[R-390] Should this work?

[Barry]

By the way, I am getting 151v at the official 150v test point on the IF
deck.

Barry - N4BUQ

----- Original Message ----- 
From: "Barry" <n4buq at aol.com>
To: <R-390 at mailman.qth.net>; "Roy Morgan" <roy.morgan at nist.gov>
Sent: Thursday, May 05, 2005 10:01 AM
Subject: Re: [R-390] Should this work?


>
> > >I then decided to take the IF output from the working radio's RF deck
> (with
> > >the radio tuned to a good strong station) and plug it into the input of
> the
> > >IF deck on the radio under test.
> >
> > Barry,
> >
> > Good idea.  Does the non-working radio show any RF signal level on the
> > meter?  Probably not.  It sounds like your RF deck is not putting out
any
> > signal(s),
> >
>
> The meters aren't installed.  I'm still refinishing those.  ("Meters?  We
> don't need no steeenkin' meters!")
>
> > Have you put some 455 kc signal into the INput of the IF deck?  Try that
> next.
> >
>
> That's what I was trying to do with the cable from the working RF deck.
> Perhaps I need to try it using a signal generator?
>
> > Then run some signals into the test points on the RF deck. Start just
> > before the last mixer and work forwards toward the antenna. (use a
> > capacitor to couple the signal in, there are likely dc grid voltages at
> > some points.)
> >
>
> I figure if I'm not getting signals through the IF deck by injecting a
> signal into the input, going further up the RF chain won't help, will it?
>
> > I wish I had a little table of frequencies to share but I have not made
> one
> > up yet.  We need a troubleshooting aid like this: frequencies and normal
> > voltages all along the RF and IF chain, by receive band and frequency.
> The
> > manual IF gain setting procedure gives you a number for the IF input
> voltage.
> >
> > You may have a broken wire in the cable feeding B+ to the RF deck or
some
> > other place.. test for B+ at a plate pin of both if deck and rf deck.
> >
>
> I'm wondering if I have a broken wire in the harness.  Given the tests
I've
> performed, that seems the logical thing to look for.
>
>
> > >Is this a valid thing to try?
> >
> > Yes, you did good. First see if the input of the IF deck gives you
> > signals.. 455 kc in (at maybe 200 mv ?) Then, move towards the input of
> the
> > radio with test signals.
> >
> > I have at least two radios with dead RF decks.  A likely culpret is a
> > shorted screen bypass cap, or open screen resistor.
> >
> > Roy
>
>
> Thanks,
>
> Barry - N4BUQ
>
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