The mechanical zero adjustment is made with the radio power OFF. It can also be made if the meter is outside the radio.
The front of the S Meter has a plastic(?) adjustment screw. It has an offset pin that engages the mechanical zero adjustment
on the meter actuator.
Note: The pin can be positioned so that it is closer to the edge of the housing or closer to the center of the housing.
The last is the correct position. If incorrect, it will sort of work but probably not good enough.
"Zero" is misleading since the adjustment is for full scale.
Use a small screw driver to position the needle on the maximum line.
NEED PROCEDURE FROM MANUAL HERE.
If it's impossible to adjust, the pot (R29) probably needs cleaning. Or replacing if you can find one.
The 500 ohm wire wound pot on the rear of the radio becomes intermittent and needs cleaning.
Remove the wire from the pot terminal that goes to the S meter. On my radios, it was the single wire that connected to the two pot terminals jumpered together. The other terminal had two resistors attached. Alternatively, remove one of the wires from the S meter.
Using an ohm meter, rotate the shaft and see if the resistance from the wiper to one end changes smoothly. Change it slowly so you can see 'opens' if they occur.
If it jumps all over the place, take it apart and clean it. I did this with two pots. One worked, one didn't.
Remove the pot. It's not worth trying this while still installed.
Remove the back cover with a pair of diagonal cutters by gently working your way around it. It will eventually slip off the round can.
Spray with cleaner like CRC. Rotate end to end. Repeat. Lather. Rinse. Repeat. Etc.
I did it with the ohm meter attached to see if it was working. If you're wondering what the black thing at the bottom is, I used
the CRC cap to hold the pot so I could take a picture.
Reassemble. I just made sure it was started straight, placed it shaft up on a flat surface, and tapped round and round with a ball peen hammer till it seemed like it was seated.
Page: /S_meter/Adjust/S_meter_adjust.shtml
Last modified: Saturday, 25 Apr 2026