Hello, retroware!
I recently purchased a Fluke 732A from a fellow EEVBlog member a month ago. I am the third owner and the unit has only been powered off twice that I am aware of. Labels on the unit indicate that it might have been manufactured in the early '90s. I have not bothered to open the lid because I do not have to for the time being.
The last time it was calibrated was in 2015:
2015-11-03, 10.00010198 V, 1.0180223 V, 1.0000035 V @ 21 °C
2015-12-01, 10.00010440 V, 1.0179920 V, 1.0000608 V @ 21 °C (I do not know why it was measured twice)
With a freshly calibrated DMM (September), I measured the following as of today:
2021-10-05, 10.0001116 V, 1.0180225 V, 1.0000059 V @ 25 °C (nulled before measurement on the 10 V range)
For the most important range, this equates to 0.14 ppm/a over the past 6 years without considering temperature coefficients. I got lucky with this unit because it has been well taken care of. The other ranges are not as stable, but they turned out well anyway. 2.55 ppm/a for the 1.018 V range and -4.43 ppm/a for the 1 V range. Looking at the specifications from the manual tells me that these values are well within the anticipated drift. These Flukes age like good wine but they need to be well maintained.
I would suggest finding a reliable DMM and having it calibrated, then use it to measure the Fluke. This is a cheaper alternative and gives you more flexibility. Replace the Fluke batteries. Do not tamper with the ovenized reference chamber unless you know what you are doing.
Good luck!
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