Huh? The measurements of January 2020 got lost?
Hello,
Nothing gets really lost.
I think selecting the calibration points with low uncertainity is better for drift estimations.
Attached all calibrations.
But be aware:
a) On measurements of 06.06.2020 we had a guard loop between 2 parallel instruments.
So the values here are ~1-2 ppm worse. (have verified this with my weekly measurements against 24Bit ADC16)
b) The measurement against Fluke7000 are not direct but as sequential ratio measurement.
So there may be additional measurement setup errors.
c) the measurements against Fluke 5520A is differential with a 34401A as Null-Voltmeter.
And I cannot guarantee that it is always the same Fluke 5520A.
with best regards
Andreas