XBM80-2 An Experimental 80m CW Transceiver G3XBM

Published on 2010-02-18 by Mark VandeWettering

I’ve been a little too busy to fire up the soldering iron and build anything, but I’ve been pondering putting together one of Roger’s G3XBM radios. I ordered a couple of high impedance crystal earphones just to be ready, but in the mean time, I’m studying the circuit diagrams fairly closely:

XBM80-2 An Experimental 80m CW Transceiver G3XBM.

The radio is simple enough that I should be able to understand it completely, but I must admit that I don’t understand the principle of regeneration very well, so staring at radio, it’s not particularly obvious to me how T1 serves as both mixer and oscillator. I also am not certain I see how the oscillator doesn’t radiate when the radio is in receive mode. I’ll ponder it some more, and maybe fire up LTSpice over the weekend to test my understanding.