[R-390] r-390a chirping CW

[James Miller]

I have found that replacing the first and/or second mixer tube may help the
chirp.  Changing AGC on the mixer seems to cause it to load down th
oscillators as the AGC increases, pulling them off frequency slightly.  Also
could be another suspect tube, maybe an osc. tube.

----- Original Message ----- 
From: "Forrest Myers" <femyers at attglobal.net>
To: "r-390" <r-390 at mailman.qth.net>
Sent: Sunday, June 13, 2004 10:33 AM
Subject: [R-390] r-390a chirping CW


> Hello,
>  I have a capehart r-390 a sn 557 that is working quite well except for a
> couple of problems. All bands and all filters work. There are a couple of
> problems though and I'm asking the learned group on this list for any
quick
> information or ideas.
>  Problem #1:
>   Good clean CW signals chirp when heard on the 390a. It sounds like the
BFO
> changes frequency with AGC levels. Checking the voltage at the audio
module
> and it's a steady 150.1 volts. Haven't checked farther into it.
>
>  Problem #2:
>   Audio level is low but sounds good. I have to run the Local Gain control
> wide open to get a comfortable listening level. This problem has crept in
> over the past year. All tubes have been replaced. the radio has been
> re-capped, including the filter capacitors in the audio module. It has
been
> aligned and the PTO is very linear after setting the end points. The rig
> works very well except for the above mentioned problems. I've been away
for
> about 9 months and haven't used the rig. Am planning on getting into it
> again after building a set of test wire extender so I can check into
> voltages and signals. Just thought I'd put out the symptoms to see what
> advice I could gather.
>
> 73 DE AG4ND
> Forrest Myers
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