[volt-nuts] Calibration Sources for Solartron 7081

[J. L. Trantham]

I recently added another Solartron 7081 to my collection that seems to be
working correctly, is stable and I have upgraded it to the latest firmware.
However, it is clearly not accurate, at least on the 10 VDC scale, measuring
my 10.000 000 standard at about 10.000 840 V while my other meters are +/-
about 10 uV of 10.000 000 VDC.

 

If I understand the calibration procedure correctly, I will need an input
short, an input open, and 'standards' for each of the VDC, VAC, and Ohms
ranges to perform a complete calibration procedure.  This would appear to be
a source for 0.1, 1, 10, 100, and 1000 VDC and VAC along with 0.1, 1, 10,
100, and 1000 kOhm and 10 and 1000 MOhm resistor standards.  I can come up
with the VDC standards and the resistance standards except the 1000 MOhm.  I
don't have 'standards' but I have references that are stable and calibrated
meters (another 7081 and two 3458A's) that I can use to measure my
references and then input their measurements into the DUT 7081 to perform
the calibrations.

 

My questions are:

 

What source could/should I use for the ACV and what frequency for the ACV?
I can come up with a power transformer and a variac for 60 Hz.  I also have
a selection of signal generators and synthesizers for amplitudes up to about
+10 dBm at pretty much any frequency you prefer.

 

What would be the lowest ACV that I could/should use for the 1000 VAC scale?

 

What suggestions for the 1000 MOhm standard?  What is the lowest value that
I could/should use for the 1000 MOhm scale?

 

My plan is to test each scale against my other meters and calibrate only the
scales that are 'out of bounds'.  Good idea or bad?

 

Thanks in advance.

 

Joe