732A Noob - First steps

[Tony_G]

Hey All,

I just acquired a 732A that supposedly works and is without batteries - I've purchased some replacement batteries for it and I'm looking for some quick suggestions on what I, as a 732A noob, should do for the first X months with the unit.

I have a 3458A and an environmental sensor so my plan was to:

• Replace/insert the batteries
• Turn on the unit
• Let it sit for 24 hours
• Connect the 3458A to the unit
• Use IanJ's measurement utility to start capturing 10V values and environmental data
• See where I am after a month or so

Any suggestions about this? Do you think it is a reasonable approach or should I do something else/additional?

Also, any recommendations on what to use to connect the 732A & 3458A? I was planning on using a Pomona Shielded Cable I have to connect them (https://www.digikey.com/en/products/detail/pomona-electronics/1167-60/736140) and would appreciate any thoughts.

Thanks,

TonyG

[ManateeMafia]

Congratulations on your 732A. I hope it is stable which most appear to be after a good warmup and settling time.

The recommended way to monitor the drift of a reference is to monitor the series-opposition voltage against a known good reference (or more).
A direct reading with the 3458A is not the best way due to its own drift potentially skewing your measured data.

If you can find someone local to you with a reference or two, I would recommend monitoring against their 10V output. The other reference should have a calibration history if possible.

NBS430 is the document that describes monitoring 3 or more references.  https://dataproof.com/Publications/NBS430.PDF

732A/B are rabbit holes because of the need for at least 3 if you want to continually monitor the drift. I have been down that hole for several years now and it got expensive real quick. A 34420A and Data Proof scanner added to the cost.

I also replace the electrolytics on the pre-regulator and regulator PCB. The last few 732A have also had all the carbon comp resistors replaced. At least half were out of tolerance after 40+ years of service. The schaffner input power filters have all been replaced.

You can use shielded cables with twisted copper wires. Networking cable is fine. Just don't use anything with nickel plating as you will be measuring into the nV range.

[Kleinstein]

When using the 3458 as the reference to compare to, one should to a regular (e.g. once a day) ACAL. There is absolute need to have fully continuous data. There are mainly 3 parts:
a) noise over some 1-12 hours or so
b) a possible temperature effect on the 732 and on the 3458
c) long term drift over days and weeks - this may get away with only a few points per day and could even have days without. So the 3458 could be used for other tasks as well.

Aften being off for a longer time that can be some additional drift for the first few days to weeks. This is not be a real problem, but it just needs time for the test. One should still record the initial phase, but the important part is more like the drift from week 3 to 8 or so.