HighVoltage,
welcome in the 3458A-Club, finally!
Your unit is from 2012, or younger.
Would you mind sending me the S/N, so a calibration date and 1st owner might be determined?
What did you have to pay for this nice, crisp Instrument?
As TiN already wrote, frequent ACAL is extremely important for this Instrument.
After a 2h warmup, and afterwards one initial ACAL DCV, this drift test (~24h) can be made.
If measuring 4W Ohm with OCOMP ON, DELAY 1 for 10k, DELAY 5 for 100k is necessary / sufficient for max. uncertainty.
Every other range needs 0.1s only.
I'm very interested, what your 3458A delivers for the LTZ, I have measured.
(I'm just sitting in front of mine)
best regards Frank
P.S.: For These DIY cables, please check, that the Isolation is made from highly insulating Plastics, i.e. PTFE, or else. PVC creates big measurment error on 10k and higher.
This can be done with a 10k or 100k resistor, either 2W or 4W mode.
Using 2 or 4 separate cables, which should not touch each other (High cables versus Low cables), this reading should not show a difference to the measurement with the DIY cables.
PVC insulation might creates Errors as high as sevarl ppm for 10k, and several ten ppm for 100k,