Hi again Mark,

I think Jake is on the right track, whatever the source of noise inside the
unit its the mechanism that radiates the noise that needs to be attended to.
In my case it was the external cables, choking them off with ferrite sorted
out my problem. To suppress the noise at source within the unit seems a bit
hard for me. I also suspect there may be more than one noise source in the
box.

73 Alan VK6BN


"Mark" wrote
Several months ago I had a high efficiency Trane XV90 natural gas
furnace and heat pump installed. Since the weather has recently been
cold enough for the gas furnace to provide heat, I have been
experiencing severe radio interference. The interference wipes out AM