[Yaesu] 1000mp chirping, cant run over 70w before happens

[Carlin Royal]

Hello all,

I have a DC model 1000mp and have been having some chirping troubles
reported from the station I am working. I have this radio on a 50amp
supply that loafs at 25amps draw, good stable voltage under load is
13.6vdc. If I try to run more than 70 watts from the radio it starts
making stange noises and sounds like a bad dx station in the middle of
the night. I am sure it is not rf related because I can drive my amp
with 60 watts drive creating nearly 900w output and everything sounds
just fine. Has anyone got suggestions that a common person mught try to
fix?

The radio has had the inrad cw mod installed and that made no differance
to this trouble, but did notice it sounds a lot cleaner at the 50w
setting when playing back the audio recorded on the computer.
Thanks
N5OE