[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 acbern at gmx.de
Thu Apr 19 11:42:27 EDT 2018

-a calibration certificate without uncertainsties is totally useless. in is not even a calibration.
-I have never understood why people are so keen on getting things calibrated at Keysight.

> Gesendet: Donnerstag, 19. April 2018 um 14:08 Uhr
> Von: "Dr. David Kirkby" <drkirkby at kirkbymicrowave.co.uk>
> An: "Discussion of precise voltage measurement" <volt-nuts at febo.com>
> Betreff: [volt-nuts] Would you be concerned if the manufacturer does not have an uncertainty budget, so can't provide uncertainties in a calibration?
> I have an HP 4339B high resistance meter. It can read up to 1.6 x 10^16
> ohms, with a basic uncertainty of 0.6%. It has a built in voltage source of
> up to 1 kV.
> I've contacted Keysight (UK) and asked for calibration cost, with
> uncertainties, for this 4339B. However, they have said they can't provide a
> calibration with uncertainties, and when I asked why, they have said they
> do not have an uncertainty budget available that suites that model. Looking
> at the Keysight website, a calibration with uncertainties is available in
> the USA, but I guess for whatever reason Keysight UK don't have this
> ability on this specific instrument. On other instruments I have sent them,
> I have never had this issue.
> I expect if I really wanted to, I could get it shipped to the USA and
> calibrated there, but I can't justify the costs that would be incurred if
> it was shipped to the USA and back.
> From a practical perspective, I don't really need the uncertainties - it
> was more for interest sake. I also have a reasonable degree of confidence
> that as a reputable company, Keysight would not calibrate an instrument
> unless they were confident they could determine if it is in or out of
> specification.
> The 4339B is a pretty obscure unit, requiring resistors up to 10^11 ohms to
> calibrate it.
> I'm sending this to Keysight with a blank EEPROM, so there will be no
> calibration data whatsoever in the instrument. Hopefully that means
> everything will be set right, and so likely to stay in specification longer
> than it might otherwise do so. There are no trimmers in the 4339B - all
> calibration is via the EEPROM. A 3458A is used for calibration of the
> voltage source. I'm confidence the voltages will be measured accurately
> enough, but a bit less confident about the values of the resistors used for
> calibration.
> Dave
> Dr David Kirkby Ph.D C.Eng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD,
> Essex, CM3 6DT, United Kingdom.
> Registered in England and Wales as company number 08914892
> http://www.kirkbymicrowave.co.uk/
> Tel 01621-680100 / +44 1621-680100
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