[Icom] Strange IC-765 40 meter problem

[Larry Benko]

Had a very similar problem with my 756PRO.  Turned out that if
I transmitted the receive would come back for minutes/hours and
then suddenly drop off again.  To diagnose the problem I connected
the radio to absolutely nothing (removed all antenna connections).
I then ran a signal generator with a few feet of wire near the
756PRO giving a signal reading of about S9.  Left the signal
generator on for the weekend on and noticed that the receive level
never changed.  Then I was pretty sure that the problem was external
to the radio (since the radio was connected to nothing).  Turned out
the problem was in the roller inductor of my external tuner.  Some 
cleaning and a little Caig Industries DeoxIT D100 fixed the problem.

I would definitely first determine if the problem is inside the
IC-765 or external.  If the problem is internal to the 765 and only
happens on 40m, I would look in the area of the octave bandpass
filters and the associated circuitry that switches them in and out.

73,
Larry Benko, W0QE