[volt-nuts] Any list members in UK who can accurately characterise a 732A and a 10K resistor

[Dr. David Kirkby]

On 14 January 2018 at 15:40, David C. Partridge <
david.partridge at perdrix.co.uk> wrote:

> I've recently rebuilt a 732A and it seems stable, but what I don't know is
> its actual output voltage down to the last ppm
>
> I've also acquired a Guildline 3330 10K standard resistor but again don't
> know its value - my 3458A says it is 10,000.43 ohms which I find rather
> hard
> to believe (way out of spec.).
>

Is there a tight spec on the nominal value?

I can't find the specification on those from a Google search, but I thought
the actual value was not very well controlled, but the stability is. So the
fact it is 0.43 Ohms high, may not mean it is out of spec.

I would imagine there's a trade-off between getting the initial value
correct and the stability. If you design the resistor for maximum
stability, you may not be able to simultaneously get the value close to its
nominal value. It you do things to get the nominal value better, they may
degrade the stability.


>
> I know someone with a recently calibrated 3458A (Keysight Calibration, not
> accredited, not Loveland), but can anyone do better?  I'd prefer not to
> have
> a pay for a formal cal lab report on these.
>

A non-accredited Keysight calibration should be no less accurate than an
accredited Keysight calibration.  From what I understand, the procedure is
the same, but you just get a few extra words on the cal certificate if it
is accredited - and pay quite a bit more. It costs Keysight money to be
accredited, so they pass the costs of that onto people that need an
accredited cal certificate.

I wonder what ones chances of going to NPL on their open-day (17 May 2018)
and getting a measurement performed as a favor?  If you don't want an
official cal certificate, but just a number you scribble on a bit of paper,
you might be able to get it done free of charge. I know the lab with a
primary voltage standard (Josephine Junction), was open to the public on
the last open-day, which was in 2016. I don't think there was any lab open
that measured resistors though.


> Thanks
> Dave
>

Dave