[ARC5] Meter Calibration

[D. Platt]

On 8/1/2013 9:25 PM, Robert Eleazer wrote:
> I have quite a collection of multimeters and voltmeters. Some PSM-6's. Some PSM-45's. A couple of Me-297's. A USM-33.   A USM-34.   A Simpson 260 in a super-nice rolltop carry case. An NLI TouchTest 20 with real red glowing LEDs. A brand spanking new HP Model 410B.
>
> And I don't trust any of them, at least not very much.  I quit using those super cheap chicom digital meters because each one gave me a different reading.  But collectively all of the others have the same problem.
>
> Anyone know how you can go about calibrating at least the voltage readings on these fine equipments?  That is, using stone knives and bearskins, not a million dollar test set.
>
> Thanks,
>
> Wayne
> ______________________________________________________________
> A
What I'd do is arrange for one of your instruments to become a transfer 
standard.  In other words, select one meter and ensure that its 
calibration is "good".   There are a number of "chemical" cells one can 
construct that, potentially, have a predictable output (at a given 
load).  Older, 1000 or 20,000 ohms/volt meters provide too much loading 
for many chemical sources.  The good old "D" cell, in new condition, can 
be useful, too.  I do see older Fluke calibration voltage sources on 
Ebay at times.  But, as others have mentioned, it depends on what kind 
of accuracy you want.  Finally, let me add a note.... I use a digital 
VOMs bought from Harbor Freight.  Its their best one and it goes, on 
sale, for about $20.  I have purchased a number of these and, comparing 
them with Fluke bench meters in known calibration, they do very well, 
indeed.  Yes, their precision is only to 3 1/2 digits, but 99% of the 
time, its quite sufficient.

Jeep - K3HVG