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Buy/Sell/Wanted / Re: FS: Affordable DMM Checkers: AC Reference, DC Reference, OHMS Reference, etc.
« Last post by tggzzz on Today at 12:13:37 pm »If you limited the claimed to, for example, "...verify the function of 3.5 digit Digital Multimeters", then the points wouldn't even arise.
What you claim here (or "elsewhere") is irrelevant; what you claim in the advert is what matters.
This is basic measurement theory. While you need higher resolution than the manufactured reference to measure its calibration error, that same calibration reference can then be used on on lower resolution instruments (assuming it is stable). If you only work in mA, you do not care what is going in pA.
So a lot depends on claims for where it should be used. And the reliablity of the maker.
FWIW, I bought one of the current and voltage references from AliExpress. It includes a sketchy paper claiming the actual values as measured by some reference down to the 7th decimal point. Turns out these measurements were within a couple counts on my Fluke 45, Fluke 8842, HP 358a and Keysight 1252.
Have no idea why I bought it since all my instruments already agreed, but it was cheap and I am a measurement junkie (work down to 500 micro meters).
Yes, repeatedly.
You bought it for fun. The only surprise is the degree of agreement.
But, as you know, it is relatively cheap and easy to get all your instruments to agree with each other. It is much more difficult and expensive to get them to agree with two other people's instruments