|Breadboard of WISPY TX - 50mW pep WSPR (100mW DSB)|
Schematic to follow tomorrow. OK, I know - there is no low pass filter on the breadboard. As the circuit is linear throughout and there is filtering on both stages the output is pretty clean, but I will add a 3-section LPF on the final transceiver version.
This is a very simple, all discrete parts, design using 2 x 2N3904s, 1 x 2N3866 (may be overkill) and a couple of 1N4148 diodes in the mixer. Again, I use a cheap 14.060MHz crystal, pulled a bit and doubled, as the LO.