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

[WB6BNQ]

Chris,

To the best of my recollection, the 730 was the designation of a "rack" that
contained, essentially, four each 731As.  the 731A's were a decent voltage
standard that, of course, has been superseded.  Having four references has value,
if, and only if, you know the temperature coefficient of each of the four
standards in the rack.  With proper technique, that information can be of great
benefit compared to having just one standard.

Having said all of that, unless the temperature coefficients are known for each;
and you are going to maintain a proper lab environment; and spend the time using
the "rack" correctly, then there is no distinct advantage.  If the price is right
and you can get it cheaper then the 731B, then by all means, IF THEY ARE WORKING,
you would not be hurt by getting it.

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


Christopher Brown wrote:

> As I understand it, the 730A refs are a older design, and the one used
> in the 731B is improved/better.  But, the 730 has 4 that can be run in
> various combinations.
>
> Thoughts anyone?  Benefit of 4 refs in one chassis v.s. issues with the
> switching combination controls? anything?
>
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