Building GM3OXX’s little OXO transmitter #HamSunday
Dave Richards decided to build GM3OXX’s little OXO transmitter. The OXO transmitter was first featured in the Autumn 1981 issue of SPRAT, the journal of the G-QRP club.
I mocked it up on a breadboard and it worked well. I noticed that the VXO, although not oscillating on key-up, was emitting some very low level spurii. In retrospect, this could well have been due to stray capacitances in the breadboard, and the fact that the circuit wasn’t built over a ground plane. Nevertheless, I decided to have the keying transistor key both the oscillator and PA.
I used an LPF from QRP-Labs. Band changing can be accomplished by plugging in a different crystal and plugging in a different LPF.
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