I recently discovered some photographs of one of my first /P events. The pictures were taken on 3 May 1972 at Burton Dasset hills in South Warwickshire. I think it was a 2m contest.
The transmitter was cut from a Pye Cambridge with valves in the RF section and a transistorised modulator. It was supposed to give 10w output but I had no way of measuring that and guess it was somewhat less as the valves were quite old.
The modulation was AM and I do not think I had modified it to the new fangled FM mode at that time. HT was supplied from the inverter on the small chassis to the left of the TX which also came from a Cambridge. Crystal control meant that there were only 2-3 frequencies available for transmit, as I remember one of the knobs on the front panel switched the crystals. This caused problems as most people had the same frequencies so that could make some channels congested.
Operating meant calling CQ on your channel then tuning high to low or low to high to find another station calling you. Very hit and miss by today’s standards.
Sometime later I built an ultra stable 8mhz VFO to replace the crystals from an article in the October 1971 edition of RadCom. It used an Oxley Temptrimmer to give the temperature stability. The VFO allowed me to quickly tune to the edge of the band where I could nab a station tuning for a reply.
Unfortunately the VFO was never suitable for portable operation so it was back to the crystals.
The RX is a Heathkit GR78 fully transistorised general coverage receiver which I still have. There was a copy of a Microwave Modules 2m converter screwed to the back. The receiver tuned 4 – 6 Mhz to cover the 144 -146mhz 2m band. This was a common way to get VHF on an HF receiver.
The antenna was a 6 element Jaybeam Yagi on a Jaybeam portable mast which later had another extension section added. The car was a battered old Morris 1100!
All good fun and relatively simple gear but it worked! No DSP, low noise front ends or massive antenna arrays, just a few watts of AM. I well remember using the same rig at home and having a QSO with F9NL in the Pyrenees whose audio quality was very good, but there again AM was always better!
(Click an image to enlarge)
