A few of the zero readings look odd and would be out of specs:
I assume these are readings are with the inputs shorted.
FWIW I get +00.00002 on the 20V range when set to 6.5d resolution - and +00.000027 in 7.5d mode.
Given that the spec seems to be ±counts in 6.5 digit mode I think that's OK and my meter is actually within specification.
But I'm not sure about the voltages that they specify - 2 counts on the 2V scale would be ±2.0µV, not 2.9µV and 20µV not 40µV for the 20V scale.
How do you get a 2001 to display 8.5 digits?
Thanks to mendip_discovery for an explanation of the differing standards levels.
Technically unless its got an uncertainty you have no way to judge the measurements.
This bugs me - as I said, I have assumed that they used a calibration source which itself was stable enough for a meter with a 12 month accuracy in the 20-30PPM range. If the rule of thumb is to have a source with 1/10 the uncertainty then you'd need to be in the vicinity of 3.5 to 2.5PPM - hence my example of the 5730A.
With regards to recalibrating stuff, unless you have good standards in the lab you risk making things worse if you adjust.
Which makes it reasonable that they would not run the meter's calibration and just run a check and only adjust if the meter was out of spec.
Just looking at the cert one of the things that stand out to me is the specification for the DC stuff, PPM then goes to show µV.
I guess working out the acceptable deviation in volts is easier for people to understand. 52µV is actually correct for the maximum deviation on the 2V range for a 1.9V input - but only for the 2001 itself. I really hoped they would have included their calibrator/meter's uncertainty as well - for approx 3.5PPM you'd have to add another ±7.0µV making the actual allowable deviation more like ±59.0µV
I also don't like the 10 Ω statement as its very rare to have a 10 Ω exactly out of a calibrator, I would no doubt be ok for the 3.5 digit meters but at 7.5 you will be in the area where a few µΩ/Ω of error is visible.
I don't know calibrators handle resistance - just switch in a precision component?
I guess the big boys will offer better precision but the best that Mouser or Farnell stock is in the order of 0.01%
I would say use this cert as it is better than nowt. How many bits of kit are sold on the bay each week with no history and statements such as "not tested" etc. At least you are buying with some confidence even if it is just a small lab doing a cheap calibration.
When I frequented rallies (I don't have time these days but might try to get to Newbury on the 25
th of June as that always used to be good) we always used to observe that there would be two bins - "Tested, working" and "Not tested".
The suspicion was always that "Not tested" meant "Not working" and I've tended to carry that logic forward to eBay.
I've no idea what the 11/09/06 date represents. It's not the date of this calibration check.
I've messaged the lab to ask what they used - if they tell me, great. If not, well, I'm no worse off than I am now and it will be a lab I know not to use