What Paul K9ERG has already played with is using real small 1/4-inch or smaller ceramic chip capacitors and soldering across the end of sockets something like this photo. Having very short leads is the trick. Not sure AARL manuals will help much here...
I don't have that much patients anymore at my age... The standard ferrite beads don't work here where the 12VDC connections are made at the board edges... That has been all I have played with and didnt have any success.
Paul had much better luck with the very small chip capacitors.
Roy Ken