Please read #32103 + 14 related messages.
It's a AGC developed by Jim, ND6P. I build it some time ago and it's working like a charm !
The AGC is audio derived, but attenuates the RF input, using pin diodes. I've used it on my Bitx40 build. The AGC acts like in a commercially build radio :)
Could be interesting ...
Herman - ON7HC