[volt-nuts] Advise to Junior Member Regarding Acquisition of Fluke 5XXX Series Calibrator

[John Devereux]

Hi Adrian

Oh I see...

But... I seem to recall the 720A also, similarly, requires linearity
validation unless you just "assume" it is inherently linear?

The manual shows a test using a second 720A! And that is "only" good to
0.2ppm.

John



acbern at gmx.de writes:

> Hi John,
>
> sure, seems I should have been more clear. What I wanted to say is
> that in order to have traceability starting from just a calibrated 10V
> (and 10k) standard, which is sufficient to adjust a 3458A, you still
> need some type of self-calibrating divider to validate the 3458A
> (which then, once validated, can be your working unit). Or, if one
> e.g. wants to calibrate a 5440 voltage calibrator from a 10V standard,
> you also need a divider. Assuming a non-calibrated 3458A, because of
> its highly linear ADC, can be used transferring the 10V into other
> voltage ranges, is not valid, the 3458A has a performance validation
> point that checks (within the testable limits) that the linearity is
> ok. So no way around a divider unfortunately.
> In the end, what we talk about is how do we get traceable volts
> measurement capabilities (to the 10V standard that has been
> calibrated, if one has a calibrated 1V too (of the 732A or whatever),
> less work, but the basic problem remains).
>
> Adrian
>
>
>
>> Gesendet: Freitag, 24. April 2015 um 11:43 Uhr
>> Von: "John Devereux" <john at devereux.me.uk>
>> An: volt-nuts at febo.com
>> Betreff: Re: [volt-nuts] Advise to Junior Member Regarding
>> Acquisition of Fluke 5XXX Series Calibrator
>>
>> acbern at gmx.de writes:
>> 
>> > A few things to keep in mind:
>> > - the 720A (and the 752A) are self-calibrating, i.e. you can (easily)
>> > calibrate it yourself before use. The 3458A, using its external
>> > artifact self-cal procedure based on only 10v and 10k, requires a
>> > performance verification therafter (at least every second time, see
>> > some military docs concluding this, I don't recall the link but easy
>> > to find; i would actually say, to comply with GUM, every time).
>> 
>> Hi Adrian
>> 
>> I don't think that this point is a fair comparison, 3458a calibration is
>> only required for absolute measurements which the 720A is incapable of
>> anyway.
>> 
>> John
>> 
>  
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-- 

John Devereux