Field weekend

Derek, Mark, Andy and Rob fitting the hexbeam to the towerFriday 29th April saw the start of the TSGARC big Field Weekend. OK, not quite the same as its BBC Radio 1 namesake but just as much fun 🙂  Setup took place on the Friday and was finished by late afternoon – much quicker and more smoothly than last year.  The event ran over the following Saturday, Sunday and everything was dismantled and removed by mid-Monday afternoon.

So a big thanks to those that came and who helped setup and/or remove everything.  An event like this was only possible thanks to some accommodating friends of John, M6EQQ who allowed us to use their field.  As a thank you the club bought them a bouquet of flowers and some beer.  I will let you work out who received what!  Like preceding days, the Monday was a relaxed start and the dismantle job only started late morning.  Unfortunately, as some people know only too well it started raining just after lunch which incentivised speedy work.  But some of us got a little damp – Rex 😉

FT-897, TSGARC field weekend 2016Over the whole weekend there where two radio tents, the first used the FT-897 loaned to the club by Derek.  This allowed HF and VHF (6m) operation using a G3TXQ Hexbeam from MW0JZE (top image).  VHF (2m) operation was possible using a 9-element Yagi from Tonna.  The FT-897 PA provided 100w on HF and 50w on 2m.  The highlight of the first day was a solid 17m contact into Japan by Derek using SSB.  But there where also lots of other contacts across the European and American continents.  The hexbeam was observed to have useful directivity mounted at 12m atop the trailer tower.

John, M0HFH working Morse code on 14MHzThe second tent used a home-brew HF (20m) Bobtail – orientated to provide East/West lobes – and a 3-element Yagi for 2m, both courtesy of John M0HFH.    This tent used the clubs FT-450 both for SSB and CW plus an FT-857 and FT-817 provided by John and Rex.  The tent also showed rebellious tendencies, opting at times, to use some rather exotic batteries which no-one wanted to be anywhere near!!  Thanks John!

There, was of course, another tent, a very important tent and one where people congregated.  The ‘brew tent’ was where we had the stove, tea, coffee and what seemed like an endless supply of bacon – thanks Jane – plus copious amounts of biscuits 🙂  The weather was mostly dry but a little on the chilly side so this was indeed a popular tent.

In total we had two big (6m x 4m) tents, the rebellious tent (2.5m sq) plus a small day tent to keep the generator dry.  These provided ample space and shelter for the weekend.  The final accommodation to mention was the chemical toilet, arguably the most important item to making the field weekend possible.

TSGARC Members at work!Everyone who went had a good time and all the equipment worked well.  Simultaneous operation of two HF stations was not really possible, or expected, due to the proximity of the antenna’s so perhaps a project for next time is to make band-pass filters.  It was a surprise to find  that even HF low power transmissions broke through on the other tents VHF (2m) activity.

With only two radio’s in operation at any time it was common to find people in the ‘Brew tent’ or contributing to activities in the field.  In the above image John, M0HFH is being helped to connect an ATU to the feed point of the HF (20m) Bobtail.

Mark helping John fit an aluminium section to the top of a fibreglass mast.There was also some genuine help.  Many hands made light work of jobs including raising the tents and preparing the operating positions.  Unpacking, assembling and raising the hex beam was made easy with great support.  Thanks also to Ron, who stuck it out in the rain on Monday to methodically dismantle the hextbeam such that it can be easily reassembled next time.

Personally, I’m already looking forward to another event next year.  But we may move the date back to the late May Bank holiday weekend as the weather should be a little warmer 🙂

Andrew
G0RVM

Raynet Talk

This Wednesday we received a talk by Mike G0JMD about the formation of Raynet groups and Mike’s experiences in and as the controller of the North Avon Raynet group.

We learnt that the idea of Raynet came about after the 1953 North Sea Floods.

Back then there were different types of group, either independent, affiliated to the RSGB or affiliated to each other. Things changed and progressed with most groups affiliating to the RSGB and then falling away as funding changed.

Mike then moved on to the North Avon group and its activities over the years. The group has only been called upon once where Avon Fire found themselves without coverage in the Severn Tunnel. However before Peter G4OST could arrive they found channel 2 on their radios allowed back to back Simplex use. The fact that the group has only been called out once is surprising considering the motorway and rail networks in the area along with chemical, gas, fuel and nuclear plants.

The main activities of the group are around support local sporting events including the Sodbury Slog, and Bath Half Marathon. Within the group a standing competition is held for the operator with the most emergency services equipment and personnel.

Raynet-Talk-G0JMD

The talk finished with a round of questions all suitably answered by Mike.

In all 18 people attended the evening including 1 visitor.

Paul
M0ZMB

Programme update

Until recently our Programme has contained On-air nights. Before our radio room came into operation last year these where necessary as all activities shared the same room. However, now that we have a separate radio room we no longer need to reserve specific nights for operation of the radio’s as this is now possible on any evening by club members. As a result the committee has agreed to remove On-air nights from our event programme.

Members are encouraged to get our club on-air each Wednesday evening and/or on other days if they so wish.

If members would like to see new events in our programme, could they please communicate with a committee member to progress their suggestion.

Andrew
G0RVM

Service outage

Members may have noticed a problem with the website tonight…..

I applied an update which seemed to work ok but which destroyed the formatting of text on our web pages.  After about 1.5hrs of trying to resolve the problem I’ve restored the backup from last night.  Thus any posts/updates people have made since 02:30hrs this morning will be missing and will need recreating.

The update still needs to be installed and I will try again when I have a little more time to investigate the cause of the problem.  Hopefully its something that is effecting other websites, so may get fixed quickly.

The webmaster

 

 

Committee 2016

After the AGM on 6th April the elected committee for 2016 is as follows:
Chairman – Andrew Gawthorpe G0RVM
Vice Chairman – Mike Davies G0JMD
Treasurer – Stan Goodwin G0RYM
Secretary – Garry Moore G7NVZ
Committee Member – Mark Beasley M6KMJ
Committee Member – Rex Laney G4RAE

Strange problems….

So, for a couple of months I’ve had a growing suspicion that I’m not receiving as well as I am transmitting.  I first noticed the problem when observing the strength of signals from GB3VHF which after one winter storm seemed much weaker than it had been.  However, there seemed to be no impact upon transmit as SWR remained negligible and stations some distance away where still receiving me well even when my transmitter was generating about 0.5W PEP!

Since first noticed I’ve worked many stations and the signal reports always seem to identify that I’m not receiving as well as the remote station.  Establishing this pattern has taken some time.  It should be said at this point that its the same antenna and feeder used for both transmit and receive.

Its been a wet Winter and not really suitable for removing weather proofing from exterior connections and outdoors work.  But now Spring has arrived things are finally starting to get dryer and warmer.  Alongside this I’ve taken down the mast and antenna for work to support an new PRO.SIS.TEL 641D rotator.  This has enabled a detailed inspection and test of feeder and antenna.

Before starting any work I thought about and identified the following possible causes:

  1. failure of the receiver, possibly signal amplifer
  2. damaged feeder, possibly a connector problem or water ingress
  3. damaged feeder at the antenna feed-point. possibly also water ingress.

Problem (a) seemed possible but without a second receiver its very hard to be sure.  But its a quality Transverter (Kuhne TR144H) and I’d be surprised if that had partially failed – remember signals are only 2 – 3 S points down on what I think they should be.

So, (b) or (c) seemed much more likely.

So with the mast down and everything removed back to a dry, warm environment I removed weather seals – no sign of water or even the slightest amount of moisture ingress.  The coax was tested with a DC Ohm meter – no shorts or higher than expected resistances; with an antenna analyser and dummy load – again this looked perfect.

InnovAntenna feed-pointSo attention shifted to the antenna feed-point, pictured before it went outside for the winter and before the connections where weather sealed. Note: Grey plastic tape overlays amalgamating tape.  Again, there was no signs of moisture ingress into the coax, but there where signs of galvanic corrosion between the aluminium driven element and the stainless steel (A2 grade) machine screws to which the feeder connected.  Actually, to be more precise between the aluminium driven element and the flat washers on each machine screw.  It was clear that the liquid rubber sealant which I’d applied had not sufficiently covered these connections and thus water had been in contact between the different metals acting as an electrolyte.

To be clear, the machine screws where not showing any significant signs of corrosion, just the washers.  So the feed-point was thoroughly cleaned and reassembled without using the washers then liberally coated in liquid rubber to seal against contact with water.

Now, at this point I don’t know if this was the problem, but it does make some sense.  Any transmit signal would be of a much higher voltage/current than a received signal so would probably cross a mildly corroded junction with marginal attenuation.  But marginal attenuation of a much weaker signal would be more noticeable.  That’s my reasoning anyway.

The acid test will be when I erect the mast and antenna again in a few weeks and see if received signals such as GB3VHF have returned to their earlier strength.  When doing this I will also use new feeder, so if signals are stronger I’m never going to be absolutely sure the problem was galvanic corrosion.  Of course the problem may still be present and it could be another cause such as the receiver!

For information, the antenna is an 8-element LFA Yagi from InnovAntennas.

Andrew
G0RVM