16 Apr 2012

My old 2m AM rig

This morning, whilst clearing out some paperwork I came across this old B&W photo showing my 2m AM transceiver from the mid 1970s. It had a tunable RX covering 144-146MHz using a free-running VHF VFO (perfectly fine for AM use) and a crystal controlled transmitter; if I recall correctly, it had a few crystals that could be switched. The TX put out around 500mW of AM and was based on the PF2AM transmitter by Pye Telecom, a project I was involved with at the time. It was built in an aluminium box covered in wood effect Fablon.

The rig was also used for CW, goodness knows how, by having an external BFO held near the rig to demodulate a CW signal. Drift was a major issue on CW as you can imagine! Using this Heath Robinson arrangement I had a weekly sked with G5UM some 80km away every Monday night for several months and regularly received 559 using an HB9CV antenna in the loft.

The rig worked some useful AM DX across the UK with the best DX from home being a station in northern France one evening but it was really used as a local natter box in the Cambridge area.

When the ubiquitous Liner-2 2m SSB rig appeared I managed to buy a second hand one and this homemade AM rig was abandoned. I cannot remember what happened to it. It is nowhere to be found, so was probably taken apart for bits, which was a pity. Today I still use 2m AM from time to time and it remains a perfectly acceptable mode for local contacts with very simple kit.

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