http://boston.craigslist.org/bmw/ele/5687633175.html
On Tue, Jul 19, 2016 at 12:00 PM, <[email protected]> wrote: > Send volt-nuts mailing list submissions to > [email protected] > > To subscribe or unsubscribe via the World Wide Web, visit > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > or, via email, send a message with subject or body 'help' to > [email protected] > > You can reach the person managing the list at > [email protected] > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of volt-nuts digest..." > > > Today's Topics: > > 1. Re: Keysight 3458A vs Keithley 2002 8.5 digit multimeters. > (John Phillips) > 2. Re: Keysight 3458A vs Keithley 2002 8.5 digit multimeters. > (Dr. David Kirkby (Kirkby Microwave Ltd)) > 3. Re: Keysight 3458A vs Keithley 2002 8.5 digit multimeters. > (John Phillips) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 18 Jul 2016 09:34:18 -0700 > From: John Phillips <[email protected]> > To: [email protected], Discussion of precise voltage measurement > <[email protected]> > Subject: Re: [volt-nuts] Keysight 3458A vs Keithley 2002 8.5 digit > multimeters. > Message-ID: > < > caneyv6bhoqhdui3m9i_abothndg3rfatfqhdgzmjope69+g...@mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > Most labs never turn 3458As off. The longer they are on the lower the drift > rate. I would rather have an 20 year old meter with new batteries than a > new meter. > > On Mon, Jul 18, 2016 at 4:11 AM, Illya Tsemenko <[email protected]> wrote: > > > Well, it's the topic many can go on and on about. > > As with everything there are specific cons and pros of both units, but > > here are my 5c: > > + K2002 is smaller, lighter (4kg vs 10kg), less powerhungry (sometimes > > it's important if you send unit for cal overseas, or take to remote > site). > > + K2002 can support scan cards (standard, or low-EMF ones) via expansion > > slot > > + K2002 DCI/ACI goes up to 2Amps > > + K2002 goes bit higher on ACV frequency (15MHz, but performance there is > > so-so) > > + K2002 natively supports thermocouples, RTDs, SPRT thermal sensors and > > custom settings > > + K2002 supports rare rainbow unicorn nanovolt preamplifier Keithley 1801 > > (substitute can be bodged up but that's not beginner's project) > > - Old K2002's require capacitor replacements (units with S/N 06xxxxx and > > 05xxxxx). Mandatory! Meters from 2005+ year have S/N starting with > 11xxxxx > > - Readings noisier than 3458A > > I have two units in use, and have worklogs for both : > > https://xdevs.com/review/kei2002/ - newer K2002 from year 2007 > > https://xdevs.com/fix/kei2002_u2/ - older K2002 from 1994 which was > > repaired after capacitor leak damage. > > Service of these Keithley meters (and 2001, which are very similar > design) > > is not complicated, but require attention and knowledge what you doing. > > There only few custom parts used. > > > > Now regarding industry standard 3458A. Reason why you saw only 3458A in > > metrology lab is simple: > > Superior ADC (many rightfully think it's best on market, ever), amazing > > linearity (JJA was required to test linearity with good confidence), very > > easy calibration (just need 10V reference and 10KOhm standard resistor to > > get 3458A calibrated to uncertainty of used standards), Artifact > > calibration (ACAL) to significantly remove impact of temperature > variation > > on accuracy, proven performance. Many labs use 3458A as main transfer > > standard due to it's ADC performance. > > > > It comes at cost though, as key components of meter's A/D are custom > > hybrids. Meaning if you got sour pill, and A/D drifting, you will have to > > replace expensive A/D board. Newer Agilent/Keysight branded 3458A's are > > essentially same boxes, just with newer hardware and likely with new > > FPGA-based digital brains. Performance is same though, unless you really > > getting early 1990's meter. Many design issues and items I got covered in > > my repair worklog: https://xdevs.com/fix/hp3458a/ > > > > Brief 10V comparison : https://xdevs.com/datalog_tcomp/ - sampling 10V > > connected to 2001+2002+3458A > > Some of the A/D noise comparisons (meter input shorted) - > > https://xdevs.com/article/dmm_noise/ > > > > So decide what fit best your needs. 3458A is overall higher performance > > instrument, but in lot of applications outside of metrology it's > > performance benefits may not cover up for higher price and size. Both > 3458A > > and 2002 are still supported and sold new by manufacturers. Regular > > calibration of these is likely be over 1000$USD, and lab-grade > calibration > > for 3458A is usually in range of 2600$USD. > > > > P.S. there are also few other 8.5d meters, but much less information > > available on those, as less people have them. Only "modern" 8.5d meter is > > 8508A, which cost even more than 3458A without much performance > improvement. > > > > 18/07/16 17:54, Dr. David Kirkby (Kirkby Microwave Ltd) пишет: > > > > I am interested to hear people's view on the relative merits of the > >> HP/Agilent/ Keysight 3458A vs the Keithley 2002. > >> > >> I noticed that when I recently visit the standard lab for voltage at > NPL, > >> the place was littered with Agilent 3458As, but I did not notice a > single > >> Keithley 2002. But maybe NPL get better discounts from HP/Agilent > Keysight > >> than Keithley/Tektronix. > >> > >> I notice that the used prices of 3458A is higher than 2002s. > >> > >> Also, are there any things ons should be looking out for when buying a > >> 3458A or 2002? I have in the past thought an Agilent front panel was a > >> better than an HP one, as it would not be as old, but this is not always > >> true - see my comment later. > >> > >> What S/N are best avoided? Does anyone have a record of S/Ns of Keighley > >> meters with time? > >> > >> Very recently I had a somewhat scruffy HP 6674A PSU with a damaged LCD. > It > >> cost me $50 or so to pick up a clean Agilent front panel with a new > >> display. The display actually turned out to be unsuitable, yet my > >> Agilent > >> badged 6674A is actually a fairly old HP unit. So white my intention > was > >> not to rebadge the PSU, that happened as a result of a legitimate reason > >> to > >> get it working. So this really indicates how an old HP 3457A could be > made > >> to look a newer Agilent one. > >> > >> Dave. > >> _______________________________________________ > >> volt-nuts mailing list -- [email protected] > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > >> and follow the instructions there. > >> > > > > > > > > _______________________________________________ > > volt-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > > > -- > > *John Phillips* > > > ------------------------------ > > Message: 2 > Date: Mon, 18 Jul 2016 19:48:35 +0100 > From: "Dr. David Kirkby (Kirkby Microwave Ltd)" > <[email protected]> > To: Discussion of precise voltage measurement <[email protected]> > Subject: Re: [volt-nuts] Keysight 3458A vs Keithley 2002 8.5 digit > multimeters. > Message-ID: > <CANX10hCBO9MMxwaT0E6HbumWrP+pW3= > [email protected]> > Content-Type: text/plain; charset=UTF-8 > > On 18 Jul 2016 17:34, "John Phillips" <[email protected]> wrote: > > > > Most labs never turn 3458As off. The longer they are on the lower the > drift > > rate. I would rather have an 20 year old meter with new batteries than a > > new meter. > > If one buys a used meter, one has no idea if it has been switched on very > occasionally or on 24/7. > > Do you keep your meter powered up during the transit between your lab and > the cal lab? I would think that quite difficult if you used a courier, but > not a problem if it was taken in a car. > > Dave. > > > ------------------------------ > > Message: 3 > Date: Mon, 18 Jul 2016 12:39:33 -0700 > From: John Phillips <[email protected]> > To: Discussion of precise voltage measurement <[email protected]> > Subject: Re: [volt-nuts] Keysight 3458A vs Keithley 2002 8.5 digit > multimeters. > Message-ID: > <CANEyv6a9Y_69qFSZnRVcEL4sKDAFsnx-PYw93= > [email protected]> > Content-Type: text/plain; charset=UTF-8 > > We do not keep them powered up for transit. > All the meter gets more stable with age. The reference gets more stable > with burn in. > We store 3458As energised even when we do not plan to use them for a while. > Most 10 year old meters are as stable as the new meters with the high > stability option. > I do not have any stats but quite often we would buy an old meter that had > a old cal sticker and find that 10 volse was still in spec. > > > On Mon, Jul 18, 2016 at 11:48 AM, Dr. David Kirkby (Kirkby Microwave Ltd) < > [email protected]> wrote: > > > On 18 Jul 2016 17:34, "John Phillips" <[email protected]> wrote: > > > > > > Most labs never turn 3458As off. The longer they are on the lower the > > drift > > > rate. I would rather have an 20 year old meter with new batteries than > a > > > new meter. > > > > If one buys a used meter, one has no idea if it has been switched on very > > occasionally or on 24/7. > > > > Do you keep your meter powered up during the transit between your lab and > > the cal lab? I would think that quite difficult if you used a courier, > but > > not a problem if it was taken in a car. > > > > Dave. > > _______________________________________________ > > volt-nuts mailing list -- [email protected] > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > and follow the instructions there. > > > > > > -- > > *John Phillips* > > > ------------------------------ > > Subject: Digest Footer > > _______________________________________________ > volt-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > > ------------------------------ > > End of volt-nuts Digest, Vol 83, Issue 11 > ***************************************** > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
