Quote:
Originally Posted by vu2nan-nandu
You may also try a series-tuned circuit across the 'aerial' & 'earth' terminals.
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The L/C cct. in that config. is usually known as an 'acceptor cct'. That's because at resonance, it's a low-impedance - so it 'accepts' the current.
Now in theory, an arrangement
could be made to have both: acceptor cct.
and rejector cct. The problem with that is that the variable caps. will be very interactive, making tuning really tricky - especially if the Q of each is high - which will be required.
Also with the acceptor cct., used with a 'longwire' and an earth connection, that earth connection does need to be a
really low Z. Otherwise the high-Q of the acceptor cct. will be seriously compromised.
A much more elegant way of solving this problem would be to devise a way of introducing a 180° phase-shift signal at the required freq., with it's amplitude adjustable, and thus eliminate the offending signal by phase-cancellation. How to physically do that? I don't know!
Perhaps someone else here just might . . . .
At the back of my memory, I think that approach was tried many, many decades ago under the name of the Jones Circuit. I have the vague notion that it have featured in the RSGB magazine / Technical Topics during the late / mid-1960's.
Al.