[R-390] Re: (BIG CORRECTION) REVISIT OF SYMPTOMS

[Jim Temple]

Hello to the group,

Sorry for the misstatements.  Below are a corrected repeat of the correct
symptoms and reply to Bill Hawkins question.



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

Jim

 ----- Original Message -----
 From: "Jim Temple" <jetemp@insightbb.com>
 To: <r-390@mailman.qth.net>
 Sent: Thursday, March 28, 2002 3:15 PM
 Subject: Re: [R-390] R-390A trouble


 Hi Roger and list,

 OK, here is what I found.  (Narrowing down the sypmtoms).

 1.  In AGC position.
     a.  RF gain at 5.  AGC voltage essentially 0.  Little rushing sound.
 Receiver apparently stable.
     b.  As RF gain is increased, background/rushing noise slowly increases
to a level that seems normal and strong.  Noise sounds normal and stable. TO
A POINT.
     c.  As RF gain increases toward 9, the AGC voltage abruptly increases
and the audio breaks into the putt, putt/screeching sound.  The AGC voltage
will continue to increase to about 7-8 volts, and the putt, putt/screeching
continues as long as there is AGC voltage.
     d.  The carrier level remains essentially 0, until the putt, putt
begins, then the carrier lever meter shows a smooth increase to 100.

 2.  In MGC position.
     a.  Symptoms are the same until the point that the background noise
becomes strong (about 9 on the RF gain), then the receiver abruptly blocks
as if from a strong signal.  The carrier level meter will JUMP to 100.

 3.  An observation is that the problem occurrs at the same position of the
RF gain control, whether the function switch is AGC or MGC.  The only
difference is that the receiver putt, putts in AGC and blocks in MGC. Both
increase the carrier level to 100 (slowly in AGC, abruptly in MGC. I hope my
observations are clear, if not please ask to clarify.  Thanks, guys.

 Jim
 73, KF4ICZ


Reply to Bill Hawkins question:

The problem begins with the RF gain at the same point, whether in AGC or
MGC.

With the RF gain control set to just below the point where the problem
starts, an increase or decrease of the IF gain control (on the IF deck)
produces NO CHANGE.  With the RF gain control set full, where there is a
putt, putt (in AGC), or the receiver is blocked (in MGC) there also is no
change.  In other words, changing the IF gain (on the IF deck) makes no
difference.

Jim