[Hammarlund] S-Meter glitch

[Peter A Markavage]

If you want the meter to rest at zero with AVC off, adjust the "Zero
Adjust" pot for zero at that position. Before doing this you should check
that R22 is still approx. 820 ohms. Once that's done, R89, R90, and R91
probably would have to be changed from their original values. These three
resistors parallel the 820 ohm resistor in each AVC position. Most likely
some or all 4 of these resistors have changed value over the years. With
my 170A, after I confirmed that R22 was still approx. 820 ohms, I put
three small pc pots from the junk box (5K I think) in series with each
resistor. Then I could manually adjust each S Meter setting as I switched
through each AVC positions for a zero resting position. Not elegant, but
it works great.

Pete, WA2CWA

On Thu, 5 Feb 2004 16:25:10 -0500 "Craig Roberts" <crgrbrts@verizon.net>
writes:
> Hrllo gurus,
> 
> My ex-basket case HQ-170A VHF is perkin' along just fine now, 
> receiving
> robustly.  There's one annoying glitch left, though:  the S-meter's 
> zero
> point varies with the AVC setting.
> 
> Here's how it's working: with the AVC at the SLOW position, I set 
> the
> S-Meter zeroing pot so that the no-signal resting point of the 
> S-meter
> needle is zero on the scale (with the RF Gain all the way down). 
> With the
> AVC in MEDIUM position, the needle's resting point is then up scale 
> (about
> S1-2 or so). If  I switch the AVC to FAST, the needle's resting 
> point is
> even further up scale (S3-4).   With the AVC off , the needle sits 
> at about
> 1/3 scale.
> 
> Obviously this bridge circuit isn't balancing correctly.  Any 
> ideas??
> 
> Thanks and 73,
> 
> Craig
> W3CRR