[volt-nuts] A Fluke 732A

[Tom Knox]

Good points Dick. A good question to ask yourself is what level of documentation do you really need? And what is the cost per PPM. You may find a local lab with less accreditation charging half then price that is fully capable of of calibrating to the limit of the 732A but cannot document to the level of a primary standards lab. Add to that the fact that the 732A cal'ed locally would not be subject to the abuse of shipping and the calibration on you bench may exceed that of a NIST JJA cal. Yes a 1-2PPM Cals is not as sexy as a .1PPM Cal but in the real world the results when used in you home lab my be the same.  
Just look at the effects of temp and humidity on calibration and you will see my point.`to yours.
Thomas Knox



> Date: Sat, 8 Mar 2014 17:17:53 -0800
> From: richiem5683 at gmail.com
> To: volt-nuts at febo.com
> Subject: Re: [volt-nuts] A Fluke 732A
> 
> Back to a few of the original issues. A big questionh would be just how 
> accurate the average volt nut needs the 732A to be? I once owned two 
> 732A, one working normally, and kept hot 24/7, and one that needed some 
> work with the charging circuits and new batteries. My 3458A being newly 
> cal'd at Agilent in Colorado Springs, I matched the two 732As to the 
> 3458A, then powered off the one with problems, worked on it off and on 
> over several weeks, then powered it back up. What I found was that the 
> one I worked on (after 48 hours warm-up) was within 0.2ppm of the hot 
> one and the 3458A. Over the next year, the drift got a little larger 
> among the three, but not by much -- a spread of about another 0.2ppm if 
> I remember right.
> 
> That's when I decided that since I wasn't going to try to be a standards 
> lab, shipping a 732A cold for cal was much easier and effective than 
> trying to do it hot, and I live about 30 air miles from Fluke in Everett.
> 
> Can you live with 1ppm uncertainty in your 732A? Some here obviously 
> can't, but I think many of us can and would be happy with that level of 
> accuracy -- certainly good enough to cal the various 6-1/2 digit meters 
> around, including the 3457 mentioned originally. And given my experience 
> of 732A stability, especially the good old ones that come on ebay and 
> the like, that 1ppm uncertainty is also a good check on the state of cal 
> of even the 8-1/2 digit boxes, which despite their resolution, are not 
> spec'd long-term for even 1ppm at 10V.
> 
> Best,
> Dick Moore
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