[R-390] R390A AGC troubles

[Bill Coleman N2BC]

Hi Dennis, it was my understanding that zero input signal state is 
around -7V.

The other measurement that is 'wrong' is the suppressor grid voltage on V504 
& V508), it is +3.4V, should be -2.5V.

The voltage on the grids of the IF strip is consistent with the -0.5V.

Externally, it sounds like minor overloading on strong signals.

THX, Bill

----- Original Message ----- 
From: "Dennis Wade" <sacramento.cyclist at gmail.com>
To: <R-390 at mailman.qth.net>
Sent: Wednesday, July 27, 2005 6:11 PM
Subject: Re: [R-390] R390A AGC troubles


I'm at work, but I don't recall that -0.5V zero signal on the AGC bus
was a problem.  When I finally got mine fixed (different problem
though, see previous posts) the small + zero signal voltage I had been
seeing became -0.4V.

What are the grids of V%01, 502 and 503 doing?  What do you "hear" in
terms of symtoms..how does the radio sound under various signal
conditions?

Dennis

On 7/26/05, Llgpt at aol.com <Llgpt at aol.com> wrote:
>
> It is quite possible the "cadaver" Z-503 is a bad one too. They are a 
> known
> troublesome part. If possible try a known good if deck. Maybe you have a
> friend  close by.
>
> Les Locklear
>
>
> In a message dated 7/26/2005 2:47:01 PM Central Daylight Time,
> n2bc at stny.rr.com writes:
>
> Along  the way I managed to destroy Z503 so I pulled one out of a 
> 'cadaver'
> IF  strip.  I noted that it's slug is fairly well centered in the core.
> Upon
> replacing Z503, the 'new' one behaved the same way.... increasing  stage
> output as the slug was cranked toward the top but it runs out of 
> adjustment
> before peaking.
>
>
>
>
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-- 
Dennis L. Wade
KG6ZI
Carmichael, CA
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