Jenny, G7CKF has now taken the 2m Fredbox design and created a 4m version called the “Fourbox”.
I feel I should drop you a line with my thanks and the link below, I’ve used your QRP AM transceivers as the basis for a 4M transceiver and published it on my blog. I’ve come back to amateur radio after a 20 year absence and since construction was always my main interest in the hobby I reached for the soldering iron.
There is no sparkling new insight to be had from it as it’s pretty much your fredbox with slightly bigger coils. There is no crystal because I am cheating and using a Raspberry Pi clock generator to make my 70.260MHz.
My QTH is IO91lw, between Bicester and Buckingham and rather low lying. Very little 4M activity hereabouts, sadly, so the chances of my actually working anyone with it are slim. But that’s not really the point of building, is it.
Anyway, hope you find it of interest, and thanks again for sharing your designs.