6 PAGES ABOUT NEW PARTS AND SETS! - JumpJet …...cost you can quickly receive the factory -built...

The First and Only National Radio Weekly324th Consecutive Issue-Seventh Year

6 PAGES ABOUT NEW PARTS AND SETS!

BRONZE BEAUTIES ARE THE NEW SILVER -MARSHALL ESCUTCHEONS. MODEL SM-809

IS ILLUSTRATED. SEE PAGE 5.

TWO ADJUSTABLE RESISTORSIN ONE CASE, EACH RESISTORINDEPENDENTLY CONTROLLED,CONSTITUTE THE NEW DUPLEXCLAROSTAT. SERIES OR PARAL-LEL CONNECTION MAY BEUSED. SEE ILLUSTRATED NEWSARTICLE ON PAGE 4, ANNOUNC-ING AMERICAN MECHANICAL

LABORATORIES' PARTS

LEADERSHIP IN THE ELECTRICAL PHONOGRAPHPICKUP FIELD WAS ASSUMED LAST SEASON BYPACENT ELECTRIC CO., WHICH NOW ANNOUNCESAN IMPROVED AND FLAT -CURVE PHONOVOX INTWO MODELS. ONE IS PROVIDED WITH COUNTER-BALANCED TONE ARM (NO. 124, ILLUSTRATEDABOVE). THE OTHER IS TO BE ATTACHED TO THEEXISTING TONE ARM OF A PHONOGRAPH (NO. 105-A,

ILLUSTRATED IN NEWS ARTICLE ON PAGE 4).

RESISTORS FORPOWER PACK ANDAC FILAMENT DIVI-SION ARE NEWPRODUCTS OFAEROVOX WIRE-LESS CORPORATION.THE CENTER -TAPPED RESISTORIS SHOWN. FULLDETAILS OF THEAEROVOX LINE AREGIVEN ON PAGE 8.

THE NEW NATIONAL DIAL, INTWO MODELS, HAS LEAPED TOTHE FOREFRONT OF DIAL POP-ULARITY. TYPE F, DRUM DIAL,IS ILLUSTRATED. THE OTHERMODEL IS TYPE E (LEFT -AND -RIGHT SCALE READING). SEE

PAGE 9

RADIO WORLD June 9, 1928

Airplane Cloth Speaker KitSpecial size 161A" x 2N", (Cat. 1086) Price, Including Unit.

Kit Consists ofairplane cloth,frame, mould-ing, unit, stiffen-ing fluid, apex,crossarm, brack-et, long cord,apex, hardwareand instructionsheet.

Rear View of the HBH AirplaneCloth Speaker

Size, 161/,x221/s Inches

Front View of the HBH AirplaneCloth Speaker

Size, 16Y2x2234 Inches

.00

An Opportunityis presented toyou to obtain akit of this spe-cial but attrac-tive size, 16Y2x22V2", becausea manufactureraccumulated anextraordi-narily largestock of them.

For $1 Extra We Build It for You!If you do not want to build the speaker yourself, at $1 extracost you can quickly receive the factory -built speaker in yourhome, all ready to play. Size 1672x2272" (Cat. 108613) . . . .

Buy a Kit and Build SpeakerYourself at These Prices

Complete Kit, 18x24", Cat. No. 1109 $10Complete Kit, 24x36", Cat. No. 1110 $12Complete Kit, 36x36", Cat. No. 1111 $14

$8.00Buy a Factory - Made Speaker,Ready to Play, at These Prices

18x24", Cat. No. 1088 $1124x36", Cat. No. 1090 $1436x36", Cat. No 1091 $16

CHOOSE WHAT YOU WANT, BUT SEND NO MONEY!

GUARANTY RADIO GOODS CO.,145 West 45th Street, New York City

Ship me the following items as advertised in RadioWorld :

Cat. No. Cat. No. Cat. No

Cat. No - Cat. No Cat. No

for which I will pay postman advertised price plusfew cents extra for postage.

Name

Address

City StateFive -Day Money -Back Guaranty

LOUDUNIT

Powerful unit, excellentfor any cone or similartype speaker, standardfor HBH speaker; veryloud. Cat. No. 1098,with apex, $3.75.

The unit is the Power -tone model, which pro-vides high degree ofvolume and is very sensi-tive. Stands great strain.Used snrepssfully in allradio receivers, includingpower pack installationsup to 550 volts on theplate. Up to 135 voltsDC may be passedthrough coils of unitwithout damage. Forhigher voltages filteredoutput is recommended,but unit has long stoodup to 180 v. unfiltered.

Unit mounting bracket,Cat No. 1113 35c.Apex. Cat. No. 1197, 25c.

GENUINE"DOPE"

Genuine HBH StiffeenminnggFluid, secret compound,with superlative effect ontone quality. Lar gesized can, enough forthree coats. Cat. No.1097, $1.50.

JUNE 9, 1928Vol. XIII, No. 12. Whole No. 324

150 per Copy.[Entered as second-class matter, March,1922, at the post office at New York,

N. Y., under Act of March, 1879.]

"UNINTERRUPTED READER INTERESEVERY WEE.K `---> EVERY YEAR

RADIO WORLD

Technical Accuracy Second to None A Weekly Paper published by HennessyRadio Publications Corporation, fromPublication Office, 145 West 45th Street,

New York, N. Y.(Just East of Broadway)

Phone: BRYant 0558 and 0559

The Ultimate ConsumerPeeks in atTrade Show

THE fascinating array of exhibits at the SecondAnnual Radio Trade Show, conducted under the

auspices of the Radio Manufacturers' Association, atthe Hotel Stevens, Chicago, proved that manufacturershave risen to new heights of versatility and havestrongly gone over to the beautiful.

It made a radioist of the constructor class sufferaches of suppressed desire to see all the tempting appa-ratus, particularly parts that are better, stronger, com-pacter and handsomer this year than ever before.

The manufacturers hobnobbed with one another atthe show, listened to a host's rival performances indemonstration rooms privately hired at the hotel, and_expatiated on the superlative merits of their respectiveproducts.

Parts showed an abnormally heavy activity, both inthe display meant for the eye and the bombast meantfor the ear. Coupled was the fact that parts manufac-turers reported very healthy business in early June,with graild prospects for the rest of this, month, andinfinitely thereafter, due to the two national conven-tions, one of which will nominate the next President,and also due to the sales acceleration residing in theother national pastime-baseball.

Every manufacturer in radio not in Europe at thehappy moment seemed to be at the show, while itwas feared for a while that the two sojourners abroadmight be tempted to do an East -to -West airplane hopfor some handshaking and other shaking at the world'scenter of radio attraction for this momentous week.

The booths were decorated and fashioned gaily orwith still more expensive quietness and reserve of tone,and it was expected that before the week was out morethan 30,000 persons would have been in attendance. Infact, more than that number would have, but they couldnot convince the boss that they were "key men" whosepresence at the show was an impressive and imperviousnecessity. However, the bosses had no trouble in con-vincing themelves that they themselves were needed,and many of them carried on a lot of prestige -buildingconversation with competitors who were friendlyenough, but never would send in an order.

The manufacturers had a merry time of it, from themoment the special trains pulled out of the East and theWest.

Many hundreds of thousands of dollars in orders weregiven, but not one cent's worth of cancellations. So

happiness reigned amid the pkvping cohorts of radio.It was a manufacturers' festival, with plenty of eat-ing and the like, and not an inconsiderable amount ofshowing. It looked somewhat like a Stock Exchange ona busy afternoon, and at times so feririd was the pur-chasing of goods still unmade, that one might imaginethe manufacturers were merely betting, using tradeacceptances for money.

Some of the manufacturers had been through a diffi-cult season,-and not all the difficulties were technical,unless the fierce side of banking can be called technical.A few were there, too, who had failed, but some of theseappeared to notice enough promising items to copy soas to keep the new wolf from the door. They wentaround looking for prospective creditors and somereported luck.

But most manufacturers did well last season and hadevery reason to look forward to striking success thisseason.

"This is THE year," the manufacturers told one an-other, as they did last year, and will next.

Some manufacturers, with a full, new line ready,exhibited largely their parts of the previous season,while others confessedly had only a little item or twohat were new. Such as had little of the new and much

of the old said that money is made in the parts businessby building- up the reputation of a given product,because it is made right originally, and needs no chang-ing. But some iconoclasts, always in the vanguard ofthe new, offered as contradictory evidence a glance attheir bank balance.

While it was a great time for the manufacturers, andcompetitors so far forgot themselves as to.be cordial toone another, and while fifty -ten -and -five were the mys-terious figures most often mentioned, nevertheless, itwas absorbing from the televised viewpoint of thecustom set builder, the home constructor, the radiodealer, the unlucky salesmen and others left at home.

The manufacturers dealt with one another and withsales representatives, but two large ears hung outsidethe hotel and two eyes-the ears and eyes of the ulti-mate consumer. "And for his especial benefit the fol-lowing six pages contain news announcements ofexhibits at the show, with a few other announcementsof new things that didn't happen to get themselves intothe picture at the Stevens.

Herman Bernard.

4 RADIO WORLD June 9, 1928

American Mechanical Labs.The American Mechanical Laboratories,

Inc., 285-7 North Sixth' Street, Brooklyn,N. Y., manufacturers of the well-knownClarostat line of precision variable resistors,announced new products. The ClarostatLight Socket Antenna Plug incorporatesseveral novel features. This device convertsany electric lightsocket or con-venience outletinto a good work-ing antenna. Theground connec-tion may be madeto the electricsystem. The plugis sturdily made.A detachablescrew base per-mits utilizingeither side a theelectric line forthe antenna. A long flexible cord connectedwith the antenna plug provides a simple andpositive method of connection with the re-ceiver. The list price is $1.50.

The new Grid Leak. Clarostat has a re-sistance range of from 1/10 to 10 megohmsin several turns of the knob. It is noise-less and holds any desired setting in range.

It is the same sizeas the Volume Con-trol Clarostat and isfinished in nickelplate with screwterminals. So gridleads may be keptas short as possibleit is provided witha special U-in.vertedbracket so that itmay be placed along-side the detectorsocket. it also maybe employed as anadjustable resistance

in resistance coupling and impedance coup-ling, and wherever a high resistance ofsmall current -handling capacity is required.The list price is $1.50.

The Duplex Clarostat comprises two vari-able resistors in one, each independently ad-justable over `a wide range, providing aunique Zevice with many useful applications.Instead of knobs, either section of the Du-plex Clarostat is adjustable by means ofan ordinary screw -driver the blade of whichengages with the recessed slotted shaft.Fixed resistance values are provided with-out knobs to cause constant tinkering andchanging. The Duplex Clarostat can func-tion as' two separate and distinct variableresistances with a common terminal; also astwo variable resistances in series or as lowerresistance with increased current -handlingcapacity when used in parallel; also as aresistance network with two variable voltagetaps simplifying the usual output circuit ofa radio power unit; also as a potentiometeror balancing resistance with variable totalresistance and variable mid -point. It maybe employed singly or in gangs. It has auniversal range from practically zero toseveral megohms for each section. The listprice is $2.25, complete with mounting. Fullinformation on these and other members ofthe Clarostat family may be had from the'above concern upon application.-J. H. C.

[Other Illustration on Front Cover]

Yaxley Manufacturing Co.Among the new line of Yaxley products

is a 12 conductor Cable Connector Plugespecially designed for AC sets, whichwill meet any AC requirements. Newinsulated tip jacks with bakelite tops,red ,and black for plus and minus, for ACsets, are announced, also a complete lineof junior rheostats and potentiometerswith special filament switches. By thetre of these switches a switching rheo-stat can easily be made out of any

Yaxley rheostat by removing the knoband lock nut, placing the filament switchover the shaft and replacing the nut.A full line of center tapped resistancesto meet all requirements is also ready,also a new 440 full Automatic PowerControl Switch. This relay has manynew features, among them that it is soadjusted as to automatically cut off whenthe battery is fully charged.

A full lice of convenience outlets forAC sets as well as for DC use, is finishedin fine, rich bakelite. Yaxley approvedradio products include pilot light switches,panel lights, pilot switching rheostats,jacks, junior jacks, pup jacks, plugs ofall kinds, nameplates, cable markers,switches of all kinds and a full line ofcables and cable connector plugs. Fullinformation on the complete line and onthe new products described above maybe had on application from the. YaxleyManufacturing Co., 9 South ClintonStreet, Chicago.

J. H. C.

Sangamo Electric Co.In addition to its line of condensers, the

Sangamo Electric Company, Springfield,Ill., offers a new line of audio frequencytransformers to meet every need for qualityreproduction. The transformers give faith-ful reproduction over the useful audio fre-quency range. They are well made. Each

transformer is tested at the equivalent of1,000 volts direct current between primaryand secondary and ground. Uniformity ofproduct is also assured by other exactingtests. There are types to meet every need.Type B, Input, is 4.5, to 1 ratio, designatedby mural blue spot; type C-171 ouput, for171 tubes, designated by leaf green spot;type D-210 output for 210 type tubes, desig-nated by lake blue spot, also for 112 typetubes. The type E output impedance is of30 henrys inductance and is marked by amandarin red spot. The type F plateimpedance is 200 henrys inductance and isdesignated by the orange spot. Sangamoengineers are working on several new prod-ucts that will be ready shortly and whichwill match up to the regular Sangamo highstandards of construction and operation. In-formation on these and on the above may behad on application to the Company, addressabove, or to Rossiter & Co., 136 LibertyStreet, New York City.-J. H. C.

R.C.A., Personnel Changes.J. L. Ray, general sales manager of

the Radio Corporation of America, an-nounced the following changes :

Quinton Adams, formerly managerRadiola Division, becomes manager of anew major sales division to be knownas the Engineering Products Division,which will handle the sale of broadcastingstations, the sale of special apparatus andvarious sales contracts of the RadioCorporation. E. A. Nicholas, formerlydistrict sales manager at New York, be-comes manager Radiola Division. A. R.Beyer, formerly assistant 'district salesmanager, Chicago, becomes district salesmanager at New York. D. A. Lewis be-comes assistant district sales manager atChicago.

Pacent Electric Co.

NEW MODEL PACENT PHONOVOX,(ELECTRIC PICKUP) FOR ATTACH-MENT TO EXISTING TONE ARM.

When the Pacent Electric Co., 91 SeventhAvenue, New York City, brought out thePhonovox, an electric pickup of phonographrecordings, enabling amplification throughthe audio channel of your set and final re-productiun through your speaker, the serv-ice took the country by storm. Now thePacent Co. has an improved pickup, in twode luxe models-No. 124 complete withcounter -balanced lone arm, list price, $13.50,and No. 105-A, without tone arm, list price,$10.50.

The pick-up itself is even more sensitivethan its predecessor and shows a relativelyflat characteristic curve. Nine months ofexpert research were devoted to the perfec-tion of the de luxe models, and they bid fairto outrank all others on the market.

One of the special features is the externallocation of the chuck, so that a fibre needlemay be used or an optional steel needle.The needle scratch almost disappears whena fibre needle is used, and volume remainsample.

The counter -balanced tone arm improvesquality and preserves record life, since theneedle does not "engrave" the record.

Each de luxe model Phonovox is providedwith special AC and DC adapters with eachoutfit. It is not necessary to remove thedetector tube to work the new Phonovox.

Louis G. Pacent, president, and J. J.Ryan, treasurer, confidently expect the deluxe models to become the market leadersin that line.

As usual, the Pacent Company has a fineand variegated line, including a new Super-Audioformer of superb tone quality, sockets,speakers, a speaker unit cleverly designedby Mr. Pacent, and a power amplifier andB supply. For further information, addressLouis G. Pacent, president, Pacent ElectricCo., 91 Seventh Avenue, New York City,and mention RADIO WORLD.

[Other Illustration on Front Cover.]

Arcturus Radio Co.An AC screen grid tube has just been

placed on the market by the Arcturus RadioCompany. AC tube manufacturers of New-ark, N. J.

In the Arcturus ACscreen grid tube there is onemore element than in thestandard tube. The filamentdraws a current of 0.35ampere and its normal oper-ating potential is 15.0 volts.The additional element, i.e.,the screen grid, is a combi-nation grid interposed be-tween the usual plate andcontrol grid and a fine mesharrangement completely en-closing the whole tube struc-ture, thus introducing acompletely shielded tube.

A new five prong base replacement tubefor use in receivers requiring a -27 typeheater tube, has been developed by the com-pany. Quick heating (between six and twelveseconds), superior sensitivity and a life com-parable with that of the best DC tubes arepoints stressed.

RADIO WORLD 5June 9, 1928

Silver -Marshall, Inc.Silver -Marshall, Inc., of 846 West Jack-

son Boulevard, Chicago, announced anextensive line of new products, all exhib-ited at the show, and all demonstratingadvanced design and skillful technique.The line is resourceful and versatile, cov-ering virtually every need of the customset builder and home constructor, andoffering attractive advantages also tomanufacturers and commercial institutionsoutside of the radio manufacturing field.

An outstanding, reservoir power unit, intwo models, is one of the special features.The models are obtainable wired or inkit form. Model 670-B has fixed voltagetaps for 22, 90, 135 and 180 .volts, with onevariable three -voltage tap for 22-90 volts.The maximum current drain is 60 milliam-peres at these voltages. The 280 rectifiertube is used. The S -M 670-B lists . at$33 in kit form and $36 wired.

The other model, 670 -ABC, has thesame foundation as the 670-B, but is addi-tionally provided with a built-in filamenttransformer, from which taps are broughtout to posts for 1.5 volts (up to 4 amperescurrent capacity), 2.25 volts (up to 3.5amperes) and 5 volts (.5 ampere). Thusup to five -26 tubes, two -27 tubes andtwo 112A or -71A tubes may be fed fromthis filament AC heating source. The670 -ABC lists at $35.50 in kit form and$38.50 built-up

New Drum DialA drum dial is another new S -M pro-

duct.. It is controlled by a knob, withwhich is connected a friction drive uponthe ,etched brass -drum. Both right andleft-hand models are provided (S -M 806-R and S -M 806-L) for 180 degree rota-tion, 0 to 100. The drum dial is $2.50list, while a bronze window is 50 centsextra.

Recognizing the rising demand for greatbeauty in front panel appearance, com-bined with simplicity of operation, Silver -Marshall has brought out one of the hand-somest escutcheons yet to appear. It is intwo models, S -M 808 for single tuningcontrol and S -M 809 for double tuningcontrol. The plates are provided withwindows. (The double model is illustratedon the front cover.) The escutcheonplates are bronze, beautiful to behold andeasy to mount. The single model lists at$2.25 and the double one at $2.75.

These escutcheons are intended for usespecially with another new product of thisenterprising concern-a steel cabinet, No.700, providing the latest in cabinet designfor custom set builders and home con-structors.

- Has Own CabinetThis steel cabinet is included in the

new Screen Grid Six Kit, (No. 710 kit, listprice about $70, including cabinet). Thecircuit consists of three stages of screengrid TRF, detector and two -stage audioamplifier. Great distance, enormous vol-ume, superb tone are outstanding advan-tages cited.

An AC model screen grid receiver is' theS -M "Coast to Coast," kit No. 740, usingone stage of screen grid RF, a 227 de-tector, a screen grid first audio stage anda power tube output-total only fourtubes. The list price of the kit is about$45, less cabinet and power supply. Cabi-net and chassis cost $8.50 extra. In con-junction with the S -M 670 ABC PowerSupply and S -M 700 cabinet and chassis,a complete AC operated receiver is con-structable for about $89.

A high mu audio transformer is usedin the AC Coast to Coast receiver, andthis transformer is another new part. Itis No. 223.

New Audio TransformersTwo new large -sized audio trans-

formers, which will not be ready for dis-tribution before June 25, are the 225 (firststage) and 226 (second stage). These

THE S -M 670 -ABC POWER SUPPLY

list at $9 each and are pronounced bythose who have heard and analyzed themas "wonderful." The curve is reported asmost excellent. In fact, so sure is Silver -Marshall of the predominance of theseparticular transformers that they stagedcomparative tests for the benefit of all -corners in Room 435-A in the StevensHotel during the show.

Smaller sized audio transformers, alsonew, are the 255 and 256, at $6 each.There is a corresponding output, No. 251.

Silver -Marshall is taking a leading partin the short wave field, also. The Round'the World Four is in the circuit (onemodel $44.30, complete, with dials).

Short Wave CoilsThe new S -M "130 Series" 5 -prong

'plug-in coils (fitting any AC tube socket),listing at $1.25 each; and the unwoundcoil forms at 50 cents each.

The new S -M 685 Public Address Uni-pac Amplifier also was demonstrated.

The new S -M 638 Copper Stage Shieldat $1.25 list is another item.

Full information is obtainable fromSilver -Marshall at the above address.Mention RADIO WORLD.


Electrad, Inc.Electrad, Inc., parts and accessories

makers of New York, are featuring in1928 a full line of radio resistance con-trols in addition to their regular stapleitems. Some of the well-known Electradproducts this year are:

Truvolts.-A complete line of all -wirevariable, tapped and fixed resistanceswhich are of especial interest to elimina-tor builders. They are particularlyadapted for use as voltage controls, anda feature is that the units are kept fromoverheating because of their unique de-sign which gives maximum radiatingsurface.

Tonatrols.-A complete line of volumeand sensitivity controls of the ElectradRoyalty Resistor type. They are offeredin types to meet the specific requirementsof all AC or battery powered circuits.They are recommended for installation in

NEW SHORT WAVEPLUG-IN COILS MADE BY

SILVER MARSHALL

standard sets or incorporating in the cir-cuit by the builder of receivers.

Royalties. -T h e well-known variablehigh resistances which Electrad has beenmaking for years. It is offered in stand-ard and potentiometer styles in elevenranges for all radio purposes requiringa resistance of its type.

Phasatrol.-A balancing device for ra-dio frequency amplifiers. The functionof this item is to suppress the oscillationsof R.F. amplifying tubes and thus elim-inate the noises and disturbances to re-ception which they cause. Owing to itsease of installation, this item has provedpopular with owners and constructors ofRF receivers who have been troubledwith oscillations.

New Truvolt Divider. - Arthur Moss,treasurer of Electrad, Inc., gave out theinformation that the company will an-nounce in the next issue of this magazinea universal voltage separator, called theTruvolt Divider.

This newest Electrad product is acomplete resistance unit for simplifyingthe construction of B battery eliminators.It is so arranged with variable taps thatthe proper grid and plate voltages areeasily obtained with any set and elimin-ator combination. By dividing the filtervoltage into usable values, it eliminatesa great dell of the mathematical calcu-lations and much wiring.

It is said that the Truvult Divider willmake it comparatively easy for even thenon -technical radio fan to construct aB power unit which will deliver theproper voltages for receivers of presentor anticipated future design.

Preliminary tests have proved that theDivider is going to be very well receivedby professional and amateur eliminatorbuilders and experimenters. Every indi-cation points to the device being one ofthe big sellers in the Electrad line thisyear.

United Radio Corp.The United Radio Corporation of

Rochester, N. Y., makers of the PeerlessSpeaker, announces several new modelsfor the coming season. Foremost amongthese is the New Dynamic Speaker, in-corporating several new principles ofdynamic design. It is equipped with arectifier element providing for lightsocket operation. It handles the outputof any tubes.

The Dynamic Speaker is offered inthree models. The Model 17-A is amahogany Gothic cabinet, similar in con-ception to the reproducers of past yearsbut considerably larger. This lists at$75. The Model 19-T is a complete built-in Speaker Table, listing at $100. Finally,there is a Manufacturer's Model, 17-C,for built-in use in Console Sets.

The Model 7-A Cone -type Speaker, inthe familiar. Gothic cabinet, will be con-tinued in the same form, and at thesame list price of $35, as last year; like-wise, the Model 7-B, manufacturer's built-in unit of this same chassis. In additionto these, a new Model, 7-T, which is abuilt-in Speaker Table; using the Model7 chassis, is offered at a list price of $50.Both this Table and the Dynamic SpeakerTable carry out in design the Gothiclines which are characteristic of Peerless.For further information address thecompany direct and mention RADIO WORLD.

SMITH JOINS PEERLESSThe United Radio Corporation of Roch-

ester, New York, manufacturers of thePeerless reproducer, announce that Her-man A. Smith, formerly sales managerof the Argus Radio Corporation, has beenappointed eastern sales manager of theUnited.

Mr. Smith will have charge of the At-lantic Coast District south of New York,with headquarters at Baltimore.


American Mechanical Labs.The American Mechanical Laboratories,

Inc., 285-7 North Sixth Street, Brooklyn,N. Y., manufacturers of the well-knownClarostat line of precision variable resistors,announced new products. The ClarostatLight Socket Antenna Plug incorporatesseveral novel features. This device convertsany electric lightsocket or con-venience outletinto a good work-ing antenna. Theground connec-tion may be madeto the electricsystem. The plugis sturdily made.A detachablescrew base per-m i t s utilizingeither side of theelectric line forthe antenna. A long flexible cord connectedwith the antenna plug provides a simple andpositive method of connection with the re-ceiver. The list price is $1.50.

The new Grid Leak. Clarostat has a re-sistance range of from 1/10 to 10 megohmsin several turns of the knob. It is noise-less and holds any desired setting in range.

It is the same sizeas the Volume Con-trol Clarostat and isfinished in nickelplate with screwterminals. So gridleads may be keptas short as possibleit is provided witha special U -invertedbracket so that itmay be placed along-side the detectorsocket. it also maybe employed as anadjustable resistance

in resistance coupling and impedance coup-ling, and wherever a high resistance ofsmall current -handling capacity is required.The list price is $1.50.

The Duplex Clarostat comprises two vari-able resistors in one, each independently ad-justable over ' a wide range, providing aunique 1evice with many useful applications.Instead of knobs, either section of the Du-plex Clarostat is adjustable by means ofan ordinary screw -driver the blade of whichengages with the recessed slotted shaft.Fixed resistance values are provided with-out knobs to cause constant tinkering andchanging. The Duplex Clarostat can func-tion as two separate and distinct variableresistances with a common terminal; also astwo variable resistances in series or as lowerresistance with increased current -handlingcapacity when used in parallel; also as aresistance network with two variable voltagetaps simplifying the usual output circuit ofa radio power unit; also as a potentiometeror balancing resistance with variable totalresistance and variable mid -point. It maybe employed singly or in gangs. It has auniversal range from practically zero toseveral megohms for each section. The listprice is $2.25, complete with mounting. Fullinformation on these and other members ofthe Clarostat family may be had from theabove concern upon application.-J. H. C.


Yaxley Manufacturing Co.Among the new line of Yaxley products

is a 12 conductor Cable Connector Plugespecially designed for AC sets, whichwill meet any AC requirements. Newinsulated tip jacks with bakelite tops,red and black for plus and minus, for ACsets, are announced, also a complete lineof junior rheostats and potentiometerswith special filament switches. By theuce of these switches a switching rheo-stat can easily be made out of any

Yaxley rheostat by removing the knoband lock nut, placing the filament switchover the shaft and replacing the nut.A full line of center tapped resistancesto meet all requirements is also ready,also a new 440 full Automatic PowerControl Switch. This relay has manynew features, among them that it is soadjusted as to automatically cut off whenthe battery is fully charged.

A full line of convenience outlets forAC sets as well as for DC use, is finishedin fine, rich bakelite. Yaxley approvedradio products include pilot light switches,panel lights, pilot switching rheostats,jacks, junior jacks, pup jacks, plugs ofall kinds, nameplates, cable markers,switches of all kinds and a full line ofcables and cable connector plugs. Fullinformation on the complete line and onthe new products described above maybe had on application from the YaxleyManufacturing Co., 9 South ClintonStreet, Chicago.

J. H. C.

Sangamo Electric Co.In addition to its line of condensers, the

Sangamo Electric Company, Springfield,Ill., offers a new line of audio frequencytransformers to meet every need for qualityreproduction. The transformers give faith-ful reproduction over the useful audio fre-quency range. They are well made. Each

transformer is tested at the equivalent of1,000 volts direct current between primaryand secondary and ground. Uniformity ofproduct is also assured by other exactingtests. There are types to meet every need.Type B, Input, is 4.5, to 1 ratio, designatedby mural blue spot; type C-171 ouput, for171 tubes, designated by leaf green spot;type D-210 output for 210 type tubes, desig-nated by lake blue spot, also for 112 typetubes. The type E output impedance is of30 henrys inductance and is marked by amandarin red spot. The type F plateimpedance is 200 henrys inductance and isdesignated by the orange spot. Sangamoengineers are working on several new prod-ucts that will be ready shortly and whichwill match up to the regular Sangamo highstandards of construction and operation. In-formation on these and on the above may behad on application to the Company, addressabove, or to Rossiter & Co., 136 LibertyStreet, New York City.-J. H. C.

R.C.A., Personnel ChangesJ. L. Ray, general sales manager ofthe Radio Corporation of America, an-

nounced the following changesQuinton Adams, formerly manager

Radiola Division, becomes manager of anew major sales division to be knownas the Engineering Products Division,which will handle the sale of broadcastingstations, the sale of special apparatus andvarious sales contracts of the RadioCorporation. E. A. Nicholas, formerlydistrict sales manager at New York, be-comes manager Radiola Division. A. R.Beyer, formerly assistant 'district salesmanager, Chicago, becomes district salesmanager at New York. D. A. Lewis be-comes assistant district sales manager atChicago.

Pacent Electric Co.

NEW MODEL PACENT PHONOVOX,(ELECTRIC PICKUP) FOR ATTACH-MENT TO EXISTING TONE ARM.

When the Pacent Electric Co., 91 SeventhAvenue, New York City, brought out thePhonovox, an electric pickup of phonographrecordings, enablinc,b amplification throughthe audio channel of your set and final re-production through your speaker, the serv-ice took the country by storm. Now thePacent Co. has an improved pickup, in twode luxe models-No. 124 complete withcounter -balanced 'tone arm, list price, $13.50,and No. 105-A, without tone arm, list price,$10.50.

The pick-up itself is even more sensitivethan its predecessor and shows a relativelyflat characteristic curve. Nine months ofexpert research were devoted to the perfec-tion of the de luxe models, and they bid fairto outrank all others on the market.

One of the special features is the externallocation of the chuck, so that a fibre needlemay be used or an optional steel needle.The needle scratch almost disappears whena fibre needle is used, and volume remainsample.

The counter -balanced tone arm improvesquality and preserves life, since theneedle does not "engrave" the record.

Each de luxe model Phonovox is providedwith special AC and DC adapters with eachoutfit. It is not necessary to remove thedetector tube to work the new Phonovox.

Louis G. Pacent, president, and J. J.Ryan, treasurer, confidently expect the deluxe models to become the market leadersin that line.

As usual, the Pacent Company has a fineand variegated line, including a new Super-Audioformer of superb tone quality, sockets,speakers, a speaker unit cleverly designedby Mr. Pacent, and a power amplifier andB supply. For further information, addressLouis G. Pacent, president, Pacent ElectricCo., 91 Seventh Avenue, New York City,and mention RADIO WORLD.

[Other Illustration on Front Cover.]

Arcturus Radio Co.An AC screen grid tube has just been

placed on the market by the Arcturus RadioCompany. AC tube manufacturers of New-ark, N. J.

In the Arcturus ACscreen grid tube there is onemore element than in thestandard tube. The filamentdraws a current of 0.35ampere and its normal oper-ating potential is 15.0 volts.The additional element, i.e.,the screen grid, is a combi-nation grid interposed be-tween the usual plate andcontrol grid and a fine mesharrangement completely en-closing the whole tube struc-ture, thus introducing acompletely shielded tube.

A new five prong base replacement tubefor use in receivers requiring a -27 typeheater tube, has been developed by the com-pany. Quick heating (between six and twelveseconds), superior sensitivity and a life com-parable with that of the best DC tubes arepoints stressed.

June 9, 1928 RADIO WORLD 5

Silver -Marshall, Inc.Silver -Marshall, Inc., of 846 West Jack-

son Boulevard, Chicago, announced anextensive line of new products, all exhib-ited at the show, and all demonstratingadvanced design and skillful technique.The line is resourceful and versatile, cov-ering virtually every need of the customset builder and home constructor, andoffering attractive advantages also tomanufacturers and commercial institutionsoutside of the radio manufacturing field.

An outstanding, reservoir power unit, intwo models, is one of the special features.The models are obtainable wired or inkit form. Model 670-B has fixed voltagetaps for 22, 90, 135 and 180 .volts, with onevariable three -voltage tap for 22-90 volts.The maximum current drain is 60 milliam-peres at these voltages. The 280 rectifiertube is used. The S -M 670-B lists . at$33 in kit form and $36 wired..

The other model, 670 -ABC, has thesame foundation as the 670-B, but is addi-tionally provided with a built-in filamenttransformer, from which taps are broughtout to posts for 1.5 volts (up to 4 amperescurrent capacity), 2.25 volts (up to 3.5amperes) and 5 volts (.5 ampere). Thusup to five -26 tubes, two -27 tubes andtwo 112A or -71A tubes may be fed fromthis filament AC heating source. The670 -ABC lists at $35.50 in kit form and$38.50 built-up

New Drum DialA drum dial is another new S -M pro-

duct.. It is controlled by a knob, withwhich is connected a friction drive uponthe etched brass drum. Both right andleft-hand models are provided (S -M 806-R and S -M 806-L) for 180 degree rota-tion, 0 to 100. The drum dial is $2.50list, while a bronze window is 50 cents.extra.

Recognizing the rising demand for greatbeauty in front panel appearance, com-bined with simplicity of operation, Silver-Marshall has brought out one of the hand-somest escutcheons yet to appear. It is intwo models, S -M 808 for single tuningcontrol and S -M 809 for double tuningcontrol. The plates are provided withwindows. (The double model is illustratedon the front cover.) The escutcheonplates are bronze, beautiful to behold andeasy to mount. The single model lists at$225 and the double one at $2.75.

These escutcheons are intended for usespecially with another new product of thisenterprising concern-a steel cabinet, No.700, providing the latest in cabinet designfor custom set builder's and home con-

' structors.- Has Own Cabinet

This steel cabinet is included in thenew Screen Grid Six Kit, (No. 710 kit, listprice about $70, including cabinet). Thecircuit consists of three stages of screengrid TRF, detector and two -stage audioamplifier. Great distance, enormous vol-ume, superb tone are outstanding advan-tages cited.

An AC model screen grid receiver is' theS -M "coast to Coast," kit No. 740, usingone stage of screen grid RF, a 227 de-tector, a screen grid first audio stage anda power tube output-total only fourtubes. The list price of the kit is about$45, less cabinet and power surIply. Cabi-net and chassis cost $8.50 extra. In con-junction with the S -M 670 ABC PowerSupply and S -M 700 cabinet and chaSsis,a complete AC operated receiver is con-structable for about $89.

A high mu audio transformer is usedin the AC Coast to Coast receiver, andthis transformer is another new part. Itis No. 223.

New Audio TransformersTwo new large -sized audio trans-

formers, which will not be ready for dis-tribution before June 25, are the 225 (firststage) and 226 (second stage). These

THE S -M 670 -ABC POWER SUPPLY

list at $9 each and are pronounced bythose who have heard and analyzed themas "wonderful." The curve is reported asmost excellent. In fact, so sure is Silver -Marshall of the predominance of theseparticular transformers that they stagedcomparative tests for the benefit of all -comers in Room 435-A in the StevensHotel during the show.

Smaller sized audio transformers, alsonew, are the 255 and 256, at $6 each.There is a corresponding output, No. 251.

Silver -Marshall is taking a leading partin the short wave field, also. The Roundthe World Four is in the circuit (onemodel $44.30, complete, with dials).

Short Wave CoilsThe new S -M "130 Series" 5 -prong

'plug-in coils (fitting any AC tube socket),listing at $1.25 each; and the unwoundcoil forms at 50 cents each.

The new S -M 685 Public Address Uni-pac Amplifier also was demonstrated.

The new S -M 638 Copper Stage Shieldat $1.25 list is another item.

Full information is obtainable fromSilver -Marshall at the above address.Mention RADIO WORLD.


Electrad, Inc.Electrad, Inc., parts and accessories

makers of New York, are featuring in1928 a full line of radio resistance con-trols in addition to their regular stapleitems. Some of the well-known Electradproducts this year are:

Truvolts.-A complete line of all -wirevariable, tapped and fixed resistanceswhich are of especial interest to elimina-tor builders. They are particularlyadapted for use as voltage controls, anda feature is that the units are kept fromoverheating because of their unique de-sign which gives maximum radiatingsurface.

Tonatrols.-A complete line of volumeand sensitivity controls of the ElectradRoyalty Resistor type. They are offeredin types to meet the specific requirementsof all AC or battery powered circuits.They are recommended for installation in

NEW SHORT WAVEPLUG-IN COILS MADE BY

SILVER MARSHALL

standard sets or incorporating in the cir-cuit by the builder of receivers.

Royalties. -The well-known variablehigh resistances which Electrad has beenmaking for years. It is offered in stand-ard and potentiometer styles in elevenranges for all radio purposes requiringa resistance of its type.

Phasatrol.-A balancing device for ra-dio frequency amplifiers. The functionof this item is to suppress the oscillationsof R.F. amplifying tubes and thus elim-inate the noises and disturbances to re-ception which they cause. Owing to itsease of installation, this item has provedpopular with owners and constructors ofRF receivers who have been troubledwith oscillations.

New Truvolt Divider. - Arthur Moss,treasurer of Electrad, Inc., gave out theinformation that the company will an-nounce in the next issue of this magazinea universal voltage separator, called theTruvolt Divider.

This newest Electrad product is acomplete resistance unit for simplifyingthe construction of B battery eliminators.It is so arranged with variable taps thatthe proper grid and plate voltages areeasily obtained with any set and elimin-ator combination. By dividing the filtervoltage into usable values, it eliminatesa great deal t of the mathematical calcu-lations and much wiring.

It is said that the Truvult Divider willmake it comparatively easy for even thenon -technical radio fan to construct aB power unit which will deliver theproper voltages for receivers of presentor anticipated future design.

Preliminary tests have proved that theDivider is going to be very well receivedby professional and amateur eliminatorbuilders and experimenters. Every indi-cation points to the device being one ofthe big sellers in the Electrad line thisyear.

United Radio Corp.The United Radio Corporation of

Rochester, N. Y., makers of the PeerlessSpeaker, announces several new modelsfor the coming season. Foremost amongthese is the New Dynamic Speaker, in-corporating several new principles ofdynamic design. It is equipped with arectifier element providing for lightsocket operation. It handles the outputof any tubes.

The Dynamic Speaker is offered inthree models. The Model 17-A is amahogany Gothic cabinet, similar in con-ception to the reproducers of past yearsbut considerably larger. This lists at$75. The Model 19-T is a complete built-in Speaker Table, listing at $100. Finally,there is a Manufacturer's Model, 17-C,for built-in use in Console Sets.

The Model 7-A Cone -type Speaker, inthe familiar Gothic cabinet, will be con-tinued in the same form, and at thesame list price of $35, as last year; like-wise, the Model 7-B, manufacturer's built-in unit of this same chassis. In additionto these, a new Model, 7-T, which is abuilt-in Speaker Table; using the Model7 chassis, is offered at a list price of $50.Both this Table and the Dynamic SpeakerTable carry out in design the Gothiclines which are characteristic of Peerless.For further information address thecompany direct and mention RADIO WORLD.

SMITH JOINS PEERLESSThe United Radio Corporation of Roch-

ester, New York, manufacturers of thePeerless reproducer, announce that Her-man A. Smith, formerly sales managerof the Argus Radio Corporation, has beenappointed eastern sales manager of theUnited.

Mr. Smith will have charge of the At-lantic Coast District south of New York,with headquarters at Baltimore.


Tobe Deutschmann Co.The Tobe A -Filter, a new product, con-

sists of a new and different dry conden-ser of 7,600 mfd. with two especially de-signed choke coils of proper size combinedin one unit to supply humless A currentto any radio set. This new filter can beattached to any good two amperecharger, such as a Tungar or Rectigon,for completely eliminating the A battery.Without a charger, only a rectifier, andstep down transformer are needed toassemble this eliminator in a few mo-ments, as the principle wiring is doneinside 'of the Tobe A -Filter. List price,$18.

ANY GOOD 2 AMR.CHARGER

et'

/DOWER CLAROGTAT10 OHMS

PLACE 6 VO 7

TO HOUSE SUPPLY -1VOLTMETER HERE

HOW TOBE A -FILTER IS CON-NECTED TO A TWO AMPERECHARGER. A TEN OHM CLARO-

STAT REGULATES VOLTAGE.

In its Radio Interference Filter No. 1,the Tobe Deutschmann Company presentsa small and compact piece' of equipmentfor use with household appliances usingmotors up to and including one quarterhorse -power. This covers the usual rangeof electric refrigerators and oil burners.No. 1, for DC and AC motors up to 1/4horse -power, price $10.

A condenser, for use in filtering 6 -voltfilament supply, which contains the as-tonishing total of 3,600 mfd. within aspace of only 5 x 53/i x 1% inches isannounced. No attention or refillingwhatever is necessary. The Tobe A -Blockis just a condenser unit in a character-istic Tobe case, and needs no more atten-tion than any other kind of a Tobecondenser. Once installed, it can be for-gotten. The development of a condenserof this type immediately makes possiblethe use of low -voltage rectified alternat-ing current, for lighting the filament ofordinary battery -type tubes from a lampsocket AC supply.

By combining the Tobe A -Block witha pair of. chokes of suitable size, and abattery charger of the proper type, com-pletely wired, reliable, 6 -volt, filtered,rectified current is available, for directelectrical operation of the filaments ofbattery -type tubes. List price of A -Block,$7.00.

Tobe Mica Condenser, of standard grid -leak size, fitting the ordinary grid -leakclip, contains an accurately mica -insulatedcondenser element, sealed into a glasstube in a high vacuum, and thus perman-ently protected from change or deterior-ation. Easily identified by the sealingtip. List prices, .0002 mfd. 40 cents ; allsizes to .006, 80 cents.

A new A -condenser of approximately4,000 mfd., is another feature. To builda condenser of extremely high capacity,but small in size and low in cost, wasthe work of months, both in the labora-tory in Cambridge and in Germany. Thiscondenser is cased in a metal can 5 x 53/4.x PA inches. The breakdown voltageof the condenser is 50 volts. The lifeappears to be indefinite when the conden-ser is used at voltages well below 50.This condenser has many uses. It canbe combined with a good trickle charger,and used to energize the field of a dyna-mic cone speaker. List price, $6.

General DescriptionHigher plate voltages now used in

high -power amplifiers call for condenserswith higher operating voltage character-istics. It is only a short time ago thatwe all used 90 volts of plate voltage forour amplifiers, with one -01-A tube in

the last socket. Developments have beenextremely rapid and we think nothingnow of using 600 volts or more with two-10 pOwer tubes in push-pull, or, twonew -50s. To provide condensers withample factors of safety for this highvoltage use, Tobe Deutschmann Companyhas developed a new 1,100 line, withsafe working voltage of 1,100 volts DC.,recommended for use with UX-210 Push -Pull Amplifiers and similar high voltageequipment. List prices, No. 1101 (1 mfd.)$5.50; 1102 (2 mfd.) $10.00; 1104 (4 mfd.)$17.50.

For further particulars address TobeDeutschmann Co., 11 Windsor Street,Cambridge, Mass. Mention RADIO WORLD.

Jensen Radio Mfg. Co.Radio and phonograph reproducers or

speakers are expcted to show markedimprovement during the next few monthsbased on information and reports comingfrom the laboratories and experimentaldepartments of leading - manufacturers.In' practically every instance, improvedtonal quality and trueness of reproductionare being obtained through the use of thedynamic principle.

The dynamic method and principles arenot new, patents .dating back to 1912.Some of the first radio speakers andpublic address systems, designed by andbuilt under the direction of Peter L.Jensen, pioneer radio engineer and recog-nized authority on radio transmission andreproduction, employed the separatelyenergized magnetic field constructionwhich is now used in this latest typespeaker.

During the past three years, Mr. Jen-sen has been devoting his entire time tothe development and perfecting of thedynamic speaker. About a year ago,speakers of this type bearing his namewere produced for the first time on asuccessful commercial basis.

In tonal quality, the new dynb.micspeakers are said to equal and exceed inability any of the other types. Theyare capable of producing great volumewithout appreciable distortion. Duringthe development work carried on by Mr.Jensen, an experimental model used toreproduce an orchestra was clearlyaudible at a distance of twenty-five miles.

In reproducing orchestras and bands,the dynamic speaker does not overem-phasize the bass notes and bring theminto the foreground which is character-istic of practically all present day repro-ducers or speakers.

The new dynamic speakers receive theirpower directly from lighting socket 110volt AC current. No rectifying or othertubes are used in the dynamic speaker,however, the AC hum being eliminatedby a simple filter system. Where 110volt current is not available, a modelusing a six volt supply from an ordinarystorage battery is also being produced.

This new speaker will handle the out-puts of receivers using the regular powertubes as well as the higher outputs ofthe latest push-pull or other type audioamplifiers using the CX-310 or even CX-350 tubes.

For further information write to JensenRadio Mfg. Co., Chicago, Ill., or Oakland,Calif., and mention RADIO WORLD.

* * *

Five appointments to the sales forceof the Jensen Radio ManufacturingCompany have been made by Thomas A.White, general sales manager. Four ofthe men have been assigned definite terri-tory and, will devote the greater part oftheir time to the jobbing trade, whilethe fifth will call on manufacturers.

J. W. Sands, with headquarters atDayton, Ohio, will contact the wholesaletrade in Ohio, Michigan, Indiana, Ken-tucky and West Virginia. Mr. Sandswas with the Magnavox Company at the

Weston CorporationThe Weston Model 537 AC -DC Radio

Set Tester is a complete outfit, adaptableto the testing requirements of every setmade, whether operated by direct currentfrom batteries or battery substitutes, orby alternating current from socket power.

It will measure the various currentsand voltages employed anywhere in theset, including those at the tube sockets.All tests can be made by using the regularvoltages normally supplied to the set by

WESTON TESTER

its batteries or socket power withoutthe necessity of changing connections.Nor is any auxiliary power required.

The set is provided with two instru-ments-an AC voltmeter and a DC volt-milliammeter. An ingenious system ofswitches and binding posts provides -forautomatically connecting the instrumentsto the circuits being tested. The ACvoltmeter has three ranges - 150/8/4volts-the lower ranges being recuiredfor measuring the filament voltages oftubes, and the highest range is providedfor measuring the line voltage. The DCvolt-milliamrneter has foiir voltage ranges-600, 300, 60 and 8 volts and two currentranges -150 and 30 milliamperes. All volt-age ranges have a resistance of 1,000 ohmsper volt. The set is furnished with thenecessary socket adaptors and a completeinstruction book. For complete data,write to Weston Electrical InstrumentCorporation, Newark, N. J., and mentionRADIO WORLD.

same time Mr. White was with that or-ganization. Prior to this recent appoint-ment, Mr. Sands was with the sales de-partment of the Splitdorf Company.

The New York City (Metropolitan)territory, in addition to the States ofPennsylvania, Delaware, New Jersey,Maryland, and the city of Washington,D. C., has been assigned to James A.Kennedy, who will make his headquartersin New York.

L. R. Hadin, with headquarters atSchenectady, will travel upper New YprkState and the New England States.

In the Northwest territory, consistingof Wisconsin, Minnesota, Iowa, Nebraska,North and South Dakota, W. V. Crowleywill be the Jensen sales representative.Mr. Crowley will make his headqu,artersat Chicago, where he was formerly withCharles H. Freshman, Inc.

C. F. Crane, who up to the time hejoined the Jensen organization was assist-ant sales manager of the Briggs &Stratton Co., Milwaukee, will call onmanufacturers. Mr. Crane will also travelout of the Chicago office.

Jobbing connections are being closedrapidly. Among those closed recentlyare K. W. Radio, New York; WholesaleRadio Equipment Company, New Yorkand Newark; Lewis Radio Jobbers, Phil-adelphia; Detroit Electric Company,Detroit; Harry Alter Company, Chicago;and Benwood-Linze Company, St. Louis.


Polymet Corp.The engineering department of the

Polymet Manufacturing Corporation an-nounced several new products.

New Center -Tapped Resistances aremade in all standard sizes from 10 ohmsto 100 ohms. The center mounting holedistance can be made to suit require-ments. A handy combination solderingand mounting lug is provided. Delicatelaboratory instruments control accuracyto a very close degree to insure properbalance of the grid of the highly sen-sitive AC tubes.

Resistance Strips, flat and flexible, arein two types. The resistance element iswound on a flat insulating strip andequipped with a unique combinationsoldering and mounting lug; or on aflexible non -inductive tubing and coveredwith an insulating sleeve. The flexible

strip is equipped with a tinned solderinglug. Light in construction, highly accu-rate, this element can be- usefully em-ployed wherever a low current carryingcapacity of resistance of low ohmage isrequired. The flat strip is made in allsizes from 1 ohm to 2,000 ohms. Theflexible resistance is made in all sizesfrom 1 ohm to 5,000 ohms.

In its metallized grid leak with pig tailsoldering connection, Polymet has suc-ceeded in developing a method of makinga positive contact between the resistanceelement and an external soldering con-nection. The grid leak can now be sol-dered directly into the circuit without theneed of an extra mounting. This meansfewer production opperations and savesthe cost of a mounting.

The new small moulded bakelite con-denser combines all the electrical andconstructional features of the large sizedmoulded Bakelite condenser into a light,compact unit for easy mounting in anyposition. For further particulars, addressPolymet Manufacturing Company, 597Broadway, New York, N. Y. MentionRADIO WORLD.

* * *

Thomas is AppointedThe Polymet Manufacturing Corpora-

tion, manufacturers of the Polymet line ofpower supply essentials, announced theappointment of Leslie G. Thomas asfactory manager.

Mr. Thomas has had a broad exper-ience in the electrical field and alliedpursuits.

He was factory manager for the F. A.D. Andrea Company, and later was withthe Freed-Eismann Corporation as worksmanager.

Cornish Wire CompanyThe Corwico AC Harness consists of a

twisted cable of heavy Corwico Flexiblewire and the necessary number of adapt-ers to fit into the sockets of a battery setto be converted to AC operation. Connectthe harness to any standard step-downtransformer, insert the AC tubes into theadapters and the old battery set ischanged into an AC receiver. CorwicoAC Harnesses are made in two types-one with adapters attached for R. C. A.type AC tubes, and one without adaptersfor Arcturus AC tubes. The Corwico ACHarness can be used to convert all makesof battery sets of six tubes- or less intoAC receivers. Type "R" for R. C. A. typetubes, $8.00. Type "A" for Arcturus tubes$5.00. Made by Cornish Wire Company,30 Church Street, New York City. Aninstruction sheet is ,obtainable on request.Mention "RADIO WORLD."

Guaranty Radio Goods Co.

FOUNDATION UNITBOTH AC AND DC

LEFT, B METER

THAT TESTSTUBES IS ATAT RIGHT

A versatile set and tube tester and troubleshooter, consisting of a foundation unit fortesting AC and 'DC tubes, with an optionalhigh resistance meter to test plate voltages,is being marketed by the Guaranty RadioGoods Co., of 145 West Forty-fifth Street,New York City. The device is known as theTwo -in -One Universal DC and AC- ScientificTroubling Shooting Test Set and lists at$10.00.

The foundation unit, in a noire metalcase of handsome appearance, containstwo meters. One is a 0-10 voltmeter. Thismeter reads both AC and DC voltages with-out necessity for any change or adjustment.The other meter reads 0-20 and 0-100 Milli-amperes, either scale being obtainable fromthe same meter simply by throwing a built-inswitch: The 0-20 scale is used for testinga single tube, usually, but if a big powertube is being tested, which means even thebiggest, like the type -50, the 0-100 milli-ampere scale is used. There are two bindingposts for the high resistance voltmeter, andhigh resistance voltmeter is to be attached.The high resistance voltmeters also are soldby the same company, at $4.50 and $5.50respectively. The combinations sell at $13.50and $14.50 respectively.

The foundation unit has four padded feet,so that the tester may be placed on a deli-cately finished piece of furniture withoutscratching. On top are the switch for thedouble reading milliammeter, two bindingposts for the high resistance voltmeter andthe plate milliammeter and filament volt-meter, as well as a five -prong and a four -prong socket. From the rear extends thelever of a grid bias switch, which enablesquick change. from positive to negative gridbias, to determine the condition of thetube by noting the change in plate cur-rent as bias is' switched. Also from therear extends the cord which connects toa five -prong plug. A four -prong adapterenables use of the same plug for a four-prong socket in a set.

To use the device, remove a tube froma socket in a receiver and insert the plug,using the five -prong plug for a five -prongsocket, or adding the adapter, if for a four-prong socket. The high resistance volt-meter is then connected to the pair ofbinding posts on the noire case. The tubetaken from the set is put into the propersocket of the foundation unit-it is im-possible to make a mistake, since only theright tube fits in the right socket-and theset is turned on. The filament voltage,plate current and plate voltage are thusread. The grid bias switch enables quickdetermination of the liveliness of the tube,while the readings not only give you in-formation on continuity but also enable youto make sure 'that too much voltage is notbeing disastrously applied to the AC tubefilaments. This question is 'very import-ant, and the filament voltmeter is so scaledthat voltages from 1% to 7%. are particu-larly easy to read. Line voltage regula-tion, by means of any approved device,thus may be accomplished by gauging thefilament voltage.

The high resistance voltmeters (0-300 to0-500 volts) are made in portable type, withfull nickel finish and 30" tipped connectingcords. The cable joining plug to the metersalso is 30" long.

Geo. W. Walker Co.(Victoreen Products)

The display of the George W. WalkerCo., of 2825 Chester Avenue, Cleveland,Ohio, attracted much attention at theshow. The display consisted of the newVictoreen AC circuit and power supply,a Victoreen DC circuit and also a com-plete new power amplifier and a C powersupply.

The company is working on a voltageregulator and a new short wave unit tobe placed ahead of a receiver. Thesetwo products, although completely de-veloped, were not exhibited at the show.

The new power amplifier is extremelyefficient, reproducing with remarkableclarity as well as volume. This poweramplifier is provided with both volumeand tone control and should reach a .nar-ket which is very much interested inpower supplies for phonograph pickup inplaces such as theatres, bazaars,, dances,etc. For full details write to the companyat the above address, mentioning RADIOWORLD.

Insulin CorporationThe Insulinci Corporation of America, 80Cortlandt St4eet, New York City, an-

nounces the production of a timely productfor owners of electric receivers and receiv-ers that have been adapted to use AC tubes.It is the Resistovolt, a small cylindrical,bakelite encased device which plugs intothe AC line, the receiver plug fitting intothe open end. It contains a specially con-structed coil which reacts when the line out-put is higher than 110 volts and does notdecrease the voltage below this point. It isclaimed by the manufacturer that this devicein addition to acting as a protector to allAC tubes, also acts' as a protective fuse,performs the functions of a lightning ar-rester, and holds back a large percentage ofannoying line noises. Type I. C. A.-7operates any electric set up to seven tubes,type I. C. A.-10 operates seven to tentubes. Both types work on AC or DC. Fullinformation as to the possibilities of thisdevice will be sent to those interested uponapplication to the above concern. MentionRADIO WORLD.-J. H. C.

Brooklyn Metal Stamping

Brooklyn Metal Stamping Corporation,718 Atlantic Avenue, Brooklyn, N. Y., hasa new home broadcaster, consisting of amicrophone, long extension cord and socket.The socket is inserted into the detec-tor of a set and the extension cord is runinto' another room, and attached to themicrophone, allowing, the user to cut intothe broadcast program, and make his ownannouncement. It can also be used 'to testout home talent on voice or music' and hasmany novel and useful adaptations. Fullinformation on this and other B. M. S.products may be had from the above con-cern upon application. Mention RADIOWORLD.-J. H. C.

SOME ARCTURUS PRICES LOWERThe Arcturus Radio Company an-nounces a price reduction on its 15 voltAC amplifier and power tubes. The listprice on these tubes has been droppedfrom $5 to $4. The prices on the 15volt detector, the type 127, the 2.5 voltdetector and the AC shield grid tubesremain unchanged.


Aerovox Wireless Corp.To meet the demand for a resistance

unit which can be easily changed to fit therequirements of electric sets and varyingline voltages, the Aerovox Wireless Cor-poration, 72 Washington Street, Brook-lyn, N. Y., is bringing out a wire woundPyrohm resistor fitted with an EdisonBase. This unit may be connected into acircuit by screwing it into any standardlamp socket or screw type receptacle.

WIRE WOUND RESISTOR WITHEDISON BASE

The various sizes are suitable for useas regulating resistances in batterychargers or DC eliminators, for primarycircuit resistors or for any other purposewhere a resistor with this type of mount-ing is required to effect quick changes ofresistance value. The unit itself is woundwith a high grade resistance wire on arefractory tube and coated with a porce-lain enamel which thoroughly covers andprotects the wire from moisture and me-chanical injury.

A new line of extremely compact con-densers is making its appearance underthe Aerovox name. These units, are non -inductively wound, thoroughly impreg-nated and sealed in round fibre tubes. Theterminals provide a convenient means formounting the condenser on subpanels ordirectly to the binding post terminals.They are suitable for use in high voltagecircuits where capacities of from .01 to .1mfd. are required. They are made in var-ious ranges to withstand working voltagesof 200, 400, and 1,000 volts DC.

IMPREGNATED SMALL CAPACITYCONDENSER

A compYete line of Tapped Pyrohm Re-sistors- suitable for use with the most pop-ular power supply units is announced.They are made in the same manner as thestandard fixed Pyrohm resistors. Theyare wound on refractory tubes, using ahigh grade resistance wire and thencoated with a porcelain enamel whichprotects the wire from moisture, oxida-tion, and mechanical injury. An import-ant feature of these units is that the wire,tube, and enamel have the same co -effi-cient of expansion which allows the unitto be used under heavy loads without dis-placement or injury to the wire. In theprocess of manufacture, the unit is sub-jected to high heat and for this reasonwill stand overheating in service' withoutinjury.

A new line of fixed wire wound resis-tors is announced. These resistor unitsare wire wound on flat fibre strips usingthe best resistance wire. They are pro-vided with positive contact terminalswhich may be used for eyeleted mounting,soldered connections, or direct mountingon socket terminals. The fixed resistorunits are available in resistance values offrom 100 to 2,000 ohms and are ideal foruse as grid suppressors or as grid biasingresistors. The same type of resistor isalso available in center tapped form foruse in AC filament circuits as illustratedon front cover. '

A unique moulded bakelite mica con-denser is another new product. An out-

standing feature is its extremely smallsize. The capacity of the unit is prede-termined by a patented process in themanufacture. The condenser is sealed inbakelite, which protects the condenseragainst extreme temperature, moisture orchemical action. The dielectric is of thefinest grade India ruby mica. The platesare tin foil and the condenser element isthoroughly impregnated. The speciallugs provided allow for screw, eyelet, orsoldering assembly. The construction ofthe mounting lugs and the insulating holesof the condenser unit permit eithermounting on metal sub -panels or bake-lite sub -panels. In mounting on metalsubpanels, the unit can be entirely insu-lated from the subpanel.

REMARKABLY SMALL -SIZEDFIXED CONDENSER

The Aerovox Interference Filter, an-other new item, is designed to preventnoises from the power line from affectingthe operation of electric receivers orpower supply devices. It may also beused to prevent radiation and interfer-ence from electric motors, electric refrig-erators, electric sewing machines, oilburners, and other electric appliances.

The corporation announces a completeline of filter condenser blocks to fit therequirements of the latest power supplydevices. These units are available in alarge variety of combinations of capacitiesand working voltages to suit the rectifierand power amplifier circuits that are nowso popular. Write to Aerovox for cata-logue and mention RADIO WORLD.

Grigsby-Grunow Co.The Grigsby-Grunow Company, Chicago,

Ill., makers of the nationally known Ma-jestic A and B power units, is ready with acomplete line of AC operated sets for im-mediate delivery. These sets include apowerful dynamic type speaker fed by thelatest development in pusi-pull amplifica-tion. Cabinets, dynamic speakers, chassesand power uits are made in six great Ma-jestic plants covering acres, of ground andemploying over 4,000 persons. There areseveral beautiful models, built to meet everyrequirement, and priced at a range of from

5 to $167.50. Chasses are uniform, com-pletely shielded, rigid and sturdy, built forlong wear and satisfaction. The dynamicspeaker is of advanced design. The fullline is displayed at the Show. Those locallyinterested may obtain full information fromK. W. Radio Co., 98 Park Place, New YorkCity.-J. H. C.

MODEL 71 MAJESTIC AC SET

National Carbon Co.

THE EVEREADY RECEIVER MODELTHAT IS MADE OF DIE-CASTALUMINUM. EVEREADY SPEAKER

AT LEFT,

The National Carbon Company, Inc.,has entered the radio receiving set field.

The statement announces that the com-pany will sell both AC (batteryless) setsand battery -operated sets, beginning withthe Fall radio buying season.

A departure in materials for productionof cabinets is the use of die-cast alumi-num for one of the receivers.

This particular Eveready receiver isdark green, with routed silver stripingforming decorative borders and a silver -striped lozenge, or diamond, at each end,and on the top surface of the cabinet.

Die-cast aluminum, which is simply hotmolten aluminum forced into a die andcast into shape by a terrific impact ofair pressure, and be moulded into thesame soft contours that distinguish thework of the master craftsmen in woods.But where a craftsman would produce butone piece of such work over a longperiod, it is poSsible by the die-castmethod to duplicate the craftsman'sachievement many times in a short while.Aluminum can be painted by the bakingprocesses employed for automobile bodies.The result is a beautiful finish which can-not be marred 13,r dust, smoke, grease orwater, and whicli the housewife simplybrushes off to restore to its natural ap-pearance despite any defacement whichwould ordinarily scar a radio cabinet.

In the casting of the Eveready cabinet,a special die was made to permit of thebevelled edge which runs around thetop of the cabinet, accentuating the two-tone color scheme. The aluminum cabinetserves as an additional complete shieldfor the entire Eveready set, in additionto imparting a distinctively smart, modernatmosphere.

Balkite Has AC SetChicago.

The Fansteel Products Company, Inc.,North Chicago, Ill., manufacturers ofBalkite power units, has added to itsline the Balkite AC receiver. The firstshowing of this receiver was held at theBalkite National Sales meeting, at the.Drake Hotel, Chicago.

The receiver does not attempt to enterthe low priced field. There are threemodels-the table model, A-5, at $235;the Highboy, A-7, at $487.50; an addi-tional model for people who want fineradio without any trimmings is the tablemodel enclosed in a simple steel case at$197.50, A-3.


Hammarlund Mfg. Co.A new product of the Hammarlund

Manufacturing Co., of 424 West 33d St.,New York City, is a set of short wavecoils, which, when used with the Ham-marlund .00015 mfd. tuning condenser,

and a .00025 mfd. Hammarlund condenserfor feedback, enables receptions of vir-tually the entire short wave band. Thefamous Midline condensers are used, ofwhich the .0005 mfd. model is illustratedherewith. The short wave circuit includesa 65 -millihenry Hammarlund RF chokecoil, also illustrated.

The company makes a new shield forthe famous Hi -Q Receiver, as well as coils,for the broadcast band, and is one of thebest known and most substantial concernsin the radio business.

A reprint on short wave data is avail-able. Write to Hammarlund Manufac-turing Co,4 at the above address, and men-tion RADIO WORLD. Also be sure to askfor data on the full Hammarlund line, in-cluding new parts.

Radiall CompanyThe famous line of Amperites, the

standby in filament rheostats that auto-matically adjust themselves, because theyalter their resistance automatically, by aheat principle, to compensate for %currentor voltage change, continues to be out-standing in the field. The 622 is the lat-est announced Amperite. It drops a 6 -volt source to 3.3 volts for the screen gridtube. Amperites . are manufactured byRadiall Company, 50 Franklin Street, NewYork City Write to the concern for theAmperite book of latest construction dataand circuits, mentioning RADIO WORLD.

Arthur H. Lynch, Inc.Always alert to serve the radio public's

needs, as well as the radio manufacturers',Arthur H. Lynch, Inc., 1775 Broadway,New York City, has produced an excep-tionally accurate and durable center -tapped wire -wound resistor, for equallydividing the voltage across the secondaryof a filament transformer. So accurateis the device that it has a very appreci-able effect upon eliminating hum, hencehas been named the Hum Killer. Thispart is made in different resistance values,so that experts in the design of AC re-ceivers, careful to watch the effect of thetotal current drain, will find the HumKiller absolutely dependable.

Another valuable part made by theLynch organization, under the directionof Arthur H. Lynch, president, is theFilgrid, a resistor, arrangement, on a

Lynch double mounting, whereby two re-sistors, when in series, give exactly theright authomatic bias for DC type screengrid tubes and likewise afford the propervoltage of 3.3 volts, from a 6 -volt source.The Filgrid is used in the National ScreenGrid Five and in other popular circuitsand has won exceptional favor amonghome constructors of radio receivers, andcustom set builders. It may be connectedin parallel for other purposes, or one re-sistor omitted, thus affording versatility.

Output potentiometers, or tapped resis-tance units, for B supplies, as well asheavy duty resistors of the same generaltype, but suitable for enormous currentloads, also are made by this corporation.A five tube deck for a compact and effi-cient receiver, single and double mount-ings moulded of Bakelite and withsecurely fastened clips that stay put in-definitely, as well as the famous line ofLynch metallized grid leaks and plate re-sistors for detector circuits and resistancecoupled amplifiers, continue to be favor-ites in the parts market, and much sought-after by manufacturers, too. Mr. Lynchwas one of the first to concentratestrongly on resistance coupled audio, ofwhich he has always been a big booster.

The company is prospering excellently,having been formed about three years agoby Mr. Lynch and William H. Bearsley.Mr. Lynch's personal popularity in thetrade and among radio set builders in thehome and custom workshop, combinedwith the excellence of the products manu-factured by the concern, are consideredthe "open secret" of the corporation'ssuccess. Readers should write to Mr.Lynch for full data on his line of prod-ucts, and also inquire about his book onresistance. Mention RADIO WORLD.

General Radio Co.General Radio Company, Cambri,ie

Mass., manufacturers of a complete lineof high grade radio instruments and partsfor receivers, has added a line of trans-formers, choke coils and speaker filtersfor use with the -50 type power tube.The type 587-A power speaker filter con-tains a choke coil having an inductanceof 15 henrys, a continuous current ratingof 100 milliamperes and a direct currentresistance of only 250 ohms. It also con-tains two 2 mfd. condensers, one on eachside of the loudspeaker, to protect thespeaker from the direct current and thehigh voltage used with the -50 powertube. The construction of the unit notonly protects the loudspeaker but also theoperator, since at no point are any highvoltage conductors exposed. The priceof this unit is $10.

The 565-B is a full -wave high voltagetransformer designed for use with two-81 type rectifiers in a full -wave rectifiercircuit. It contains one center -tappedwinding of 1,200 volts, and two 71/2 voltwindings for the filaments of the rectifiertubes and the amplifier tubes. It is ratedat 200 watts and is for use on a line offrom 105 to 120 volts and 50-60 cycles.

Those who are interested in these newparts and others in the same line mayreceive full information by writing to themanufacturer. Mention RADIO WORLD.

National Company, Inc.Renowned as a manufacturer extraor-

dinary, with an aesthetic taste in designand skill of execution, the National Com-pany, of Malden, Mass., under the direc-tion of W. A. Ready, president, has a lineof new apparatus that is fetching. In-cluded are the new National dials withhammered silver escutcheon, in two types,one (Type F) for drum control, where thecondenser, in' single or gang formation,is mounted parallel with the front panel,the other (Type E), for condenser mount-ing at right angles to the front panel.The famous velvet vernier feature is re -

Ferranti, Ltd.

The Ferranti au(lio transformers, famousin this country for radio use for severalyears, thus acquiring some of the fameattaching to the name in England, havecompanion inductances this season inchoke coils for B eliminator designs, aswell as output transformers and push-pullcouplers. The company has a fine de-scriptive book. Inquire for it by address-ing Ferranti at 132 West 42d Street, andmention RADIO WORLD.

Pierce-Airo, Inc.

Pierce-Airo, Inc., 119 Fourth avenue,New York City, has a new model chassis.It is made of heavy gauge, drawn andwelded steel, housing all the componentreceiver parts, including power supply. Itis rigidly constructed. It is controlled byan. illuminated single drum dial operatedby bakelite knob, positive friction drive.Compensating control makes possible ex-treme selectivity and easy tuning. Onestage of transformer audio amplification andone stage of power push-pull are usedafter three RF stages and detector. Thepower supply is an integral part of thechassis. Type -26, -27 and 171A tubesare used. The panel is 7x18 inches. Fullinformation on this may be had from theabove concern. Mention RADIO WORLD.-J. H. C.

tamed in all its smoothness and perfectionin each model. The dials met with in-stantaneous success and bid fair to be thereigning favorites of the season.

A radio frequency assembly for the Na-tional Screen Grid Five, consisting of twocoils, two condensers, one drum dial, pilotlight and a frame on which these aremounted, is another fetching product ofthis factory. The input coil, in the an-tenna circuit, has an inductive trimmer,while a third winding on the interstagecoil is adjustable likewise, and serves asa tickler, as in the Browning -Drake hook-up, of which the National Screen GridFive is an improvement. The familiarImpedaformers, arranged for two resistiveplate loads and one inductive plate load,for equalized frequency characteristic,constitute the audio channel, the output ofwhich is through a National Tone Filter.


Housing a PortableBy Walter j: McCord

/4"

SIN

HINGE

9 OR/LC

r -

O

FIG. 1THE BATTERIES FOR THE PORTABLE RECEIVER ARE PLACED IN A COM-PARTMENT UNDER THE RECEIVER PROPER AS SHOWN IN THIS SKETCH.THE LOOP IS MOUNTED INSIDE THE BOX ON A SPECIALLY PREPARED

FRAME. THE LOUD SPEAKER IS PUT AT THE BACK.T N the June 2d issue a portable "that1 perks even in stubborn places" wasdescribed. Here is how the receiver isencased and powered.

The carrying case is made of wood ofsuch dimensions that not only the receiverproper can be installed in it but also thebatteries, the loop and the loudspeaker.Fig. 1 gives the inside dimensions of thebox.

The batteries are placed in a compart-ment below the receiver. This compart-ment is 3 inches high and 14 inches long.For portable purposes small dry cells mustbe used for all the batteries. Three No.6 cells connected in series constitute theA battery. The cells are placed at theleft in the battery compartment and laidon the side. The cells are 21/2 inchessquare and slightly over 6 inches long.Hence they will occupy 71/2 inches of thelength of the battery compartment andlittle of 6 inches of the depth.

The "B" consists of 5 small 22% voltbatteries each of which is 21/2 inches high,2 inches wide and 3 3/8 inches long. Theyare stacked in a row one back of theother so that the total depth requiredfor the 5 is 10 inches. Since these, cellsmay take a little more room that thenominal it is well to make the insidedepth of the battery compartment 11inches or more.

The "C" is one 71/2 volt battery havinga height of 2 7/8 inches, a width of 7/8inch and a length of 4 inches.

Ample Room AllowedAll the batteries occupy 11 3/4 inches of

the total 14 inches of the length of thebattery compartment. Hence there is aspace of 2 1/4 inches left. This may beused for spare parts and tools.

A hinged door is provided in front ofthe battery compartment. This may bemade of such height as to cover the

panel of the set as well as the batterycompartment if it is not desired to havethe tuning controls exposed while the setis not in use.

Mounting of the loop is always one ofthe problems in portable designs. Onemethod in use is td wind the loop on adetachable frame fitting into the front ofthe receiver. When the set is set upfor use the loop is taken out and plugged

-into a jack provided for this purpose.But this method is not very convenient.

LIST OF PARTSLo-One loop.Cl, C4-Two .0005 mfd. tuning con-

densers, ganged (Karas).L1L2L3-One three -circuit tuner with

large primary for shield grid tube (BrunoSG tuner).

AF1, AF2-Two audio frequency trans-formers (Karas Harmonik).

C2, C5, C6-Three .001 mfd. mica fixedcondensers (Aerovox).

C3-One .00025 mfd. grid condenserwith clips (Aerovox).

R4-One standard Clarostat.R1-One No. 20 Amperite.R2-One Lynch 5 meg. metallized grid

leak.R3, R5, R6-Three No. 4v199 Amperites.SW-One Yaxley No. 10 switch.1, 2, 3, 4-Four sockets (Frost).Ant., Gnd.-Two XL, bakelite push

posts.OP-Two X -L bakelite push posts

(speaker +, speaker -)One 7x14 inch front panel.One 9x13 inch baseboard.One National type E dial (not drum).One small knob for tickler shaft.One 222 Vac -Shield and one 201A

Vac -Shield.One No. 45 Universal peewee clip and

5 inch flexible wire.

to circuit diagram,published last week, issue of June 2.)

Another way of mounting the loop isto wind it on a frame which just fits intothe case and then leave it permanentlyin place. The set as a whole can thenbe turned to point the loop into the di-rection which gives the greatest pick-up.

Loudspeaker Built InThe loudspeaker is another problem

that must be solved for every portablereceiver. A horn large enough to be ofmuch value occupies too much space. The

(Concluded on page 18)

FIG. 2TOP VIEW OF THE RECEIVER


Turkey's Brief TurnBy Tim Tu key

1

R2'NANO -

2 ,

L5

KZ>

77 3,

PL

tZIC

5-/-

0 Bt RinP

0 Bt DET0 MO -01 /7

R- c7c

o C-0 C-",9

FIG. 1

A SIMPLE, EFFECTIVE ECONOMICAL CIRCUIT, ADAPTED TO -99 OR -01A TUBES FOR SOCKETS 1, 2 AND 3,AND -20 OR 112A TUBE FOR SOCKET 4, BY MERELY INSERTING THE APPROPRIATE BALLAST, R3. THE FUN-DAMENTAL DESIGN USED IS THAT OF THE 4 -TUBE UNIVERSAL. THE CIRCUIT IS A DX GETTER.

THERE is a large number of fans de-voted to the simple four tube receiver

consisting of one radio frequency amplifier,a regenerative detector and two stages oftransformer coupled audio amplification.

Those fans who still give their allegianceto the four tube circuit do so for obviousreasons. That circuit gives more receptionvalue per dollar of first cost and per dollarof maintenance cost than any other receiver.It is selective, for it has two sharp tunersand regeneration in the detector. It is sensi-tive, for it has a high amplification at radiofrequency, a high detecting efficiency and ahigh audio amplification. It is easy to tune,for it has only two tuning controls. It iseasy to control, for it has a tickler withwhich the volume can be controlled. Itreaches out for distance, for it has a highoverall amplification and usually is operatedwith a good outdoor antenna. It is inex-pensive to build, for it has only a fewstandard , parts. It is not very expen-sive to maintain, for it has only four tubeswith moderate plate voltages. It is capableof high quality, for high type audio trans-formers can be obtained at a reasonable costand up-to-date transformers now give unex-celled quality when worked in conjunction

FIG. 2THE SIMPLICITY OF CONSTRUCTION AND CONTROL OF THE FOUR TUBEREGENERATIVE RECEIVER IS REFLECTED IN THIS ATTRACTIVE

PANEL LAYOUT

with adequate tubes and voltages.The circuit is so easy to build that it is

scarcely necessary to give more than thediagram, photographs and list of parts, forthose fairly well versed in radio. So hereare those data. Try the circuit. You'lllike it.

FIG. 3INTERIOR CONSTRUCTION OF THE FOUR TUBE REGENERATIVE RE-CEIVER HAVING LOCALIZED TUNING CONTROLS AND EFFECTIVE

REGENERATION CONTROL

LIST OF PARTSLl, L2-Two Bruno RF transformers for

.0005 mfd. condensersL5-One General Radio 60 mh choke coilTl, T2-Two Silver -Marshall audio fre-

quency transformers, type 220Cl, C3-Two Bruno .0005 mfcl, tuning

condensers with drum dialsC2-One .01 Aerovox condenserC4-One .00025 mfd. Sangamo grid con-

denserC5-One Hammarlund junior condenser

(15 mmfd.)C6, C7,-Two 2 mfd. by-pass condensersR1-One Electrad 50,000 ohm variable re-

sistorR2-One Lynch 2 megohm metallized grid

lead with mountingR3-One No. 1 AmperiteSw-One Yaxley filament switchPL-One pilot lightOne Yaxley terminal capable and con-

nectorFour binding postsFour Benjamin socketsOne 7x24 panelOne 7x23 sub -panelTwo Bruno brackets


INTERFERENCE ON 'PLANE TESTED

(Chas. Curtis)PLANE USED IN TEST FLIGHTS BY M. B. SLEEPER (RIGHT), WHOSEEKS. TO MAKE FLYING PROMPTER AND SAFER BY OBTAININGWEATHER AND LOCATION DATA BY RADIOPHONE. THE SET-UP INFOREGROUND IS USED FOR INVESTIGATING MICROPHONIC INTER-

FERENCE

Flight Tests of RadioPromise Safer Travel

By M. B. SleeperEngineers, after a lengthy investiga-

tion, have found that radio communica-tion can provide the most important con-tribution to safety in the air. Onlyradio can answer the questions, "Whatis the weather ahead?" and, "Where am.I?", asked by the airplane pilot.

They found no scientific data availableconcerning power and range; no analysisof skip distance effects in relation towavelength on altitude. Reference tothe war -time use of radio disclosednothing useful. beyond the fact that mil-lions of dollars' worth of airplane radiosets sent to France were promptly in-carcerated in warehouses.

More recent record showed that radioserved no useful purpose on planes pilotedby Byrd, Mrs. Grayson, and Bertaud,while Lavine, Jack Frost, and Hinchcliffe,after planning to install sets, lost con-fidence or interest in radio.

Yet Fitzmaurice, in one of the firstcommunications from Greenely Islandsaid, "If we had a radio, ,we would havereached New York!"

Decides to Buy PlaneThus the Pilot Company decided to

purchase a seven -passenger Stinson mon-oplane, specially built for use as a flyinglaboratory, to investigate radio conditions

in the air. With the plane completed,the radio research work is now underway, and tests are already in progressbetween the plane and the field labor-atory.

There are many special features aboutthe machine which will interest you.First of all, the Wright Whirlwind motorand the ignition system are electricallyshielded to prevent spark interferencewith the receiving equipment.

Instead of using a wind -driven gener-ator, useful only when the plane is inthe air, we had the Wright Companybuild in a generator drive gear box,from which the generator can be run.The welded steel tubing which forms thefusilage frame work, the under-carriage,and all the metal parts were bonded to-gether with low resistance connections,for they serve as the radio ground.

To Test AntennasSmall pipe sockets were built into the

wing's, so that an antenna can bestretched across the wings. The distanceis about 40 feet between sockets, amplefor a short wave antenna. This is inaddition to the trailing wire antennawhich can be reeled out through thecabin floor. Comparative tests will bemade between the wing antenna and

trailing wire to determine their efficiencand directional properties.

The fusilage and wings are not coverewith aluminum paint, as is customarybut with non-metallic lacquer. This wadone to prevent possible absorption' iithe thin metallic sheets presented by thialuminum paint.

At the rear of the spacious cabin iscompartment for the radio equipment. Iiaddition, a shelf can be put in placeextending out over the rear seat, fo:extra apparatus.

Makes Trip, Detroit to N. Y.To give you an idea of the ,usefulness

of radio in passenger and express routesimagine yourself taking a trip which wemade from Detroit to New York, tcbring the machine to the Pilot Air Portwhere the radio equipment is being in-stalled.

We took off from the Ford Airport al11:20 A. M. No weather reports wereavailable to tell us what might be en-countered ahead. The sun was shiningbut masses of heavy cloud sent succeedingshadows over the field. Our course,plotted on strip maps, took us southover the Lake, and then east, across thelength of Pennsylvania, past Pittsburgh,Middletown, Pa., where we planned torefuel, then over New Jersey, comingout past Staten Island. New York Harbor,down Long Island, landing at Mineola.

No sooner had we started across theLake than the rain fell in torrents. Itseems to rain harder in the sky than onthe land, if that is possible. And it rainedin small areas. As we came into thefoothills of Pennsylvania we encounteredsnow. The mountains, or those tremen-dous ridges, over which our course tookus, are likely to be covered by an im-penetrable mist.

Important QuestionsShould we take the rain and snow as

a warning against crossing the mountains?Should we take a chance that the moun-tains would be clear? And having crossedthem, what would conditions be in Jer-sey and Long Island?

Between the mountain ridges are farmsto offer fair emergency fields, but thesteep ridges are thickly grown with tim-ber. Only one valley is entirely wooded.

Still, the fields are of no use if it isimpossible to distinguish hill or valleythrough the mist. One of the mail pilots,injured in a forced landing in the moun-tains, crawled for five days 'until hecame to a road where he was found-only to die in a hospital. Anther pilotflew directly into the side of a mountain.The remains of the plane were not founduntil weeks later.

Need Weather ReportsSuccessful commercial flying is not

merely a matter of flying only when theweather is known to be good. If condi-tions promise to be bad at the destina-tion, the pilot must iet through if pos-sible, or at least go as far as he can.

On our trip, however, we should havehad a weather repoit as we entered Ohio,for that would have told us the true

.significance of the rain and snow we en-countered. We should have had a re-port at least 50 miles before we reachedthe mountains in Pennsylvania. No in-formation was available at Middletown.where we landed. Over Jersey we shouldhave had a report for New York andLong Island.

Safety Measures,Flying at 3,000 to 5,000 feet above the

ground an airplane may or may not beheard on the ground. It cannot be iden-tified, for the numbers on the wing can-not be seen. Suppose our ship had beena passenger or express plane, flying on


chedule from Detroit to New York. Andsuppose the engine quit, bringing thenachine down for a forced landing. The'ccupants might travel- twenty to fiftypIles to find assistance. If the planejvas not seen coming down, its disappear-nce would not be known until the planeailed to arrive at its destination at thefcheduled time. Its location would benown only as somewhere betweenetroit and New ,York.On the other hand, suppose the pilot

eports by radio at intervals of 20 mileslong the course? That would be in in-rvals of ten or twelve minutes. Then,

case of a forced landing, the shipuld be located along a 20 -mile line,d aid sent to the plane promptly.

Radio ProblemsAll airplane radio equipment must be

bnsidered with full regard for the factsat: (1); it is not possible to make a

pde operator of a pilot; (2), the pilotpes not want to wear headphones allle time, for he wants to listen to his4otor; (3), radio telegraph transmittersre much lighter in weight, for a given--ansmitting range. than telephone trans-itters ; (4), every pound represented inidio apparatus is a pound deducted fromie pay load.The first equipment, then, to be de -.loped by the Pilot Company, to pro-de weather data reception and positionporting will functions in this way:As the pilot approaches a weather sta-)n, he will put on the headphones andess down an automatic calling key.le operator on watch at the ground0.tion will hear a telegram signal in-rcating a request for weather, infor-iation, and the indentifying call of thearie. Referring to his reports received

radio or land wire, he will give the?cessary reply by radio telephone. Any['der messages to the pilot will be de-ered at the same time.

hereupon, the pilot will proceed withI confidence that he can get throughthe next weather station, or he will

spare to land at the first intermediated. Such weather stations would berked by special beacons at night.o eport his position at 20 -mile in-

vals, the pilot will push another auto -tic key buttton. This will send histifying call on a different wavelength,

h a signal to indicate that he is re-'ting his position.

1

, n the ground, the weather stationsalso serve for dispatching. An

omatic recorder, giving the time ofeption, would .zegister the plane's call.Mese are among the problems forich the Pilot Airplane Radio Labor-.ry will be used. Nor is this looking

,far into the future. either, for alreadyns are underway to open a trans-

( tinental plane -train passenger service,\ ch must have these radio aids to nav-2. ion as a part of its operating equip -

1 lt.

_,$teners Identify

Stations by VoicesCincinnati.he personality of a radio station'souncers is as identifying as its call

rs, according to Powell Crosley, Jr.,ident of the Crosley Radio Corpora-, which took over the controt ofAI in addition to retaining WLW.r that reason announcers of WLWWSAI will be the only memberswill confide their efforts to onlyof the stations. Regular dialers,

sley contends, locate their favoriteo stations by the voice of the an -peer as much as by listening forletters.

A DIZZY TASK ON AERIAL TOWER

A SURE FOOT AND STEADY NERVES ARE REQUIRED BY THESEWORKMEN REPAIRING AND PAINTING THE GIANT ANTENNA TOWEROF A BERLIN STATION. MOST PERSONS GET DIZZY JUST LOOKINGAT THE PICTURE.

External ResistanceSpares Power Tube

Rapid strides have been taken in thepower side of radio and the improvementin B power untis, power packs and poweramplifiers has kept pace with the rapidtube, circuit and speaker advances.Within the memory of us all is the timewhen 90 volts applied to the plate seemeda veritable Niagara of power; and thepioneers in the use of 135 volts wereregarded with awe. Nowdays, 200 volts isthe average and the advanced fan is usingas high as 450.

Supply High Voltages

However, many of the present daypower units, bought and home built, ac-tually supply, voltages of 400 and over,even under load, resulting in the over-loading of the 71 type tube. This tendsto shorten the life of the tube as wellas causing distortion, preventing the tubefrom doing its best work. This appliesalso to the other types of power tubes.When the cost of the power tubes isconsidered, not to mention the sacrificeof quality expected from them, this be-

comes a serious matter. However, theremedy is simple and inexpensive. Everypower unit should be provided with acontrol for the maximum output tap,especially in the case where the latesttypes of gaseous and filament rectifiersare used; if they are provided with anadjustable resistance control for the RFand detector, so much the better and somuch more precise and smoother theoperation.

Inserts ResistorTo counteract overloading, the insertion

of a precise variable resistance such asthe standard Clarostnt in the B plusmaximum lead will prove effective,smoothing out all the trouble and actingto a great extent as tube insurance.

J. A. C.

GET READYThe Democratic and the Republican

conventions soon will be held, so now isthe time to get- your set in perfect work-ing order.


How TelevisionTO R,470/0

PHOTO-ECECTR/C rirrwYsmi TTER

/9/77PL/P/ER

TRANSMITTER

FROM BROADCASTRECE/VER

A NEONL A/77R //77RGE

LENS

RHEOSTAT

IKECEIVE1

V/EW/IVaSCREEN

0/5C

By Neal

ENLARGED//77,9GE

Z. /a HTSH/7.DE-

FIG. I.AT LEFT ARE SHOWN THE ESSENTIALS OF A TELEVISION TRANSMITTER FROM THE LIVING PICTURETO THE RADIO BROADCAST TRANSMITTER. AT RIGHT ARE SHOWN THE ESSENTIALS OF A TELEVISION

RECEIVER FROM THE OUTPUT OF THE AUDIO AMPLIFIER TO THE VIEWING SCREEN.

11 lu

FIG. 2.THIS SHOWS HOW THE PHOTO -ELECTRIC CELL AND THE NEON GLOWLAMP DESIGNED FOR TELEVISION TRANSMISSION AND RECEPTIONAPPEAR. AT RIGHT IS THE PHOTO -CELL AND AT LEFT THE NEON

GLOW TUBE.

TELEVISION has captivated the radiofans, just as radio broadcasting cap-

tivated them seven years ago.There are many systems of television.

Some are exceedingly complex and en-tirely outside the range of broadcastingat the present time. Other systems aresimple and are quite suitable for broad-casting and for reception by the radiofan.

One system in particular is attractingwide attention at this time because ofits simplicity and because vision is ac-tually broadcast regularly by it by aradio station within tuning range of abroadcast receiver. That system is the onedesigned by Dr. E. F. W. Alexandersonand his co-workers of the General Elec-tric Co. of Schenectady, N. Y. Thestation broadcasting is WGY, operatingon a wave of 380 meters.

The principle in brief of this systemis as follows :

A lens system, such as an ordinarycamera, throws an image of the sceneto be transmitted on the flat side of arevolving disc, near the periphery of thatdisc. The disc contains 24 small holesarranged in a spiral and spaced 15 de-grees apart in the angular direction and1/16 inch in the radial direction. Theseholes pass in review, one after the other,across the image. Only one hole at atime is on the image. As soon as onehole leaves the image the next enters,and so on. One hole traces a line acrossthe image 1/16 inch below the precedinghole until the last or inner hole hasfinished. Then the first hole re-entersand the process is repeated. This repe-tition occurs 18 times every second.

Photo -Electric Cell UsedThe light that passes through any hole

enters a photo -electric cell. The amountof light that passes through depends onthe intensity of the light in the image.The photo -electric cell converts the vary-ing light that enters it into a correspond-ing varying electric current. The cell re-


s Tuned InFitzalan

sponds instantaneously and accurately tothe varying light so that the conversion isexact.

The varying current given out by thecell is amplified and impressed on a radiowave just as a voice current is impressedon the radio wave of a broadcasting sta-tion. Thus the carrier wave of thestation is modulated according to thelight and shade values of the scene thatwas scanned by the disc.

Vision Tuned InThe picture modulated radio wave is

tuned in with any receiver having ade-quate sensitivity.

The receiving apparatus is almost areplica of the transmitting apparatus. Therevolving disc is t he same in everyrespect. It is driven by a small electricmotor at exactly the same speed as thetransmitting disc. If the speed of thetwo discs' is not the same the imagewill not apear. It will only be a blur.The speed of the motor driving thereceiver scanning disc is controlled man-ually in the Alexanderson system, and itis simply done by putting a rheostat inseries with the line feeding the motorand varying the resistance. A universalmotor is required.

In the receiver the photo -electric cellis replaced by a neon glow lamp whichhas a luminous plate at least 1% inchessquare. The output of the broadcast re-ceiver is impressed across the terminalsof this glow lamp, and in addition asuitable high voltage is impressed on itto cause it to glow. The output of thereceiver causes the intensity of the glowto vary, and this variation is exactly thesame as the variation of the lights andshades of the original scene.

Viewed Through HolesThe glow lamp is viewed through the

holes -in the revolving disc. When thetwo discs are in synchronism, that is ro-tating at exactly the same speed, theimage will appear on the disc. Thisimage will be I% Inches square. If alarger size image is required the discmay be viewed through a lens systemwhich magnifies it to the desired extent.The image of the disc formed by thelens system is focused on a ground glassfor observation.

The fan should be very careful in buy-ing television receiving equipment to getsomething suitable for the purpose. Thescanning holes should be accuratelyplaced and the size of each hole shouldnot be too large. The diameter of eachhole should be just slightly greater thanone half the radial separation betweentwo successive holes. A suitable size foreach hole is .035 inch when the radialseparation between two successive holesis 1/16 inch. If they are larger therewill be too much overlapping of adjacentscanning lines and the image will not beproduced with the highest possibledefinition of which the system is capable.

The size of the luminous plate on theneon lamp must be at least as large asthe area covered by the scanning holes.

, If it is smaller there will be no imagenear the edges. The lamp used shouldhave been designed for the purpose.Makeshifts will only result in failure.Neon lamps having a luminous area of1Y2x1/A inches which have been designedfor receiving television and to operatedirectly from the output of a -71A,type receiving tube are available.

Many fans will no doubt like to ex -

A TELEVISION TRANSMITTER

(Underwood and Underwood)HOW A TELEVISION

The interior view of a simple televisiontransmitter shows a scanning disc driven bya small electric motor, a photo -electric celland an optical system for focusing the imageto be transmitted., Part of the housing ofthe optical system can be seen back of thebox containing the disc. The image to betransmitted is focused sharply on the disc.Light is admitted from the image to thephoto -electric cell through the small holesin the disc.

The disposition of the holes in the discand the size of the image are so adjustedthat only one hole at a time is on the image.

TRANSMITTER LOOKS

The outside hole covers a fine line on theupper edge of the image. The next holecovers another line 1/16 of an inch lower,and so on until the last hole covers a lineacross the lower edge of the image. Thereare 24 holes in all and the speed of the discis such that every hole crosses the image 18times every second.

A receiver for this television transmitteris an exact duplication of the apparatus ex-cept that a glow lamp is used instead ofthe photo -electric cell and a viewing screenis used as the optical system to replace thepicture transmitted.

periment with television transmission aswell as reception. This they can dowithout getting a radio transmitting li-cense for it is not necessary to use radiowaves at all. Interesting experimentscan be performed by transmitting fromone room to another by means of con-necting wires.

The necessary photo -electric cell isavailable. In fact there are now severalphoto -electric cells on the market. Oneis made with the same physical dimen-ions as' the neon lamp having the liAx1% inch plate. This makes it possibleto_ use two identical units, one for trans-mitting and one for reception. In onethe photo -cell would be used and in theother the neon lamp.

South Africa. Preparesfor Television Tests

Washington.Installation of television apparatus in

South African broadcasting stations isreported under consideration in thatcountry, the American Trade Commis-sioner at Johannesburg, Edward B. Law-son, has advised the Department of Com-merce.

A British television company is offeringbroadcasting television apparatus toSouth African radio stations at a pricebetween $2,500 and $3,000. Receivingsets for television reception are beingquoted at about $150 in Britain.


List of Short Wave StationsCall

Signal8XK

Wavelength(meters)Variable

Frequency(Kilocycles)

Variable

Power(Watts)

40,000

4XE Variable Variable 250to 200 to 1,499

8XP 10-150 29,982 to 5001,999

2XAL 30.91 9,700 500

8XAO 32 9,370 756XBR 40 and 105 7,496 and 500

2,8558XAL 52.05 5,760 500

7XAO 53.54 5,600 100

2XBH 54.02 5,550 150

8XJ 54.02 5,550 50-250

3XL 59.96 5,000 30,000

9XU 61.06 4,910 500

2X BA 65.18 4,600 50

2XAQ 65.4 4,610 50

6XAI 66.04 4,540 50

8XF 66.04 4,540 500

6XUA 104.1 2,880 50

6XBR 105 2,885 50

9XAB 105 2,885 50

1XY 105, 109 2,855 and2,751

50-250

7XC 105.2 2,850 5-250

' 6XAN 105.9 2,830 250

6XA 107.1 2,800 100

6XAK 108.2 2,770 50

6XBA 108.2 2,770 250

6XAL 108.2 2,770 50

6XAF 108.2 2,770 100

1XAA 200 1,499 7.5

2XE 236.1 and 1,270 and 50106 2,828

2XAD 19.73 15,200 Var.

2XAF 31.4 9,550 Var.

Controlled byand Location

Westinghouse El. &Mfg. Co., East Pitts-burgh, Pa.Wm. Justice L e e ,USNRWestinghouee El. &Mfg. Co., East Pitts-burgh, Pa.Experimentor P u b.Co., Coteysville, N. J.WJR (Inc.)Warner Bros., L o sAngeles, Calif.Crosley Radio Corp.,Harrison, OhioWilbur Jerman Inc.,Portland, Ore.Charles G. U n g e r,Coney Island, N. Y.Ohio State Univer-sity, Columbus, OhioR. C. A., BoundBrook, N. J.Mona Motor Oil Co.,Council Bluffs, IowaWAAM (Inc.) New-ark, N. J.L. Bamberger & Co.,Newark, N. J.Los Angeles RadioClub, Los Angeles,Calif.Radio A i r ServiceCorp., Cleveland, 0.Times Mirror Co.,Los Angeles, Calif.McWhinnie ElectricCo., Venice, Calif.R. J. Rockwell,Omaha, Neb.Booth Radio Labor-atories, Tilton, N. H.Northwest RadioService Co., Seattle,Wash.Freeman Lang, LosAngeles, Calif.Los Angeles EveningExpress, Los Ange-les, Calif.F. Wellington Morse,Eureka, Calif.Echofone Mfg. Co.,Los Angeles, Calif.L. E. Taft, LosAngeles, Calif.Clarence B. Juneau,Los Angeles, Calif.Stanley N. Read,Providence, R. I.Atlantic Broadcast -Company, Richmond

Hill, N. Y.General Electric Co.,Schenectedy, N. Y.General Electric Co.,Schenectedy, N. Y.

Caldwell Finds LawPoor But Workable

Orestes H. Caldwell, Federal RadioCommissioner, speaking over WOR fromits studio in New York City, recently,said:

"The Davis -Dill clause, [equalizationof new radio law] while containing noprovisions for the improvement of radio

reception, can, if properly applied, be usedas a lever to effect this end.

"The language of the bill is plain, andthe Commission has no option but tocomply with it, despite thousands of pro-tests from the public.

"It is no longer a secret that certain

members of Congress, after having se-cured the passage of the Davis -Dillamendment hardly six weeks ago, wouldtoday like to see its enforcement indefin-itely postponed, now that they havediscovered what will be its effect onthe various States and on their own poli-tical reputations when actually applied.

Can Be Made Useful

"But whatever the hardships that willbe imposed uopn present broadcastersand radio listeners by the general re-distribution of wavelengths required bythe Davis -Dill clause. It is also evidentthat such enforced reallocations can beused by the Commissioft in the publicinterest as an opportunity to adjust timeand powers of stations so as to grant re-lief from the present overcrowding ofchannels.

"What the public itself has been de-manding, and has a right to expect fromthe Commission, is prompt relief fromthe unhappy radio reception conditionswhich still persist. These conditions haverendered large parts of our radio spec-trum useless, particularly to distantlisteners on farms, ranches and in remotecommunities.

Must Reduce Stations

"This is the real situation which theCommission was created to correct, andwhich the millions of the public havepatiently waited to have remedied. Thisis the situaltion of nightly interferencewhich will again be upon us in September,after Summer static has rolled away. Itcan be remedied only by reducing thenumber of stations permitted to operatesimultaneously on the air during nighthours.

"The requirements are well known toall radio engineers. have onlyeighty-nine wavelengths. For good radionot over 160 stations of the 500 -watt and5,000 -watt classes can operate simulta-neously on eighty-five of these wave-lengths. On the remaining four channelswe can tuck in a couple of hundred little50 or 100 -watt transmitters. And thereyou have the outline of the possibilitiesin the present state of the art."

Dr. Stanley MarieNow CeCo Chemist

Ernest Kauer, chief engineer of theCeCo Company, announced the appoint-ment of Dr. Stanley Marie as chief chem-ist of the CeCo organization.

Dr. Marie has published about 100 tech-nical papers. He has taught science andradio in Boston English High School, isa member of the American ChemicalSociety, American Association Advance-ment of Science, American Society forTesting Materials, and the AmericanElectro Chemical Society. He also hashad considerable experience as a RadioAmateur, his license being for 11C and10F.

He was at one time chief chemist of theAcme Smelting Company, and consultingchemist for a good many organizations,among them being the U. S. Smelting andRefining Company, Columbia Laccuer andPaint Company and others.

Dr. Marie was educated at WentworthInstitute, Franklin Union, and Harvard,receiving his Ph.D.

NEXT WEEK-The advantages of an electrically re-

corded record for reproduction throughyour audio channel, using a pickup, willbe detailed. Also antenna, an electricset and the dynamic speaker will be dis-cussed.


162 Stations Must QuitOrdered Off Air August 1, Getting 60 -day Lease of LifeMeanwhile, With Chance to Prove They Should Not

Be Barred

Washington.The Federal Radio Commission, in or-

dering a blanket extension of all radiobroadcasting licenses from June 1 untilAugust 1, announced the adoption of ageneral order terminating the licenses of162 stations on August 1. The Commis-sion stated in the order that it has notbeen satisfied that public interest, con-venience or necessity will be served bygranting them renewals of their licenses.

The station affected were given a hear-ing before the Commission on July 9at Washington. They were asked toshow cause why they should not be de-leted from the list of broadcasting sta-tions as ordered.

Third Zone EscapesNinety-one of the stations are 'in the

the first; 30 in the second and five infourth radio zone. Thirty-one are in thefifth. The third zone of Southern Statesescaped without any deletions.

Text of OrderThe general order sent to those to be

eliminated (General Order No. 32) fol-lows in full text:

"The Commission, after an examinationof the applications for renewal of stationlicenses of the below named stations, hasnot been satisfied that public interest,convenience or necessity will be servedby granting these applications.

"It extends for a period of 60 days theexisting licenses of these stations subjectto all modifications and extensions, to ter-minate at three o'clock a. m., August 1,1928.

"The Commission fixes Monday, July11, ten o'clock a. m., in its offices in Wash-ington, D. C., as the time and place fora hearing for each of these applications."

Another general order (General OrderNo. 34) extends the existing licenses toall portable broadcasting stations untiTJuly 1, after which they must go offthe air.

List of Those Ordered OffThe stations that must quit the air,

unless they can prove good public reasonsfor continuing, are by zones as follows :

Stations Ordered Off AirNO. 1

WIBS-Elizabeth, N. J.WBMS-Union City, N. 5.WKBQ-Standard Cahill Com=

pany, Inc., N. Y.WKBO-Jersey City, N. 5.WSGH, WSDA-Amateur Radio

Specialty Company, Brooklyn.WWRL-William H. Reuman,

Woodside, N. Y.WGCP-May Broadcasting Com-

pany, Newark, N. J.WLBX-John H. Brahy, Long

Island City.WLBH-Joseph J. Lombardi,

Farmingdale, N. Y.WINR-Radiotel Manufacturing

Company, Bay Shore, N. Y.WHPP = Bronx Broadcasting

Company, Englewood Cliffs, N.J:

WLBM-Cambridge, Mass.WRAH-Providence, R. I.WTRL-Midland Park, N. J.WBES-Takoma Park, Md.WRES-Quincy, Mass.WAIT-Taunton, Mass.WGOP-Flushing, N. Y.WLOE-Chelsea, Mass.WCON-Danbury, Conn.WPCH-Hoboken, N. J.WJBI-Red Bank, N. J.WOKT-Binghamton, N. Y.WHRJ-Jamaica, N. Y.WAAT-Jersey City, N. J.WCOH-Greenville, N. Y.WBBC-Brooklyn, N. Y.WCGU-Coney Island, N. Y.WCLB-Long Beach, N. Y.WEVD-Woodhaven, N. Y.WGI.:-Secaucus, N. J.WMBQ-Brooklyn, N. Y.WCDA-Cliffside Park, N. J.WCOT-Providence, R. I.WC13M-Baltimore, Md.,WMES-Boston, Mass.

NO. 2

WFTC-Akron, OhioWBRE-Wilkes-Barre, Pa.WKBN-Youngstown, OhioWLBY-Trop Mountain. Mich.WHBT-McKeesport, Pa.WJAY-Cleveland.WTBK-Ynsilanti. Mich.WLAD-Philadelphia.WABW-Wooster. Ohio.WMBS-Leyone, Pa.WRAK-Erie, Pa.WGH-Jeannette, Pa.

WMBW-Youngstown, Ohio.WQBZ-Weirton, W. Va.WBBP-Petoskey, Mich.WRAX-Philadelphia.WFBG-Altoona, Pa.WBWB-Norfolk, Va.WBBL-Richmond, Va.WTAZ-Chesterfields Hills, Va.WABF-Kingston, Pa.WFAN-Philadelphia.WEBE-Cambridge, Ohio.WFKD-Frankford, Pa.WBMH-Detroit.WMBG-Richmond, Va.WKBZ-Ludington, Mich.WHBC-Canton, Ohio.WABY-Philadelphia.WPBE-Cincinnati.

NO. 3Not affected

NO. 4WLBO-Galesburg, Ill.WJBL-Decatur, Ill.WMBB-JOK-Homewood.WDZ-Tuscola, Ill.WCAZ-Carthage, Ill.WLIB-Chicago.(Does not include WGN)WJAK-Kokomo, Ind.WLBC-Munice, Ind.WCBS-Springfield, Ill.WLBI-Wenona, Ill.WFBZ-Galesburg, Ill.WBAO-Decatur;WTAD-Quincy,WKBV-Brookville, Ind.WNBY-Brookville, Ind.WLBT-Grown Point, Ind.WNBA-Forest Park,WHBF-Rock Island, Ill.

WEHS-Evanston,WRAM-Galesburg, Ill.WKBE-Joilet, Ill.WMBD-Peoria Heights.WTAS-Elgin, Ill.WEBQ-Harrisburg, Ill.WTBA-Joilet, Ill.WLBQ-Atwood, Ill.WTAX-Streator, Ill.WEDC-Chicago.WSBC-Chicago.WPEP-Waukegan, IILWRFC-Chicago.WKBS-Galesburg,INTTRC-La Salle, Ill.WK13T-Chicago.WCLS-Joilet, IILWFKB-Chicago.WLTS-Chicago.WQJ-Chicago.

WSAX-Chicago.WJBZ-Chicago Heights.WCRW-Chicago.WRAF-Laporte, Ind.WWAE-Hammond, Ind.WCWK-Fort Wayne, Ind.WMBE-White Bear Lake,

Minn.WHAY-St. Louis.KWKC-Kansas City, Mo.WIAS-Ottumwa, Iowa.WFAM-St. Cloud, Minn.WHAL-Omaha.WKBH-LaCrosse, Wis.WIBU-Boynette, Wis.WIBA-Madison, Wis.WCLO-Kenosha, Wis.WAIZ-Appleton, Wis.WKDR-South Kenosha, Wis.WEBW-Beloit, Wis.WHBY-West de Pere, Wis.WOMT-Manitowoc, Wis.WGWB-Milwaukee.KFKX-Chicago.KGFB-Iowa City, Iowa.KFHL-Oskaloosa, Iowa.KFHR-Sioux City, Iowa.KFIZ-Fond du Lac, Wis.KGCA-Decorah, Iowa.KWOR-Cedar Rapids, Iowa.KPHP-Muscatine, Iowa.KICK-Red Oak, Iowa.KFVG-Independence, Kan.KFDZ-Minnea polls.KGHC-Slayton, Minn.KWUC-Lemars. Iowa.KGCN-Concordia, Kan.KGFQ-Minneapolis.KFOA-St. Louis.KFWF-St. Louis.KGBX-St. Joseph, Mo.KFOX-Omaha:KGBY-Columbus, Neb.KGCH-Wayne, Neb.KGDW-Humboldt, NebKGFS-Central City, Neb.KGFW-Ravenna, Neb.KGFO-Grand Island, Neb.vrRz-York. Neb.KGCR-Brookings, S. D.KGDA-Dell Rapids, S. D.KDI,R-Devils Lake. N. D.KGDY-Oldham. S. D.KGFN-Aneta, N. D.

NO. S

KFPR-Los Angeles.KFUS-Oakland, Cal.KGDH-Stock ton, Cal.KOOS-Marsh field, Ore.

KFUT-Salt Lake City

VOICE THRILLING

BEATRICE BELKIN, GIFTED COLOR-ATURA, WHOSE VOICE IS A RARETREAT AND DELIGHT, IS KNOWNAS "THE RADIO SONGBIRD." SHEIS ONE OF THE ROXY ARTISTS,

AND WHAT A ONE!

Riga to Increase PowerWashington.

Another increase in the Riga broad-casting station's !power, which wasdoubled some time ago to three kilowatts.is expected this year, according to a re-port from the American Consul at Riga,A. W. Kliefoth, made public by the De-partment of Commerce.

During 1927, when the doubled powerwas on, it was stated, radio listeners inLatvia increased from 10,518 to 16,049,and the additional power under consid-eration is expected to raise that figurestill further.

"Soundproof" Walls.Dwellers in modern apartment houles,

being told the walls are soundproof, movein with the usual result that they canplainly hear the next neighbor's radio,even to understanding what the an-nouncer says, provided it is in tolerableEnglish. One tenant told the superin-tendent about it, only to be told : "Youknow, radio waves penetrate everything,even concrete buildings." He didn't sayanything about sound waves.

NEW CORPORATIONSGene Austin, Radio broadcasting-Atty., R.'Aronstein, 1650 Broadway, New York, N. Y.Radio Broadcosting Corp. of New York-Atty.,

M. F. Cantor, 45 W. 57th St., New York, N. Y.Consolidated Radio Sales Corp., Newark, N. J.-Attys., Green & Green, Newark, N. J.Weston Rad'o Corp.-Atty, S. Solomon, 2 La-fayette St., New York, N. ,Y.

18 RADIO WORLD. June 9, 1928A THOUGHT FOR THE WEEK

SURELY the younger folk can stand"When You and I Were Young, Mag-

gie," once in a while on the air, when theirelders have so often sat for hours listeningto such unwistful bits of jazzerine as "MyWell -Rouged Gal," "Sallie's My Pally,""Gee, but She's a Hot Petater," to say noth-ing of that brilliant effusion entitled, "SheMay Not Be a Lady but She's Too DarnedGood for Me." After all, time ham*squeezed all the melody and beauty out ofthe good old ballads.

The First and Only National Radio Weekly

Radio World's Slogan: "A radio set for every home."'

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(Dated Saturday of same week)FROM PUBLICATION OFFICE

HENNESSY RADIO PUBLICATIONS CORPORATION145 WEST 45TH STREET, NEW YORK, N. Y.

(Just East of Broadway)ROLAND BURKE HENNESSY, President

M. B. HENNESSY, Vice -PresidentHERMAN BERNARD, Secretary

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EDITOR, Roland Burke HennessyMANAGING EDITOR, Herman BernardTECHNICAL EDITOR, J. E. Anderson

ART EDITOR, Anthony SodaroCONTRIBUTING EDITORS:

James H. Carroll and Capt. Peter V. O'Rourke

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Entered as second-class matter March 22, 1922, atthe Post Office at New York, N. Y., under the Act ofStarch 3, 1879.

Music Close By TravelsA Stuttgart (Germany) radio paper pub-

lishes in facsimile a postcard from a listenerin London. Referring to a recent relay of2XAF, Schenectady, N. Y., by Stuttgart, hewrites that from 11:30 to 11:45 P. M. onApril 16 he was able to listen to dance musicbroadcast from a well-known hotel about amile away, via 5XX, this relayed by 2XAFand 2XAF's broadcast again relayed by theStuttgart station.

The distance was 6,000 miles.

Build Televisors AtOwn Risk, Rice Warns

WGY is experimentally broadcasting radiotelevision signals on a regular schedule andthese are available to anyone who has con-structed suitable apparatus but, according toMartin P. Rice, manager of broadcastingfor the General Electric Company, nospecific information on the construction oftelevision receivers can be offered the public.

The art is still in the early stages of de-velopment, hardly comparable with radiobroadcasting eight years ago, explains Mr.Rice, and in the course of experimentationthe whole system of transmission may bechanged overnight.

The schedule is adopted to assist the Gen-eral Electric Company engineers in the de-velopment of a system of television trans-mission and reception and, while the publicis welcome to experiment with the signals,it should be understood that the plan is pure-ly experimental and subject to change atany time. To offer circuits or constructionplans for a television receiver, Mr. Ricestates, would be unfair as it might implythat the station will continue indefinitely thetransmitting of signals suitable for the typeof receiver described.

But fans are greatly interested.

STURDY CHASSIS CONSTRUC ION OF HOME-MADE SETS IS ALL THERAGE, STARTED BY LEO FENWAY LAST YEAR WITH THIS MODEL 4

CONCERTROLA

The 4 -Tube Portabie(Concluded from page 10)

simplest solution to this problem is to usea cone or a stretched diaphragm. It isnot necessary to use a cone or diaphragmof much depth, measured from the apexto the plane of the periphery. An inchor an inch and a half will be sufficient.The most convenient place to mount thisis at the back of the receiver. The dia-

phragm may constitute the back wall ofthe containing case. This is the methodemployed in this portable receiver. Thedriver unit is mounted inside the set andmounted on a bracket. There is ampleroom for this in the set.

A suitable handle attached to the coverof the receiver will complete the port-able set.

FIG. 3

A KNOB MAY BE PLACED ON THE SWITCH, SO' THAT THE APPEARANCEAT LEFT AND RIGHT IS THE SAME. THE NATIONAL TYPE E DIAL HASSCALE READING FROM LEFT TO RIGHT. THIS IS NOT THE DRUM DIAL,

WHICH IS TYPE F AND HAS THE SCALE READING UP AND DOWN

I lune 9, 1928 RADIO WORLD 19

El+Pkva.

OB'''AMP08,0E17

A*.

2 AMPEREDRY CHARGER 'R frLTERI

0 + +

0 0 0 0 -FIG. 1

A DIAGRAM OF A COMPLETE RADIO INSTALLATION EMPLOYING A RAYTHEON TYPE B BATTERY ELIMINA-TOR AND A TORE A- FILTER WITH A 2 AMPERE DRY CHARGER. A TWO WAY SOCKET ADAPTER IS USED BE-TWEEN THE WALL OUTLET AND THE PRIMARIES OF T HE TWO POWER TRANSFORMERS IN THE CIRCUIT.THE LINE SWITCH SHOULD BE PUT BETWEEN THE TWO WAY SOCKET ADAPTER AND THE WALL SOCKET.

Filter Easily SolvesA Supply Problem

The A -filter which has recently madeits appearance on the market has solvedthe problem of electrifying receiversdesigned to operate on DC. The filterconsists of two electrolytic condensers inone unit and two low inductance chokescapable of carrying the current requiredby the average radio receiver. The totalcapacity of the condensers is 3,600 mfd.and the inductance of each of the twochokes is .05 henry, and capable of carry-ing 2.5 amperes.

The A -filter is designed to filter therectified output of A battery chargers sothat the current can be used directly forheating the filaments of DC tubes with-out the use of a storage battery.

The maximum current that should beused is 2 amperes, and therefore thecharger used should be one that can de-liver that current. That is enough to sup-ply a circuit using 8 quarter amperetubes. Therefore it will handle nearly allreceivers,, including most of the super -heterodynes. The hum which results fromthis combination of charger and A -filter is so slight as to be inappreciable,and probably if any at all is audible itcomes from the B battery eliminator

rather than from the A battery eliminator.Many circuits of course do not require

the full 2 amperes. But a two amperecharger may be used nevertheless. If

T T

only one ampere is required, that is allthat is taken from the charger. Underthis condition the charger will last twiceas long and the filter will be much moreeffective in eliminating any hum.

Many fans have trickle chargers whichdo not deliver as much as 2 amperes. Inmany of the chargers the limit is .75 am-pere. Such may be used with the filterprovided that no more than .75 ampere beused. The effectiveness of the filter cir-cuit will be just as good as if a 2 amperecharger were used.

Circuit Illustrates AdaptationIn Fig. 1 is shown a complete DC radio

receiver which has been fully electrifiedby means of battery eliminators. A reg-ular B battery eliminator employing aRaytheon rectifier is used to supply theB and C potentials. A two ampere chargerwith a Tobe A -filter is used to supplythe filament current to the five tubes inthe circuit.

The charger consists of a suitable step-down transformer working between 110and about 12 volts AC and a dry typerectifier. The "A" consists of a Tobe ABlock which contains two condenser sec-tions, and two choke coils of .05 henryeach. For a heavy duty rectifier filter ar-rangement a power Clarostat of 10 ohmsresistance- is used to cut the output volt-

AMP. DET -

B+ 13÷ B+ Er0 0 0TO

\

i9 MINUS HERE

\C"2 `C- I

FIG. 2

AT LEFT IS A B ELIMINATOR, WITH EXTERNAL'RESISTORS USED FOR C BIAS. AT RIGHT THIS ISSHOWN SCHEMATICALLY, WITH THE A -FILTER

AND CHARGER LABELLED "RECTIFIER."

t

age down to 6 volts. The Clarostat hasto be adjusted for different current drainsto maintain the output voltage at 6 volts.

The advantage of the A -filter readilycan be appreciated by all fans who haveused storage batteries with or withouttrickle chargers. If a trickle charger isused the relay which throws on the powerwhen the filament circuit is closed andwhich throws tle charger on the battery 'when the filament circuit is opened oftengets out of order and ceases to function.If the relay is not used it is always necessary to close and open two circuits whenthe set is turned on and off. That is al-ways an annoyance.

If the storage battery is used with aheavy duty- charger, to replenish thecharge periodically there is always thechance that the battery will become ex-hausted at a critical moment of reception.

All these difficulties are done awaywith when the A battery eliminator is

used. Perhaps the greatest advantage ofthe system is the elimination of the stor-age battery, which with its acid has al-ways been an unwelcome part of the radioreceiver.

Arrows Show Current DirectionIn Figs. 1 and 2 the arrows show the

direction of flow of direct current. In Fig.1 the B supply, with Cl as the lower andC-2 as the higher C bias, is thus desig-nated. In Fig. 2 this is duplicated for aneliminator that has no bias taps, but whereexternal resistors are used. The tube atright in Fig. 2 is the detector tube, takenmerely as a symbol to represent plate cur-rent flow. Some plate current goesthrough the A supply.

e PWR.

B+ Rm P

5+ VET.

(F -)4-

C- 1

C- 2

1

mARKED 9- ON Etat» INAroP


145 WEST 45TH STREET

Subscribe for Radio World

10 weeks for $1.00

To carry you over your vacation

Parts forFRAME

The wooden frame, with cop-ing of decorative moulding,may be purchased in stand-ard sizes and used as such,or may be cut down froma larger standard size to asmaller special size, and clothcut by purchaser accordingly.The frames come completewith moulding and hardware,in factory sealed carton.13x1634" Cat. No. 1103A-$2.0018x24" Cat. No. 1103.... 5.0018x36" Cat. No. 1104.... 52524x36" Cat. No. 1105.... 5.3536x36" Cat. No. 1106.... 5.50

Airplane Cloth SpeakersCLOTH

Genuine airplane cloth, sameas used for best airplanes;great tensile strength, lightweight. Govt. specifications.13x164" (with 7x7 for baffle).

Cat. No. 1099A $1.0018x24" (with 7x7 for baffle).

Cat. No. 1099 $1.5018x36" (enough extra to cut

own baffle with shears).Cat. No. 1100 $1.80

24x36" (enough extra to cutown baffle with shears).Cat. No. 1101 $2.00

36x36" (enough extra to cutown baffle with shears).Cat. No. 1102 $2.50

60" Connecting Cord. Cat. No. 1107B

APEXThe Apex is of the doubletype, so that one metalshield is placed outside thediaphragm and the other in-side, but the same apex maybe used on any type of conespeaker. Each apex isequipped with threaded sleeveand thumbnut for fasteningunit drive. Highest qualityand durability of metal used.Outside diameter of apex,1Y4". Guaranteed to be en-during and serviceable. Firmgrip assured.Cat. No. 1107 25c

30c

SPECIAL: 13x163/4" Speaker, with Diamond Unit,Airplane Cloth, Cord, Frame, Moulding (com-plete kit). Cat. No. 1107C Only $5.00GUARANTY RADIO GOODS CO.

NEW YORK CITY

A

(1/49mintits,

Strong, Rugged Loud UnitThat Drives Any Cone Speaker and Reproduces

Fine Tone at Great Volume!This unit has a full floating armature,

which means that armature is mounted sothat it acts like a plunger between two setsof magnets or pole pieces. As the magnet-ization of the armature changes under theinfluence of the signal it plunges first towardone pair of pole pieces and then toward theother.

The large field magnet used insures astrong and permanent polarizing flux, whichprotects against loss of sensitivity from self -demagnetization to which some loudspeakerunits are subject.

The cone driving pin is directly coupledto the full floating armature at that pointon the armature where the force is greatest.This insures against loss of power throughcomplicated levers.

The sturdy construction and heavy weightof the assembled unit prevent motion of theunit itself and insure that all the power istransformed into sound.

The armature is adjustable from an exposed knobin the back.

Apex, chuck and thumbscrew supplied with ach unit!This unit stands 150 volts unfiltered.

With filtered output the unit has stood upto 550 plate volts continuously withoutdamage.

Each unit is supplied with an apex, con-sisting of two metal plates, so that any typeof airplane cloth or cone speaker may bebuilt; also with each apex are supplied athreaded chuck and thumbnut for engagingthe pin. The screw firmly grips the pin.Besides, a 60 -inch cord with tips, is alsosupplied with each unit.The Powertune Giant Unit, complete withapex, chuck, screw and 60" cord; totalweight, 3 lbs. (Cat. No. 1098) $3.75

SEND NO MONEY!

r- -, GUARANTY RADIO GOODS CO.,

145 West 45th St., New York City.

Please send me one cone speaker unit (Cat.1098), as advertised, with apex. I will paypostman $3.75, plus few cents extra for post-age. Your 5 -day money -back guaranty isaccepted.

Name

Address

City State5 -DAY MONEY -BACK GUARANTEE!

LiteratureWanted

THE names and addresses of readers ofRADIO WORLD who desire literature

on parts and sets from radio manufactur-ers, jobbers, dealers and mail order housesare published in RADIO WORLD on re-quest of the reader. The blank below maybe used, or a post card or letter will doinstead.

RADIO WORLD,145 West 45th St., N. Y. City.

I desire to receive radio literature.Name

Address

City or town

State

Frank Farmey, 3821 Canon Ave., Oakland, Calif.Joseph D. Copeland, 85 Main St., So. Portland,Maine.L. S. Maxfield, M. E., 446 Prospect Avenue,Brooklyn, N. Y.Weslie E. Tucker, R.F.D., No. 1, Norway, Me.A. I. Goldstein, 884 West End Avenue, NewYork City.C. E. Whittier, PA West Canal, Penacook,New Hampshire.Stephen R. Gildersleeve, 223 E. 58th Street, NewYork City.Louis Snipper, 402 Badger Ave., Newark, N. J.P. H. Beckman, Redfield, South Dakota.Wm. H. Mallon, Fort Hancock, New Jersey.J. H. Richmod, c -o Richmond Radio Repairs,124 9th Street, Mt. Vernon, Wash.Ralph J. Monson, Fredericksburg, Virginia.Chas. E. Lyman, 575 Menlo Avenue, Hawthorne,California.Gerald Kohler, Route 5, Rome, New York.E. E. Cauch, Box 61, Carpenteria, Calif.Bernard A. Duffy, 194 Norton St., Rochester,N. Y.R. S. Bush, 630 E. 8th St., Portland, Oregon.R. J. Burkett, 11270 Cumpston, N. Hollywood,

Calif.Lt. H. V. Evans, 6th Infantry, San Juan, P. R.D. F. Hopkins, 7050 Ruskin Lane, Upper Darby,Pa.Walter Fuller, 212 1/2 S. Washington St., Spo-kane, Wash.William Emboirty, Washington Depot, Conn.Malcolm Macleod, Lenox Apartments, Atlantic

City, N. J.Conrad Paul Mohr, Box 137, Staffordville, Conn.W. B. Clifton, 108 Pike St., Seattle, Wash.Arthur Robertson, P. 0. Box 23, Verdun, Canada.G. Neuman, 144 Pearl Street, N. Y. C.E. J. rates, Laverty, Okla.F. G. Murry, Box 91, Greenville, Texas,Thos. Netlund, 302 East Bowman, South Bend,Ind.Wilson Leeman, Room 18, Y. M. C. A., Norfolk.Nebraska.

THE DIAMONDOF THE AIR

Using General Purpose Tubes

4 Tube Set uses three type As tubes and one 112 type;has TRF stage, regen-

erative detector and two stages of trans-former coupled audio (This is not ShieldedGrid Diamond.)

5 Tubes Same RF and detectoras the other, but hasone transformer andtwo resistance coupled audio. Especiallysuitable for B battery operation. (NotShielded Grid Diamond.)

Guaranty Radio Goods Co.,145 West 45th Street, New York City.Please send me one newly printed official blue-print of the --

o 5 -tube Diamond of the Air 4 -tube Diamond of the Air

(Check off one you want.)and the textual data giving full directions for con-struction.

Enclosed please fird 25 cents to defray all ex-pense.

NAM)

ADDRESS

CITYSTATE

(These are not Shielded Grid Diamonds.)

(tine 9, 1928 RADIO WORLD 21

R. C. A. Tube ClauseIllegal, Says Board

Washington.The Radio Corporation of America was

charged with restraining competition inimposing limitations upon the use ofvacuum tubes in radio receiving setsmanufactured under its patent licenses, ina complaint filed by the Federal TradeCommission.

Notice was served to the corporationthat a hearing on this and other chargesset forth in the complaint will be held at10:30 a.m., July 23, in the offices of theFederal Trade Commission at Washing-ton.

The complaint criticises "Article 9" ofthe patent licensing agreements whichthe Radio Corporation of America haswith other manufacturers of radio sets.Under "Article - 9" the manufacturersbuilding sets under R. C. A. licenses mustagree to equip them initially withvacuum tubes manufactured by theR. C. A.

The complaint further alleges that pat-ent rights on vacuum tubes to which theR. C. A. and affiliated companies claimexclusive manufacturing rights expired in1924 and 1925, prior to the licensing agree-ments. The manufacture of these tubes,it is stated. has since been open to thepublic.

Colonel Manton Davis, attorney for theRadio Corporation of America, said inNew York :

"The act solely relates to Article 9 ofthe Radio Corporation's license contractsto radio receiving set manufacturers. Itis the contention of the Radio Corpora-tion of America that this provision is gov-erned entirely by the patent law, but thatall of the issues involved in that complaintare under submission to the Circuit Courtof Appeals at Philadelphia, and the Radio

Make any Good ReceiverBETTEReg.

TUBES

C.E. MFG. CO.Providence

R.I.

Corporation would consider it inadvisableto discuss the complaint prior to the de-cision of the Philadelphia court."

BE SURE TOBUY or SPECIFY

'GENUINE

; A rril rA\7

PARTSin building the 4 -Tube Port-able described in this issueby WALTER J. McCORD.

If your dealer does not stockKaras Parts, send your orderdirect to us and we will seethat you are supplied.

Karas Electric Co.4039FB. N. ROCKWELL ST.

CHICAGO

1

NEXT WEEKAn expert consideration of antenna

values, with advice on how to improvereception considerably, will be published.The article, by James H. Carroll, con-tributing editor, also tells how to de-termine approximately the natural periodor wavelength of your antenna. Otherarticles will include a discussion of thesingle meter that measures both AC and'DC, and dynamic speaker facts.

TIOVelvet Vernier Drum Dial

Type E

This Is the New Velvet Vernier 01x1for driving a condenser with shaft atright angles to the front panel. Henthe same mechanism as the famousType B Velvet Vernier Dial.. Ratio20. I . Beautifully Hammered-.SI Ivorfinish Escutcheon Plate. Easy toinstall. Price. 52.75. Type 28Illuminator, 50c.

National Co., Inc.Malden. Atass. W. A. Ready, Pres.

c, !id for Pune:ill R1V-130

-) WAVE TRAP, $1.50GenuineMoulded Bake-lite Casing,panel or sub -panel mount-ing option, orplacement atopof cabinet,mark this newmodel wavetrap that cutso u t interfer-ence. Sendcheck, P. 0.money order,or postagestamps.

Five-day money -back guarantyGuaranty Radio Goods Co.

145 West 45th St., N. Y. City

RADIO WORLD FOR SEVEN WEEKS, $1.004 -TUBE SHIELD GRID DIAMOND OF THE AIR BLUEPRINT FREE WITH EACH SUCH SUBSCRIPTION!At 15c per copy, each week for seven weeks, Radio World costs you

$1.05, but if you subscribe for seven weeks at $1.00 you will also get theofficial blueprint of this circuit FREE! The blueprint was designed byH. B. Herman from the original laboratory receiver. Size of blueprint,27 x 27 inches. All connections, leads, parts, etc., shown actual size.

Very simple toHome constructors of radio receivers, and custom set builders, by

following the blue print, can build a distance -getting and voluminousset, the parts for which list remarkably low.

The new shielded grid tube is used as the radio frequency amplifier.That is why the amplification finally is boosted forty times over andabove what it would be if an -01A tube were used instead.

Such simplicity of construction marks the receiver that it can becompletely wired, skillfully and painstakingly, in two and a half hours.

DISTANCE JUST ROLLS IN THOUGH SET IS EASY TO TUNE!Great stability! No neutralization required! No shielding necessary!All you have to do is to follow the official blueprint, and lol a new

world of radio achievement is before you! Distant stations that four -tube You'll be overjoyed. But you should place every part in exactlysets otherwise miss come in, and come in strong. No tuning difficulty the right position. Stick to the constants given, and, above all, wireis occasioned by the introduction of this new, extra powerful, startling according to the blueprint!tube, but, in fact, the tuning is simplified, because the signal strength When you work from this blueprint you find that every part isis so much greater. shown in correct position and every wire is shown going to its correct

The circuit consists of one shield grid stage, detector and two trans - destination by the ACTUAL ROUTE taken in the practical wiring itself.former audio stages, with 112A in the last stage. Mr. Herman's personal set was used as the model. This is a matter -of -

When you work from the official wiring diagram you find everything fact blueprint, with solid black lines showing wiring that is above theso delightfully simple that you marvel at the speed at which you get the subpanel, and dotted lines that show how some of the wiring is doneentire receiver masterfully finished. And then when you tune in-more underneath.marvels! 'Way, 'way up, somewhere around the clouds, instead of onlyroof high will you find the amplification!- - - v-1.- - -- - - - - - - - - - - - - Everything is actual size.

I EVEN A NOVICE CAN BUILD THIS CIRCUIT SUCCESSFULLY!RADIO WORLD, 145 West 45th St., N. Y. City. I

Enclosed please find:Not only is the actual size of the panel holes and instruments given,

0 $1.00, for which enter my name on your list of mail subscribers for seven but the dimensions are given numerically. Besides, it is one of those1weeks and send me FREE at once one official blueprint of the Four -Tube Shielded deligntful blueprints that novice and professional admire so much-one

Grid Diamond of the Air, as designed by H. B. Herman, and described by him of those oh -so -clear and can't -go -wrong blueprints.in the February 4th, 11th and 18th issues of Radio World. No other premium 1

this offer. 0 45c extra for Feb. 4th, 11th and 18th issues. Be one of the first to send for this new blueprint, by all means, andRenewal ID Present subscribers may renew for seven weeks under this offer. f build yourself this outstanding four -tube receiver, with its easy control,

Put a cross next to word "Renewal." ' fine volume, tone quality, selectivity and utter economy. It gives moreI than you ever expected you could get on four tubes-and the parts areI well within the range of anybody's purse.

Complete official list of parts given on each blueprint; also theschematic wiring diagram (besides the picture diagram of the wiring.)

CilY l SEND YOUR ORDER TODAY!

NAME

ADDRESSSTATE


"DOUBLE R"METERS

Our Complete Cotalogueof Meters is Contained

in This AdvertisementPOCKET AMMETER

No. 1 -For testing dry cells, 0-40 ampereDC scale pocket meter $1.50

POCKET AND PORTABLEVOLTMETERS

No. 8 -For testing A batteries, dry or stor-age, 0-8 volts DC scale $1.65

No. 10 -For testing A batteries, dry or stor-age, 0-10 volts DC scale 1.6

No. 13 -For testing A batteries, dry or stor-age, 0-16 volts DC scale 1.65

No. 50 -For testing B batteries, dry or stor-age, but not for B eliminators, 0-50 voltsDC scale 1.65

No. 39 -For testing B batteries, dry or stor-age, but not for B eliminators, 0-100 voltsDC scale 1.85

No. 40 -For testing A and B batteries, dryor storage, but not for B eliminators; doublereading, 0-8 volts and 0-100 volts DC scale 2.25

No. 42 -For testing )3 batteries, dry or stor-age, but not for B eliminators; 0-150 voltsDC scale 2.00

No. 346 -For testing B voltages, includingeliminators. High ressitance water 0-300volts DC scale 4.90

No. 347 -Same as No. 346, except that scaleis 0.500 volts 5.50

No. 348 -For testing AC current supply line,portable, 0-150 volts 4.50

VOLTAMMETERSNo. 18 -For testing amperage of dry cell A

batteries and voltage of dry or storage Abatteries, double reading, 0-8 volts, and0-40 amperes DC $1.85

No. 35 -For testing amperage of dry cell Abatteries and voltage of B batteries (not Beliminators); double reading, 0-50 volts, 0-40amperes DC 2.06

PANEL VOLTMETERSNo. 335 -For reading DC voltages, 0-8 volts $1.65No. 310 -For reading DC voltages, 0-10 volts 1.65No. 316 -For reading DC voltages, 0-16 volts 1.65No. 326 -For reading DC voltages, 0-6 volts 1.65No. 337 -For reading DC voltages, 0-50 volts 1.65No. 339 -For reading DC voltages, 0-100 volts 1.75No. 342 -For reading DC voltages, 0-150 volts 1.75No. 340 -For reading DC voltages, double read-

ing, 0-8 volts, 0-100 volts 2.25

(Panel meters take 2-5/64" hole)

PANEL AC VOLTMETERSNo. 351 -For reading 0-15 volts AC $2.25No. 352 -For reading 0-10 volts AC 2.25No. 353 -For reading 0-6 volts AC 2.25

(See No. 348 under "Pocket and PortableVoltmeters.")

PANEL MILLIAMMETERS No. 311 -For reading 0-10 milliamperes DC -$1.95

No. 325 -For reading 0-25 milliamperes DC 1.85No. 350 -For reading 0-50 milliamperes DC 1.65No. 390 -For reading 0-100 milliamperes DC 1.65No. 399 -For reading 0-300 milliamperes DC 1.65No. 394 -For reading 0-400 milliamperes DC 1.65

DC PIN JACK VOLTMETERSNo. 306 -For Radiolas No. 25 and 28, 0-6 volts

DC $2.50No. 308 -For No. 20 Radiola, 0-6 volts DC 2.50No. 307 -Desk type voltmeter with cord, 0-6

volts DC 2.50

6 -VOLT A BATTERYCHARGE TESTER

No. 23 -For showing when 6 -volt A batteryneeds charging and when to stop charging;shows condition of battery at all times $1.85

PANEL AMMETERNo. 338 -For reading amperage, 0-10 amperes

DC $1.65

SEND NO MONEY!GUARANTY RADIO GOODS CO.,145 W. 45th St., N. Y. City.

Please send at once your meters, cataloguenumbers:

for which I will pay postman advertised priceplus few cents postage.

Name

Address

Europe at 1 a.m. HearsBremen Fliers in N. Y.

Twenty German broadcasting stations anda network of Austrian stations, connectedby telephone lines, successfully rebroadcastthe New York reception of the Bremenfliers by picking up 2XAF, the General Elec-tric short wave station, at Schenectady,N. Y., and on Wednesday, April 30th, aDublin, Ireland, station picked up theSchenectady station.

An English radio publication "World -

.4IDEAS!

A handy manual of 36 pagesand cover -88 illustrations -over 20,000 words -practical-concise - understandable -prepared by Austin C. Les-carboura and our engineer-ing staff. That's "The Gate-

way to Better Radio" -yours for 25 cents,either from local radio dealer or direct fromus by remitting stamps or coin.American Mechanical Laboratories, Inc.

Specialists In Variable Resisters285-7 N. Sixth St. Brooklyn, N. Y.

C AROST 153.Reg us , -

The Aerovox Research Worker is a freemonthly folder that will keep you abreast

of the lateSt developments in Radio.A postcard will put your name on

the mailing list. Write to-day. Aerovox Wireless

Corp., 72 Wash-ington Street,

Brooklyn,N. Y.

Radio" in a column edited by Jay Coote, hasthe following descripion of the rebroadcasts:

"The last ten days or so have furnishedmany surprises in the shape of interestingtransmissions of which no mention was madein the published programs. Personally, Ienjoy them, although on most occasions de-votion to my Super -Het. entails late hoursand a corresponding lack of high spirits thefollowing morning.

"However, in common with most radiofans, I think it is worth it.

The Eventful Night"Germany, during these last days, was re-

sponsible for the majority of the specialrelays, and on many nights .the WGY trans-mission could be picked up on the Stuttgartand other Continental wavelengths."

"On that eventful night of Saturday -Sunday, the Berlin transmitter gave out thatthe German aviators were on their way byrail to New York, and it was hoped tobring to the ears of their compatriots theofficial reception given to Captain Kohl andhis colleagues. All German studios stoodby and, via Munich, the Austrian trans-mitters were roped into the telephony sys-tem. From about 1 to 1:30 A. M. fromSchenectady many speeches in English wererelayed, including a few words of greetingby Mr. Walker, the Mayor of New York.

"Later, personal messages were sent inGerman by Baron von Hunefeld and Cap -(Continued on next Page)

VICTOREENSuper CoilsSend for Folder

Geo. W. Walker Co r?.'2825 Chester. Avenue

Dept. B Cleveland, 0

EVERY FRIDAY at 5.40 P. M. (Eastern Day-light Time) Herman Bernard, managing editor ofk..wo V or id, broadcasts from WGBS, the Gimbel

.ration in New York, discussing radio topic,

Take Your Choice of 6Other PublicationsFor NEW RADIO WORLD Subscribers Ordering NOWRadio World has made arrangements-To offer a year's subscription for any one of the following publications with one year'ssubscription for RADIO WORLD -RADIO NEWS or POPULAR RADIO or SCIENCE AND INVENTION or BOYS' LIFEor RADIO DEALER or RADIO (San Francisco).

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Radio World's Special Two -for -Price -of -One Subscription BlankRADIO WORLD, 145 West 45th Street, New York City.Enclosed find $6.00 for which send 'me RADIO WORLD for twelve months (52 numbers),beginning and also without additional cost, Popular Radio, orRadio News, or Science and Invention, or Radio Dealer, or Radio (San Francisco), orBoys' Life (or $10.00 for a two-year subscription to one address), thereby getting RADIOWORLD and the other selected magazine, BOTH for two years. No other premium withthis offer.

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MONEY -BACK GUARANTY

NO OTHER PREMIUM OF ANY KIND WITH THIS OFFER!

June 9, 1928 RADIO WORLD(Continued from preceding page)

tain Kohl; Major Fitzmaurice also addeda few words in reference to the Green Isleof Erin and the lesser Greene-ly Islandon which they had landed.

Twenty German Stations 'Join In"It would be difficult to estimate the num-

ber of listeners in Great Britain who pickedup this broadcast either direct on shortwaves or through the Continental stations,but as some twenty German broadcasterstook it, this interesting event was placedwithin the reach of many million hearers.

"Finally, quite unexpectedly, Dublin, onApril 30, at the end of its evening program,announced that an attempt would be made tobring America to the ears of its subscribers.The relay of a transmission by WGY,Schenectady, via 2XAF, was a success ; thebroadcast was carried out from 11:20 to11:47 p. m. and again from 11:57 p. m. to12:22 a. m. with a transmission of gramo-phone records during the intervals."

Sidetracks Opera OpeningIn the same publication appeared the fol-

lowing added information on the "Bremen"broadcasting:

"A relay was made by Berlin last Satur-day from Schenectady of the preliminaryreception given to the Atlantic fliers in NewYork. In view of the double attraction ofa topical event and a relay from America,the Funk Stunde undertook to interrupt itsprogram the moment the aviators arrived inNew York-and this in spite of the factthat it was taking the long-awaited broad-cast from the reopened Opera House in Un-ter den Linden. Fortunately, the necessitydid not arise until 12:33 a. m.

"The American short-wave station wasvery well received in Germany, many of thewords coming through with astonishingpurity. Atmospherics were non-existent,the only palpable defect being an abruptkind of fading, which, however, did notprevent the remarks from being understood.

Fitzmaurice Amuses"The Mayor of New York, Mr. Walker,

gave a hearty welcome to the aviators, whothen spoke, Baron von Hunefeld and MajorFitzmaurice in English, and Captain Kohlin German.

"Major Fitzmaurice, whose address wasthe shortest, caused amusement by his con-cluding remark that he could not say howpleased he was to be there, 'because, as Ihave already mentioned, you never knowwhat might happen. Goodnight !'

"The Mayor added that Major Fitz-maurice was looking very happy and that itwas for them to see that every moment he

\ LYNCHFilgrid control for screen grid tubes.

Complete with mount, $1.50.ARTHUR H. LYNCH, INC.

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spent on American soil was equally happy.Then the broadcast continued until 1:15,when Schenectady resumed its regularprogram and Berlin closed down.

"It was evident from the remarks ofthose taking part in the informal proceed-ings that they thoroughly appreciated thefact that Germany was listening to them."

A FILTER

TOBE A FILTER and a Rectigon,Tungar or any good two amperecharger will give quiet, simple fila-ment supply for your set.No need to bother with the messyA BATTERY any more.Write for Pamphlet on this newA FILTER AND A CONDENSER.

TOBE DEUTSCHMANN CO.Cambridge, Massachusetts

New York Office: 117 -Liberty StreetIn Charge of Arthur J. LyonsTelephone: CORtlandt 3446

Subscribers: Look at the

Expiration Date on

Your WrapperWe do not like to take your name from

our subscription list without specific in-struction to do so because many of owreaders wish to keep a complete file of thepaper.

Please, therefore, look at the subscrip-tion date stamped on your last wrapper,and if that date is earlier than the issuecontained in the wrapper, please sendcheck to cover your renewal.

In this way you will get your copieswithout interruption.

Subscription Dept., RADIO WORLD,145 West 45th Street, New York City.

ListPrice$4 50

The use of Ionized Helium gives to theRaytheon "BH" Tube a superior rugged.ness, a far longer life and a sustainedvoltage. Be sure you get a RaytheonBH for your eliminator when the tubeneeds replacing, which is generally everynine to twelve months.

.4.47°vainear

4-40. LONG LIFE RECTIFYING TUBE

BLUEPRINTand Instruction Sheet

for the Silver -MarshallShielded Grid Six

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Powerful Kick.Guaranty Radio Goods Co.

145 WEST 45TH STREETNEW YORK CITY

KARAS SHORT WAVE SET, three tubes, 13to 750 meters, described in the March 31, April7, 14, 21 and 28 issues. Send 60 cents for thesefive issues and get blueprint free. RADIOWORLD, 145 W. 45th St., N. Y. City.

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NEW SHIELDED GRID TUBES for Dia-mond, S -M Six or Laboratory Super, Tyrman 70.Price $5 each. Philip Cohen, 236 Varet St.,Brooklyn, N. Y.

RECENT ISSUES of Radio World, 15c each.Be sure to give date of issue when writing. RadioWorld, 145 West 45th Street, New York City.

LET us add $40.00 to your pay each week with-out interfering with your present occupation.Pleasant interesting work. Hike Dirt Co., Polk,Pa.

"CALIFORNIA STATIONS" Three in onenight, 3 tube Foreign Circuit Blueprints 50c.A. R. S., Box 18, White Plains, N. Y. 6-30-28

GUARANTEED Safety Razor, with strop, in neat,strong carrying case, 25 cents. First-class, new.Send coin, M. 0. or stamps.-P. Cohen, 236 VaretStreet, Brooklyn, N. Y.

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THE NATIONAL SCREEN GRID 5, describedby James Millen in April 14th, 21st and 28th issues.Fully illustrated, including picture diagrams ofwiring. Uses screen grid tube for the single RFstage, four other tubes standard. Send 4k forthese three copies and get blueprints free. RADIOWORLD, 145 West 45th St., New York City.


AScientific

(I) Onemeterboth.PhDC

(2) Onetochangeoverwhich

(3) Onewith

(4) Onedetectorfor

(5) One(6) One(7) One(8) Two(9) One(10) One

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DC milliammeter,100 milliamperes,

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resistance voltmeter,to measure B voltages.

30 -inch cordand one 4 -prong

change bias.

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Price

$ 1.....--

[Outfit consists of two units, one being the 0-300voltmeter (Cat. No. 346), the other the testerwith enumerated parts built in. (Cat. No. 215.)J

Shooting Amazingly Simplified!TroubleInstead of bearing the expense of an assortment of meters, servicemen, custom set builders, home constructors, experimenters,teachers, students and laboratories can now fulfill their set -testingand tube -testing needs with the Two -in -One Test Set.If you want to test a tube or associated circuit, remove the tubeand insert it in the proper socket of the tester. You can't make amistake, because the number of prongs on the tube base confinesyou to only one of the tester sockets :Now insert the plug in the vacant socket of the receiver-using thefour -prong adapter if the tube came out of a four -prong socket.Attach 0-300 voltmeter to two binding posts. Turn on the receiver.Presto! You read filament voltage (AC or DC), plate current andplate voltage !

Absolute 5 -Day Money -Back Guaranty!Get one of these Two -in -One Testers and try it out. If not com-pletely satisfied return the outfit and your purchase price will berefunded. If you're not delighted we're not even satisfied.[Some may prefer 'to read higher plate voltages than 300 volts. Inthat event a 0-500 high -resistance voltmeter (Cat. No. 347) maybe obtained instead, at $1 extra; total $14.50.]

GUARANTY RADIO GOODS CO.,11145 West 45th Street, New York City. SEND NO MONEY !iPlease send me at once, on a five-day money -back guaranty, one corn- You can obtainthe T in 0 e Tester= with 0-300 or 0-500vsollir

meter, simply by, filling returrii'for

plete Two -in -One (AC and DC) scientific trouble -shooting test set, con- prandnC. 0. D. at the specified prices, plus a liegw centsp postage. NOsisting of one Na. 215 and one No. 346, far which I will pay the C. 0. D. to foreign countries, however.postman $13.50, plus a few cents extra for postage.

1

Remember that our five-day money -back guaranty is absolute0 If 0.500 v. high resistance voltmeter No. 347 is preferred, put cross and unqualified. You run no risk whatever.in square and pay $14.50, plus postage, instead of $13.50, plus postage. Cat. No. 215 Two -in -One Universal Tester (Outfit complete

except for high resistance voltmeter) $10.00El One No. 215 alone $10.00. Cat. No. 346 High resistance voltmeter, 0-300 volts 4.501 Cat. No. 347 High resistance voltmeter, 0-500 volts 5.50

NAME

ADDRESS]

GUARANTY RADIO GOODS CO.

1

145 West 45th StreetCITY STATE NEW YORK, N. Y.ALL METERS SOLD ON FIVE-DAY MONEY -BACK GUARANTY

(Few doors east of Broadway)1

6 PAGES ABOUT NEW PARTS AND SETS! - JumpJet …...cost you can quickly receive the factory -built...

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Transcript of 6 PAGES ABOUT NEW PARTS AND SETS! - JumpJet …...cost you can quickly receive the factory -built...