[Collins] 75S-1 Receiver S-Meter Adjustment Potentiometer

[Dr. Gerald N. Johnson]

On Fri, 2007-03-23 at 07:45 -0400, Jim Walker wrote:
> Can anyone tell me of a source for a replacement S-Meter adjustment pot?
> It has a long brass slotted screw end sticking up from the chassis and
> the schematic shows the value as 250 ohms.  The current pot is extremely
> touchy and seems to have worn spots on it.  I have tried a cleaner which
> helped but the problem remains.
> 
>  
> 
> Thanks,
> 
> Jim KZ5AW
> 
Cramolin, the makers of DeoxIT have a cleaner product especially for
potentiometers. 

In Mouser I find (and in stock) their catalog number 594-148-1102. Its
about the same size, though square instead of round but has the same
mounting bushing and shaft with a screwdriver slot in the end of the
shaft. The value is 1K, a bit high, but it will work pretty good if
shunted with a 330 ohm 1/4 watt fixed resistor, carbon or metal film
these days. $7,88. www.mouser.com, page 543 in the printed catalog.

The S-meter adjust in the 75S-3B is different and uses a 500 ohm
potentiometer the same one as used for the 32S-3A balanced modulator or
mixer balance. This same Vishay Spectrol pot would work there if shunted
with a 1K resistor.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer