From: "Ken, WA2LBI" 
Subject: Re: [drakelist] R4A AGC inop.


George,

Since this receiver is new to you don't overlook the possibility of MULTIPLE
problems. I serviced a R-4B last year that had similar symptoms, among others,
to yours and it turned out to have several bad tubes and resistors. Of course I
had swapped tubes in order to isolate the problem but I was actually swapping
one bad tube for another! Talk about chasing your tail!

Have you checked all the voltages and resistances against the corresponding
charts in the manual? That is a good place to start with a new rig with an
unknown history.

Keep us posted on your progress.

Ken, WA2LBI

Quoting Garey Barrell :

>
> George -
>
> OK..
>
> Measure the voltage at TP-2 (on top of the chassis, just in
> front of the Passband tuner.)  Should measure -1.35 volts
> with the the Preselector detuned on any band.
>
> Have you tried both Fast and Slow AVC?  If no AVC in either
> position, try swapping the Calibrator tube, 12BA6, with
> either of the IF tubes, V4 or V5.  Something is loading the
> AVC line.  If this doesn't help, try swapping the RF Amp, V1
> with another 12BZ6.
>
> Beyond this, you'll have to find what is either loading or
> shorting the AVC line.  Possibly one of the grid resistors
> of V1, V4 or V5 cracked or open.  They can go up in value
> considerably without affecting the AVC, so unless they are
> open, look elsewhere.
>
> Let us know what you find.
>
> 73, Garey - K4OAH
>
>
>
> George wrote:
>
> > To add to that it is an 11 tube model (no 12av6)
> >
> > George NE2I
> >   ----- Original Message -----
> >   From: George
> >   To: drakelist{at}www.zerobeat.net
> >   Sent: Thursday, April 08, 2004 9:00 PM
> >   Subject: [drakelist] R4A AGC inop.
> >
> >
> >   Just bought an r4a and it seems like the agc is not working at all
> >   I have to ride the rf gain or I get way too much audio and distortion
> >   It has good sensitivity and is spot on frequency wise.
> >
> >   Also when I select NB or cal the s-meter pegs and I dont get any audio.
> >
> >   Thanks
> >   George NE2I
> >
> >
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