On 21 April 2018 at 09:32, Florian Teply <use...@teply.info> wrote: > Am Fri, 20 Apr 2018 14:37:22 +0100 > schrieb "Dr. David Kirkby" <drkir...@kirkbymicrowave.co.uk>: > > > 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 > matter. > > Best regards, > Florian >
Florian, how do you determine that the resistors are not assumed to be the nominal value? As far as I can see, taking the example of a 1e11 ohm resistor grounded at one end (very last entry on table), the meter should read 1e11 +/- 0.0573e11 ohms. My meter read 0.010e11 ohms high, so was in spec, as 0.010e11 is less than 0.0573e11. As far as I can determine, the fact the permissable range of the meter is +/-x, rather than +x, -y, means the nominal values are assumed. I put the complete cal certificate here. http://www.kirkbymicrowave.co.uk/tmp/1-9690444179-1-combined-file.pdf What I also find a bit odd, is the 16340A RC box used for calibrating the meter, is itself not due for calibration for over a year. I am awaiting a call/email from the calibration manager at Keysight (UK), and I've been advised Keysight (UK) have contacted Keysight in the USA to see what they can provide, as a calibration *with* uncertainties is listed on the Keysight (USA) website. I have no formal requirement for needing the uncertainties, but I am a bit worried the fact that Keysight (UK) seem to use a resistance box that is calibrated less than once/year, and can't provide the uncertainties, and as far as I can tell (although you disagree), it would appear the nominal value of the resistors are used. . It does not exactly inspire a lot of confidence. Dave _______________________________________________ volt-nuts mailing list -- volt-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.