If you’d like to try something really different, you could get on the air using FT-8 on 2 meters! The North Texas Microwave Society is holding informal FT-8 nets on 144.174 USB each Monday at 19:30 local. Any antenna you have will be better than nothing, but a horizontal antenna is preferred. If you have a coat hanger to spare, you can make a 2-meter dipole suitable for this net. I’m going to give it a try.
ANOTHER UPDATE: recordings of my interference can be found here: 30 Hz, and here: 120 Hz. Careful listening and lining up the audio files in Audacity suggests to me that the interference is really always at 120 Hz, but that I was fooled by every fourth pulse being stronger than than others during some conditions. Of the ARRL samples, the light dimmer sounds most like what I’ve got.
Passing along an invite: The North Texas Microwave Society is holding an FT-8 informal net on 2 meters (144.174 USB) starting about 7:30 pm central time on all Monday’s. There are some folks on the air prior to that for tuning and band condition checking. This is all done to hopefully increase traffic on 2 meters.