Wednesday, November 4, 2009

Polyakov I/Q-SDR update

Some success but some fall backs too. The regular reader will know, I was working on a subharmonic SDR design for a while, with decent breaks however.

The design involves a 5.0688MHz canned oscillator, two pairs of anti-parallel diodes and some audio amplification (TL082).
Theoretically there also is a front end with a J310, but, it is not working, God knows why... need to look into this... Not oscillation, no attenuation, no amplification, no nothing....

I/Q works, however, the correct phase-shift adjustment is not easy, three parameters to play with. The sideband suppression (image canceling) is surprisingly good, with the proper phase-shift.

Presently the fun is spoiled by a major 50Hz contribution, I've seen that before, proper tins required ;-)