June Meeting Report

Last month we had the pleasure of a fascinating illustrated talk about Lundy given by Brian G4CIB, aided by his wife Leta G4RHK, both of whom are prominent and active members of the Gloucester club.

Lundy lies in the Bristol channel some two hours sailing time from Ifracombe in North Devon, it’s long and thin island about 3 miles north-to-south and about one quarter of a mile wide. There’s one pub, one shop and one landing stage. It’s had many owners over the years and is now in the hands of the National Trust but leased to the Landmark Trust as they are better placed to renovate and restore the old buildings which had been neglected by earlier owners. The only permanent resident on the island are employees of the Landmark Trust but there are a number properties of various sizes which are available for holiday lets and these have proved to be very popular. The island generates its own electricity using a large diesel engine which normally runs from 6am to mid-night. There are plans for a wind turbine, Lundy is a haven for wild-life, particularly puffins which have thrived since the non-indigenous black rats were eradicated several years ago.

Brian and Leta began holidaying on the island many years ago and quickly become so enchanted by the place that they’ve visited it every year, sometimes twice, ever since. They enjoy walking the island and watching the wild-life. And visiting the island’s pub! Radio gear is usually taken, which has to be lightweight because of baggage restrictions. Operation is usually fairly low-key with sessions around 7 to 9am and 4 to 5pm. Their next trip will be from 21st to 28th September.

The talk was very well received, members found it interesting and entertaining. We are very grateful to Brian and Leta for making the trip to Cheltenham to visit us. Incidentally instead of accepting expenses for their trip to us they asked that CARA make a donation to the Lundy Field Society which the club has now done – a nice gesture on their behalf.

May Meeting – Report

On 16th May we held an auction of, mostly, stuff from the shack of the late G7CVC (not a CARA member) from Tewkesbury. Tony G3YYH was, as usual, the auctioneer, Andrew M0MVA kept records of bids and successful bidders, Peter G3YJE collected monies owed, and Tim G8PZD acted as gatekeeper checking that lots were not taken away before payment had been made. They did a superb job and many thanks to them for all their good work. The bidding was a bit slow at times and Tony did well to ensure that everything was sold. All present appeared to enjoy the meeting and many thanks to those who opened up their wallets, so to speak, to make purchases.

March Meeting – Report

CARA’s annual Constructors’ Exhibition took place on 21st March, a meeting where members show items they’ve built at home during the last year or two.   We were treated to a very interesting range of exhibits many of which were constructed to a high standard.

Here’s a list, in no particular order, of the items on display:

A partially complete LV and HV power supply for vintage ex-military equipment such as the BC-348 receiver and the Collins ART-13 transmitter – shown by Tony G3YYH.

A QRP Labs QCX 5W CW transceiver for 40m built from a kit (some 6,000 such kits have now been sold) – Peter G4IOA.

A range of products, including antenna insulators and small cases, produced by his 3D printer – Alan M0NRO.

A portable power unit with solar panel for use with an IC-706 HF/VHF transceiver – Christopher M0YNG.

A demonstration of Mastodon, a Twitter-like app specially adapted and promoted by the exhibitor for radio amateurs world-wide – Christopher M0YNG

A components tester which tests and measures transistors as well as resistors, capacitors and inductors, assembled from a kit – Derek G3NKS.

A CFR (Controller Feeder Radiation) half-wave vertical dipole for 2m for use with his motor-caravan – Derek G3NKS.

The judges, Jon M0JMM and Roger G3REB, made the following awards:

The Bill Brown Cup for Best in Show to Peter G4IOA for his superbly built QRP Labs kit transceiver.

The Pat Moore G3IKR Memorial Cup for Innovative Construction to Christopher M0YNG for his novel portable power unit.

The Roger Kendall G0UPU Memorial Cup for best Computer/Software related Project to Alan M0NRO for his 3D printer project.

Many thanks to all the exhibitors, the judges and everyone else who attended, we had an enjoyable and successful evening.

February Meeting – Report

The Table Top Sale on 21st February proved to be another popular and well attended meeting. The tables were well populated with items for sale, including antennas, linear amplifiers, hf and vhf transceivers, computers and test gear – plus lots of bits and pieces such as components, cables, tools and mast hardware. Something for everyone perhaps!

Some sellers were content but others reported that trade was disappointing. However that’s how it goes! Your reporter has often taken stuff to several rallies in succession without out any interest being shown in the kit, but then at the next one it sells easily!

We were pleased to welcome to their first meeting – Dom M7PKW and Shaun M6OII. We look forward to seeing them again soon.

The new venue again proved its worth, being comfortable with good acoustics.

The next meeting is the Constructors’ Exhibition on Thursday 21st March at the same venue, the Robin’s Nest, Cheltenham Football Club.

Derek G3NKS

Christmas Lunch

There were 17 of us the CARA Christmas Lunch on 18th December, and a good time was had.  We enjoyed a three course meal accompanied but much lively chat.  Here are a few photos.

                                                   l-r Barry M0HFY   Tony G3YYH   Peter G4ENA   Ken G3LVP
                                      Some of the ladies.  l-r G3LVP/2   G3TEV/2   G4ENA/2   G3NKS/2

Annual General Meeting

The CARA’s 42nd AGM took place on Thursday 13th December 2018 with 32 members present.

Members at the AGM

Tony G3YYH, Chair, reported a successful year highlighting many notable events including two enjoyable Fun Field Days, Foundation and Intermediate courses with high pass rates, a fascinating visit to Ben Nock’s Military Wireless Museum and a good display of home-built equipment at our annual Constructors’ Exhibition. 

The Bernard King Memorial Cup awarded for noteworthy and praiseworthy on-the-air activities was presented to Tony G3SNN for his superb DXCC scores achieved over many years of sustained effort.  The John Holt G3GWW Award for exceptional work for the club went to Smurf M0URF for his outstanding contributions to Fun Field Days.

The Treasurer, given the healthy state of the Association’s finance, proposed that the annual subscription remain at £13.  Approved unanimously.

The Committee for the year 2019 was elected.  Chair – Tony G3YYH, Secretary – Derek G3NKS, Treasurer – Peter G3YJE, ordinary committee members – Andrew M0MVA, Alan M0NRO, Christopher M0YNG.  Accounts Examiner – Tony G3SNN.

Any Other Business.  Tim G8PZD queried whether a decision had been made regarding the move to a better venue for our monthly meetings.    Two venues were contenders, one tried in November and one suggested at the meeting.  The Chair asked that, following further investigations, the Committee be allowed to make the final decision regarding the move – this was agreed.   Tony G3SNN proposed a vote of thanks to the 2018 Committee for their good work and to  the Editor, Christopher M0YNG, for producing such excellent newsletters every month.

Following closure of the formal meeting members enjoyed a light finger buffet and lots of chat.

October Meeting Report

The “Skills Evening” held on 18 October proved to be very popular, with one of the highest attendances so far this year. Six members manned tables around the room to demonstrate, explain and talk about an aspect of amateur radio – usually one which was a particular interest of theirs. Ken G3LVP explained how make properly make-off coaxial connectors such as BNC and N-type, with examples and supporting diagrams. Peter G3YJE demonstrated a “Tuna-Tin” QRP transmitter, showing the output waveform on a ‘scope. He was also promoting the American Radio History website to which he has been contributing for several years. Paul 2E0IFV had a display of DMR radios, including hand-helds, and demonstrated their use. Tony G3SNN showed his fine collection of exotic QSL cards for his 160m and 6m activities. Barry M0HFY had a live demonstration of FT8 (one of the latest data-modes which is currently very popular), making several contacts during the course of the evening. Mike G4GUG was extolling the virtues of Linux, and telling how well this Operating System would run on older machines. Each of the tables attracted a gathering of members for much of the evening, and much general and lively chat took place as well. Very many thanks to the six members who kindly “volunteered” to man the tables and indeed to everyone else who made an appearance; you all contributed to the undoubted success of the meeting. We were pleased to enrol Chris M6NZC as a new member and John 2E0GCR who re-joined after an absence of a year or two. Thanks once again go to Alan M0NRO for kindly manning the kitchen. Thanks also to the several members who, without being asked, helped clear away the tables and chairs at the end of the evening – your efforts are much appreciated.

July Meeting Report

Last month we were pleased to welcome back Peter G3RZP, a well known speaker at amateur radio functions – at local, national and international levels.

The title of his talk was “Clean Signals” and he proceeded to tell us why transmitters, and SSB transmitters in particular, emit signals which are much wider than they should be – and so cause interference to stations on adjacent frequencies. SSB transmitters are essentially “linear” amplifiers, amplifying a signal generated at low-level up to the desired power required for transmitting a signal to wherever. However, the amplification process is not actually truly linear because of the inherent characteristics of the active devices, be they thermionic valves or solid-state devices. In an SSB transmitter the non-linearity gives rise to what are known as “intermodulation products” which spread out either side of the main signal. Intermodulation products are, in the simplest case, caused by two discrete signals being amplified mixing together, because of the non-linearity, to produce low-level signals spaced from each other by the difference in the frequency of the two signals. The further away from the main signal the weaker these products become. But even low-level “spurii” can cause QRM to near by stations.

So the way to minimise such interference – sometimes called splatter – is to make the transmitter/amplifier operate as linearly as possible. This can be done by making sure that the equipment is not over-driven – ie by not turning the mic gain up too far, by using minimal amounts of ALC and by making sure that the transmitter sees the correct load impedance. In the design stage negative feedback can be introduced to improve linearity, but this can cause other problems if not done carefully. One way to check that the transmitter is being operated corrected is to inject two audio tines into the mic socket and look at the RF output with a suitable ‘scope, the tops and bottoms of the waveform seen should be nicely rounded. Peter’s view was that in general valve amplifiers are inherently more linear than solid-state ones.

The talk was well received to judge by the number of questions asked. Many thanks to Peter for travelling from Swindon to see us once again.

JUNE MEETING REPORT

A good turn-out of members enjoyed an interesting display of exhibits from members’ radio rooms (or shacks if you prefer!). The exhibits ranged from early types of detectors of radio signals to a modern piece of kit to power radios from solar energy. Also on display were a selection of old QSLs cards, an Elecraft Miniature ATU, a once popular IC-202 portable 2m SSB rig from the past, a Retevis RT82 DMR hand-held, a portable station in a box and a dog! To add further interest to the evening Mike G4GUG gave a short talk on how to set-up a rotator for satellite working.

Many thanks to everyone who brought along something to show, to Mike for his talk and to Peter G3YJE for manning the kitchen (yet again!).

MAY MEETING REPORT

Several members attended the Thursday evening meeting to listen to Colin G3VTS and Jon M0JMM talking about the construction of their antennas.

Colin who was awarded the G5BK cup at the Constructors’ Exhibition for his 5 band cobweb antenna. He described his cobweb as 5 dipoles in a square shape with 1⁄4 wave sides with the feed point in one corner. The impedance was found to be about 12 ohms needing a 4:1 balun to match 50 ohms coax cable. Colin made good use of a projector and photographs he took during the construction period which took place in his garage and then testing it on the garage roof. He found that the bandwidth was narrow and although no DX was worked, Colin will no doubt be tweaking it leading to further trials in the future.

The second speaker Jon, talked about his 2 metre 3 element Yagi antenna manufactured from a Tape Measure, plastic water pipe, Jubilee hose clamps and a small piece of wire to form a match to 50 Ω coax cable. The tape was cut to lengths suitable for the driven, reflector and director elements, with the driven element cut in half to form the dipole. They were mounted on the plastic tubing to form the Yagi antenna using the hose clamps to hold them in place. At the dipole centre, a hairpin match and the coax cable were soldered to the centre of the dipole. For more information on construction and dimensions of this antenna, look up “Tape measure antenna”.

Jon said that it was ideal as a DF antenna for fox hunts because it was portable, light weight, had a good front to back ratio, a reasonable gain and above all cheap and easy to make.

The talks were well received by the members and it was good to see that the spirit of ‘homebrew’ is still alive !