From: Garey Barrell 
Subject: Re: [drakelist] R4A AGC inop.


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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