GMRT 2023

GMRT 2023 meeting report

Attendees making their way to the 11th Scottish Microwave Round Table (GMRT) in Burntisland on Saturday 11th November enjoyed a crisp, clear, sunny winter’s morning with superb views over the Firth of Forth towards Edinburgh.  What an uplifting way to start what was to be a very enjoyable day!

As usual, the venue was the Museum of Communication (MOC), with a good turn-out of 46 attendees.  Peter Dick GM4DTH was on the door again from 9:30 AM to give everyone a friendly welcome and collect the dues.  In the background, the sound of familiar voices emanated from within as everyone caught up with friends and acquaintances and made new ones. 

Having briefly visited the conference room to pick up refreshments many of the attendees had migrated to the display area on the ground floor to examine and discuss the wide range of microwave equipment, components, and test equipment that were on sale, before the best items were spoken for.  Brian Flynn GM8BJF and David Stockton GM4ZNX had set up the test and measurement facility - already in operation, and open for business throughout the day during breaks in the presentations.

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, after which Andy Sinclair MM0FMF (secretary of the Lothians Radio Society) took over as chair for the morning session.

Andy showed the gathering the RSGB Jock Kyle trophy, awarded to the GMRT for its contribution to amateur radio last year.  He accepted it on behalf of the GMRT at the 2023 GMDX convention in Stirling in April.

The first speaker was Mark Hughes GM4ISM whose talk was entitled “Test Equipment for Amateur Radio”, an important issue when trying to establish that your microwave communications system is working as intended.  Mark started out by outlining common problems, what we used in the past, and why we need good measurement capability.  He described the test gear that was essential, as well as some useful extras, key aspects being to understand the capability, limitations, and measurement accuracy of what you have, and when it might or might not matter.  Most importantly, knowing how to use your test equipment to get usable results to a known accuracy is essential!

A short break ensued, after which Paul Dobie GM0PJD started his talk “Getting Started on 23cm EME – the first 200 contacts”.  This was a fascinating story of how Paul became motivated to reach his goal of 200 Earth-Moon-Earth (EME) contacts from a standing start before the 50th anniversary of the first Apollo moon landing on 20-Jul-19.  He covered all aspects of his journey, including the physical attributes of the moon relevant to EME, how the moon reflects signals, the history of EME activity, path loss calculations, station requirements, doppler and libration, and propagation modes.  He also gave tips on technical considerations, building a station, mounting the dish, and tracking the moon.  Afterwards several attendees were heard discussing how they might get going on 23cm EME!

As usual we were asked to vacate the conference room while lunch was being set out and re-assembled in the museum where the entries for the GM4LBV Projects Trophy were displayed, and where Ian White GM3SEK and David Stockton GM4ZNX examined the entries.  The MOC volunteers are renowned for their superb buffet lunches, so the call that it was now ready brought everyone back to the conference room to enjoy the fine food on offer, and to continue chatting.

Brian Flynn GM8BJF, took over as chair for the afternoon session.  No chance for a postprandial nap when Neil Smith G4DBN took the floor for his lively and entertaining presentation about “Reconstructing Cold War Spy Bugs”.  Neil explained how he became involved in this task after the BBC invited him to make a replica of a top-secret listening device found in 1952 in the US Ambassador’s residence in Moscow in 1952.  He talked us through the political background and the technology involved in developing this bug, which had no batteries or wire connections, and the challenges he faced in producing a working replica.  Members of the audience were able to examine some of the replicas Neil had produced.  He finished with a brief description of the aftermath to the discovery of the bug.

Another short break followed before the next presentation, which was about “Microwave in Mobile Networks” by Gavin Taylor GM0GAV.  In this talk Gavin walked us through the history of the backhaul link for mobile networks operating at 1800 MHz and feeding into leased lines.  He illustrated how the capacity of these links within a fixed bandwidth has improved over time to accommodate the increased usage of the mobile networks through the use of ever developing techniques, migrating towards Internet Protocols (IP) since 2015.

Immediately following Gavin’s talk we had the conclusion of the construction competition and award of the coveted GM4LBV Projects Trophy.   The entries were:

·         An Arduino controlled microwave step attenuator by Brian Flynn GM8BJF

·         13cm, 9cm and 6m feedhorns for a 1.2m offset dish by Peter Bates GM4BYF

·         A fox hunting miniature VHF transmitter by Mark Hughes GM4ISM

·         An MAR7 drop-in substitute for the obsolete OM34S used in signal generators 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 the drop-in replacement for the OM34S, because of its usefulness in bringing dead signal generators back to life.   

Brian 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, Brian also thanked the organising committee, and in particular Brian Howie GM4DIJ who had put together the programme.

The formal closure of the meeting was followed by ongoing chat, which continued right up until the doors closed at 17:00.

Many attendees (and some spouses and partners) moved on to the Kingswood Hotel in the evening for further socialising and an excellent meal – the new owners did us proud.  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!

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 Gentle GM4WZP, Colin Murray GM4EAU, Peter Bates GM4BYF, and Brian Howie GM4DIJ.

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