[R-390] Should this work?

[John KA1XC]

Yeah, you should of heard something. Even with no input to the IF deck I 
think you can still hear the noise spectrum change when the IF bandwidth is 
changed around.

Since that IF module tested OK it sounds like a wiring problem. The audio 
path is somewhat twisted - out to the Diode Load (is the jumper there?) - 
back into and out of the Noise limiter circuit and front panel control - and 
then to the audio deck.

John



> Working on the "new" R390A.  I have it mostly back together (at least 
> enough
> to run some tests).  I tested everything except the RF deck by 
> substituting
> the modules into my working radio and everything I tested checked out
> functional.
>
> When I powered up the radio, I got nothing on the audio except a small hum
> when the volume is turned up to 100%.  I didn't figure on hearing anything
> in the way or radio signals since the RF deck is in complete need of an
> alignment, but I did expect to hear some noise.
>
> I injected the audio signal generator into pin 7 of the plug that connects
> the IF deck (P112) and was able to get good audio on both line and local.
>
> 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.  Since I had checked the IF deck by
> substituting it into the working radio and it does work there, I figured I
> should get some signals that way.  Still nothing.
>
> Is this a valid thing to try?  I realize the IF deck still needs a touchup
> for alignment, but it should be close enough to hear something through the
> chain.  It worked when I substituted it into the working radio a few weeks
> ago so I assume it should still be working.  Unless something has broken
> since then (and I'll try substituting it again to make sure), I would 
> think
> this should produce some signals.  No?
>
> Thanks,
>
> Barry - N4BUQ
>
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