Perhaps interesting retrospective test, showing 10V data over ~7 days, measured by five different 3458A meters.
Few ACALs were performed in middle to see jumps and spread. All meters were in variable ambient room temperature.
Source is Fluke 5720A/Hulk1 programmed to output 10V -2ppm value. For verification purposes 5720A and other 10V standards (
792X with xDevs.com FX inside, Fluke 732B, Fluke 732A) were logged using
Dataproof 160A scanner and
Keithley 2182A nanovoltmeter in opposition mode. This data shows maximum deviation of 5720A output less than 0.2 ppm, which is well below daily stability spec of 3458A (0.55 ppm)
Logging settings for each 3458A (bottom side of the plot at around -2ppm for all meteres):
NPLC 100, NDIG 9, DELAY 0, TRIG SGL, Guard float on meters, and local on calibrator. Logging performed by
xDevs.com Python Teckit app with thermal control inhibited.
RAW data-fileOne can spot vast difference between my
old "golden" 3458A's and standard 3458A in terms of 10V temperature coefficient and stability. Ambient temperature in lab was jumping around between 20.6 and 23.4 degrees due to aircon cycling. This little test again shows that even mighty 3458A DMM cannot be used as calibration standard on ppm-level without proper verification and very careful attention to environment conditions and previous historical data/stability validation.