[volt-nuts] Calibration and Certification - Trust and detail

[Orin Eman]

On Sun, Aug 11, 2013 at 2:55 PM, Dr. David Kirkby <drkirkby at gmail.com>wrote:

>
>
> How useful is this
>
> http://www.ebay.com/itm/281149723636 ?
>
> On the fact of it, the device would give one a reasonly high
> confidence something is working readlably well. I wonder if that is
> good enough for a 3457A.
>


It would give a reasonable check for gross errors.  They do claim to be
using a 3458A to cal them and give the 3458A cal certificate number.

Personally, I use a Geller Labs SVR-T for voltage checks at 10V

http://www.gellerlabs.com/Voltage%20References.htm

Joe Geller's calibrations are NIST traceable through his Fluke 732B.  A new
Agilent 34461A reads the SVR-T at about -3ppm, though it's a moving target
due to the temp-co of the '61A.  The goldenrubi supplied 3456A reads the
SVR-T at 8ppm high - inside 24 hour specs, but uncertain given the SVR-T's
claimed transfer accuracy of 5ppm.

I also have a Geller SVR that has been back twice for calibration.  The
first time back it was found to have changed by 1ppm.  The second time
back, I specified a different temperature so there was no as received
data.  The SVR is a reasonable choice if your lab stays at a constant
temperature.

I should go get the kelvin clips out and compare the 3456A against the '61A
on some 10k precision wirewound resistors I have.

Orin.