Electronics > Metrology

Attaining confidence

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RobK_NL:
So, I have a Fluke 732A of unknown providence that has been standing around (powered) in my lab for the past six years or so.

I'm looking to sell it (as some of you already noticed  ;)), but the question that keeps popping up is: Is it stable? (dental drills optional)

How best to go about in getting some data?

I don't have an HP3458, but I do have two Fluke 5440's (which I also want to sell), so the idea is to hook all three up to my HP3457 and periodically measure the differences between them (A-B, A-C, and B-C). Throw in a temperature measurement as well, so as to have all relevant data.
I have an old laptop I can dedicate to this, so I was thinking about a two week run, with measurements ever 15 minutes.

Any comments or suggestions (especially w.r.t. the number crunching) welcome.

Echo88:
Is the 732a able to be shipped hot? I dont think so, since the battery life is specified with 12h at 23°C. Maybe with an additional battery pack which powers the 732A, its possible to ship it powered to someone with better equipment? If thats possible i suggest you PM the user plesa and ask if he can help you.  :-//

Another possibility: A few users in Germany own 3458As, so maybe its possible to compare the 732A to own of those and get an indication whether your 732A drifts.

I dont have a clue about the number crunching 732A against 5440s.

Maybe users with more metrological knowledge like Dr. Frank or Kleinstein can suggest better ways to check your 732A.

Anyway: Id be interested in getting a 732A/B and maybe one of those 5440. Goddamnit, the voltnut-rabbithole is really deep.  :palm:

TiN:
3458A alone is not stable enough (4.15ppm/90 days) to verify properly operating 732A (1.5ppm/90days).

5440B has better stability spec, so perhaps your best would be connecting 3457 on lowest range in null-meter mode between 5440B and 732A to obtain differential voltage between them.
Given that both of your 5440B's are stable, you can verify setup operation first by using two 5440's in null-meter mode. That's best way you can do, without additional investment.

RobK_NL:

--- Quote from: TiN on October 17, 2017, 11:22:51 am ---connecting 3457 on lowest range in null-meter mode between 5440B and 732A to obtain differential voltage between them.

--- End quote ---
Yes, that's exactly what I had in mind. My assumption is that, by measuring all three instruments against one and other, I will end up knowing something about the stability of each.

Andreas:

--- Quote from: RobK_NL on October 17, 2017, 09:04:16 am ---I have an old laptop I can dedicate to this, so I was thinking about a two week run, with measurements ever 15 minutes.

Any comments or suggestions (especially w.r.t. the number crunching) welcome.

--- End quote ---

Hello,
I would start with around 24 hrs continouosly logging of the difference voltages. (all 15 minutes gives too low information about noise).
By calculation of the Allan Deviation (e.g. "plotter" software from Ulrich Bangert) from the logs you get a quick overview of the stability of each pairing.
From this you can decide on the further tests.

with best regards

Andreas

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