Fw: [R-390] R-390A trouble

[Jim Temple]

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

----- 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
>
> ----- Original Message -----
> From: "Roger L Ruszkowski" <rlruszkowski@raytheon.com>
> To: <r-390@mailman.qth.net>
> Sent: Thursday, March 28, 2002 1:09 PM
> Subject: Re: [R-390] R-390A trouble
>
>
> >>
> >> Hi Roger and list,
> >>
> >> OK, I want to fix this receiver. Here goes. Jim 73, KF4ICZ
> >
> > Jim, your on it now. Roger.
> >
> > The question please.
> >
> >
> > Does this putt, putt occur when in the MGC function?
> >
> > If no, then its most likely an IF deck AGC voltage generation problem
and
> > not the RF deck at all. If yes, then it is not and AGC problem at all
and
> > we are looking for a bad CAP.
> >
> > Roger.
> >
> >
> >
> >
> >
> > _______________________________________________
> > R-390 mailing list
> > R-390@mailman.qth.net
> > http://mailman.qth.net/mailman/listinfo/r-390
> >
>