Glenn Ashmore wrote:
This has been discussed on Rparts forum a couple of times. The power unit
of the BD series of compressors is a variable frequency inverter and is
notorious for creating RF noise. Danfoss makes an aluminum shielded model
but they are hard to find and don't help with conducted noise. The digital
thermostat is not normally a source.

Some things that will help are ferrite chokes on all wires going to the
power unit to reduce conducted noise. You may have to experiment with the
size to cut the frequencies that you need. Also lining the compressor
locker with metal screening tied to ground reduces radiated noise.

Glenn,
You are right. It is not the digital thermostat. I disconnected the
thermostat leads from the compressor module and put a jumper between the
terminals to turn on the compressor. The noise is still there. It is
being radiated. I have clamp on ferrites on all the wires to the
thermostat, power leads, etc. Any idea where to purchase the shielded
module. The local marine refrigeration shop didn't seem to know anything
about it.
krj