Danfoss Interference

Ray, I have a boat fridge that uses a danfoss compressor. This gave me lots of unwanted noise on the Hf band and also some noise on the medium wave band.
I tried lots of things, including running the fridge on a seperate battery, but with little success.

I found the noise radiates from the compressor electronics and is picked up by the HF antenna.

A big reduction in interference was noted by simply connecting a good earth strap to one of the copper pipes at the compressor housing and connecting this directly to the fridge battery negative. Make this link as short as possible - mine is about 50cm long.

I also have a noise filter unit in the 12V supply lines to the fridge but this by itself made little improvement.
I further mounted the fridge compressor electronic board in a shielded & earthed metal box rather than the plasic one it came in, its a major job though and not recommended unless you are very familiar with electronics.
More trials were noise filters at the radio power leads but, since the noise gets in through the antenna, they did little good.

have fun, it can be a vexing job.

Klaus

Hi,
Have mailed it...let me know how you go.

Cheers