Using Diversity to notch out a strong noise source

[W4NNG]

Have seriously strong (-73dBM) noise that is wide and has recurring peaks spaced ~20Khz. Each occurrence is ~8 Khz wide. My guess is telemetry. It's coming off the power line but I haven't been able to isolate the source. Even good old NR2 is no match.

My lowest noise receive antenna is an 80 meter dipole that has a cable shield isolating balun. (Balun Designs 1116d). Using 'Diversity' to phase steer a notch on the QRN, I tried various 'receive only' reference antennas with marginal notch success.

What did work, and work well, as a reference was my 160 meter (built for power) antenna. It almost completely notched the QRN. I tried background noise floor tuning it with an antenna tuner. That significantly improved the notched cancellation and completely removed the noise.

One addition piece of info - The main antenna also needs to matched before doing the notched steering. My amp (RF-Kit) has a built in ATU. The amp also needs to be put into Operate (vs Standby) before steering the notch. {guess OP mode introduces some phase shift)

Hope this is helpful,

Bob W4NNG