[majoconz]

I made a 'qrm eliminator' a couple of years ago now. I surveyed the schematics of quite a few after Googling - some were very complicated but in the end I settled on two to try - the only real difference between the two was how the phasing transformer was wired - one gave a very sharp peak but didn't seem to work very well over a wide band of frequencies. Looking back to the original maker's diagram he had a switched coil pack, almost an antenna tuner! Fine if you have a single wire lead-in but no good for coax. My final arrangement gave an easily tuned peak and was wideband from the MW AM right up to about 18MHz. Unfortunately it made itself obsolete when I got an 8-channel multicoupler to feed 6 HF receivers all on different frequencies!