SURREY RADIO CONTACT CLUBFounded in 1935

DECEMBER 2014 – No: 868

CLUB NET 1.905 MHz Sunday 9:30am

CLUB NET 145.35 MHz +/- 25kHz Friday 9.00pm

CLUB Internet WEB Site: h ttp:// ww w.g3src.org.u k

Hon. Sec. John Kennedy G3MCX22 Croham Park Avenue

SOUTH CROYDONSurrey CR2 7HH

020-8688 3322

E-Mail: secretary@g3src.org.uk

MONTHLY MEETINGS 1ST AND 3RD MONDAYS 7.30 FOR 7.45pm

Meetings at Trinity School, Shirley Park, Croydon CR9 7AT*******************************************************************************************

1st MEETING: Monday 1 December. Club Construction Competition.

2nd MEETING: Monday 15 December. Move-it-On and Fix-it Session led by John G8MNY and pre-Christmas Social

SRCC Committee 2014/15

Chairman & Club Meetings G4FDN Pat McGuinness 020 8643 0491Vice-Chairman G3ENG John Mathews 020 8652 6604Secretary & Communications G3MCX John Kennedy 020 8688 3322Treasurer& Membership Records G4FFY Ray Howells 01732 357474Contest Co-ordinator, Newsletter Editor & Publicity G8IYS John Simkins 020 8657 0454Web Master G4FYF Steve Jones 020 8406 0919 Chief Fund-raiser, Liaison, Recycling, Equipment G4DDY Maurice Fagg 020 8669 1480Committee Member M0LEP Rick Hewett 01689 851472

Dear Members & Friends,

Hello and welcome to the December 2014 issue of the Newsletter, edited by John G8IYS. I wonder how many readers spotted the error in the banner for last month's Newsletter. Although all the content related to November, the banner remained unmodified from that for October. That is the danger of using the previous month's header as a template. Thanks to Jim G4WYJ for spotting that. Only one member received a corrected Issue 2, because the original posting did not arrive in his in-box. I did not bother to re-send to anyone else, apart from the SRCC Website archive. Anyway, now sorted.

You will be pleased too to note the return of the Chairman's Blog from Pat G4FDN. This is also an opportunity, on behalf of the SRCC Committee to wish the compliments of the season to all members and readers from other clubs and organisations.

THIS MONTH'S MEETINGS

First Meeting: Monday 1 December Club Construction Competition.

Second Meeting: Monday 15 December.Chat & Fix-it Evening and pre-Christmas Social.

LAST MONTH'S MEETINGS by Hon Sec John G3MCX

First Meeting. Monday 3rd. November. Short Talks Evening.

The Chairman opened the meeting with the question: "Are we ready to kick off?"and reminded all present that the next Meeting on Monday 1st December would be the Annual Construction Contest. Pat also mentioned the

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forthcoming event at Kempton Park and CATS Bazaar.

First up was Bryan G6ODE, with a talk about valves. This was followed by John G3ENG on how to fit a PL 259 to a coax cable.

Bryan had a visit from Murphy before he came tothe meeting. Some of the exhibits he intended to bring with him were in the loft. The rope to pull the loft ladder down broke and there was nothinghe could do about it.

Note from Editor: I have augmented the meeting notes with a bit more on history because I think that many readers will have forgotten, or perhaps never knew, about the series of incidents and accidents by which rectifying and amplifying valves were developed.

The thermionic valve, otherwise known in north America as the vacuum tube, was a branch-off from the development of the electric light bulb. Work on the latter began in the early 19th century in Europe and the USA but it was not particularly fruitful until the tail end of the 1870s.

By 1878, Joseph Swan had a patent for a lamp, enclosed in a glass envelope and using a Carbon Arc, ie no filament, but an arc struck between two carbon terminals. This had high power consumption and limited life, because the carbon was consumed during its operation. In 1880, Swan obtained a patent for the first practical light bulb using a carbonised filament.

Edison Carbon Filament Light Bulb

In 1879, Thomas Edison obtained a patent for a bulb with a carbon filament and a high vacuum within the glass envelope. The lamp's life was 13.5 hours! During his experiments, he noted that the inside of the glass envelope blackened while the lamp was running. This was one problem that persisted, but was to have consequences for the development of valves.

Remember that at these dates, the only source of electricity was DC batteries. AC generation and distribution had yet to be developed. In 1884, when Johan Hittorf was working with hot cathode gas discharge tubes, he noticed that the device would conduct an electric current with the applied voltage in one direction but not in the other. He had discovered the rectifying diode but did not recognise its significance.

Back in 1880, Edison had noticed that the envelope blackening of carbon filament lamps had an area that remained clear. It consisted of a stripe running down the glass directly in line with the two vertical wires that formed the filament, but only on one side. Edison later positioned a plate between the wires to screen off the carbon, but this did not cure the blackening problem. He did notice however that a current would flow to the plate when it was positive, but not the other way round. This was called the "Edison Effect" also sometimes referred to as Thermionic emission. Just like Hittorf, Edison did not move on from these observations, but maybe it is why Americans persist in referring to the Anode as the “Plate”.

Fleming Diode

Enter John Ambrose Fleming. He was aware of Edison's work and also worked on the blackening bulb problem. Whilst working on the Poldhu transmitter for the first telegraphic communication across the Atlantic, he identified the receiver as being the weakest link. Becausehe was hard of hearing, he wanted a visual indication of the presence of a wireless signal. Detecting (rectifying) the signal was then achieved by the Coherer or a magnetic detector.Coherer reception was either erratic or insensitive. In 1904, he realised that the "EdisonEffect" might help. He recovered one of Edison's bulbs with the additional plate and rigged up an experiment. The bulb used as a

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rectifier (detector) in the receiver was much moreefficient. The Thermionic Diode had been born.

In 1906, Lee De Forest added a third electrode to his version of the Fleming Diode. His first attempts met limited success, but changing the third electrode from a plate to a grid of wire improved the valve's control over the electron flow. De Forest called his development the "Audion". He claimed this device could amplify. This was maybe not true, but the new grid certainly helped. It was not until Dr Arnold of Western Electric USA perfected the device in 1913 that amplification was proven.

We can skip much of the rest of history – suffice to say that further developments followed, such as introducing more elements into the envelope, achieving massive increases in gain, power delivery, efficiency and frequency of operation, not to mention introducing ceramic/metal into the envelope and forced air or water vapour for cooling the device.

One of the earlier discoveries was that the closer the grid was to the filament, the higher thegain of the valve ie change in anode current output per unit change in grid voltage.

Bryan mentioned the 2C39 uhf/shf triode which he said was a wonderful valve which is specified up to 2 GHz, but he has had one working up to 3.4 GHz.

Bryan had two valves on display.

Bryan G6ODE

One with a broken envelope was a CAT6, datingfrom 1926/1927. The anode ran at 20KW and the heater at 22volts at 30amps = 660 VA. The other similar, but complete, valve was a Mullard TX12-12W. These are still used in Poland and were used by the BBC in large numbers. They are water cooled and were also made by GEC.

The valves were run until the filaments burned out. The filaments were originally made of pure tungsten, but later this was changed to an alloy to lower the working temperature. The intention was that they worked between 1200 and 1400 degrees Celsius rather than 2000 degrees. The result was increased life.

Bryan said that he had opened up many valves to see how they worked. He explained how it was possible to weld them up again. Using a turntable it was possible to cut the glass and, with a gas flame, it was possible to weld it up again. Bryan worked for Mullard and obtained much information from their library. He came across air cooled valves at Pirbright, gained more information and a few samples. The BBC's Long Wave transmitters at Droitwich did have the water cooled CAT 27 valves. At that station, he observed a 3HP motor driving a water cooling pump for the valves.

At this stage, Bryan said his Company's main customer was the motor trade, but Japanese companies had cornered that market - so he retired and got married! One or two questions were asked before a break for coffee. One of which was what gas is most commonly used in a rectifier. The answer was that if not a vacuum,then mercury vapour or Xenon.

After the break John G3ENG took over. Many will have seen the high standard to which he works with any construction project. His demonstration of the best way to fit a PL259 was no exception. He had several pieces of

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cable to pass round to illustrate the various stages.

John said that most mistakes are made with soldering the copper braid of the cable to the connector body. John used a pipe cutter to carefully remove about two inches of the outer sheath without damaging the braid. He then thoroughly tinned the surface of the braid which rendered it rigid. He employed two different sizedpipe cutters. He then carefully removed enough of the end braid with the insulation so that the body of the plug would cover the braid that remained. He reminded constructors to put the outer shell on the cable before fitting the plug body onto the braid.

The body is then screwed tightly onto the braid with the inner conductor wire projecting from theend of the hollow inner tubular conductor of the connector.

The best plugs have four holes in the body, but many only have two. He then carefully soldered through all the solder holes and then the inner conductor is cut just proud of the inner tube. Solder is applied to the end of this wire so that itis slightly domed and then smoothed off with a file. The outer shell is screwed down over the body and the job is done.

If time and care has been taken to fit a plug like this, it should never be the source of a problem during use.

We thank Bryan for an interesting talk and John for making the perfect fitting of a coax plug easyto follow/pics this time.

Second Meeting Monday 17 NovemberChat and Fix-it Evening.

This followed the usual format of fixings, consultation and informal chat. I am sorry that there are no pics this time.

Chairman's Blog by Pat G4FDN

You were all spared my usual blog last month because of a trip to Germany, but it resulted in a good selection of other contributions. I appeal once more for members to let us know

what they have been up to in either words or pictures, or both. Contributions, long or short, tobe sent to our editor John G8IYS.

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Winter Weather: It has happened in the past when there have been adverse weather conditions on a Club meeting night, that either Trinity has closed the school, or we have decidedbecause members anticipate travel difficulties, to cancel the meeting. To avoid wasted journeys, I maintain a list of mobile telephone numbers of those members who have requested to be notified by SMS text, when these conditions occur. If you would like to be added to the list, please let me know. Our Hon. Sec. John G3MCXwill also advise members by phone call if he is requested to do so by those individuals.

Christmas Day Nets: There will be two short nets to exchange greetings, the first at 0930 GMT on 1.905 MHz LSB, with John G8MNY probably as net controller, and the second at 1000 GMT 1.942 MHz AM with Martin G4FKK as net controller, no doubt using some of his vintageAM equipment.

Bluetooth: Many of us will be familiar with this technology from our mobile phones, and the first one I had that was so equipped was an Ericsson T39, around 2001, I think. Ericsson developed the standard in 1994, so the technology is now 20 years old. Bluetooth is a wireless technology

standard for exchanging data over short distances (using short-wavelength SHF radio waves in the ISM band from 2.4 to 2.485 GHz) from fixed and mobile devices, and building personal area networks (PANs). Up until recently, I had only used it for synchronising data between my mobile and my laptop, and had not explored hands free or wireless headsetuse. However, that changed last month when we purchased a car with Bluetooth handsfree built in, for phone calls, and that also supported music streaming over Bluetooth from your phone. I was pleasantly surprised at how straight forward it was to set up and configure the pairing such that anytime I get in the car it pairs with the mobile automatically and all my contacts and call lists are accessible via controls on the steering wheel, or the ICE (Information Communication Entertainment) console, or by voice control too. The microphone is built into the front dome light just above the windscreen, and it uses the speakersfrom the ICE system. All the varied functions of the ICE system including navigation voice direction and display appear to have been thought through carefully, as you get an integrated display showing who you are calling/speaking with, the time/date, inside & outside temps, navigation, etc, controlled in a context sensitive way.

I was also pleasantly surprised to find while driving on the continent that the SatNav real time TMC (Traffic Management Control) messages still came up in English. Their use allowed us to avoid a 30 minute delay queuing into the Antwerp Ring. I have diverged slightly from the topic of Bluetooth;. I will now return as it occurred to me that the car’s hands free system would make an interface for safe mobileoperation. A small number of VHF/UHF transceivers, handhelds and mobiles haveappeared that offer Bluetooth as an option, albeit as quite an expensive one (£60 to £100). As a result, there have been a couple of designs for home brew interfaces. The most sophisticated being the one by KG4JJH who had a construction article in QST, details here: http://www.kg4jjh.com/Bluetooth.html There was also a device made by Jabra, the Jabra A210, which was designed to allow mobiles withBluetooth, to be used with a Bluetooth wireless headset. An article describing the adaptation of the latter for amateur radio use is located here: http://www.alexloop.com/artigo35.html Bluetooth, as a standard, offers many ‘profiles’ or modes of operation depending on the device

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application. Another popular use is for data transmission avoiding a wired serial or USB connection. An article describing a homebrew project of this type by M1GEO is located here: http://www.george-smart.co.uk/wiki/Bluetooth_Radio_Interface

So, my thoughts at the moment are around constructing a KG4JJH type interface so I can take advantage of my car’s hand’s free system with a VHF/UHF transceiver for safe mobile operating. The main Bluetooth module that formsthe core of the kit is available in the UK for around £26. Commercial adapters for PMR operation have been available for some time but they tend to be expensive. A few examples are: http://www.sena.com/product/adapters/sr10/ and http://hamgear.wordpress.com/2014/03/30/baofeng-bluetooth-adapter/ and http://www.commercial-radio.co.uk/Bluetooth.html and http://www.headsetusa.com/bluetooth-for-2-way-radios-and-cellular-phones/

Kempton Radio Fair 9th October: As usual, the SRCC had its normal stand led by Maurice G4DDY and assisted by myself, Rick M0LEP, and also John G3ENG for the initial unloading. Attendance by SRCC members was also good, and I managed to snap the following:

Ivor M0IMJ

At the peak time, it seemed a little less packed than last time, but the number of traders was up, and I understand from Ray G4FFY, one of the organisers, that all available trading space was taken.

John G4EWX

Peter M1PFS

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Terry G4CDY

Andrew G4ADM

Maurice G4DDY

Denis G0OLX

One of the new stands were taken by Denis G0OLX, the well known GB3NS/GB7NS repeater keeper, with his stand promoting DMR UK and operation on DMR in general.

Our own ’Mr Fix-It’, John G8MNY, was manning the Home Counties ATV stand, and we managed to snap Ray G4FFY at the same time during one of his inspection tours of the floor.

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John G8MNY (L) & Ray G4FFY

Pat G4FDN (L) and Rick M0LEP

I also saw and chatted with Victor G3YIS there too, when I took a break from manning the club stand. My purchases at Kempton were fairly modest being a selection of ferrite toroids from Robin G3NFV’s Sycom stand.

Home brew filters, and testing on a VNA (Vector Network Analyser): At the second meeting in November, Steve G4FYF brought along a board he had made with adjustable 20m and 40m bandpass filters that he had made for his evolving QRP transceiver. He wanted to see whether their characteristics were as designed, and how much tuning they needed to get them centred with an acceptable shape. We achieved the desired result and the filters looked good when tuned. What we neglected to do on the night was to take some screenshots to record theoutcomes. Afterwards, Steve emailed me asking about the possibility of testing his homebrew crystal filter. Unlike his 20m and 40m filters whichwere designed for 50 ohm characteristic impedance, the inspection of the circuitry surrounding the filter indicated that its impedance

was of the order of 200 ohms. This means that ifone is to test a filter it needs to be terminated and driven from a source that matches its impedance and that impedance needs to be transformed to that of the VNA. In this case, a simple 4:1 balun or unun transformer would be suitable. To demonstrate what happens to a mismatched crystal filter I set up a 10.7 MHz filter from a Pye Westminster in the VNA and measured the loss through it. The filter is designed for around a 500 ohm termination, I think, but the VNA is designed for 50 Ohms, so quite a magnitude of mismatch.

As you can see from the above plot, the bandpass becomes extremely rippled. For reference, I also measured the phase characteristic, shown below:

If one doesn’t know the characteristic impedance of a filter it can be determined from measuring the input impedance under open circuit and short circuit conditions alternatively on the output and then calculating the geometricmean of the two measurements.

Pre-Christmas get together 15th December: There will be the usual fare of warming spirits and hot mince pies, so not to be missed. John G8MNY will be running a normal Fix-It session as well for anyone who needs assistance. If you

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can let him know in advance your needs he can come better prepared.

Sign-Off: Looking forward to a good turn out and many entries for the Construction Contest onthe 1st December. 73. Pat G4FDN.

Re-vamped Frequency Counter by Steve G4FYF.

I had a large liquid crystal display (LCD) module and a box doing nothing so earlier this year I decided, in an idle moment, to turn them into an easily visible bench PIC frequency counter.

The circuit was, in fact, that of the club construction project back in June 2007 based on the original design by Eamon Skelton (EI9GQ) and incorporates mods described by John G8MNY to enhance the lower frequency sensitivity. I have tweaked the PIC code to display my callsign.

The PCB, using surface mount components, is nut/bolt attached to the LCD module which is then attached to the box aperture using strong double sided foam tape.

With John’s use of his accurate frequency generator one fix-it night, once the value of the capacitor across the crystal was adjusted, the meter was calibrated. Really handy bit of (cheap!) bench kit that I can use without changing glasses!!

Refs: http://homepage.eircom.net/~ei9gq/counter.html

http://62.49.17.234/technical/Testgear/PIC_Freq_Counter_Mods.pdf

RSGB Affiliated Societies Contests (AFS)by Quin G3WRR

To those SRCC members who read their Newsletter assiduously (all of us, I am sure….) this item may look like a bit of déjà vu – particularly as, being a keen recycler, I am recycling some of the text from the January 2014 issue. But it’s that time of the year again, and this is a reminder that four of the six annual Affiliated Societies Contests (AFSs) take place between now and the middle of February 2015.

The background is that every year, the RSGB Contest Committee (CC) runs a series of contests for its Affiliated Societies (of which the SRCC is one). Whereas the majority of contestsare structured around entries by individual stations, the contests in the AFS series introduce a club component by allowing the formation of teams of up to 4 stations belonging to the same club. The club’s score is obtained by adding up the individual entrants’ post adjudication scores: listings of both club and individual scores are provided to let both clubs and individuals see how they are doing in comparison with their fellows and the opposition. In fact clubs are not limited to a

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maximum of 4 stations – they can put on as many stations as they like, and these are grouped into teams by the Contest Committee. Some of the larger groups are able to get enough stations on the air to enter A, B, C teamsand D teams are not unknown.

There are 6 AFS contests throughout the year, covering a good spread of frequencies (both HF & VHF) and modes, as follows (dates shown are for 2015):

EVENT DATE BAND MODE

TIMEUTC

HF AFS (CW)

Sun 11 Jan 80m CW only

1400 -1800

HF AFS (SSB)

Sat 17 Jan 80m/40m

SSB only

1400 -1800

432 MHzAFS

Sun 8 Feb 70cm Mixed mainlySSB

0900 -1300

50MHz AFS

Sun 18 Oct 6m Mixed mainlySSB

0900 -1300

Club Calls (160m AFS)

Sat 14 Nov 160m SSB only

2000 -2300

144 MHzAFS

Sun 6 Dec 2m Mixed mainlySSB

1000 -1600

As if this wasn’t enough, clubs’ entrants in the 6 individual AFS contests are aggregated by the Contest Committee into a sort of pan-AFS Championship referred to as the AFS Super League, which runs annually from the 50 MHZ AFS in October to the 432 MHz in the following February.

There was a good level of activity by SRCC members in the 2013/14 AFS Super League, with one or more stations taking part in all the individual events except the 144MHz AFS. Overall we achieved 27th place out of 112 entries by participating AFSs, with SRCC club results in the contributing events as follows:

50MHz 32/38Club Calls 39/49144MHz No entryHF CW 27/87HF SSB 52/91432MHz 26/44

SRCC individual members’ results in the contributing events were as follows:

EVENT CALL OP QSO POS50 MHz

G3WRR G3WRR 9 55/65

Club Calls

G3WRR G3WRR 22 67/98

HF CW G3SRC G3WRR 233 36/245

HF CW G0SAC G4WGE 188 95/245

HF CW G3MCX G3MCX 87 186/245

HF CW G4FYF G4FYF 35 227/245

HF SSB G3SRC G3WRR 183 56/246

432 MHz

G4WYJ G4WYJ 45 29/74

The 2014/15 Super League season is already under way, with the 50MHz and Club Calls events already passed. I put in a (sort of) entry in the 50MHz one, improving from 9 QSOs in 2013 to a sparkling 23, but missed out on Club Calls as the only antenna up at this QTH was a 6m dipole and these are not noted as top line performers on 160m! And I’m hoping to be on inthe HF CW event (and probably the HF SSB one too) from Peter G3RQZ’s excellent Godstone QTH again in 2015 (subject to his saying “yes” – I haven’t asked him yet…must dovery soon!)

As you have already no doubt guessed, this is really a gentle request to members to come on in one or more of the AFS contests and represent the club. Certainly contests aren’t everybody’s cup of tea and there’s certainly no attempt to arm lock members into doing something they don’t want (this is a hobby after all, and we’re supposed to enjoy it!) – but if you’ve taken part in contests before, or haven’t but think you might like to try something different, why not come on in one or more of theAFS contests and give it a try? The 2015 rules are currently available from the RSGB CC website at http://www.rsgbcc.org//cgi-bin/readcal.pl?year=2015 (VHF) at http://www.rsgbcc.org/cgi-bin/hfreadcal.pl?year=2015 (HF)

If you are interested and have any queries, please do contact me by e-mail at q.g.collier@btinternet.com or face to face at a club meeting. And I’m very happy to help with after the event activities such as log preparationand co-ordination of their submission.

73, Quin Collier G3WRR

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FUTURE SRCC MEETINGS

1 Dec Club Construction Contest

15 Dec Pre – Christmas Social

5 Jan The 5 MHz Experiment Updated G0TLK

19 Jan Fix-It. Move-it-On + Advice Clinic

OTHER CLUBS' MEETINGS

28 Nov

12 Dec

Wimbledon & District ARS

Surplus Equipment Sale

Christmas Social Contact Jim Noon M6AVV - 020 8337 4940. email jamesanoon@hotmail.co.ukWeb site:- http://www.gx3wim.org.uk

Normal meetings are usually at 8pm on the 2nd and final Friday of each month at Martin Way Methodist Church, MertonPark (corner of Buckleigh Avenue), SW19 9JZ.

11 Dec

Sutton & Cheam RS

Christmas Junk Sale. Note Date! M0SXD.

@ Vice Presidents Lounge, SuttonUnited Football Club, Gander GreenLane, Sutton – 8pm. Sec: JohnG0BWV 020-8644 9945

16 Dec

Bromley & District ARS

Q&A session for F & I Students during the year plus Mince Pies

Normal Meetings 7.30 for 8.00 pm @Victory Social Club, Kechill Gardens,Hayes, Bromley, Kent. Contact: Andy Brooker G4WGZ 01689 878089

5 Dec

Crystal Palace R & EC

Christmas Social, Amusing Video and Station on the Air.

All Saints Church Parish Rooms, Beulah Hill from 7:30pm. Bob G3OOU 01737 552170 (Meet normally monthlyon 1st Friday) http://www.g3oou.co.uk/

? Dec

Dorking & DARS

Christmas Dinner. No further info.

Contact: Garth Swanson G3NPC 01737 359472 email G3NPC@swansons.org.uk

Meetings held at The Friends MeetingHouse, Butterhill, Dorking, RH4 2LE. Meetings commence at 7.45 pm. Web site:- www.ddrs.org.uk

08 Dec

Coulsdon ATS

AGM

Meetings normally held @ St. Swithun’s Church Hall, Grovelands Rd, Purley 8pm 2nd Monday each month.

Steve Beal G3WZK. Secretary@ catsradio.org. Tel: 01883 620730.

6 Dec

18 Dec

Horsham ARC

Christmas Bash. The Countryman, Shipley.

Christmas Social. Holmbush, Faygate.

Meetings normally held on 1st Thursday each month at 20.00 hoursGuide Hall, 20 Denne Road, Horsham,West Sussex, RH12 1JF. www.harc.org.uk. Hon Sec Alister Wattemail: g3zbu@hotmail.com

STOP PRESS

Will members please check their details in their copy of the current membership list and advise before Christmas of any required changes. A new membership list will be produced in time formailing with the January 2015 newsletter.

That is it for another year. Vy 73. John G8IYS.

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