I had the same "harmonic" noise with my TIC ring rotors, including
BC station harmonics that came and went while the
ring is turned. In my case the source was the contact between the
drive gear and the ring gear. I have their largest model which uses
a gearhead motor with direct drive to the ring gear. I ran several braids
from the ring to the tower with enough slack to allow full rotation. This
provides an alternate path for RF that finds itself on the ring to the tower
other than through the drive gear. Also, I noted that before I fixed this
problem, it was much worse on yagis that had uninsulated elements vs
elements insulated from the boom. (boom currents?) The black rollers
are good insulators and didn't have an effect. I now have a large log
periodic mounted on a pair of TIC rings stacked 5 feet apart with a
connecting vertical mast (for vertical stability) and with the rings grounded
through braid, the harmonic noise problem is gone. I suspect that if you
insulated the boom from the ring that might help as well.
73,
Chuck...K1KW
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