[R-390] R-390A trouble

[Bill Hawkins]

Great progress, Jim.

You have proved that the problem is not in the RF deck.

The MGC test proves that the set is in fact breaking
into self oscillation. The noises in AGC are the result
of the AGC trying to control the internal oscillation.

You should also be able to swap the IF deck without any
trouble, compared to the RF deck. Or did you mean IF
when you said RF deck? People do that, sometimes. I do
it more often as I age.

Key question: Have you checked the gain of the IF deck
per the manual? Simple clue - if the IF Gain pot is
fully clockwise, someone tried to "soup up" the set.
Simple test - turn it CCW and see if the MGC can be
turned to full CW in MGC mode AND the receiver has
acceptable sensitivity. Not all the way CCW, but a
bit at a time - or set MGC full CW and back off the IF
gain to see if it will stop. If the IF gain pot doesn't
do anything, that could be it right there.

There aren't any wires running from IF Output to RF
input, are there?

Regards,
Bill Hawkins

[taking a break from covering a Hammarlund with fresh
cat skin.]


-----Original Message-----
From: r-390-admin@mailman.qth.net [mailto:r-390-admin@mailman.qth.net]On
Behalf Of Jim Temple
Sent: Thursday, March 28, 2002 2:46 PM
To: r-390@mailman.qth.net
Subject: Fw: [R-390] R-390A trouble


Hi Roger and list,

OK, I have a friend who inherited a R-390A from his father.  I picked up his
RF deck, and upon installation in my receiver, the symptoms are exactly the
same as with the original symptoms below.  Now what??

Jim