Hi Loris, I have installed that circuit on my uBitx v5 and have not noticed any significant reduction in volume in the presence of a strong signal. Maybe I have tied that to the first IF instead of the second? I should have a detailed look at that. I even changed the op amp IC from the LM324 to the TL084 but noticed no difference.
PS: Do you or anyone happen to know where I can find a nice panel microammeter like the one supplied with that AGC circuit?
73, George, SV1DEQ