Hey guys:
I happen to a "Cutler Hammer" breaker (Eaton) breaker box in the house. I added a circuit to the "shack" last fall and AFCI'd it. No nuisance tripping problems here, and I have a SWAN350 for HF, and the breaker box is on the other side of the wall from the "shack"
Being as I am in the Chicago area, the house is all steel conduit, and if not conduit, steel armored cable. Seems to make a pretty good shield. I am almost wondering IF the problem the original poster is having is the house wiring acting as an antenna possibly a "resonant one". I am a licensed electrician, and I know most of the country uses non metallic cable for residential work. The suggestion of ferrites at the service panel MIGHT not be a bad idea, if the wiring is acting as antenna
Hope this is of some help.
de Howard, N9KTW