OPEN UNIVERSITY AMATEUR RADIO CLUB
NEWS LETTER no:43
G0OUR Affiliated to the OU Club and the Radio Society of Great Britain
This newsletter is a little earlier than usual, however please make a note of our forthcoming 2016 AGM on Thursday 18th February at 12.30pm. We’re in the same room as last year: Central Meeting Room 14, on the first floor. This is accessed from outside via the East Central Meeting Rooms entrance, near the shop. An email reminder will be sent nearer the time, and local members are urged to attend if they can. Subscriptions are due in January and remain at £5. Note that our Treasurer Fraser is retiring in December, but until further notice please continue to send subs to OUARC, c/o F. Robertson, S1021 Venables Building, O.U., Walton Hall, MK7 6AA. (Email g4bjm@hotmail.com).
Back in January we had a problem with our old refurbished P60 mast. Following a weekend of very high winds, we noticed that one of the three lattice uprights had failed, just above the top of the base section, due to rust. On the Monday we temporarily re-guyed the mast to make it as safe as possible. More wind was forecast for the Wednesday, so on Tuesday lunchtime we gathered some helpers and put a recovery plan into action. By some miracle the plan worked and we were able to telescope the broken section safely down into the base section. Many thanks to Brendan, Tom, Ian, Paul, Fraser, and last but not least, José, whose fearless can-do attitude (Ian’s too for that matter), saved the day. It was a potentially dangerous situation, and the prospect of having the mast and antennas end up broken and stuck in nearby trees some 15m above the ground was a daunting prospect to say the least. The moral of the story is firstly, don’t buy a dodgy looking used mast (as we did 24 years previously), and then if you repair it, having had it fail, make sure the rest of it is completely sound. We are now using the mast at a slightly reduced height, with the faulty part safely down within the base section. Repairing the mast is not easy so we will leave it as is for now. So note that: This mast (supporting the Hexbeam) must not be raised any higher than its current position.
The club’s ETO 91ß amplifier was repaired in January, after developing a fault in November. Unfortunately it transpired that the HV winding on the mains transformer was partially breaking down to ground, blowing the mains earth leakage trip. The amplifier is about fifteen years old and is no longer made, but luckily we found two alternative suppliers for a replacement transformer. The new transformer cost just over £500, but we had little choice, without it the amplifier was totally useless, and to replace the amplifier would have cost a lot more. The old transformer makes a good doorstop until someone can think of a better use for it.
During the summer we finally got round to doing the maintenance on our heavy duty P60 mast. We had to remove part of the beam elements in order to tilt the mast down close to horizontal. The winch cables and guys were replaced, the broken 17m delta loop removed (now replaced by the Hexbeam), and some other general maintenance was undertaken. So I’m pleased to say that all three masts have been refurbished over the last few years, and the antennas too, so hopefully they will be reliable and need minimal maintenance for some years to come. The photo overleaf shows the mast luffed over with the beam elements partly dismantled. Also in view is the trailer we borrowed to clear out the junk shed. We took four loads to the OU’s WEEE recycling area, so we can finally get in the shed and see what’s in there. A lot of the junk had been carted to and from several boot sales, so the recycling bin was the best place for it.
Unfortunately we were unable to attend the two local boot sales this year. We have sold the club’s Flex 1500SDR (the KX3 replaces this) and the faulty Ten Tec Omni6+, plus other odd bits of ‘junk’. Earlier this year we bought a Winkey kit (PC interfaced keyer) which replaces a similar unit that was on loan. Thanks to Paul for assembling the kit. This year the subvention received from by the OU Club from the University has been considerably reduced. Therefore we decided not to bid for any equipment funding this year. Finally, the shack PC has been upgraded and is now running Windows7, thanks to OU IT for this, and also for repairing it recently when the motherboard suddenly died.
A few more SDR (Software Defined Radio) links for those interested, showing details of a 50-4000MHz SDR transceiver, which was a ‘badge giveaway’ at the Chaos Computer Camp: @rad1obadge A video about the transceiver explaining its development, along with hardware details and software options is here: https://media.ccc.de/browse/conferences/camp2015/camp2015-6884-the_rad1o.html See also http://amsat-uk.org/2015/08/13/michael-ossmann-chaos-computer-camp/
Another link that may be of interest is the revamped VOACAP Propagation Planner: www.voacap.com/planner.html This is a planning too for HFl. You can model results for a range of different antennas. Finally a great video showing a professional antenna installation in France: https://www.youtube.com/embed/qJHlXe_RnYo
That’s about it for now; hope to see some of you at the AGM in February.
Contact: Adrian Rawlings adrianrawlings@googlemail.com