GMRT 2024 meeting report

The photos from the event are after the written report.

The 12th Scottish Microwave Round Table (GMRT) took place on Saturday 9th November in its usual venue of the Museum of Communication (MOC) in Burntisland, with doors opening at 09:30. Greeting us at the door and giving everyone a warm welcome was the familiar face of Peter Dick GM4DTH who was keeping the register of attendees and taking payments for the event and the evening dinner. The turnout for the round table was a healthy 48, almost filling the venue to capacity.

On arrival, attendees tend to split into two groups depending on priorities – those heading for tea, coffee, and other refreshments in the conference room, and others making a beeline for the display area to look through the stalls containing microwave equipment, test gear, and components that were for sale, looking for the best bargains before they disappeared. The test and measurement facility run by Brian Flynn GM8BJF and David Stockton GM4ZNX was already in operation (and was open for business throughout the day during breaks in the presentations). However, the activity in both areas was dominated by the sound of voices renewing old friendships and acquaintances and making new ones, and both groups intermingled as the start of proceedings approached.

The formal event opened at 10:30 AM and Professor Tom Stevenson from the MOC gave the customary welcome to the venue, including domestic arrangements and safety announcement. Martin Hall GM8IEM, the UK Microwave Group (UKuG) Scottish Representative, then welcomed the participants, and acted as chair for the morning session.

The first speaker was Mark Hughes GM4ISM whose talk was entitled “Printed Circuit Boards for Small Projects”. He started by briefly describing how breadboarding had changed over the years, and how modern surface mount components had improved performance and reliability. This has led many amateurs to start using Computer Aided Design (CAD) techniques to design their own printed circuit boards, because high quality factory-made boards are now available from the Far East at remarkably low cost. The minimum order quantities of 5-10 have also led to some useful ‘extra’ boards being passed on to other experimenters and a wide variety of functionality becoming available commercially, e.g. on eBay. Manufacturers require Gerber files to make the boards to order, and Mark went into detail with advice about CAD tools suitable for amateur use and design tips to ensure the populated boards would work when manufactured. He covered the best approach to achieving the desired result, including the importance of good circuit design, breadboard design and test, ground planes, vias, RF decoupling, thermal design, multi-layer boards, silk-screening etc. Most importantly he described the pitfalls to avoid during the overall process from initial concept right through to delivery of boards that work, including the checks that are needed at each stage of the development.

Following Mark’s presentation and response to questions there was a short break before Brian Flynn GM8BJF started his talk about “Frequency Standards for Microwaves”. He began by outlining the performance requirements for amateurs, and why we need frequency stability – primarily to find stations so we can work them. He then reviewed the historical background and how frequency standards had improved over the years together with evolving modulation methods and operational techniques. This covered everything from klystrons through Crystal Oscillators, Rubidium standards, TCXOs, OCXOs, DOCXOs, Caesium standards, to the latest GPSDOs, in which he looked at the benefits the technology provided in terms of frequency stability, availability and cost for amateurs. Brian reminded us that although GPS Disciplined Oscillators are locked to a Caesium atomic frequency standard in GPS satellites that propagation from transmitter to receiver introduces jitter, and that the overall performance depends very much on the quality of the oscillator design. He then presented the pros and cons of different standards for modern amateur radio activities, including base stations and portable operation, covering power requirements, convenience and cost.

After Brian had answered questions from the floor, we vacated the conference room so that lunch could be set out by the MOC volunteers. We re-assembled in the museum where the entries for the GM4LBV Projects Trophy were displayed for examination by the judges Ian White GM3SEK and David Stockton GM4ZNX. When the call went out that lunch was now ready everyone returned to the conference room to enjoy the fine food on offer, and to continue chatting.

Andy Sinclair MM0FMF, President of the Lothians Radio Society, took over as chair for the afternoon session and introduced Malcolm Hamilton GM3TAL as the next speaker. The first slot after lunch is a difficult one to fill, but Malcolm was up to the task with his light-hearted and engaging talk addressing his problems of “Getting Started on 23cm”. He started by describing his objectives – aiming to be fully operational on the band by 2025 whilst adopting a low-cost approach. He’s already started, though it’s early days yet, and is aware that “things are different above 1000 MHz”, and is finding that “some things are new to him”. He described the approach he’s adopted to building up a 23cm station, and where he’s reached operationally. Having considered make or buy he’s decided to buy, rather than build, and to develop the station one stage at a time. He’s now considering options for future stages, and presented system and equipment options for linear amplifier, sequencer, transverter, antennas and phasing options, and looked to the floor to help him make his choices, which led to some lively debate. Malcolm finished his talk by thanking those present for help in deciding how he should proceed.

There was another short break before the next presentation, entitled “Working Towards EME and DSN” by David Anderson GM6BIG. By way of introduction David explained that the NASA Deep Space Network (DSN) is a worldwide network of spacecraft communication ground segment facilities located in the USA (California), Spain (Madrid) and Australia (Canberra) which supports NASA’s interplanetary spacecraft missions. He illustrated the status of spacecraft being tracked in real time by this network by logging into https://eyes.nasa.gov/apps/dsn-now/ . Receiving signals from interplanetary spacecraft isn’t just for huge dishes – amateurs can do it too. David’s project is to set up a 3m dish to track and receive interplanetary satellites in the 2200 and 8400 MHz bands. He described in detail the theoretical architecture of his receiving system and the practical problems that need to be overcome to track and receive signals from such distant spacecraft with a large dish. He compared this with the requirements and problems being addressed in EME (moonbounce) systems. We look forward to hearing more on this subject in the future.

Immediately following David’s talk, we had the conclusion of the construction competition and award of the coveted GM4LBV Projects Trophy. There were only 2 entries this year:

• A GPSDO by Brian Flynn GM8BJF
• A transverter control board by Mark Hughes GM4ISM

The judges Ian White GM3SEK and David Stockton GM4ZNX gave a review of each, pointing out their respective merits and achievements. After some deliberation they decided that the winner was Mark’s transverter control board, because it had more utility, and he was duly presented with the trophy.

Andrew Holland G4FVL then presented his “A Man-portable QO-100 2400 MHz System”, describing and demonstrating a very versatile system that could be used in lightweight (8-9 kg), SOTA (manpack), and ultralight (5 kg) versions. This is based on an 80cm dish, SDR dongle and PC. He described how the systems are used, mentioning the importance of keeping the dish away from the ground, e.g. by mounting it on trigpoints on hilltops.

Andy Sinclair then provided the closing remarks, thanking the museum volunteers for keeping us well supplied with tea, coffee, biscuits, and scones throughout the day, as well as providing the splendid buffet lunch, and they were given gifts in appreciation to a round of applause from the audience. To further applause, Andy also thanked the organising committee, and in particular Peter Bates GM4BYF who had put together the programme.

The formal closure of the meeting was followed by a brief appeal by Heather Nickalls M0HMO for someone in Scotland to offer a receiving site for the 6m Beacon project. Afterwards, the chat continued as attendees slowly drifted away until the doors closed at 17:00.

Twenty attendees (including some spouses and partners) moved on to the Kingswood Hotel in the evening for further socialising and an excellent meal. An auction of items was undertaken, and thanks go to those who made the donations. The proceeds from the auction, other donations, and a small surplus from the door takings are donated to the MOC to support their activities. Further discussions continued until late!

Post meeting notes:
a. We gave a donation of £236 (our excess funds, details above) to the MOC for which they were very grateful.
b. Peter GM4BYF has asked for feedback on the event, ideas for future talks, and any offers of future talks. Please contact him by email – his address is available on qrz.com.

Thanks go to the organising committee of Roger Blackwell GM4PMK, John Cooke GM8OTI, Brian Flynn GM8BJF, David Stockton GM4ZNX, Colin Wright GM4HWO, Ian White GM3SEK, Peter Dick GM4DTH, Andy Sinclair MM0FMF, James Gentles GM4WZP, Colin Murray GM4EAU, Peter Bates GM4BYF, and Brian Howie GM4DIJ.

Prepared by Martin Hall GM8IEM, with contributions from the organising team.