In article , rec-radio-amateur-
says...

///////////////////////////////////////////
Analog VOM expert needed

Posted: 21 Aug 2020 07:16 AM PDT
https://forums.qrz.com/index.php?thr...needed.721010/






The meter is not 50 uA but somewhat less. There is a big pot that you
set it to 50 uA.

Go here to find a manual for the meter. If they do not have a
calibration manual for that series, most any one is similar.

http://www.simpson260.com/downloads/downloads.htm