8 Sep 2012

WISPY now transmitting!

Breadboard of WISPY TX - 50mW pep WSPR (100mW DSB)
Very pleased with my little 3 transistor DSB 28MHz WSPR transmitter. Since turning it on at 11.34am I've received around 30 reports from stations in Europe despite the power being just 50mW pep ...and as I write my first spot from Africa: -14dB S/N (a good report) from EA8FF in the Canary Islands!

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.

1 comment:

Anonymous said...

A job wel done, 73 PA2RF