[R-390] Should this work?

[Barry]

> >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