[volt-nuts] Calibration of voltage standards

[wb6bnq]

To amplify Chuck's point,

The only meter worth considering, if you are going to get one, is the 
FLUKE 845.  Preferably, the battery operated version which has a higher 
isolation leakage resistance.  However, the 110
volt rack mount model would do just as equally.

Bill....WB6BNQ


Chuck Harris wrote:

> To do a comparison of the sort you are asking about, the
> sensitivity of the null meter is much more important than
> its ultimate accuracy.
>
> So, neither of your meters is really the right meter to
> use for this task.  What you want is called a null meter,
> and is generally sensitive to the microvolt region.
>
> -Chuck Harris
>
> Ken Peek wrote:
>
>> 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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