On Thu, 23 Dec 2021 20:28:19 -0000 (UTC), Cydrome Leader <presence@MUNGEpanix.com> wrote:>Klaus Kragelund <klauskvik@hotmail.com> wrote: >> 23.12.21 03:03, jlarkin@highlandsniptechnology.com wrote: >>>On Thu, 23 Dec 2021 02:54:27 +0100, Reinhard Zwirner >>><reinhard.zwirner@t-online.de> wrote: >>> >>>>Hello, >>>> >>>>Due to the used RMS converter low level AC measurememts with this DMM >>>>are less precise to incorrect. There is a lab note as to this problem >>>>by Gellerlabs containing three pictures. I have this note which, >>>>unfortunately, lacks the mentioned pictures. And, unfortunately too, >>>>the link to this note >>>> >>>><http://www.gellerlabs.com/34401A%20AC%20zero.htm> >>>> >>>>doesn't work any more. Has anyone of you those pictures and could >>>>provide them? Many thanks in advance. >>>> >>>>Regards >>>> >>>>Reinhard >>> >>>That DVM has a huge amount of noise kicked into the front end from the >>>VF display. They hid that by zeroing AC measurements much below 1 mV. >>> >>>I like the Fluke better. >>> >> >> The 34401A was my first bench DMM. Bought it in 1998. >> >> I have never calibrated it, could not afford it >> >> This year I went the consultant route, so bought 3 Siglent DMMs. Just for fun, I connected the same references voltage to the 3 Siglent and the 34401A >> They measured the same except for minor last digit difference >> >> Not willing to spend on calibrations, the next best thing is to compare to other instruments. Quite unlikely that they would drift in the same direction ? >> >> By the way, I paid a lot for the 34401A, now I can get 4 Siglents for the same price >> >> >> -- >> Klaus > >I like the 34401, even with some of the faults. As you've seen they're >basically accurate forever. Not sure how the new keysigh stuff compares >for long term reliability.We use mostly Keithleys in our test stands. They're OK. I really like my Fluke 8845A. It's the winner when you want to measure a few microvolts. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
Low level AC measuremets with HP 34401
Started by ●December 22, 2021
Reply by ●December 23, 20212021-12-23
Reply by ●December 23, 20212021-12-23
Klaus Kragelund <klauskvik@hotmail.com> wrote:> 23.12.21 21:28, Cydrome Leader wrote: >>Klaus Kragelund <klauskvik@hotmail.com> wrote: >>> 23.12.21 03:03, jlarkin@highlandsniptechnology.com wrote: >>>>On Thu, 23 Dec 2021 02:54:27 +0100, Reinhard Zwirner >>>><reinhard.zwirner@t-online.de> wrote: >>>> >>>>>Hello, >>>>> >>>>>Due to the used RMS converter low level AC measurememts with this DMM >>>>>are less precise to incorrect. There is a lab note as to this problem >>>>>by Gellerlabs containing three pictures. I have this note which, >>>>>unfortunately, lacks the mentioned pictures. And, unfortunately too, >>>>>the link to this note >>>>> >>>>><http://www.gellerlabs.com/34401A%20AC%20zero.htm> >>>>> >>>>>doesn't work any more. Has anyone of you those pictures and could >>>>>provide them? Many thanks in advance. >>>>> >>>>>Regards >>>>> >>>>>Reinhard >>>> >>>>That DVM has a huge amount of noise kicked into the front end from the >>>>VF display. They hid that by zeroing AC measurements much below 1 mV. >>>> >>>>I like the Fluke better. >>>> >>> >>> The 34401A was my first bench DMM. Bought it in 1998. >>> >>> I have never calibrated it, could not afford it >>> >>> This year I went the consultant route, so bought 3 Siglent DMMs. Just for fun, I connected the same references voltage to the 3 Siglent and the 34401A >>> They measured the same except for minor last digit difference >>> >>> Not willing to spend on calibrations, the next best thing is to compare to other instruments. Quite unlikely that they would drift in the same direction ? >>> >>> By the way, I paid a lot for the 34401A, now I can get 4 Siglents for the same price >>> >>> >>> -- >>> Klaus >> >>I like the 34401, even with some of the faults. As you've seen they're >>basically accurate forever. > > At the place I worked before they used it per default. I asked the > instrument responsible and he said when they were sent for calibration > they were never out of spec. Not even a single instrument. So they > prolonged the calibration interval to 2 years > > > -- > KlausCalibration is mostly just a racket, although I completely agree you need to check instruments to make sure they're not broken. I have the hardest time with stuff like capacitance meters. As for calibration of things like rulers, I confirmed that yes, I can hand draw a 1 foot ruler that's only 11 inches long on a paper towel and sent it it for calibration at a metrology lab, and that with the calibration chart it would be be considered accurate and for a few bucks more I could claim NIST traceable for my fine instrument. Would it be useful? No, as long as all the errors are documented, it's better than a Starret scale with no paperwork, at least in the eyes of retarded places ike NASA.
