[Test-Equipment] HP 8640B Option 323 Meter Driver

[Miles Anderson]

I have an unmodified military surplus USM-323 signal generator a/k/a HP
8640B Option 323.

The front panel meter does not zero with the RF switch OFF and the RF
verniew fully CCW. I assume this is abnormal and means that the RF detector
and/or meter amplifier must be recalibrated.

The detector & meter driver seems to be a small card on the top chassis
parallel to the front panel located immediately behind the hours counter and
the panel meter. The board is marked "A1 Meter Driver." The board contains
three pots and 4 test points on the top edge marked, in order from left to
right: [R29 Meter Driver] (Meter) [R14 Meter Offset] [R15 Det Offset] (AC
In) (Det) (Buffer).

This board seems much simpler than the meter driver boards (marked "A2" and
"A4") shown in the manuals on LOGSA, and the component nomenclature does not
correspond.

Does anyone have a print of this subassembly and the calibration procedure
applicable to it?

Miles Anderson, K2CBY

16 Round Pond Lane

Sag Harbor, NY 11963

k2cby at optonline.net