[volt-nuts] Calibration of voltage standards

[Ken Peek]

Hi Group,

I have heard of a few different ways to measure one 10V voltage standard
against another 10V voltage standard.

Assume we have two 10V voltage standards.  One is calibrated, the other
not only needs to be calibrated, but probably adjusted.  For the sake of
simplicity, let's say the two standards are Fluke 732B's.

I *think* the best way is to connect the two units' (-) terminals
together, then connect a calibrated meter in between the (+) terminals,
and measure the difference.  I have also heard that to remove thermal
EMFs, you should use a low-thermal-EMF DPDT switch or a low-thermal-EMF
relay to reverse the connections on the DMM, so you can take the reading
forward and reversed, then split the difference.  There is the
possibility to introduce thermal-EMF errors from the switch/relay as
well, so I'm wondering if this is a good idea.  This sort of makes sense
to me, but I'm not a metrologist, so I would like to hear what others in
this group think about this.

So, just what is the proper way to accomplish this task?

BTW-- I have an Agilent 34420A and an HP 3458A, which would be the
better instrument for this task?

Best Regards,
Ken Peek
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