I think I found the source of RFI in my apartment

[bob91343]

My EMI problem is on the 40 and 80 meter bands. Intermittently, especially evenings, I get a surging roar that is somewhat tunable. It's strong, S9 typically, and suddenly will stop. I am sure it's nothing in my own house but beyond that I'm stumped. It surges at about 1 Hz rate and seems to move frequency at random. I have tried to correlate it with the heating system and the refrigerator to no avail. It's gone during daylight hours.