Keith wrote:
That "morse code" sound is a NEMA sentence bleeding into 12V wiring
through an improper connection. Check out this excellend site for info.
on how to check and correct.
http://www.shipmodul.com/en/connections.html

I don't think a Danfoss BD-50 compressor uses NEMA anyplace. That's the
only equipment turned on except for the SSB. The noise is radiated, NOT
coming through the 12V wiring. Disconnected the antenna from the SSB and
the noise goes away. Of course, the station being monitored goes away
alswo with no antenna.