Aha! :) Hi David, First few sour points to make sure you got what to expect. * 520$USD is bit steep for 2001 from 90's you got, and VFD seem to be fairly faded according to auction pics. * It may be still have issues internally, even though showing reading does not reveal anything in first glance. 2001's are fairly capable DMMs and I personally dealt with no less than 7pcs of them over last years. Currently I still own four units of same age as your win (judge from S/N). While they are worse than 2002/3458 in terms of stability/noise, I would not trade my 2001's to fancy 3446X/34470 meters. Also 2001 support scan-card addons so you can easily expand DMM with scanner function, or even nanovolt-preamp if you dedicated enough. I'm working on nanovolt support with 2001, but that's long story. Some details with DIY card I covered here: https://xdevs.com/review/ema10/ To get you ready: 1). It's bit tricky to setup and need little bit of time to get familiar with, but otherwise on par with modern 34470/DMM7510 with bit worse resistance/current specs. No RS232, so bit more expenses to come for GPIB interfacing if you don't have that already. As Todd pointed out already to my repair article, some bits of info are linked there, as well as firmwares and documentation. Here's example test log with reading 1mV DC voltage with three meters : 2001,2002,3458. https://xdevs.com/datalog_tcomp/ 2001 also using almost exactly same ACV TrueRMS converter as 8.5 Model 2002, so that's good too if you into AC stuff. I also have thread on EEVBlog: http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/ in case you missed it. 2) I never played with 3457A, but 2001 should offer better stability, less noise and more functionality in smaller package. I do take 2001 with me to remote locations sometimes to do some testing, thanks to it's relatively small size and weight. 4-5) You should update firmware to A08, which I hosted on links above, if you desire to have meter calibrated by accredited lab, such as Tektronix service center. Otherwise they might charge you for replacing simple PLCC ROM. Your digital board is older version, so you tied to A-version smaller firmwares w/o support of unobtanium nanovolt Keithley 1801 preamp. You will not loose existing calibration on firmware update. 6) This is my favorite part. Here's what you have to do: * Receive meter, take the cover off * Remove transformer, carefully remove plastic cover of analog board (top side) * Get the board out. * Replace ALL electrolytic capacitors on it. Follow my article for details. This is requirement, believe me. * If you already see gunk, liquid from caps - carefully clean board, restore any damaged traces/parts. If it leaked under ICs - you have to desolder them, clean in IPA thoroughly and solder back. * If your VFD too dim and you desire bright nice glow - you can buy Keithley 7001 switch with good screen from ebay (they can be found for 100-150$) and swap VFD. Not worth to bother asking Tek for new VFD, they sell front panel board only for ridiculous tag. * Replace caps on bottom digital board. * Install memory option if you like * You can deyellow plastic front panel with peroxide: https://xdevs.com/guide/plastic_bleach/ * Enjoy the meter. I sent one of 2001's for official cal here in Taiwan, it was 500$ for full cal with data. Cheaper than 8.5 DMMs but still bit pricey. To do user calibration you will need very stable 2V, 20V, 20kOhm and 1MOhm standards. Make sure you have meter running at least for a week before sending to cal, to get everything stable. P.S. there is no much point in 8.5th digit from 2001, as it's just down in noise. BR, Illya

Hi Illya: When I try to view your web page the message is: Secure Connection Failed -- Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html The lesser of evils is still evil. -------- Original Message -------- > Aha! :) > > Hi David, > > First few sour points to make sure you got what to expect. > * 520$USD is bit steep for 2001 from 90's you got, and VFD seem to be fairly faded according to auction pics. > * It may be still have issues internally, even though showing reading does not reveal anything in first glance. > > 2001's are fairly capable DMMs and I personally dealt with no less than 7pcs of them over last years. Currently I > still own four units of same age as your win (judge from S/N). While they are worse than 2002/3458 in terms of > stability/noise, I would not trade my 2001's to fancy 3446X/34470 meters. > > Also 2001 support scan-card addons so you can easily expand DMM with scanner function, or even nanovolt-preamp if you > dedicated enough. I'm working on nanovolt support with 2001, but that's long story. Some details with DIY card I > covered here: https://xdevs.com/review/ema10/ > > To get you ready: > > 1). It's bit tricky to setup and need little bit of time to get familiar with, but otherwise on par with modern > 34470/DMM7510 with bit worse resistance/current specs. No RS232, so bit more expenses to come for GPIB interfacing if > you don't have that already. > As Todd pointed out already to my repair article, some bits of info are linked there, as well as firmwares and > documentation. > Here's example test log with reading 1mV DC voltage with three meters : 2001,2002,3458. https://xdevs.com/datalog_tcomp/ > 2001 also using almost exactly same ACV TrueRMS converter as 8.5 Model 2002, so that's good too if you into AC stuff. > I also have thread on EEVBlog: http://www.eevblog.com/forum/testgear/restoration-glory-of-keithley-2001-dmm/ in case > you missed it. > > 2) I never played with 3457A, but 2001 should offer better stability, less noise and more functionality in smaller > package. I do take 2001 with me to remote locations sometimes to do some testing, thanks to it's relatively small size > and weight. > > 4-5) You should update firmware to A08, which I hosted on links above, if you desire to have meter calibrated by > accredited lab, such as Tektronix service center. Otherwise they might charge you for replacing simple PLCC ROM. Your > digital board is older version, so you tied to A-version smaller firmwares w/o support of unobtanium nanovolt Keithley > 1801 preamp. You will not loose existing calibration on firmware update. > > 6) This is my favorite part. Here's what you have to do: > * Receive meter, take the cover off > * Remove transformer, carefully remove plastic cover of analog board (top side) > * Get the board out. > * Replace ALL electrolytic capacitors on it. Follow my article for details. This is requirement, believe me. > * If you already see gunk, liquid from caps - carefully clean board, restore any damaged traces/parts. If it leaked > under ICs - you have to desolder them, clean in IPA thoroughly and solder back. > * If your VFD too dim and you desire bright nice glow - you can buy Keithley 7001 switch with good screen from ebay > (they can be found for 100-150$) and swap VFD. Not worth to bother asking Tek for new VFD, they sell front panel board > only for ridiculous tag. > * Replace caps on bottom digital board. > * Install memory option if you like > * You can deyellow plastic front panel with peroxide: https://xdevs.com/guide/plastic_bleach/ > * Enjoy the meter. > > I sent one of 2001's for official cal here in Taiwan, it was 500$ for full cal with data. Cheaper than 8.5 DMMs but > still bit pricey. To do user calibration you will need very stable 2V, 20V, 20kOhm and 1MOhm standards. Make sure you > have meter running at least for a week before sending to cal, to get everything stable. > > P.S. there is no much point in 8.5th digit from 2001, as it's just down in noise. > > BR, > Illya > > _______________________________________________ > 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. >

Try again, I had my clumsy fingers in server console... 25/06/16 0:49, Brooke Clarke пишет: > Hi Illya: > > When I try to view your web page the message is: > Secure Connection Failed >

Ah, the Keithley 1801 Nanovolt Preamp in combination with the 2001 brings back memories. Although I never got to use either, I remember the advertisements for them. I went looking for the Keithley 1801 Nanovolt Preamp on their web page a couple of years before Tektronix bought them and could not find it. Your web page says they discontinued it which answers my first question. Did they replace it with some other integrated product like the currently produced 2182A Nanovoltmeter? My last experiment with low noise involved a pair of LT1028s configured as a standard x1000 differential amplifier with a pair of LTC1150s correcting their low frequency noise by driving their offset adjust pins. The next step up would have been a low noise discrete JFET input stage for lower input bias current but I was working with low impedance sources so the LT1028s were fine. Three things scared me about this circuit: 1. I measured the low frequency noise using a Fluke 8505A by taking DC voltage measurements and calculating the standard deviation to get the RMS noise. The numbers I got back were exactly as theory predicted. The Fluke did not have the AC measurement option and given the low frequencies involved, it would not have worked for what I was doing anyway. 2. Measuring the RMS noise allowed me to adjust the frequency breakpoint between the LT1028s and the LTC1150s for minimum total noise. The empirically determined breakpoint was also exactly as theory predicted. 3. This x1000 preamplifier could be used to accurately measure the resistance of low values resistors just from their Johnson noise. At this point I started to wonder if I was dreaming, living in a simulation, or unknowingly part of the cast of a horror or science fiction movie. On Sat, 25 Jun 2016 00:38:49 +0800, you wrote: >... > >Also 2001 support scan-card addons so you can easily expand DMM with >scanner function, or even nanovolt-preamp if you dedicated enough. I'm >working on nanovolt support with 2001, but that's long story. Some >details with DIY card I covered here: https://xdevs.com/review/ema10/ > >...