I have recently acquired a 3458A from the estate of a friend. I've replaced the NVRAMs, and have started to do the drift tetst from service note 18. The meter has likely not been on for quite a number of months before I did the NVRAMs, and I'm seeing what appear to be quite large changes in the CAL ?72 values with each ACAL, but this may just be because it has beon powered off for a long time.
Does the meter need to be powered on for a "length of time" before doing this check? If so how long should I leave it on before starting to log the values of CAL ?72 ?