[1000mp] Cooling fan causes buzz in transmit audio on Mark V

[Ed Gosch]

It looks like whenever the cooling fan in my Mark V runs, it
causes a buzz in the transmit audio.  It happens with a MD-100
and Heil Goldline.  The only connections to the radio are:
Antenna, mike, external speaker and earth ground.  Does anyone
else have this problem and/or a fix?  Just starting to trace out
the fan circuitry in the service manual to see if some by-pass
caps or shielding of the fan wires might be needed.
Ed
W2UV