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.

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 -- volt-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there.

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 <illya@xdevs.com> 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 -- volt-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >> and follow the instructions there. >> > > > > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips*

On 18 Jul 2016 17:34, "John Phillips" <john.phillips0@gmail.com> 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.

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) < drkirkby@kirkbymicrowave.co.uk> wrote: > On 18 Jul 2016 17:34, "John Phillips" <john.phillips0@gmail.com> 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 -- volt-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > -- *John Phillips*