[ICOM] IC-765 Internal Audio Noise

[KD7JYK DM09]

"Anyone run across this before?"

Yes, with many, many rigs across many decades, some intentional, some 
not, depends on design, but both tube, and solid state. Sometimes a 
radio physically generates noise with modulation. Sometimes one 
component, sometimes several.

Depending on the rig, and cause (aside from monitor/side tone/RF 
intrusion), changing settings, or microphones can change/eliminate it.  
It may not be the exact issue, or cause in your instance, but in phone 
rigs going back almost a century now, it's been a "thing", at times.  
AM/SSB rigs the most susceptible, as it's associated with amplitude.

A quick easy test is battery power, short leads, into a load, starting 
at lowest power output, away from the shack, and house, such as a park, 
or field, away from anything else that may generate noise and be 
confusing.  Bring a friend, have that person speak into the mic as far 
away from the rig as physically possible, directly into the mic, cupping 
a hand/hands over it to prevent you from hearing, increase power 
until/if you hear the sound when you place an ear on the radio.  You may 
have to listen to different areas of the radio.  The idea is to 
completely isolate the radio and associated connected wires, and 
feedline, first.  In the past I've also used a tone generator in an 
electrically shielded, and mechanically dampened box with about 3" of 
shielded wire to inject audio into an isolated rig, self contained, no 
potential for stray RF, or microphonics.

Just some random trouble shooting ideas for that particular issue, with 
other rigs.

""Name and callsign would be nice.""

I found this never had anything to do with the actual issue, or how to 
address it...

Kurt