[time-nuts] Calibration procedures - what is normal?

Joseph Gray jgray at zianet.com
Fri Feb 12 15:14:03 EST 2016


I sent my HP 3457A in for cal. I should be getting it back next week.
I won't mention where I sent it, but it wasn't Keysight (I don't like
that name). I recently changed the SRAM battery and purposely did not
save the cal constants. I bought the meter second hand and it wasn't
in spec when I bought it. I didn't care what the past data was.

The service manual lists an entire sequence of procedures for
calibrating this DMM, starting with storing values for zero and full
scale into the SRAM. All of this is done via the front panel, by
pushing buttons.

I just found out that this part of the procedure is not normally done
(at least by the lab I sent the DMM to). With no pre-existing cal
constants, the tech I spoke to was rather annoyed that he was having
to spend the time doing the hookups and pushing buttons for each
function and range to store the zero and full scale values. I was told
this added an extra hour to the normal procedure.

Not knowing what is normally done in the cal lab, I assumed that the
entire procedure as listed in the service manual would be done. It
seems that I was wrong.

In the end, the lab decided not to charge me for the extra time
involved. I thanked them for that.

My question is, do any cal labs (including Keysight) normally perform
the zero and full scale procedures as listed in the service manual?

Joe Gray
W5JG



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