[volt-nuts] A Fluke 732A

[Richard Moore]

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