There has always been a problem with a few boaters complaining about
Danfoss BD refrigerator compressors producing radio interference.
These complaints have not been of a large enough magnitude to get the
attention of companies assembling boat refrigeration systems. The
basic problem is only a few boaters are concerned with refrigeration
transmitted EMI/RFI. When I have ask friends with single SSB radios
and Danfoss compressor refrigeration, cruising in the Bahamas about
radio noise they report no problem. The problem is recognized now by
Danfoss by this statement posted on their web site, (The increased use
of more sophisticated radio receiving devices such as Sat Nav and GPS
means the issue of EMI is a real factor, both conductive and radiated
interference needs to be addressed.)

Each upgraded model of Danfoss's electronic module was reported to
have less RF noise transmission. Today Danfoss offers two separate
noise reduction modules for either the BD35 or BD50 compressors.
Danfoss's Electronic EMI 101N0220 and their Extended EMI that includes
added Conduction Extra Filtered, what ever that means. P/N 101N0900 is
their current answer to the noise problem. I have no knowledge of any
boater that has purchased one of these modules or venders that sell
them.

Danfoss does offer six different electronic modules for BD35 and BD50
compressors with each offering an extended performance function but
none incorporate all desirable functions.
1.The new standard module has standard protection circuits but only
manual speed control by changing a resistor.
2. and 3. The two EMI modules above are the same as a standard module
but have the added noise control functions.
4. The Electronic Energy Optimization (AEO) module is the same as the
standard module except it automatically controls compressor speed,
much like an automobile transmission controls engine speed for best
energy efficiency. It also incorporates a cooling fan.
5. Electronic BD50 high start unit is a standard module that can
overcome false starts do to overloaded temperature/pressure starts,
this is common on a compressor trying to start when set to run at high
RPM. This is not a problem with the AEO model as it already has a soft
start function.
6. Electronic module with a AC/DC converter appears to be a resent
module but still not offered by ice box conversion refrigerator
manufacturers. AC/DC operation will prevent battery stress when
compressor is run from batteries connected to a battery charger while
at the dock.