[R-390] Image problem solved - Not.

[Jim M.]

What about the first mixer V202 (6C4) - if it isn't getting good AGC, or
insufficient oscillator injection, can an overload in that stage cause this?

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of Mark Huss
Sent: Thursday, October 25, 2007 9:40 PM
To: Tony Casorso
Cc: r-390 at mailman.qth.net
Subject: Re: [R-390] Image problem solved - Not.

For what it is worth, Tony, I asked around about your problem with 
people who have had extensive experience with troubleshooting R-390A's. 
All four said the same thing. AGC on the First RF Stage is driving it 
too hard, and into distortion. I just gave the symptoms, not that you 
had worked on the AGC Transformer. That may not be it, but it is the 
first place they would start.

Tony Casorso wrote:
> Sorry everybody,
>
> I lied. I didn't mean to but I did. Tonight I tried to repeat the 
> experiment and it doesn't work.
> Lifting the ground from one side of the balanced input does absolutely 
> nothing to help the situation.
>
> I'll bet that I had a bad connection to one side of the balanced 
> connector since I had to jerry rig it to connect my BNC from the 
> antenna to the balanced input without ground. I hear no harmonic at 
> all when only one pin of the balanced input is connected to the 
> antenna. I also hear only a faint hint of a harmonic when I use the 
> unbalanced input.
>
> So, I still have the problem (if it's really a problem). It's not an 
> image problem really. I'm sorry I called it that. It has nothing to do 
> with the IF.
>
> I'm going to go away now. I'll make sure everything is repeatable 
> before I bring it up again.
>
> I feel like the Rockies must feel after the disaster in Fenway last 
> night. Well, maybe not quite that bad.
>
> Tony
>
>
>
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