the manual defines a 4 hours warmup time. after tat the meter is supposed to be within spec.
then the note 18 test can be started (ACAL and reading the cal constant).
then it should be left on for a couple of days before a new acal is done, ideally as long as the note 18 specifies (7days iirc) , however if you see there is no drift (against a known good 732A e.g.), then it might be shortened.
my experience is, if an AD board has a drift issue, it drifts quite a bid in short time in most of the cases, have seen 10+ ppm a day.
also, note 18 covers two drift issues, AD and REF board related drift. do not confuse.
the manual defines a 4 hours warmup time. after tat the meter is supposed to be within spec.
then the note 18 test can be started (ACAL and reading the cal constant).
then it should be left on for a couple of days before a new acal is done, ideally as long as the note 18 specifies (7days iirc) , however if you see there is no drift (against a known good 732A e.g.), then it might be shortened.
my experience is, if an AD board has a drift issue, it drifts quite a bid in short time in most of the cases, have seen 10+ ppm a day.
also, note 18 covers two drift issues, AD and REF board related drift. do not confuse.
> Gesendet: Mittwoch, 10. Januar 2018 um 12:34 Uhr
> Von: "David C. Partridge" <david.partridge@perdrix.co.uk>
> An: "'Discussion of precise voltage measurement'" <volt-nuts@febo.com>
> Betreff: [volt-nuts] 3458A drift checking question
>
> How long does the meter need to have been powered on before it makes any
> sense to perform the Service Note 18 drift test?
>
> Thanks
> Dave
>
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