I want to ask if anybody implemented a variable coupling between RF amp and detector?
Are we talking about a regen set or a TRF or what?
Is it needed?
If this is in a Regen set and the RF amp is providing the "isolation" in order to prevent the antenna Loading the detector, then NO the variable coupling is not needed!(not to prevent loading by the antenna)
If the purpose of the "variable coupling" is for the purpose of controlling bandwidth/selectivity(and not to prevent "loading") then maybe it is needed(or just desirable not actually needed).
what is the best way ? and so on.
Without knowing more about what you are trying to achieve, in what type of set, I cant really provide any other answers.