Calibrating 8.5d meter is a challenge, but it's not as bad to need JVS. Even with that, Your nearest NMI will be happy to provide you top notch calibration, that is magnitude better than even 24 hour specification of the meter, be it 3458A or whatnot. Main power of the 3458A that makes it so special is ultra-linear ADC (which is very fragile), which makes feature like ACAL self-calibration possible with just known 10V and 10k. So if one to buy 8.5d meter for business purposes, getting cheaper meter + paying for full calibration with data might be well the same as getting used 3458A, *IF* lab has known 10V/10kOmega standards or want to invest in those.
I've recently got calibration by NMI directly vs JVS/QHR on my references (U=0.02ppm 10V and 0.16ppm 10kOhm), hand-carry those home, calibrated my 3458A's and 5720A and same day performance verification yield results well under 24 hour specifications of HP3458A/002. Even INL data for 3 out of 4 is well inside "typical" 0.05ppm from HP: https://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/INL_10V_3458abcd.png Sure, one has to have high-performance MFC, but giving the amount of DMMs I have, trying to ship (international air shipping is no fun) even fraction on them to standards lab calibration would cost more than getting own calibrator and getting that in shape. Currently doing some more tests, but I will be listing one fully-calibrated 3458A, need to cut the TEA pile. AFAIK Keysight Loveland Standards Lab calibration is >$2.2K shipping/handling excluded. With 8.5d anything, it's pretty much pay to play game, either way with "cheap" meter and expensive calibrations, or expensive meter and...expensive calibrations :) No exceptions. Datron 1271/1281 have also 100% overrange, so it can measure up to 200mV/2V/20V/200V/1kV, which might not be obvious on first glance thru spec sheet ;). P.S. As happy K2002 owner, DMM7510 not even in the same league, sorry. Hurdles with logging/fancy histograms do not sound serious in 2019, given plenty of free open-source options available to interface and log meter data. All one need is GPIB interface and RaspberryPi or alike, and few evenings to figure out the basics. ---- On Mon, 01 Jul 2019 10:28:37 +0800 David C. Partridge <mailto:[email protected]> wrote ---- Sad to say that Ametek no longer provide any support for the 7081. They also scrapped the Commodore PETs they had with the calibration software for the 7071 and 7081 (I so wish I could have acquired one of those). The huge "elephant in the room" problem is finding a calibration lab with an error budget that's actually good enough to calibrate *any* 8.5 digit meter. More like than not (barring faults) your meter will probably be more accurate and stable than any of their calibration equipment. I don't know of any in the UK apart from Fluke and Keysight (I would love to hear that there are others). Keysight UK can't do the top spec calibration on a 3458A (so called Loveland calibration) so if you want that, AFAIK it has be return shipped to California, USA (though I've heard that Germany *may* have a Josephson junction setup). Of course it's not under power for that time and you risk destruction of the custom VFDs ... I suspect that my Datron 4808 is as good as or better than most cal labs in the UK (though there must be some with at least one calibrated Fluke 5700A/5720A/5730A or Datron 4808 or similar). PS Transmille produce an 8ppm calibrator (4010) and a 4/9ppm meter (8100) so could probably do the job, but whether they'd do "other brand" calibration ? David -----Original Message----- From: volt-nuts [mailto:mailto:[email protected]] On Behalf Of J. L. Trantham Sent: 01 July 2019 01:21 To: 'Discussion of precise voltage measurement' Subject: Re: [volt-nuts] What are the best of the low(ish) cost 8.5 digit multimeters? David, Have you considered the Solartron/Ametek 7081? If I'm not mistaken, you posted some images of their EPROM's several years ago. It's slow sampling at 8.5 digit resolution but seems user friendly and, at least several years ago, was able to be calibrated by Ametek in England. I sent two over there for calibration. Good luck. Joe _______________________________________________ volt-nuts mailing list -- mailto:[email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there.
