[RFI] Rectified 120Hz RFI?

[Kelly Johnson]

I am hearing a new RFI source at my home.  It's different than the
other sources.  The other 2 sources of noise are definitely powerline
poles: one in a neighbor's hard 2 doors down and the other in my back
yard.

The definite powerline pole noise is definitely rectified 60Hz.  I've
recorded that noise and run it through an FFT and sure enough, the
primary signal is 60Hz.

The new RFI definitely sounds different, so I recorded it this morning
and ran an FFT on it.  What I see is that the primary signal of this
one is 120Hz; not 60Hz.

I'm finding it very difficult to locate the source of the new RFI
because the signal strength decreases with increased frequency and
thus I can't hear it while walking around my neighborhood with my
432MHz yagi or 144MHz yagi.  The signal is very strong on 20m and 40m
(like S7 to S9), but drops to about S5 on 6m.  I can get a direction
on it from the house, but that just puts it somewhere east of me.
There are powerlines east of me as well as homes.

Anyone have a theory about what would cause RFI with a primary 120Hz
component instead of 60Hz?