[Hallicrafters] SR-150 problem

[Burton Pratt K4PRF]

I wonder if you SR-150 owners have ever run into a strange problem with
the receive audio.  The audio is raspy sounding.  Even the 100kc calib.
tone is not pure.  The audio sounds as if it is rapidly pulsing, not
quite distortion in the usual since.  Now I know that the first thing to
check is the filters in the power supply and all the electrolytic caps
in the transceiver, check the tubes, voltage check at each pin,
resistance check at each pin,  good speaker etc.  I even ran it on two
other PS-150 power supplies.  Same problem.  This is not distortion
caused by hum.  I have an idea that an oscillation is getting into the
receive audio string somewhere and is beating with the BFO.  I am told
by on the air contacts that the transmitted audio is fine with no trace
of ripple or distortion.  This thing just about has me stumped.  I have
had this rig since it was new and it just turned forty.  Anyone have a
suggestion?

Burt Pratt
K4PRF
pratt at zebra.net