2 Jul 2008

Micro80 4-transistor transceiver QSO

After some time without use, I resurrected the little Micro80 4 transistor transceiver for 80m last weekend. To increase the power a bit I've now got provision to run it from an external gell cell battery at 12v, so giving me about 2dB more RF out compared with the 9V internal pack. Using it with the bench PSU was impossible because of 50Hz hum pick-up. I also managed to improve the AM breakthrough by around 10dB at least by putting a 4n7 cap across the base-emitter junction of the first stage of the darlington in the RX AF. This makes it a usable radio on 80m at night now as it is not obliterated by the BC stations around 4MHz. Success soon followed with a solid QSO with G3XIZ in Biggleswade around 30 miles away late Sunday afternoon.

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