Timewave ANC-4 works
I've been battling very bad line noise, and made the jump to buying a noise reduction device from Timewave, the model ANC-4. It uses a second antenna, picks up the noise, moves it 180 degrees out of phase, and removes the noise before it hits your radio.
It sounded too good to be true, but it does work.
It's not simple, and not 100 percent. After reading reviews, I saw a lot of positive, but also saw people who said it did nothing and they returned it.
For the first couple days I was in the did nothing category, but I kept experimenting with different receive antennas, until I found a combination that worked. If you aren't picking up the noise on the second antenna, you can't use it to phase out the other noise. So that's the key.
Now I'm using the dipole as my main antenna, and the vertical as the noise antenna. I have it set up so I can switch antennas quickly, using the vertical as main and dipole as receive.
Meanwhile, my noise has gotten worse, so this is the only thing keeping me on the air right now. A video is attached, showing how it works