[volt-nuts] Would you be concerned if the manufacturer does not have an uncertainty budget, so can't provide uncertainties in a calibration?

[acbern at gmx.de]

understand, it is maybe different here in Germany then, there are a number of labs with pretty low uncertainties who also support old gear adjustments.
on the other hand, you have to know who you are working with for what gear. Otherwise you can have unpleasant surprises.
in your case, if you have no nobody calibrating your meter with a specified uncertainty, maybe an option is to build your own decade of resistances and use a precisiion high voltage source (calibrator) and a 3458A as current meter. that brings you to say 10nA/100Gohms. if thats sufficient.



> Gesendet: Donnerstag, 19. April 2018 um 18:41 Uhr
> Von: "Dr. David Kirkby" <drkirkby at kirkbymicrowave.co.uk>
> An: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> Betreff: Re: [volt-nuts] Would you be concerned if the manufacturer does not have an uncertainty budget, so can't provide uncertainties in a calibration?
>
> On 19 April 2018 at 16:42, <acbern at gmx.de> wrote:
> 
> > -a calibration certificate without uncertainsties is totally useless. in
> > is not even a calibration.
> >
> 
> Having bought the meter, it is not so useless if it tells me it is working
> or not, but I do have some concerns I must admit.
> 
> 
> > -I have never understood why people are so keen on getting things
> > calibrated at Keysight.
> >
> 
> Well, quite simply there's nobody else I would trust to calibrate much of
> the Agilent equipment. I did contact one UKAS acredited lab, who quoted to
> calibrate loads of bits of my equipment, but declined this meter. But when
> I checked the companies uncertainties, I was totally unimpressed. For
> example, their uncertainty on capacitance at 1 MHz was well in excess of
> 0.05%, yet they quoted to calibrate the meter, which has a basic
> uncertainty of 0.05%. I also found their prices were much higher than
> Keysight.
> 
> Most companies are not going to be able to adjust Agilent stuff if it is
> out of spec anyway, as often the software to make the adjustments is not
> available. So I'm not convinced there is any half-sensible alternative.
> 
> Dave
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