamente pour youzeigen combien lo progres gemachtbabe," and so on. It was quite a longletter, rather rambling at times, but

550

it comprised, I felt certain, the majorportion of her vocabulary in at leastfour languages, and obviously wasthe result of a great effort.

In the text, so far as I could gather,reference was made to me in the guiseof a French cousin, a German Vetterand, apparently influenced by a waveof affection, as a carissimo cugino,which sounded quite refreshing.

If anything, the work showed signsof originality, for notwithstanding theconventional phrases invariably adop-ted by the teachers, she made noreference to pens, ink, and paper,the gardener's irrepressible child, or toa visit to the railway station.

Moreover, she scrupulously avoidedsuch involved sentences as : "I haveone son and no daughter; two sonsand one daughter; no son but threedaughters," or, "Yes, I have abrother and two sisters; I have onlyone brother; I have no brothers andno sisters," so typical of the indefiniteand vague answers given by theauthors of conversational books.

Two Heads Better than OneThat afternoon, proud of her work,

Molly came to tea; we were, she said,to take these courses together, astwo heads were better than one.It would also, she thought, make herwork much easier, as she had oftendesired my assistance.

So you see, when the local stationbroadcast an Italian lesson, we bothsat facing the loud -speaker, she witha notebook on her knees, and apencil ready to take down the dicta-tion and I well

We made considerable progress, Iadmit, and such words as lo t' amo,carissima, un bacio and other endear-ing terms usually associated withromantic operas came readily to mylips. Her vocabulary-with illus-trations-was rapidly extended.

How the lessons progressed doesnot interest you in the least, but weare spending our honeymoon inFrance, Germany, Switzerland, andItaly. It would be such a pity if herlanguage courses were wasted, and Iam entirely with you in maintainingthat education by radio is a blessingin disguise.

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The New CAN: H.T.Accumulator

Have you had details of ournew range of high tensionaccumulators ? Supplied in tovolt units or 3o volt groups of2,50o 5,000 and ro,000 milliamphour capacity, this entirely newand original H.T. is suitablefor every class of receiver.

Tile OriffinalJelly acidBattery.

Wireless Magazine. December. 19291

ALL POSITION Ir NON -SPILLABLE

Weight for weight and size for size the C.A.V. Jelly Acid Battery has a better capacityand higher efficiency than other non -spillable types. The special construction of

the container, and the use of Jelly Acid allows it to he plaeed and used inany position, without the risk of spilt acid. It is both the safest and

best for your portable. Recommended in the constructionalarticles of the Wireless Press, and standardised in many

popular portable sets, the C.A.V. Jelly AcidBattery, provides the most reliable and the

safest non -spillable battery obtainable.

The new C.A.V. Radio accumulatorcatalogue and battery maintenance

handbook will he suppliedfree upon application.

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The New C.A.V. H.T.Accumulator

To those seeking a perfect sourceof H.T. current we recommendthe new C.A.V. H.T. Accumu-lator. Absolutely silent in opera-tion, handsome and compact,inexpensive in first coot and

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CARTRIDGECONDENSERS.

These condensers are idealfor the man who likesto experiment. In a second,you can pull one out ofthe clips and put in anotherof a different value. Theyare made in values from.000i mfd. to mot mfd.Overall length, 45 mm.

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Interesting 16 po. Booklet, with circuits,regarding this DYNAMIC SPEAKER inpart.eular and others in general.

AMATEUR WIRELESS said (10. 6. 29):-"Above the average, for its sensitivity and uniformity of re-sponse throughout the audible register were notable features.Some moving -coil speakers have a reputation for undulyaccentuating the bass, even when the coil impedance iscorrectly matched to the preceding valve or valves; in thisspeaker, however, the treble and bass appeared well matched."

CL4UDE LYONS LTD.76 OLDHALL STREET, LIVERPOOL

Advertisers take more interest when you mention " Wireless Magazine"

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Wireless Magazine. December. 1929,

If You Have Electric Light in the House, Says ALAN S. HUNTER,

USE A MAINS -OPERATED SETTHANKS to a big and concerted

push by radio manufacturers,mains -operated sets have capturedthe set -buying public's imagination.

By abolishing batteries, the nuisanceof run-down accumulators and batteryrenewals, the mains -operated set madea tremendous appeal to visitors toOlympia, where, during the RadioExhibition, the huge increase in thenumber and variety of mains -operatedsets was the outstanding feature of theshow.

What Are They?What are these all -mains sets, and

wherein lies their alleged superiorityover the battery -operated set that hasserved, and is serving, most of us sowell?

These and other pertinent ques-tions are being asked by WIRELESSMAGAZINE readers, who want toknow whether the all -from -the -mainscry is merely a stunt sales policy or adefinite change in radio fashions;radio has fashions, as was surelyproved last year, when portables wereconsidered the last word in reception.But at this year's exhibition, port-ables, although still in great demand,have to yield in interest to the on-slaught of the all -from -the -mainscampaign.

As a matter of fact, the powersupply.of the set is the most import-ant thing to be considered by the setbuyer. Because this is so, everyprospective purchaser of a set, andthere are many WIRELESS MAGAZINEreaders who come within this cate-gory, will welcome an explanation asto the superiority of the all -mainsset. That is the object of this article.

Mains LimitationsMains -operated sets naturally re-

quire an electric -light supply tooperate them,and since the number ofset buyers with mains in their homesmust be considerably smaller thanthe number without, this new typeof set cannot possibly oust the batteryoperated set from general use, atleast, not for several years to come.

We must retain a sense of propor-tion when discussing mains sets; somemanufacturers appear to have run

away with the idea that the wholecountry has miraculously been wiredwith electric -light supplies; in this,they give the Central ElectricityBoard rather more credit than theirslowly developing " grid " system ofdistributing electricity merits !

Up to a reasonable point the de-velopment of mains sets in this

The Marconiphone model 39 is availableas a mains -operated set. It uses a screened -

grid valve, and the price is £21

country is quite logical; for it mustbe true that those best in a positionto spend money on a set are usuallythose who have a sufficient income toinsist upon the luxury of electric light;itis still a luxury in all but the newesthouses.

It is the set buyer with electric -

A report on this Kolster-Brandes KB169all -electric three-valver set will be pub-lished next month. Its price is £17 10s.

752

light in his house who, as the mostintimately interested purchaser of amains set, needs to be given a lead inthe matter. I say quite uncondition-ally that such set buyers would be ill-advised to consider buying a battery -operated set; they should back upthe efforts of the manufacturers inpopularising mains -operated sets asfar as the distribution of electricitypermits. The mains -operated set isnot a snare, but is a decided andimportant factor in the improvementof broadcast reception.

Quality and MaintenanceAs a rule, two things worry the set

buyer; one is whether the qualityof reproduction is satisfactory; theother is how the set is maintained.With mains sets, quality is nearlyalways excellent and maintenenceworries are practically non-existent.The reason for the superiority in thequality of mains sets goes down to thevery heart of things; let me explainwhat I mean.

The average three -valve set with bat-teries differs from the average three -valve mains set only in the last valve.The battery set embodies a smallpower valve, because the batteriescannot economically deliver the extracurrent required by the big powervalves used in mains sets. Thesebig power valves, requiring a highvoltage and passing considerablecurrent, can develop a lot of power,so that good volume can be obtainedwithout forcing the set.

Importance of Last ValveI have said that up to the last

valve the mains and battery setsbear a close resemblance; if we assume,as we reasonably may, that a givensignal receives equal treatment bythe first two stages of each type of set,we can see that the last valve is theone that most affects the quality.

A big power valve, as used in themains -operated sets, will not neces-sarily give greater volume than thesmaller power valve, but with itsgreater reserve of power, it willimpart a higher degree of quality tothe reproduction.

(Continued on page 554)

1

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Wireless Magazine, December 1929

USED BY THE"WIRELESS MAGAZINE"

WITH THE"OUTPOST FOUR" SET

Note the surface plate of Insulatingmaterial and countersunk Sockets en-suring security against short circuiting.

NO PITCH: NO WAX. LONCER LIFE IN USE.A REVOLUTION IN POWER PRODUCTION.

"OBETA D!represents the

CREATEST ADVANCE EVER ACHIEVED inBattery construction.

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Construction

POWER60 Volt 10/3 ( 6" x 51" x 3r)105 16/6 (101" x 51" x 31")

"OBETA" FLASHLAMP BATTERIES ARE SUPREME IN VITALITY.

Telegrams:LESINGHAM, SOWEST,

LONDON.

F. L. LESINGHAM,13, VICTORIA STREET, LONDON, S.W.1

Telephone :VICTORIA 2919.

4 -POLE BALANCEDARMATURE CONE UNIT

Central Adjustment. Cobalt Steel Magnet.Best Bakelite Casing. Full Volume.Extremely Sensitive. Pure Tone.

If you are building your own Loud-speaker, the W.B. chassis is whatyou want. Holds any Unit. Only10'6, complete with cone and fittings.

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Telephone: Mansfield 762Telegrams: "W hitebon, Mansfield."

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GIVE RADIO THIS CHRISTMAS !When replying to advertisements, please mention " Wireless Magazine "

553

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Wireless Magazine. December 1929

Use A Mains -operated SetThe absence of maintenance

troubles greatly off -sets the highinitial cost of a mains -operated set.It must be admitted that the prevail-ing prices for a good "family" setworking from the mains are on thehigh side, and possibly out of reach

The Amplion Standard mains -operated three-valver ispriced at £50

of listeners with a modest purse.But when giving consideration to

cost, do not overlook the fact that amains set involves no expense inbattery renewals, which are oftenquite a heavy item, and a constantly -recurring one, in the battery setThe mains valves will eventuallyrequire renewal, but not so soon asordinary valves, owing to their morerobustly constructed filaments.

I know several listeners who, al-though quite satisfied with the qualityof reproduction produced by theirbattery sets (I am not suggestingthat battery sets cannot give goodquality), most emphatically dislikethe worry of battery maintenance.

No -trouble MaintenanceThe charging of the accumulator

and its annoying habit of runnirgdown just when the set is mostwanted are disadvantages that arcviewed with disgust; to these goodpeople, I point out that, apart fromall other considerations, a mains -operated set entirely eliminates theworry of maintenance and that isindisputably one of the biggest sellingpoints of the mains set.

So far as I can gather from varioussources of information, there are asmany homes wired for direct -currentas for alternating -current electric -light supplies; this mixed state ofaffairs is a hindrance to the mass pro-duction of a mains -operated set,

for the apparatus is quite differentfor each type of mains. In general,the D.C. mains sets is cheaper thanthe A.C. mains set, because in theformer no rectifying apparatus isrequired.

As the D.C. supplies are being con-verted as rapidly aspossible to A.C.,manufacturers have

concentrated moreon A.C. sets. Thereare other reasonswhy D.C. sets areless general thanA.C. sets, one reasonbeing the extra diffi-culty in manufac-ture. But such D.C.mains sets as theGambrell and Ekcotypes can be thor-oughly relied uponand are, in my

opinion, just as good a solution as theset having a D.C. mains unit for thehigh-tension supply, as advocated bymanufacturers who only make A.C. sets.

The cost of running a D.C.-mainsset is about twice as high as that

Continuedof an A.C.-mains set, but since theA.C.-mains set can be run at almostnegligible cost, the extra cost willnot make much difference to theelectric light bill.

I am sometimes asked to recom-mend a set suitable for use with a.mains unit; but where the supply is,A.C. I strongly urge the set buyer to.get a mains -operated set and not anordinary set with -.a separate mainsunit. The all -mains set has theadvantage that it embodies mainsvalves, with working characteristicssuperior to those of valves derivingtheir filament current from an accu-mulator, which would have to beused with the mains unit.

Safety of Mains SetsFinally, let me dispel any doubt that

may still conceivably exist in theminds of readers as to the safety of theall -mains set. Conforming as they do,almost without exception, to therecommendations recently issued bythe Institute of Electrical Engineers,mains sets of to -day are every bit assafe in use as the domestic vacuumcleaner or electric fire.

An Improved Linen Loud -speaker(See Page 520 for Constructional Details)

CoCCIOS

IC.

'JOS 111MOCTIS

67

COLOPOLD VON, OF COOLWAY., %WOO Coll.

Half -scale blueprints of this linen loud -speaker can be obtained for half-price (that is,6d., post free), if the coupon on page iii of the cover is used by December 31. Ask for

No. WM172

554

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[-Wireless Magazine. December 1.9*

-a completeH.T.MAINS UNIT

Yes! and what's more it's the very best obtainable.It simplifies wiring by the use of two screenedcomponents only instead of many, at considerablyless cost.The Unit, complete, is the ideal method of pro-viding the mains drive, both H.T. and L.T. for anyA.C. Mains Receiver.The Power Box is equipped with a low meltingpoint fuse, flex lead and adaptor and two additionalterminals to deliver raw A.C. for A.G. Valves (4 voltsup to 4 amps).

A.C. Power Boa No. 1 £2.10.0 Filter Compact No. 1 £1.10.0120 volts at 20 raia

A.C. Power Boa No. 2 13.10.0 Filter Compact No. 2 £2.0.0180 volts at 30 rraa

Our ART BOOKLET-free on application-gives fullParticulars, and contains much interesting informat on on

Radio from the Mains."

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When you send your order don't forget to say you " saw it in the W.M.'"

555

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Wireless Magazine, December 1929

THE NEW acolLsIN view of the progress which

takes place in radio from year toyear, many readers will have won-dered whether any improvementshave been made in Q coils.

While the coil undoubtedly sup-plied a big need at the time 'when itwas introduced, it was obvious thatthere were several minor points inwhich it could be modified withadvantage. Against such modifica-tion, however, must be placed theinconvenience occasioned to thosewho already possess Q coils.

It was, indeed, with considerableregard to this aspect of the questionthat the original Q coils were de-signed.

Marked AdvantageAfter a time, however, the advan-

tages of some new experimental coilsbecame so marked that it wasdecided to make a change. This wasdone with as little alteration to thegeneral arrangement of the coil aspossible, such matters as the terminalconnections being left exactly asbefore. The principal alterations arein the windings of the coil itself andin the switching associated with it.

The original Q coil utilised aseries -parallel scheme which, whileeffective, necessitates a multi -contactswitch and, despite all precautions,trouble was experienced in manyinstances from this source.

A switch contact may make a quitegood joint as far as a D.C. test is con-cerned and yet have a considerableresistance to high -frequency currents,and this gives rise to many cu: ionseffects. The method of placing thecoils in parallel was, therefore, modi-fied so that a simple push-pull switchcould be used,and instead ofplacing the twosections of thecoil in series onthe long waves,only one sectionwas employed.

This methodhas the advant-

NC

By J. H. REYNER,B.Sc., A.M.I.E.E.

considerably, the average high -frequency resistance being 7 ohms,as against rather more than twicethat figure with the older form ofwinding.

The efficiency on the long wavesremains of a high order, as before,the actual figure depending upon theparticular method of construction ofthe long -wave coil, which varies withthe different makes.

V

5

Connections for QAT (aerial) coil

The base has been reduced in sizeand also the coil diameter itself, whilethe push-pull switch is mounted atright angles to its former position, asthis had become, for various reasons,the most popular and convenientarrangement. Apart from this change,the QSG and QSP coils (for screen -grid and neutralised H.F.) remain thesame as before, the terminal connec-tions being identical.

The aerial coil has always been asomewhat unsatisfactory proposi-

age that the per- "r_formance of thecoil on the shortwaves it improved

Connections for the QSi' coil

NT

5

Connections for QSG (screened -gridtransformer) coil

tion. Right from the start it wasfound to be difficult to produce acoupled aerial coil capable of givinggood results on both wavebands. Forthis reason the most common arrange-ment was the connection of the aerialthrough a .000r-microfarad con-denser, either across the full coil or,later on, across a portion of the coilonly, as with the QAA coil.

The QAR and QAM coils wereattempts at Reinartz or coupled -aerial arrangements, but were notaltogether v.ti-factory, being tooselective on the short waves forordinary operation.

Where the Difficu:ty LiesThe difficulty lies in the fact that

the aerial coupling winding tunes theaerial circuit, and where one has tocover such a large band of wave-lengths as 250 to 2,000 metres, it is amatter of great difficulty to avoid thetune of the aerial circuit lying at anawkward place within the actualtuning band of the secondary.

For a long time the problem seemedinsoluble unless two distinct aerialcoupling windings were employed.

The discovery of the solution was,to some extent, accidental. The newQ aerial coil is at once particularlyselective and yet lively, that is, thesignal strength has not suffered.

This particular coil, therefore, willbe different from the previous aerialcoil and, indeed, it entirely replacesall the other three types, there beingonly one aerial coil now marketed.

On this r and 2 are connected tothe tuned winding. The aerial is con-nected to terminal No. 4, while anentirely separate reaction coil is con-nected between termLals Nos.5 and 6.

The coils arenow obtainablewithout difficulty,the firms licensedbeing LondonElectric W ireCo. & Smith'sLtd.; Wright &Weaire, Ltd.; andR ady R Ldio.All coils have beenreduced to 15s.,irrespective oftype.

556

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Wireless Magazine. December: 19291

DOITOUREMEMBEIV

The fame of Squire Loud -speakers spreads through-out the land. From all hands come tributes to thewonderful reproduction afforded by our cones andcrac les.It is a position of which we feel proud, and one thathas been attained by dint of putting the best we knowinto everything we turn out.Our programme includes a moving coil Speaker, a triplecone, a ouple cone, and several single cones of varioussizes. Our No. 97b Cradle will take any of the Units atpresent on the market, and we will gladly supplyleaflets giving full prices and particulars on request.

THE BEST PANELTO USE IS

AS USED IN

THE BEST SETSAlso The Original Becol Low Loss Former,made in eleven sizes. Look for Trade Mark.

Sole akers:The BR TISII EBONITE Co., Ltd., HANWELL W.7

" HOOKITE " LOUD -SPEAKER(Trade Mark.) RUBBER BEADING

NO VIBRATIONNO RESONANCE

As used by the WIRELESS MAGAZINE.

CARTON CONTAIN:NG 12 ft., 2s. Od. each, through al

Wireless dealers, etc. Send P.C. for nearest stockist to

DAVID B. HOOKE, LTD.,4 QUEEN ST. PLACE, LCNDJN E.C.4.

TELEPHONE: 6197 CENTRAL.

557

That used to be the usualfinish to each broadcastitem. Sometimes it wasten minutes -- sometimeseven tif teen, somehow wedidn't seem to mind then.Vv hat was a few minute'ssilence here and there ina wonderful " Wireless"programme 1 It wasn't aprogramme as we knowit now either - only acouple of hours in twenty-four-but we enjoyed itto the full. Now we askfor better things - butthat was seven years ago.Yet, even then --and yearsbefore too-T.C.C. Condensers were being usedin transmitter and receiveralike. They were thestandard of those days --they are still the standardto -day. Remember thiswhen next you want acondenser-use only the"condenser in the greencase"- and be safe.

T.C.C. Condensers are made intybes for all Purposes. Here isillustrated a z,000 mf. Electro-lytic Condenser, mice s 5s. od.There is also the Double Type-4,000 mr.-pice 27s. 6d.,and the new goo mf. 4.0 v.Type, price zos. od.

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Wireless Magazine. December, 1929

INSTRIV TS heORCHESTRAAVING given some account ofthe wood -wind, the brass, and

the percussion instruments, I proposethis month to write about the stringedinstruments of the orchestra.

I gave a few notes upon the stringquartet in the May issue, as a matterof fact; but only from the point ofview of the combination of twoviolins, a viola, and a 'cello as arecognised group of solo instruments.

Only a Loose TermIn any case, when considering the

full orchestra the addition of thedouble -bass is necessary, apart fromwhich it should be made perfectlyclear that the string quintet is onlya loose term, because five only wouldbe quite inadequate; it does notstrain the imagination of anyone torealise that five stringed instrumentswould never be heard against wood-wind, brass, and drums.

Indeed, many a conductor of amunicipal orchestra, where expense

C. WHITAKER-WILSONDiscusses the Strings

has to be considered, has had to fighthis council on the matter of obtainingenough strings. The larger bandswill have as many as thirty firstviolins; such a number is by nomeans uncommon.

In broadcasting, however, the diffi-culty is solved another way : byplacing the stringed instrumentsnearest the microphone and thebrass farthest away a reasonablebalance is easily obtained. But sucha method can only apply where amicrophone is used. In "real life,"so to speak, unless enough strings beemployed it is impossible to securea proper orchestral balance.

The stringed instruments arenaturally important-they are themost important of all, so far as thatgoes-and it may be of interest tolisteners to treat them here from thepoint of view of broadcasting. Let us

consider the violin first. It is an instru-ment which is entitled to great respect,if only upon account of its antiquity.

It is not known who first con-structed a perfect violin; it is quitelikely that several good ones weremade by different men about thesame time. But such names asStradivarius, Amati, and Guarneriuscome to the mind immediately onethinks of a violin.

Extraordinary HistoryThere is something extraordinary

about the history of the violin com-pared with that of the piano. With-out going deeply into the evolutionof either instrument, I might doworse than point out that the factthat no one wants a new violin if hecan get an old one and no one hasany use for an old piano if he canget a new one.

It is an odd thought that theviolin has passed its height of per -

(Continued on page 56o)

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Wireless Magazine, December: 1929

The Instruments of the Orchestra Continuedfection two centuries ago and thatthe piano has yet to reach its perfectform. Every day of the month newpatents are t2k n out for the pro-tection of some improvement inpiano action.

Perfect Tone and TouchI played upon a new one by a

leading maker a few months agowhich had what seemed to me to bea perfect tone and touch. It oughtto have had, for the price was overfioo. Such a sum would not be out

of the way for a violin by Stradi-varius, by any means ; but if onepaid that amount for a piano twohundred years old it would only bebecause it was something of a curio.Neither would it be a real piano; itwould probably be a harpsichord-one of the predecessors of the piano.

But a violin two hundred years oldis younger than ever it was. Tohandle an instrument by Stradi-varius or Amati is something of athrill; one finds one's self wonderingwho has played upon it, loved it, and

coaxed the tones from its very soul.But a piano, or rather a harpsi-

chord, of that age is merely a curio,a relic of the past; it has little or nomeaning in these days. So that theviolin is, as I have said, entitled tosome respect. We can afford tohonour it as a broadcasting medium,for it "comes through" as well asany instrument in the orchestra.

I have several friends who areviolinists, and we are always arguingthe matter of the comparative diffi-culty of playing a stringed instrumentwith that of a keyed instrument likethe piano or the organ. It is uselessfor me as an organist, for example,to say that I have to use both handsand both feet to produce my notes;the violinist always throws it in myface that he has to make his notes,whereas mine are already there.

There is not space here for me tolay forth both sides of the argument,but it has often proved to be interest-ing. Have you ever examined aviolin ? If you have, you cannothave failed to be impressed by the

apparent simplicity of its construc-tion : a resonant body of wood, afinger -board, a neck terminating ina head or scroll, and four stringscarried from a tail -piece over aslight -looking bridge to tuning pegsin the neck.

The strings are of varying thick-ness. The thickest is the G string,and is tuned to the G below middle Con the piano. The next is the Dstring, the third is tuned to A, andthe fourth to E. So that the violincannot sound below the G, but eachstring is capable of being raised con-siderably by means of what is calledstopping, effected by the fingers ofihe left hand.

Shortening the StringEach note of the scale-up to a

considerable height-may be pro-duced by placing the fingers on thestring-shortening it, in other words-while the sound is produced by thebow held in the right hand, or bymeans of plucking the string with

(Continued on page 562)

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Wireless Magazine. December 1929

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561

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Wireless Magazine, December 1929

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The Instruments of theOrchestra- Continued

the fingers of the right hand, anexcellent device (known as pizzicato)occasionally employed.

To those who play the violin thisexplanation will not be particularlyinteresting, but I am supposed to beaddressing those listeners who donot themselves play any orchestralinstrument. .

First and Second ViolinsOne other point about the violin

as used in the orchestra; it is thequestion of first and second violins.The "firsts" play a part higher thanthe seconds. That is all; there is nodifference in the actual instrumentsthemselves.

Now let us consider the third ofthe so-called string quintet-theviola. Not many people an easilyrecognise a viola from a violin-atleast, at a distance. It is really aboutone -seventh larger in size than theviolin; it is consequently lower inpitch. That is a rule with orchestralinstruments : the larger they are, thelower they are in tone.

The viola has a G string, just ashas the violin, but it is not its loweststring. It possesses one tuned towhat is called tenor C; that is tosay, the C below middle C on thepiano. The other three strings arethe same as the three lowest on theviolin, that is G, D, and A. Conse-quently the viola cannot soar ashigh as the violin, nor does it suit itto do so.

There is something very differentabout the viola-it is not so brilliant.All the same, it is a great mistake tosuppose, as many do, that it is nota solo instrument. It is, on the con-trary, exceedingly effective whenplayed solo.

Corresponds to TenorIn its place in the stringed portion

of the band it corresponds to thetenor in a vocal quartet; in fact, it isoften called the tenor. Some veryfine compositions have been writtenfor the viola; str ngely enough,many of the great composers playedupon it rather than upon the violin.

If you happen to see any work forviola in the broadcasting programmes,may I suggest that you listen care -

562

fully, comparing your impressionswith those you gain when listeningto a violin ?

The fourth of the stringed instru-ments is, of course, the violoncello-usually called the 'cello (chello, notsello, as it is sometimes mispro-nounced).

This noble instrument is easilyrecognised owing to its considerablesize. It is tuned one octave belowthe viola and its strings are muchthicker. Also, the bow for it is widerand shorter altogether than thatbelonging either to the violin or theviola.

Favourite InstrumentThe 'cello has always been a

favourite instrument with Englishaudiences, probably on account of itsdeep, sonorous tone. As a solo instru-ment it is largely a one -stringedinstrument; by which I mean that

(Continued on page 564)

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Wireless Magazine. December: 1929J

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The Instruments of theOrchestra Continued

the top string is in great demandowing to its melodic value. In theorchestra, however, the 'cello gener-ally plays a much lower part.

It forms the bass of the stringquartet and usually plays a bass partin the full orchestra, even thoughthe double -bass is able to go downso much lower. As a matter of fact,the double -bass is generally playingthe same part as the 'cello an octavelower.

Suiting the Microphone

The 'cello is always worth listeningto on the wireless because, not soar-ing too high nor yet descending toolow, it seems to suit the requirementsof the microphone. Perhaps there isno instrument which is more effec-tive on the wireless.

There is something very nobleabout the tone of sixteen or twentyof them when playing together in alarge orchestra, and more than everwhen fifty of them play together, asthey do in concerts given by some ofthe 'cello schools of music.

We now come to the last and thelargest of the stringed instruments-the double -bass or contra -basso. Thisunwieldy instrument is the makingof the orchestra, for its depth of tonemakes it as valuable to the orchestraas the pedals are to an organ. I amnot sorry I do not play the double -bass; I always feel sorry for thosewho do, because of the difficulty oftaking it about. It generally meansa taxi everywhere !

A Good JokePerhaps you may have seen the

excellent picture which appearedsome years ago in one of the humor-ous papers of a double -bass playerwho was extremely annoyed becausea small urchin followed him alongthe road. (He was carrying hisinstrument on his back.) In responseto his inquiry, the boy said he waswaiting to see him "chin" thatthing !

The double -bass may have eitherthree or four strings; four is thegeneral number in this country. Itslowest note is E-the lowest E onthe piano-but the music is written

564

for it an octave higher, merely as amatter of convenience in both writingand reading.

It is not a solo instrument in anysense of the term; neither can it besaid to be wholly satisfactory on thewireless, because its lowest notes areso low that the microphone is in-clindi to miss them. The same thingapplies to gramophone recording :it is difficult to be sure of the deepestnotes getting through.

But there has been a great de-velopment recently, and the daymay come quite soon when we shallfeel the grip of the double -basses inorchestras which are broadcast andrecorded.

A Great ContrastLooking at the strings as a whole,

there is no doubt that they afford agreat contrast with all wind instru-ments, whether wood -wind, or brass,and there is no mistaking their toneon the wireless.

After you have searched the 9 -pagereview of loud -speakers in thisissue, write for book let M.S. 2

describing in plain language

POCHMOVING -COIL SPEAKERS

The finest range of M.C. speakers inthe world.

14 DIFFERENT MODELS to suit allrequirements.

Model 66 has made "Epoch" one of themost cherished names in thousands of homes,

NOW THE NEW MODEL 991Big advertising can "sell" anything, but Epochmanufacturing facilities are taxed to their utmost

through recommendations by actual mere I

Ask your friends, or have a speaker for 7 days' approvaland compare it yourself against any or all makes.

EPOCH RADIO MANUFACTU iINGFARRINGDON AVENUE, E.C.4.

Phone : Central 197118 lines)

Page 121: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. December .1-W1

following models :-Modet B.D., tor Battery Operation 127 lbModel D.C. 'or D.C. Maine Operation . 430 0Mode' A.C. for A.C. Hain. Operation .. 570

I

1,1; rite

1?ARMEKO MANUr CTURE AMAINS TRANSF RMER ANDCHOKE SUITABLE FOR EVERYELIMINATOR OR MAINS OPER-ATED RECEIVER PUBLISHED INTHE TECHNICAL PRESS.

fo: full Particulars and Illustrated Catalogue

26, DOVER STREET,' :1 A & MEE* LTD74LNOEN

DON,11

Fv? Rc ST

LEICESTER. Museum 5070

THE MODERN MODE IN HOME MUSIC

YOUREXISTING

RADIORECEIVER

GOESHERE

RADIO ORGRAMOPHONE MUSIC

AT THE TOUCH OF A SWITCH/

The Instrument which convertsyour existing Radio Receiver intoa modern Radio Gramophone

Specification: Garrard double spring motor with 1210. Turntab e,B.T.H. Pick-up. doubie balanced Armature Speaker, handsomeOak Cabinet, Fiench polished antique Satoh. Height, 3 ft.; width,23 in.; depth. 17 In.

PRICE 12 19s, 6d.The Adaptagram is also supplied as a complete Radio Gramophone,Incorporating our famous 3 -valve Screened Grid Receiver In the

00

stoned by all good Dealers. Supplied on Hire Purchase terms.

Illustrates folder from:THE BRITISH RADIO GRAMOPHONE. CO., LTD.

77 City Road, LONDON, E.C.1

750 WATT "Q.M.B."SWITCH 2/6.

LYONS' NEW "B.A.T."(Best -After -Test) QMBSwitch breaks 3 amps. at250 volts!For H.F., L.F., H.T.,L.T. circuits. For A.C.Sets, Mains Units,Granao-Motors, and asMoving Coil SpeakerField Switch. Send forFREE 4 -pp. circular;request at the same timeour famous 28 -pp."CLAROSTAT" Book(all about D.C. and A.C.Mains Units, with scaledrawings).

CLAUDE LYONS, LTD.,76 OLDEIALL STREET,LIVERPOOL, ENGLAND

"GRAWOR" The 4 -PoleBalanced ArmatureCone Unit that

equals manymoving

coilspeakers

211-Post Free

Exceptionally heavy magnets. Solid yet scieaticallyconstruct d. Easily mounted. Suits all sizes of cones.

Complete with heavy flex lead.

"Grawor" Guarantees r atisfactionHENRY JOSEPH, 11 BLEODNILONN Svrc A2R E ,

'Phone: Chancery, 8770

THE MUSICLOVER'SCHOICE!R ad i o - Gramophoneand Sm. ech reproducedwith amazing and un-canny realism. Themost efficient speaker

money can buy.

BAKERsSQUelt(A.6Ce

SEND TO DAYF30 R6 UPRAF R EG EE

Offices: 89 Selburst Rd.,S. Norwood, S.E. 25.BOOKLET Works: 42C erry Orchard

"Sound ildvicl" Rd., E. Croydon.

YOU WANT AN" ELECTRADLX " RADIO I ESTER10 GET EXACT RESULTS

TheDIX-ONEMETERis the Highest Grade possible.Used us Admiralty, L.C.C.,

G.P.O., and the 'Varsities.Price : "DIX-ONgIVIETE.R"IN CASE, READING 40MICROAMPS, PER DIV.,WITH a MULTIPLIERS.

£4 : 1 0 : 0A Wonderful Stock of Radio

and Scientific Apparatus.Send us your inquiries for Moving Coil SpeakersMains Sets, Chokes, Gramo-motors and Amplifiers,Microphones, Recorders, Relays, Special Apparatusfor Transmission and Testing. Dynamos andMotors, all sizes. Bridges, Galvos, Switch andControl Gear of every description in stock.NOW READY, NEW EDITION OF 72 PAGEILLUSTRATED CATALOGUE, 4d.Send Stamped Addressed Envelope for November

Sale List.

218 Upper Thames Street, London, E.C.4Telephone: City orur

11111briiro RELEU GUIIDE tiklg'1296ILIIAL31111=111TY

A Complete List of a//that is best in Radio

et /feenest PricesTrod. Enywries Inwred

4.33.TA.viLo 171 & cc'20 Rod'oHo..1,19^CAULAY STREET,HUDDERSFIELD. Phone 341.

Advertisers like

USE

TREBLEDUTY TERM I NALS

AND OTHER WIRELESS ACCESSORIESJ. J. EASTICK 6 Sees

EELEX HOUS ROW LONDON Ek..I

to know whence

MICROFUSESSAVE VALVESMicrofuses operate at f om 20 toseveral hundred milliamps. Gold

fives, not wire. Type CDB carries 50 mia

Type is used in the "W.M." 1930 FIVE.indefinitely and blows at 100 We,. 100 m/s.

2/.. complete. Refills lie.MICROFUSES, Ltd., 3 Finsbury Square, E.C.2

the business comes-please mention " W.M."

565

Page 122: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. December, 1929

Peak Value ! Three readings on onedial, 0.15 volts, 0.6 volts, 0.30 m.a.,Res. 5,000 ohms, perfect acctiracy, re-markable reliability, and so useful manylisteners would pay double its pricerather than be without it ! A sensationon its production, the Wates Meter stillleads as the original and pre-eminent3 -in -1 meter. It makes set handling ascience, and gives you the true appre-ciation of what good reception really is.The "Wates" Three Range Standard Model.Price 8/6. Case, 2/6 extra. Panel MountingModel, 13/9. Panel Mounting Milliammeterswith Jewel Bearings, 0-50 or 0-25 M.A., 9/6.

°blamable f ram Raiford's Stores, Curry'sStores and all Radio dealers, or direct.

THE STANDARD WET BATTERY CO.Dept.(

184/188 Shaftesbury Avenue,W.M.) LONDON, WAY.

IF you want genuinefuses see the name

" Compete " stamped onthe cap and orangecarton. Ordinary cheapflashlamp bulbs arevery unsafe to ass.

Ask firmly for"COMP ETA."

Obtainablefrom allthe bestDealers.

Advt. of A, F. BULGT9 & Co.. 9/10/11 Comte, St., Landon, E.0.4

PARATUSTESTEDBy J. H. REYNER, B.Sc., A.M.I.E.E.

'TEW PROCESS COSSOR VALVESN ATE have recently tested the ne -eV V range of Cossor 2 -volt valves intro-

duced fot the coming wireless season;The characteristics of these, as will beseen from the figures given, are a dis-tinct improvement on last year's types,such results being obtained with the aidof a filament capable of providing a stillgreater emission.

It is interesting to note that theposition of the electrodes has :low beenaltered, and the filament, grid arid plateare mounted horizontally in the buA V-shaped filament is employed, sup-ported at three points.

The first valve tested, a 21oRC, provedto have an A.C. resistance of approxi-mately 6o,000 and an amplificationfactor of 32; for such a valve the mutualconductance is commendably high. Thisvalve is intended for use with resistancecoupling or normal H.F. coupling, andshould preferably be employed with ahigh impedance in the anode circuit.

The next in the series, the 2 ToHF,with an A.C. resistance of 20,000 and anamplification factor of 17, makes anexcellent general-purpose valve, suitableeither for H.F., detector or even first -stage low -frequency work.

The third in the series, known as the2ioLF, is designed primarily as a first -stage low -frequency amplifier, and has anA.C. resistance of 13,000 with an ampli-fication factor of 11.

The 220P, which, as its designationimplies, consumes .2 ampere, is intendedat a normal power valve and has animpedance of approximately 4,500 ohmswith an ampiification factor of 8. The23oXP is a special power valve, capableof handling grid swings of 15 volts at150 volts H.T1 and makes an excellentfinal stage amplifier.

A pentode, known as the 230PT, isalso included in the range and has greatlyimproved characteristics. The A.G.resistance is only 20,000, but the amplifi-cation factor reaches 40.

The final valve in this series is knownas the 22oSG and with an A.C. resistanceof 200,000 ohms and an amplificationfactor of 170 is exceptionally suitable forscreened -grid work. These values are allwell in accordance with the maker'sfigures and the valves can be recom-mended.

OBETA BATTERIESHE amateur of to -day is not re-stricted in his choice of H.T. bat-

teries. He is able to choose from avariety of 'makes at varying prices andhe must sometimes be bewildered as towhich particular type to buy.

In deciding upon the relative merits oftwo makes the principal test is, ofcourse, that of the service rendered andthis is largely a matter of the conditionsunder which the battery is used. In somecircumstances the battery is not used

566

a great deal, in which case shelf life (thecapability of the battery to maintain itsvoltage when not in action) is important.

Where the battery is given heavy use,, on the other hand, its capacity to supply

current without serious drop in voltageE4 important and its capability for recu-perating during the idle periods is alsoa fa -tor to be taken into consideration.

A s ample test of the performance undernormal_ conditions is obtained by dis-charging the battery continuouslythrough a tannstant resistance until the

-44.1 half of the initial value.I of the Obeta battery whichwe recen tly received for test, theinithi voltage is higher than normal andduring the first few hours of use thevoltage drops more rapidly than over therest of the discharge.

FrinfiLa00010121M(4111322200, argil

2.0

0 ETA 2,3 A 7 -I -ER y

10 1---------.....___

T.,' -........\

tiarasda p. aa .100 .2110

Life curve of Obeta battery on test.In the circumstances, we deemed it

advisable to continue the test slightlybeyond the usual point and the batterywas actually discharged to 0.7 volts percell.

Under these conditions, the batterylasted for 202 hours, corresponding to amean discharge of 1,060 milliampere.hours. This is up to the standard for acontinuous discharge for a battery of thepresent size.

Under practical conditions where thebattery is used intermittently somethinglike twice this capacity would be ob-tained. It is supplied by F. L. Lesingham ,

of 13 Victoria Street, S.W.J.4

CLIX PLUG AND SOCKET

jIECTRO-LINX, LTD., of 234 Vaux-hall Bridge Road, S.W.r, who are

wal-known manufacturers of Clix plug::and sockets, have submitted for test anew type of these useful gadgets havingvery material advantages over ordinarytypes when used for high -voltage work.

The sample tested consisted of a plugand socket completely shrouded in blackpolished insulated material; not only isthe socket protected in this manner, butthe point of the plug is also totallyenclosed in a shroud which, when inposition, fits over the metal pin of thesocket. In reality the plug is made inthe form of a socket and vice -versa.

Efficient electrical contact is ensured(Continued on poge 572)

Page 123: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

114/AiEfr

:ssTLOUD - SPEAliER UNIT

WATES DOUBLECONE CHASSIS,with brackets.

12 /-

Complete unit,with DoubleCc ne Chassis, inOak Cabinet,

£4-0-0Mahogany,

£4-6-0as illustrated,ready for use.

You realise immediately thatthe Wates Star Duplex isdefinitely an advance on anyother speaker, irrespectiveof price. The liquid beautyof the softer cadences blendwith the verve and volumeof the louder chords that isa joy to hear. Experts andthe everyday listener ac-claim it. Deliberately builtabove the standard of "builtdown to a price speakers"-avliilst dearer in price-itbecomes an investment inbouts of happy entertain-ment and superlative repro-duction.

Obtainable as a separateunit, or with special DoubleCone Chassis, or as illus-trated in complete Cabinetarm in mahogany or oak.

THE SHAFTESBURY RADIO COMPANY(Dept. W.M.),

184-188 Shaftesbury Avenue, London, W.C.2

Sent against cash on14 days ahhro. if rosedes or cannel supply

WATES STARDUPLEX. Unit

only, 36/-

M.B.

Mention

Wirel

The only panel Terminalentirely insulated whenconnected or disconnected.

Write for descriptiveleaflets of Clix 21

Varieties for perfectcontact.

CLIXALL -IN PLUG

and SOCKETTERMINAL

Entirely supersedesthe old type of panelterminal. Shorts andburnt out valves areimpossible when it isused.Every plug is en-graved for its partic-ular use; also H.T.+and G.B.- plug - insections vary in sizeand safeguard yourvalves.Wherever a terminal of anysort is required, the CH: Plugand Socket can be utilised.With it you will obtain safer,speedier and better contact.

Price 841, Complete

Panel Ad. Flex 4d.Portion Portion

LECTRO LINX LTD.254, Vauxhall Bridge Rd.,

5

5

5

5

5

5

5

5

5

5

5

5

3

5

House YOUR Wireless NOW !RADIO FURNITURE De Luxe

Nothing to touch! The snug way Moss untidydusty parts, trailing wires and batteries orecompactly enclosed will delight you I An im-provement the MODERN set demands 1 Enhances -"

the home and a proud assetCraftsmanship of high repute, honoured in use by FamousPeople,Leading Experts, Radio Press it. over 3000 clients.SENT ON APPROVAL FREE!

£3.15.0 or 15.5.0 up to E11.11.0models, just as you wish to afford. A Guaranteedproduct. Hand French -polished (Piano Finish),

sturdy construction.DIRECT FROM ACTUAL MANERSThe Soundness of our product brings orders forall we can make-without wholesalers or expensive ,3showrooms. An exceptional value that needs to rbe seen to be realised. You may return at our

expense if you wish to part with it.XMASMakes a splendid Xmas present-we supply ready for existing (or New

sets) and send to any address packed FREE.51.."

PHOTOGRAPHS and cull Particulars Free!

PICKETT'S Wireless Furniture 5Makers,

"M.G." Workshop, Rexleyheath, .eutte%)t0)e7).. toateze.e2) ter-- .

ss Magazine. December, 1929

VEREIGNCone Kit-a perfectcone suspensionat last .

cutecheap

All Poptdar snakes ofspeaker units may beused with the SovereignCone Kit including theOrmond, Brown 'Pee,'Walnut, or Blue Spot,Remember no easilycone cradle required

The Sovereign ConeKit provides com-mercial efficiencyat a quarterits cost. Fullassemb y de-tails in envelopewith Cone andbush, and Spiderready for imme-diate assembly.

I-From allDealers

This new and wonderfuldevelopment immenselyimproves home assembledspeakersQURPASSES every other speaker kit on" the market for simplicity, rapidity andsuccess of assembly. Faithful reproductionand extreme sensitivity assured. All popular makes of speaker units, driving aSovereign Cone with the patent Prov. Pat.9098 231 spider suspension, builds a mar-vellously efficient speaker. It gives pleasingquality and volume-you can wish fornothing better.

Stocked by all dealers throughout the country.

In cases of defficulty applyto the manufacturers

J. R. Wireless Co.6-8 Rosebery Av., London, E.C.1i'Vlanu for hirers of Dual -Range Coils, Poten-tiometers for the "Magic Three,- Rheostats, Six -

pin Bases, Plue-in Coils, X -Coils, etc., etc.

-SOLVE ALLH.T. TROUBLES

Per doe No. 1. No. 2.s. d. , d.

lure (waxed) .. 1 3 1 II

sacs 1 2 1 9discs 10 11Rubber Bands (24) 4 4Terminals 8 10

Special sic. for Pentode,

WETBATTERIES

TAYLEX SELF --

GENERATI

LONG LIFE:SILENT: ECONOMICALSample do, (18 volts), complete with bandsand electrolyte. No. 1. 4/1; No. 2, 5/_post 9d., terminals extra. No. 3, with ter-minals, 7/6 (10,000 milliamps). Sample unit,dd. Orders 10/. cart. paid. New .1Iustrated,:ItAI,Ue post free.

FREE. Bargain7 LRep.csiNernert.s..,A. TAYLOR, 57 Studley Road,

Stockwell, London

of the r Wireless Magazine" will ensure prompt attention

567

Page 124: Wireless Magazine - JumpJet .info€¦ · Why Signals Fade, By J.H.Reyner 496 The Brookman’s Push-Pull Three 498 Are Radio Critics Justified? By Andrew Soutar 503 “W.M.” Set

Wireless Magazine. De emt;er. 19291

TO PERFECT RADMIffilingaIMENIC2MIn addition to [hair own extensiverange Peto Scott offer you every knownRadio Receiver or Component-all on

FASYNERAisSERVICE AFTER SALES

t he following list is merely representativeand we ask you to till in the coupon be-low or send us a fist of your requirements.

SPECIAL SETS IN THIS ISSUETHE BROOKMAN'S PUSH-PULL THREE.Kit including valves and cabinet. Cash

,4 I 1 s. Id.orsendonly.6 9, balancein 11 monthly instalments of 26 9.THE NEW Q THREE. -Kit including valvesand cabinet. Cash £ 1 2 5 . 01 or send only22/6, balance in 11 monthly instalments of22/u.THE CONCENTRATOR.-Klt including valvebut not cabinet. Cash £ ?. 1 5s 0 . or sendonly 1 0, u, balance in 5 monthly instalmentsof 10' -THE ADAPTAGRAM.-Con erts your exis-ting lbid.o Receiver to a modern RadioGramophone. B.T.R. Pick-up, Garrard Motor,Balanced Armature Speaker, polished oakCabinet. Cash 812 19 6 or send only 39/6,balance in 11 monthly instalments of 22/-.NEW OSRAM MUSIC MAGNET.-Cash£9 0 0 or send -only 16/6, balance in 11monthly instalments of 16/6. Valves included.MULLARD " OROOLA" KIT.-lneludingCabinet and Valves Cash 810 15 11 or sendonly 20/-, balance in 11 monthly Instalments01 20/-.COSSOR 1930 THREE VALVE KIT.-Cash£8 15 0 or send only 18/-, balance in 11inotatily instalments of 16/-.REGENTONE, EKCO, and all leading makes0111.T. Eliminators from 4/7 down.EXIDE, 120 volt H.T. Accumulator TypeW.J., in crates. Cash 113 16 0 or send only6/11, balance in 11 monthly instalments of6/11.ULTRA AIR CHROME U 12.-Cabinet modelLoud Speaker. Cash £3 19 6 or send only7/4, balance in 11 monthly instalments of 7/4.All Chassis and Cabinet Models also avail-able.CELESTION C.12 LOUD -SPEAKER, in Oak.-Cash 85 12 6 or send only 10/4, balancein 11 monthly instalments of 10/4. InMahogany, cash 65 17 8or 12 monthly instal-ments of 10/9.

All goods sent Carriage Paid.Everything available for cash if preferred.

OUR NEW CATALOGUEcontains 48 large pages profuselyillustrated and with detailed descriptionsof the 1929-30 products of ALL THELEADING MAKERS. Receivers, Com-ponents, Radio Gramophones, Pick-ups, etc., all are dealt with ; in factyou wit find the new Easy Way Cata-logue a veritable guide to Radio. Get

your copy now.MailCoupon in unsealed envelope under id. stamp,

PETO SCOTT ""LTD.Please send n, your new 48up. illustrated Catalogue

NAME.

ADDRESS

W11112/29

Free demonstrations and advice by qualifiedengineers at our shops -

11 CITY ROA.), LONDON, E.C.1.62, HIGH HOLBORN, LONDON, W.C.1,

4, MANCHESTER STREET, LIVERPOOL.as, WHITELOW ROAD, CHORLTON-CUM

HARDY, MANCHESTER.

'Wireless MagazineREFERENCE SHEETS

Compiled by J. H. REYNER, B.Sc., A.M.LE.E.

Month by month these sheets can he cut '613, .....1,.."49ptiaabler /or -sonal choice. In a short time

and filed-either in a loose-leaf folder or on the reader rbitY.- able to compile for himself

arils-for reference. The sequence or filing is a valuable referni e look.

//VC, Reference, Sheet

Power Output, UndistortedTHE power output obtained from a valve depends upon

the relation between the external impedance in the anodecircuit and the internal resistance of the valve itself. Of thetotal power developed in the circuit a proportion is wasted inthe valve itself, the remainder being developed usefullyexternal to the valve.

In accordance with the well-known law of electricalengineering, the maximum power output is obtained whenthe external and internal impedances are equal. We thenobtain one-haff of the total power output in each portion ofthe circuit, giving us a 5o per cent. efficiency.

It is not practicable to do this, however, in the case of apower amplifier, for it is necessary always to ensure thatthe anode current variation is a reasonably faithful copy ofthe voltage input and this condition will not hold concur-rently with the condition for maximum power output.

The maximum undistorted power output,was obtainedwhen the external anode impedance is greater than thatof the valve. The extent to which it should be greaterdepends upon the characteristics, of the valve and the ex-tent of the curvature at the negative end of the characteristic.The value generally lies between two and three times.

The difference in actual power output, according to whe-ther the external impedance is two or three times that ofthe valve, is not large, but in both cases the output isdistinctly less than the maximum power." The power output is

p=m iEe nn (n+

100

75

50

25

No. 156

liP

ig

0 a 3RATIOrt-IMPLOARet

4

How power wispy varies with im-pedance ratio

where m ---amplification factor ofvalve.

r= internal resistance of valve.E=RMS grid swing.n= ratio of external to internal

impedance.

Alt_tAZ I N E Aelerence .Sheet

H.F. Leakage,ONE of the biggest troubles in compact

receivers, and more patricularly portablereceivers, is that high -frequency currents circu-late in the low -frequency stages. The effect ofthis is to cause thin quality, som mimes to giverise to L.F. instability and generally tocause the set to function in an inferior manner.Particular care must be taken, therefore, toavoid this difficulty and to confine the high -frequency currents to their legitimate circuit.

Apart from direct transfer of high -frequencyenergy through capacity coupling, which is avery prevalent form of trouble wherever a com-pact layout is adopted, there are two otherways by which the high -frequency energy canenter the L.F. stage.

The first of these is from the rectifier itself.The anode circuit of the rectifier valve carrieshigh -frequency and low -frequency currents. It

is essential to separatethese, which can onlybe done by providingseparate paths for thetwo currents, each ofwhich must have alow impedance to itsown current and ahigh impedance to theunwanted currents.

GOO /45

Typical H.F. Stopper

Prevention ofNo. 157

The filtering here is usually accomplished bythe use of a high -frequency choke between theanode and low -frequency coupling device, onthe anode side of which must be a condenserconnected either directly to earth or ultimatelyto earth through some reaction device. Pre-ferably both these arrangeinents should beadopted.

In many cases even these precautions are notsufficient to cure the trouble completely, andthis is particularly found to be the case wherethe battery begins to run down. A set willoften work satisfactorily until the battery hasbeen in use for two or three weeks, whentroubles will begin to develop. These may becompletely obviated by preventing any high -frequency current passing through the battery.

When the battery develops any internalresistance, the high -frequency current flowingthrough it sets up voltages which are immedi-ately produced into the low -frequency stagesand cannot be filtered out by the usual methods.

The circtlit accompanying this referencesheet gives a resistance -capacity filter which maybe employed very successfully in this connec-tion. A resistance of Boo ohms is includedin the lead to the anode of each high -fre-quency valve, and at the end of this resistancea large condenser is taken to earth.

568


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Douglas John Soutar Sheila Fraser Valentine · Douglas John Soutar Sheila Fraser Valentine ... wives tale about births and deaths coming together came true when Granny Nelson died

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Bacon AN ACTIVE WRESTLER - JumpJet .info

Bacon AN ACTIVE WRESTLER - JumpJet .info