[volt-nuts] Quality Multimeters

[Brian Kirby]

Roy Phillips wrote:
> Hello to all the members
>
> There has been considerable discussion on the time-nuts site regarding the HP3458, which I would like to add to my other HP DVM's. This is a problem due to the relative rarity, and therefore cost in the UK. But I have got a 3457 and a 3456 in my lab.
> What is the general opinion of the 3457 - is it a good deal short of the 3458 - I gather it is all down to the voltage reference device. 
> It would seem that obtaining a good DC voltage standard (mine is a Fluke 731B), is much more difficult than the frequency standard, with a heap of GPS and other gear at inexpensive price levels. Any good designs for this purpose, or is it best to find commercial products.
> Any advice on these matters would be welcome.
> Roy
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>   
Its up to the references and the A/D converters have to be very linear. 

I recently had my cal lab to do a test on the 3457A (7-7-2009).  I had 
them to hook it up to their calibrator system, A Fluke 5700A, which they 
rated at 1.0000000V at 8 ppm and I had them to let the meter average the 
measurement for 10 minutes.  The mean reading was 1.000002V and the STD 
Dev was 137.3x10-9.  I also had them to read 10V, using their Fluke 732B 
which was certified at 9.999959V at +/- 0.4 ppm.  The instrument read 
9.999956, the STD Dev was 5.358x10-6 for ten minutes.  I read somewhere 
that HP rates the instrument at 5 ppm, and from the 10V readings that 
appears to be very close.

The 3456A is rated 2 ppm, but you can only read 6 digits.

Brian - KD4FM