[Hallicrafters] SX-28 S-meter adjustment

[Julian Bunn]

Actually I am beginning to think my problem isn't anything to do with
the S-meter. I have checked the S-meter pot, the 100 Ohm parallel resistor,
and the voltages around the S-meter tube, and everything looks fine.

The symptoms of the problem suggest something wrong in the AVC circuit.

With AVC off, the meter needle hovers around the zero (leftmost) position.
If I tune in a strong signal on the BCB, then the needle moves a little
higher. If I then turn the AVC on, the needle moves up the scale
and starts indicating something plausible as a signal strength.

(As I understand from the manual, the S-meter reading is only valid with
AVC on.)

However, after a short while, the meter needle swings off hard to the right. Sometimes
this happens almost immediately after turning on the AVC, and sometimes the
needle hangs around for a few seconds before swinging off.

If there is no strong signal tuned in, the meter needle does not do this.

It's almost as if there is some delayed feedback, and the AVC is too
"aggressive".

Any comments much appreciated.

Julian

HallicrafterSX28 at aol.com wrote:
> Check the S-meter pot most of them get shorted .Remove the S-meter pot  check 
> resistance from any of the terminals to casing.
>  
> By the way The S-meter is adjusted to zero with the AVC off doesn't matter  
> whether the antenna is connected or not .
> 
> 
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