I picked up yet another "perfectly working" Lowe receiver. This one would
howl for the first 5 minutes of operation, the FM detector didn't work for
this time because of low I.F. injections level, and system gain would be low
during this time.
I traced the problem to a 100uF lytic cap near the audio amp. After the unit
warmed up, I hit several components with freeze spray. After I found this
problem component, I removed it completely and the problem became much
worse. When I tacked a cap into the circuit to test my theory, the receiver
started working properly. The cap must have been leaky, because when I tried
to parellel another cap across this one, no change was noted.
This receiver uses the same audio amp as the HF150, so if you have a
receiver that howls even with an external speaker, this could be the
problem.
Between myself and some other friends, this is the 6th unit I have run into
that needs at least some kind of repair. It would seem that folks get scared
when these receivers start to malfunction, and "jump ship", so to speak.

Pete