RSGB 144MHz TROPHY and SSB FIELD DAY - 2016




In recent years the club has been very successful in contests when running mostly VHF stations only. This time, with two RSGB contests running more or



less concurrently, we set up stations for both on the site on the east side of Chapel Hill with its superb views over Cambridge.




The VHF station was entered in the Open section of the 144MHz Trophy contest and ran at 400W. This station was managed and almost entirely supplied by Dave G6KWA who had spent most of Friday afternoon and evening setting up the mast, aerials and tent.



The VHF QSO Map

An early start on Saturday enabled checking of antenna performance using beacons before being joined by David G0LRD and XYL Denise who arrived with the HF gear. Others who helped to set up were Richard G4AWP, John G0GKP, Bob G3PJT and Darren. The 2m Trophy contest started slowly with about 25 QSOs in the first 90 minutes. Logging was performed on computer with G0GJV's Minos Logger, backed-up using pencil and paper.



Before long, the old problem of the linear amplifier tripping out raised its head once again and this was to plague us for the rest of the contest. There were other technical issues with configuring of the station to suit operators and failure of a new headset.

Nevertheless, we enjoyed a lot of good contacts with the European mainland, averaging over 300 points per contact over extended periods.

The early hours found the 2m station short of operators. Several had brought their tents and stayed overnight but, by this time, were grabbing a few hours of well-deserved shut-eye. We missed that enthusiastic duo – LRD and AWP – who had put in such good service on VHF back in July but this time they were busy operating the HF station.


VHF STATION KIT

The 2m station comprised KWA's Scam trailer mast fitted with his two Tonna 9-element Yagis. In the tent, KWA's home-built twin-tube linear amplifier was driven by his Icom IC-7100 transceiver.

Power for the whole was supplied by LRD's inverter-based 2.8kW Hyundai petrol generator.


Dawn on Sunday arrived and KWA nipped home to check the transmission quality. He was able to report the signal as excellent with no phase noise detectable and the audio, with Ludo M0GDR on the mic, as outstanding.




The HF station was entered in the Restricted section of the SSB Field Day and ran at 100W. This was managed by David G0LRD and comprised LRD's radio equipment installed in one of the club's old frame tents. For logging, PCs were used running EI5DI's SD Logger.


HF STATION RIG

included a multiband doublet, fed via a remote auto-tuner at the base of the mast, and another Icom IC-7100 transceiver.

Powered by a 120Ah lead-acid battery topped up via a charger from KWA's petrol generator which also powered the ancillary computer monitor used for logging.

No interference could be detected between the two stations.


Richard G4AWP supplied and transported the HF mast, having dismantled it from his own garden and re-erected it specially for this event.

This mast was placed under a fairly heavy vertical load and subjected from the outset to some rather rough weather. At one point, on Saturday



afternoon, we did suffer a minor collapse when a telescopic joint slipped but this was quickly fixed and no further trouble was experienced.



Distribution of HF QSOs across the Bands

Operators for the HF station were readily forthcoming and, not in strict order, they comprised Richard G4AWP, David G0LRD, Ludo M0GDR, Hamish G0GLJ, Will G0OPL, Steve G8CRB and Richard G3TFX. All these operators performed excellently despite facing poor HF propagation conditions - there was nothing on 10m and we managed only a couple of QSOs on 15m.

The equipment, particularly the IC-7100 and the auto-tuning doublet system, performed very well.



Operation of the SD logger program was picked up easily by everyone and its ability to extract the rig operating frequency is a very useful feature indeed.

Additionally, previously worked stations are identified as you tune through them in real-time and the log always records the correct band.



The HF QSO Map

The only equipment failure in the HF station was the battery charger being used to float charge the large, lead-acid battery.

Steve G8CRB reported a strange noise that interrupted his operating for a short period and it was soon discovered that the charger was dead. At this point, with only 5 hours remaining of the contest, the battery had more than enough in hand to see us through.



Subsequent inspection of the charger revealed that the varistor connected across the 230V input for protection against transients had exploded (see photo), blowing the board-mounted fuse at the same time. This has now been repaired leaving only concerns about the regulation on that particular generator.

HF ANTENNA



The HF antenna was based on a G5RV but modified using a model created with the EZNEC program to take into account the shift in resonances that would result from hanging it as an inverted-V instead of horizontally.

It was found to match very well on 80m, 40m and 20m but was, as anticipated, more of a challenge on 15m and 10m. The plot shows how this particular configuration provides reasonable resonances on 80/40/20 without a tuner, such that the auto-tuner had it very easy on these three bands.


The HF station achieved a total of 385 QSOs, mostly to Europe - particularly Germany and Belgium.




The greatest challenge to the whole enterprise was the weather. Setting up the stations on Saturday morning was fine but the sky got steadily gloomier and by mid-afternoon it was raining and the wind was getting up. The worst of the rain came through at about 18:00 but the wind peaked later at 23:00.

THOSE WHO ATTENDED

DaveG6KWABobG3PJT
JudithXYL-KWASteveG8CRB
DavidG0LRDJohnG0GKP
DeniseXYL-LRDLudoM0GDR
RichardG4AWPMartinG8OFA
HamishG0GLJSteveG4WSZ
WillG0OPLRichardG3TFX
DarrenGraham & Luisa
DavidM0ZEBCharles & family



Darren's gazebo tent proved solid as always but the HF tent could only just cope with the rain and buffeting on Saturday night. It also turned out to be less than 100% water-proof. Fortunately, most of the drips were onto the operators, not the equipment!

Visits from Judith XYL-KWA and Denise XYL-LRD were much appreciated as was the delicious food they brought with them. Darren did his usual excellent job, combining the duties of catering manager and security officer.

After dark his flood-lighting covered all areas, although the tripods did occasionally get blown over in the powerful breeze. His unending supply of hot drinks and snacks was much appreciated by all.

The SSB Field Day ended early on Sunday afternoon, followed an hour later by the end of the 2m Trophy. Helped by several members and visitors we packed the stations up in glorious sunshine – a real contrast to the weather of the previous afternoon.




As always, on these occasions, thanks are due to many people: Firstly, thanks to the landowners for permission to use their lovely meadow. Particular thanks to Dave KWA, David LRD, Richard AWP and Darren for the generous loan, transport and operation of enormous quantities of equipment and consumables as well as hours of work in preparing and planning. Thanks to Judith and Denise for sustenance. Thanks to all members and visitors who helped by setting-up, operating,


logging and packing up. Apologies for any omissions.

Finally, nearly all who attended made contributions of cash or fuel to support the enterprise. These field days cost a considerable amount to put on and this support is very much appreciated. If you forgot to contribute on the day, it’s not too late to submit your donation to either Dave G6KWA or David G0LRD.

Thanks to all contributors to this report – Dave KWA and David LRD for text, photos and diagrams – Martin OFA for photos.

© 2016 CDARC - CAMBRIDGE & DISTRICT AMATEUR RADIO CLUB