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OPEN UNIVERSITY AMATEUR RADIO CLUB
NEWS LETTER no:48

G0OUR Affiliated to the OU Club and the Radio Society of Great Britain


I trust this finds you in good health. Due to Covid 19 and resulting tight restrictions on campus, we will be holding the AGM online: 2021 AGM, Thursday 14th of January at 12.30pm. The plan is to use Microsoft Teams. Please get in touch beforehand if you are able to take part. Let’s hope we can meet again in person for the following AGM. Subscriptions are due in January and remain at £5. Please send to the OUARC Treasurer, Paul Maher, Berrill Ground L0 South, Open University, Walton Hall, MK7 6AA. Email: paul.maher@open.ac.uk. paul.maher@open.ac.uk.

I’m pleased to say that the intermittent fault on the club’s amplifier has finally been tracked down and fixed. The fault had appeared to have fixed itself as it went away for perhaps a year, but inevitably returned. The problem caused the amplifier to trip out, even with a watt or so of drive. It was checked into a dummy load and with different cables and drive radio to verify that the fault was in the amp itself. The trip circuitry is on the control board behind the front panel, so it could be worked on without getting involved in the high voltage areas. Four different circuits can cause the amp to trip, so the trip function was disabled (diode-OR circuit grounded) and each of the trip circuits investigated. It turned out to be the reverse power circuit. The wiper of the trimpot was open circuit (slightly oxidised?). This caused the comparator input to float down to 0V, so it would trip with just a sniff of RF applied. The pot was swept through its range and returned to the correct position and all is well. This probably also explains the intermittent forward power display (set by another pot). At some point (next time there’s a problem) it will be worth resetting all the trimmers on that board.

While on the subject of repairs, have you checked out any of the Mr. Carlson’s Lab videos on YouTube? This guy is a Canadian ham (VE7ZWZ) who has a very well equipped and stocked workshop. His excellent videos cover repairs and refurbishment of ham equipment, plus other solid state and valve gear (radios, Hi-Fi, guitar amps, even broadcast transmitters). Well worth a look. He also runs electronics courses via his website. Also on YouTube, see W2AEW, and TRX Bench. The RSGB convention and the Dayton hamvention, and no doubt others, were held online this year, the presentations are available to watch online. Who needs a TV?

In March a fault developed with the 40/30m dipole. Most likely due to the prolonged periods of high winds we’d been having. We suspect that this has caused the ladder line connection at the feedpoint to fail. This happened some years back, although the 80m dipole fed in the same way never gave a problem. So the strain relief needs rethinking. We had just arranged to meet up at the shack to repair the antenna (it was unusually a perfect calm, sunny day) when the news came through that all OU club activity was put on hold due to the coronavirus. We were literally stopped in our tracks half an hour before leaving for the OU. Needless to say the problem remains to be fixed.

Despite having no access to the shack due to the campus lockdown, we have been able to air the club callsign. GX3OU was active in the CQ WPX (worked all prefixes) contest. We were the only GX3 active, so were relatively sought after as a prefix points multiplier. We had over 500 QSOs, all on the Sunday, covering all bands 160-10m. More recently G3OU put in an appearance in the RSGB Club Calls contest on Topband. We only made 52 contacts with a low rather mediocre dipole. I remember when we won that contest from the club shack many years back. Sadly we no longer have a Topband antenna at the club. We have also made other contacts using the club call, some from the shack before it was off limits.

We have recently had a Risk Assessment approved which will allow us occasional access to do safety/integrity checks. This is particularly important now that we’re into Winter weather, to check that the masts, guys and antennas are ok, and the shack background heating, alarm, equipment etc. is all in good order. This involved jumping through various hoops and was by no means a given. The OU are quite rightly being extremely careful, and in fact the campus has been locked down continuously since March. Many staff are working remotely, and very tight restrictions are in place controlling who is allowed on campus. Fortunately the location of the club shack and antennas is well away from office areas. Only one committee member at a time will carry out these checks, with checks being spaced at least ten days apart, so any potential risk of cross infection is virtually zero.

So sadly any plans we had club wise have all been put on hold, that being the situation for all OU clubs, and rightly so. Hopefully as vaccines are rolled out en mass and restrictions can gradually be eased, so we can start to get together again and pick up where we left off. We look forward to putting the actual club station back on the air. Remember also that members can activate our club callsigns from home or elsewhere, (it’s no longer a licence requirement to add /A when operating from an alternative address). If so please email a copy of the log for club records.

That’s about it for now; hope to see some of you online for the AGM on Thursday 14th January. Meanwhile have a great Christmas and New Year.