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

Florian Teply usenet at teply.info
Sat Apr 21 04:32:00 EDT 2018

Am Fri, 20 Apr 2018 14:37:22 +0100
schrieb "Dr. David Kirkby" <drkirkby at kirkbymicrowave.co.uk>:

> 2) Measure the resistors in the 16340A. What puzzles me here, is that
> when I had another 4339B calibrated, the limits on measuring those
> resistors were symmetrical about the nominal values of 1e6, 1e7, 1e8,
> 1e8, 1e10 and 1e11 ohms. I would have expected the limits to be
> asymmetrical, because those resistors are probably not their nominal
> value.
> The columns below, from left to right are
> Device type (whether the DUT is floating, or grounded one side).
> Resistor setting (ohms)
> Votage (V)
> Measurement time (Long or Short)
> Test limits (+/- ohm)
> Test results (ohm)
> FLOAT 1E6 100 SHORT +/- 0.0086E6 -.0019E6
> FLOAT 1E7 100 LONG +/- 0.0063E7 -.0016E7
> FLOAT 1E8 100 LONG +/- 0.0073E8 -.0027E8
> FLOAT 1E9 100 LONG +/- 0.0093E9 -.0032E9
> FLOAT 1E10 100 LONG +/- 0.0273E10 +.0095E10
> FLOAT 1E11 100 LONG +/- 0.0453E11 +.0080E11
> FLOAT 1E11 100 SHORT +/- 0.0550E11 +.0086E11
> FLOAT 1E11 10 LONG +/- 0.0546E11 +.0113E11
> GROUND 1E7 100 LONG +/- 0.0065E7 -.0017E7
> GROUND 1E11 10 LONG +/- 0.0573E11 +.0107E11
> That strikes me that the assumption is the values are what their
> nominal values are, but I wonder how accurate they are.
I might be wrong, but to me it seems like the resistors are not
exactly nominal but slightly off. But the uncertainty of the
measurements is larger than the deviation. Or were you referring to the
notion that the uncertainties are symmetrically distributed? I'd be
pretty surprised if the uncertainties were asymmetrical for that

Best regards,

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