[volt-nuts] Voltage standards, Fluke 730A v.s. 731B

[Christopher Brown]

On 8/19/12 2:40 AM, WB6BNQ wrote:
> Chris,
> 
> Otherwise, if you are just looking for a working voltage standard then go for a
> 731B and have it calibrated by a responsible credited LAB.  You can possibly save
> calibration costs if you specify that you are only concerned with the 10 volt
> output.  The other output taps are only good if no current is drawn from them by
> using a proper null detector, specifically the Fluke 845.  The 10 volt output has
> a low output impedance providing the ability to handle some small amount of
> loading, such as the nominal 10 Meg Ohm input on good DMM's with very minor error
> due to the loading.
> 
> Bill....WB6BNQ


On that front, please check my understanding.


As I understand it, the 3456A is itself rated as a transfer standard
with a nominal input impedance in the .1, 1 and 10 VDC ranges of 10Gohm
and with due care (controlled environment, proper test leads, everything
clean and free of potentially conductive residue degrading isolation,
etc...) suitable for direct connection to a standard such as a 730A or
731B for calibration of said standard.  Also usable (in a pinch and only
below 11VDC) in place of a NULL detector.


Am I off kilter here?


Thanks,
Chris
WL7CLA