[ICOM] Help with Severe Electrical Noise

[michael morgan]

I am sorry this is not directly related to Icom radios except the usage of
them.  I have an Icom 756Pro II that I am using with a Gap Challanger
antenna.  Also has been well for the last few years.  For some reason about
three days ago and started getting a s9 or higher "White Noise" on all
bands.  It is over powering all but the strongest of signals.  The is
happening on all bands.  I have tracked it down to something electrical
around my desk.  I did this by the following means. If I power the radio
from a 12V marine battery and kill the breaker to  my Shack area the noise
diminishes.  If I power the breaker back on the noise returns.  I tried to
unplug everything with the breaker on and I get the noise.  I am stumped.
It is there if I power from a battery or my 12V power supply.  I
disconnected everything from the rig exept power and antenna and it is
there.  Any help would be greatly appreciated.  Also this is occuring on my
other rigs as well which are a Icom 706MKIIG and a Kenwood ts450s.


Thanks in advance

Michael, AA5SH