OPEN UNIVERSITY AMATEUR RADIO CLUB
NEWS LETTER no:45
G0OUR Affiliated to the OU Club and the Radio Society of Great Britain
Please make a note of our forthcoming 2018 AGM which is on Friday 2nd February at 12.30pm. As last year, we’ll be in: Central Meeting Room 06, on the ground floor. This is accessed from outside via the 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. Please send to OUARC Treasurer, Paul Maher, IT, Berrill Building, O.U., Walton Hall, MK7 6AA. Email paul.maher@open.ac.uk.
We’ve suffered a few set backs on the antenna front in recent months, firstly with respect to the old P60 mast that was repaired and refurbished back in 2013. The middle section had needed one of the uprights welding. Subsequently in a bad storm we had another problem with that section, so we used the mast in a semi retracted but safe position (the faulty part being retracted well inside the mast). Recently the masts were inspected by an outside contractor at the behest of Estates for insurance purposes. Unsurprisingly they condemned the P60 (even though we were using it in a safe retracted state). This mast supports the Hexbeam, the doublet for 30/40m, and the 6m, 2m and 70cm vertical. These antennas can still be used, but obviously with much reduced performance at their current low height with the mast fully retracted. There have been various proposals on how to proceed with this, and we’re hoping for a positive outcome.
In late Summer, Adrian M0ANS, Paul M0OOM and Fraser G4BJM took the M100 down and luffed the mast over horizontal. This was partly for inspection purposes, but one leg of the topband dipole had come adrift at the feedpoint, so it needed to come down anyway. This mast supported the 160m, 80, and 40m wire antennas.
The HD P60 has also been inspected and remains operational, supporting the Optibeam Yagi for 20, 15 and 10m. When we bought this mast (new) we replaced the K1550 luffing winch with the heavier duty K2550 winch, along with heavier duty cable than that supplied with the mast. This was ‘belt and braces’ due to the large Yagi and heavy duty PST61 rotator. When we replaced the cables on this mast we didn’t replace this luffing cable as it had been upgraded and had literally only been used a handful of times, and of course is normally not taking any load. However for some reason the inspectors removed this cable and we are awaiting an explanation, and for them to replace it. For now they’ve strapped the mast so it can’t be luffed.
Equipment wise, all was going well, unitl just recently the linear has started tripping out, even with just a couple of watts drive. It’s a problem with the amplifier itself, as swapping antennas or the drive radio doesn’t cure the problem. This will take some investigation. It’s two years since the linear’s mains transformer failed, and looking through the documentation, the amp is now twenty one years old. We bought it second hand in 2004, so I guess we can’t complain.
The club’s high power dummy load (MFJ oil filled paint can with SO259 socket on the top) has disappeared from the shack. So if someone has borrowed it please let us know, and return it as soon as possible, as it will be invaluable when fault finding on the linear.
Earlier in the year the electrics in the shack were inspected by outside contractors. The contractors subsequently replaced the consumer unit, and also fitted twenty six new mains sockets in the shack! We were recently inspected for asbestos, which seems to be an annual ritual.
Unfortunately we are plagued with very bad local broadband interference, particularly on the LF bands but extending through HF too. We have traced this using a portable receiver to a large fume extractor system that has been installed on a nearby building. One of the staff there kindly offered to switch it off for a test, and the interference instantly disappeared. We have made enquiries about getting this resolved, perhaps by the installer fitting RF filtering, and we are waiting to hear back about that. If we can’t get this resolved there is little point in re-erecting the LF antennas, as the high level interference renders these bands unusable.
A big thank you to Paul M0OOM who single handedly manned our pitch at the DDRC boot sale at Stockwell Park, Luton back in May, raising £135 for club funds. We did not bid for OU Club funding this year, and we have had minimal expenditure. We have bought some new tools for the shack though: a multi-toolkit from Maplin, and a heavier duty toolkit from Halfords.
This year has been fairly quiet in terms of club activity, and we urge members to make use of the G0OUR station, and in particular to put in an appearance at club meetings in the shack on Thursday lunchtimes, from 12.30ish. New active members are also very welcome. If other days would suit members better let us know.
That’s about it for now; hope to see some of you at the AGM on Friday 2nd February. Meanwhile have a great Christmas and New Year.
Contact: Adrian Rawlings adrianrawlings@googlemail.com