High voltage precision source for calibration - Page 1
Forum section: electronics / projects

author: caall99
author_rank: Regular Contributor
timestamp: June 09, 2014, 07:01:20 pm
content: As many of you on these forums, i am trying to build up a near "standards" quality calibration lab at home. The volt-nut in me strives for perfection, 6th digit has to be dead on the money, not 30 ppm out (still in spec is not good enough).I recently acquired a NIST traceable Agilent 3458A, which is effectively my "transfer" standard. Unfortunately, i cannot transfer much of anything, without having a source to characterize. In order to calibrate my other 6.5 digit multimeters I will need a precision 10 VDC to 1000 VDC source (already have an EDC MV105 for sub 10 volt), with very low noise and drift.I looked into hacking electrophoresis units, but they are all far too noisy and fluctuate output levels at such low frequencies that no capacitor could possibly filter to a stable level.A cockcroft-walton multiplier seems like another option, but potentially will sag its output under any load, in which case impedance matching of the 3458A and unit under calibration will be necessary. Perhaps a voltage follower op-amp would work, but i have not found any high voltage op amps that are suitable.What are my low cost alternatives to have a precision 0 to 1000 VDC in my home lab? Can i potentially go the digital route, leveraging some very high end 20+ bit DACs (i already have some on hand)?

author: jpb
author_rank: Super Contributor
timestamp: June 09, 2014, 10:00:25 pm
content: I've got similar problems in that I have a calibrated K2000 and want to use it to "calibrate" or at least fully check other meters.Personally I'm not bothered about 1000V but getting to 100V might be nice. Getting to 30V is straight forward (just using a lab power supply and smoothing) which at least is in the 100V range.A brief search of voltage regulators suggests something like the TI783 might take you to 125V - perhaps using two in a row to get to 100V better smoothed:http://www.ti.com/product/tl783This approach is probably not precise enough for your needs but with the two meters in parallel and warmed up you only need the digits to stay reasonably steady to check the calibration - setting it requires an exact 100V to stay steady which is more difficult.

author: robrenz
author_rank: Super Contributor
timestamp: June 09, 2014, 10:56:06 pm
content: Three HP 6115A power supplies in series will give you 300V with extreme stability and very low ripple/noise.

author: skipjackrc4
author_rank: Regular Contributor
timestamp: June 09, 2014, 11:02:47 pm
content: HP 740B will go to 1000V with 6 digit precision. I have one, and the high voltage is a bit out (I think it's due to some aging neon choppers that I plan on replacing some day). It's a pretty serious piece of gear, and can be hard to find. I got one for $50

author: Marco
author_rank: Super Contributor
timestamp: June 09, 2014, 11:13:13 pm
content: Just use a class A amplifier? (Use a high side current source instead of a resistor to get better ripple rejection.) It's not very efficient but since you only have the meters as a load you don't need to be able to supply a lot of current. This can then filter the droop from a multiplier HV source.

author: KJDS
author_rank: Super Contributor
timestamp: June 09, 2014, 11:14:41 pm
content: Quote from: robrenz on June 09, 2014, 10:56:06 pmI've got a pile of four of them in the repair pile should anyone want to make me a reasonable offer.I've also got a HP6902B calibrator that's a bit iffy on it's 10A range as well as a couple of Fluke 5100B calibrators both of which have AC faults.

author: casinada
author_rank: Frequent Contributor
timestamp: June 09, 2014, 11:56:56 pm
content: You would need a Calibrator to get a full range of Voltages, Currents and Resistance.A FLuke 343A or 332A/D or 3330B would gibe you DC Voltages to 1100V. A Fluke 5100B will give you All the range of voltages to 1100V, AC Voltages to 1100V ( discrete range of frequencies depending on the voltages), DC and AC currents and Discrete resistance values as well. The Fluke 5100 is good to 4 1/2 digits, if you want better you have to get into Fluke 5700 or 5500 series but those cost lots of money. Yes, it can get expensive by the time you have the resources to calibrate DCV, ACV, DCI, ACI, OHMs, not to mention frequency, and temperature.

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 12:26:04 am
content: Thank you all for the responses. I understand that I could simply splurge the $1000 on another piece of precision instrumentation such as the fluke 5440b or 332/335d. But given that the 3458a already did enough damage to the bank account, the objective here is to repurpose another lower cost high voltage source (i.e. electrophoresis example) and modify it for higher stability, and perhaps add adjustability, or build something from scratch all together. I know this is breaking the mold, but I feel sourcing a stable 1000v shouldn't cost me thousands. I also do not need to dial in digits, a variable potentiometer to adjust the output and characterize it with my 3458a would be sufficient.

author: retrolefty
author_rank: Super Contributor
timestamp: June 10, 2014, 01:17:56 am
content: The volt-nut disease is indeed a near fatal condition.

author: ManateeMafia
author_rank: Frequent Contributor
timestamp: June 10, 2014, 01:18:42 am
content: I came across this the other day and wondered if I could ever justify building a 1kV(or more) standard.http://www.ti.com/lit/an/sbaa203/sbaa203.pdfYou could use it as a precision bug zapper.

author: skipjackrc4
author_rank: Regular Contributor
timestamp: June 10, 2014, 01:24:35 am
content: Quote from: ManateeMafia on June 10, 2014, 01:18:42 amIt looks like someone had fun writing that app note. I love the 100kV reference!Quote from: caall99 on June 10, 2014, 12:26:04 amHow about an electrophoresis supply with a stack of these on the output (with a suitable resistor, of course):http://www.mouser.com/ProductDetail/Vishay-Semiconductors/BZX85B100-TAP/?qs=sGAEpiMZZMtQ8nqTKtFS%2fKE3JtglsWdkPKybwMyla%2fE%3d1 kV ceramic caps aren't expensive, so you could add some capacitance to help stabilize the output.

author: saturation
author_rank: Super Contributor
timestamp: June 10, 2014, 02:10:22 am
content: I went through this several years ago:https://www.eevblog.com/forum/projects/poor-man-calibration-facility/msg97350/#msg97350You won't have an exact 1000Vdc source, but it is stable to make a 'transfer' from a calibrated DMM to one needing comparison. Likewise, as you stack the 9V batteries, you can generate voltages between 9-1000Vdc to check various parts of each range. Below 10Vdc, use the EDC references as a voltage source.I have not done the battery method to 1kV, only to 100Vdc or so as my key concern was checking accuracy between 0-100Vdc.http://www.cheap-batteries.com/9V.htmlFor the rest of your DMM calibration, its hard to find high stability Vac to 1kV at multiple frequencies and stable quality ac current sources. So after waiting a few years, I chanced on a full calibrator in as-is condition that provides kV dc and ac, up to 10A AC and DC, and various resistances for under $100 which I can use as a source to compare a calibrated 6.5 digit DMM against my other DMMs. The metrological issue comparing 2 6.5 digit DMMs against each other, the Test Uncertainty Ratio, TUR, issue, can be minimized by making multiple fine adjustments over hours to days until the 2 devices are not just in spec, but read identically.Calibrating the 3458a is IMHO very hard DIY because its the very top of pyramid as a DMM; there is little to compare against it except costly primary or secondary references: JJ or Fluke 732a type. The 732a is a very elusive device to get cheaply and if you are successful in obtaining one, the only way to avoid the high cal cost is to know someone who has a cal'd 732 that you can reference to tweak yours until its perfect, again because of the TUR error effect.In the end you still need to have one calibrated device to which you can use your cal lab to distribute its calibration to your other devices. I've found the only way to avoid this cost is from a friend who has a cal'd DMM that you trust is calibrated, if it doesn't have formal calibration itself, or pay to have your best device calibrated by an NVLAP lab or Agilent itself.Quote from: caall99 on June 09, 2014, 07:01:20 pm

author: cellularmitosis
author_rank: Unknown
timestamp: June 10, 2014, 02:31:35 am
content: Well, at least up to the 30V range you can use a chopper amp directly. Here's a circuit which is simply a modified version of fmaimon's circuit from LM399 10V reference thread (https://www.eevblog.com/forum/projects/lm399-based-10-v-reference/). I'm trying to make a transfer standard for my HP 3478A and Keithley 196.These are all Vishay foil resistor values available used on ebay for about $5 each, so the price isn't totally unreasonable.(the voltages are of course not exact, but as close as I could get to about 2.9 in each range, using the resistor values available on ebay).(also, the LT2057's output can extend to the negative rail, which I think means this isn't guaranteed to start up, as it may be stable at 0V output...).

author: Galaxyrise
author_rank: Frequent Contributor
timestamp: June 10, 2014, 02:35:00 am
content: If you have a supply that can do just under what you want but without perfect stability, and you have a really good voltage reference and a really good voltage divider, then you can fill in the gap with an opamp. I did this for 100V:https://www.eevblog.com/forum/beginners/why-does-my-op-amp-circuit-need-a-capacitor/(Note there's a current limiting resistor missing from that schematic.) The resulting 100V is very stable.I used aCaddock 1776-C6815for the divider, but put the 96V on the 900K. It's rated to over 1000V on the 9M, so you should be able to use it to divide 1000V down to 10V.

author: saturation
author_rank: Super Contributor
timestamp: June 10, 2014, 11:11:18 am
content: Additional references:http://www.radiomuseum.org/forum/nimh_battery_packs_for_high_voltabe.html?language_id=4This would meet a precision need; but I've not found one at reasonable cost; rarely posted model, the 1030:http://www.ebay.com/itm/EDC-KH-Krohn-HITE-1030-DC-Reference-Standard-Calibrator-Voltage-1000V-VS1030-/151231994691?pt=LH_DefaultDomain_0&hash=item2336211b431000Vdc with 100uV resolution, right in the 3458a alley.

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 11:15:14 am
content: Quote from: casinada on June 09, 2014, 11:56:56 pmYou're right that a 5100B is only really up to calibrating 4.5digit meters, but for a transfer standard, the Fluke 5100B will stay stable to a single count on a 6.5 digit meter for minutes at a time.

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 12:20:58 pm
content: Quote from: skipjackrc4 on June 10, 2014, 01:24:35 amRegarding the electrophoresis supply: Are you suggesting that i take the 3kV from an electrophoresis supply and clamp it with 10 x 100V diodes in series (i.e. a total forward voltage of 1000V), and then smooth/filter the output with a capacitor? This seems pretty plausible, just worried about heat build up in the diodes, and unfortunately have no way of adjusting the output.

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 12:27:07 pm
content: Quote from: saturation on June 10, 2014, 02:10:22 amSaturation, my 3458A has recently been calibrated, and will receive annual calibrations from here on out. I am still looking to source DC voltage cheaply and am not overly concerned about drift. My 3458A is characterizing all my sources, so the source's inherent drift or long term instability is not as important.I just need voltage levels that are stable for a transfer reading when calibrating other DMMs. Effectively, my 3458A is my transfer standard traceable to NIST.

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 12:35:56 pm
content: Quote from: saturation on June 10, 2014, 11:11:18 amBattery options are intriguing, but i am looking for something a little more "hardwired" and "permanent". What you linked is my EDC dream machine, but i don't think i can justify the price without selling my other two units. The DIY option seems preferable. I would like to learn something in the process as well.

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 12:39:27 pm
content: Quote from: KJDS on June 10, 2014, 11:15:14 amThis is great to hear! i was thinking something along the lines of this if i don't go the DIY route. I do not need to dial in 6.5 digits on my source, all i need is a stable enough source so i can transfer the calibration from my 3458A to a 34401A (for example). The 3458A can resolve 8.5 digits, and if the stability in the reading is sufficiently high, I can transfer to 6.5 digits. The 5100B would also allow me to transfer DC V/A and AC V/A etc...

author: saturation
author_rank: Super Contributor
timestamp: June 10, 2014, 01:00:43 pm
content: Yes, in fact you can do it now with what you have around, check any AA battery and you'll be surprised how stable it is and the precision of the output voltage [ i.e., uV the limits of my 3456a] so long as the load is very large. Note primary batteries are better as rechargeable have a bigger self discharge rate and freshly charged batteries have very high self discharge until equilibrium.I'd be interested to see tests on your 3458a to see how low you can resolve, nV ?, stably on an AA battery.Achieving battery level quietness will not come cheap in active devices.As for a Fluke 5100B calibrator as a solution, inevitably that's what I did, find an old analog calibrator, mine was a one in the Rotek 300 series from the late 1960s early 1970s. The Fluke 5100B will be a bear to maintain and costly to buy, whereas an old style analog calibrator is pot based, often dumped, just wait for them to come on line via eBay. They are boat anchors, be forewarned. Cost me $40 to buy, $60 to shipand a better value than 100 9v batteries.http://rotek.com/They were designed also forDMMhand held multimeter type calibration. But they generate stable Vac, Vdc, Iac, Idc, and resistances you need to transfer your 3458a values to your other devices. Accuracy is rated typically in the 0.005%  , but the short term accuracy , or 'transfer accuracy'  is even higher, to ppm if you test them yourself. Back when they were made, they didn't specify transfer accuracy.These analog calibrators are like the EDC devices on steroids. Since you aren't concerned with the calibrator holding its cal over a year but using it as a transfer, they maybe perfect for you. Also, big and spacious, easy to service and MILSPEC derating design, they like the EDC references, last a lifetime. So its buy once, and forever.Now with your calibrator, you an even sell you services to pay for your 3458a cal, now that Geller's Lab is out of businesswe could use another volt-nutQuote from: caall99 on June 10, 2014, 12:35:56 pm

author: Bill158
author_rank: Regular Contributor
timestamp: June 10, 2014, 02:25:18 pm
content: The problem is quite simple to resolve. Over the past 25 years I have accumulated:Fluke 332D, Fluke 332B, Fluke 335A, Fluke 5440B, Fluke 5440B/AF, Fluke 5200A/5215A, Fluke 730A, Fluke 731B, Valhalla 2734A, ESI SR104, GR1444A, Fluke 540B, 6 ea Fluke 732A, Fluke 720A, Fluke 750A, Fluke 721A, Fluke 845AB, 2 ea HP 3456A, 2 ea Fluke 8502A, HP 105B, Fluke 752A, Fluke 5450A, 2 ea HP 3458A, Fluke 742A-10k, Fluke 742A-1k, Fluke 742A-1, a set of Holt model 20 high frequency thermal converters, and lots of O'scopes and their Cal equipment. And lots of other test equipment too numerous to mention.HELP!!! I am a VOLT junkie.You can get help for drug and alcohol addiction, where do you get help for "volt" addiction?I suddenly realize I am one sick puppy!Bill

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 02:52:18 pm
content: Quote from: Bill158 on June 10, 2014, 02:25:18 pmIf these are truly your personal belongings, bought with hard earned cash, then you my friend... are indeed the sickest person i know. I wish you luck

author: Bill158
author_rank: Regular Contributor
timestamp: June 10, 2014, 03:40:54 pm
content: Quote from: caall99 on June 10, 2014, 02:52:18 pmYes they are all mine, Yes bought and paid for with my hard earned cash. Some acquired from local "junque" stores, a lot from fleabay. When I found ebay my sickness really took off. Don't ever forget "He who has the most toys when he dies, wins".Bill

author: Marco
author_rank: Super Contributor
timestamp: June 10, 2014, 06:13:01 pm
content: Quote from: caall99 on June 10, 2014, 12:27:07 pmYou didn't reply to my suggestion of a class A amplifier ... googled a bit for a design :http://electronicdesign.com/components/1-kv-piezo-amplifier-keeps-cost-noise-lowMaybe you could use low voltage MOSFETs for Q2 and Q3 and use a second battery and a high voltage MOSFET as a cascode to get better rejection of the power supply?

author: caall99
author_rank: Regular Contributor
timestamp: June 10, 2014, 06:14:59 pm
content: Quote from: Marco on June 10, 2014, 06:13:01 pmSorry, must have missed this. Something i wasn't very familiar with so i may have glossed over when looking at your post. i will investigate now. Thank you!

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 07:01:19 pm
content: I've hooked up a Fluke 5100B to four Keithley 2015THD to see what the short term stability is like.First picture taken at 8pm UK time, I'll carry on at hourly intervals for the rest of the evening.

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 08:51:56 pm
content: 9pm UK time

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 09:01:59 pm
content: 10pm UK time

author: jlmoon
author_rank: Unknown
timestamp: June 10, 2014, 09:31:40 pm
content: Quote from: retrolefty on June 10, 2014, 01:17:56 amYou're not kidding! I just spent $5500 on a 'NIST Standards 3458A' boy did they reel me in..but it's dead nuts on!

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 10:01:24 pm
content: 11pm UK time

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 11:04:12 pm
content: 11.45pm UK time, 10V

author: KJDS
author_rank: Super Contributor
timestamp: June 10, 2014, 11:05:44 pm
content: 11.45PM UK time, 1000V, followed by 12pm UK time, 1000VIt looks like it's fine for a 6.5 digit transfer standard once it's all warmed up.

author: caall99
author_rank: Regular Contributor
timestamp: June 11, 2014, 12:14:40 am
content: Thank you for taking the time to check the 5100B stability. In summary, did you see the last digit move in a 5 minute time span? I figure 5 mins is all i need to transfer, if not less.

author: KJDS
author_rank: Super Contributor
timestamp: June 11, 2014, 06:35:52 am
content: Quote from: caall99 on June 11, 2014, 12:14:40 amThe last digit will sometimes flicker from one count to the next, but never more than that in five minutes once warmed up.

author: caall99
author_rank: Regular Contributor
timestamp: June 11, 2014, 12:17:03 pm
content: Quote from: KJDS on June 11, 2014, 06:35:52 amThanks. How does resistance, AC volts and current, and DC current look @ 6.5 digits?

author: KJDS
author_rank: Super Contributor
timestamp: June 11, 2014, 08:59:52 pm
content: Quote from: caall99 on June 11, 2014, 12:17:03 pmI checked resistance this evening, it moved two counts in an hour when set for 10k.Tomorrow, once I've done some real work I'll hopefully have enough space in the lab to move things around and get a Clarke Hess calibrator out and see how stable that is.

author: qno
author_rank: Frequent Contributor
timestamp: June 12, 2014, 10:36:35 am
content: Buy yourself an electric fly catcher.A battery operated tennis racket type.They are a few dollars (including batteries)They are usually around 1000 V.Compare with an other meter.

author: caall99
author_rank: Regular Contributor
timestamp: June 12, 2014, 12:55:58 pm
content: Lol, this idea crossed my mind several weeks back... i may have been too hasty in my dismissal of it. I figured that the voltage sag due to differences in meter impedance would not allow it to work, and that it was only around 300v to 400v. Then again, i can also connect both meters at the same time, and they should be seeing the same value at any given point in time. I'll buy an el cheapo harbor freight fly swatter.

author: jpb
author_rank: Super Contributor
timestamp: June 12, 2014, 01:00:43 pm
content: Quote from: qno on June 12, 2014, 10:36:35 amQuote from: caall99 on June 12, 2014, 12:55:58 pmI can see that this is good for checking the meters, but if you want to adjust the cal don't you need to apply exactly 1000V? Or do you have some means of entering a cal constant directly? Though perhaps you could use a simple resistive voltage divider.

author: caall99
author_rank: Regular Contributor
timestamp: June 12, 2014, 01:03:57 pm
content: I believe i can type an actual cal value into my 34401A when calibrating.

author: G0HZU
author_rank: Super Contributor
timestamp: June 12, 2014, 06:56:22 pm
content: QuoteThe cheapest and sanest option is to wait until you actually 'need' to measure/test something with such precision at 1000V dc? Maybe you could be waiting a lifetime?

author: caall99
author_rank: Regular Contributor
timestamp: June 12, 2014, 07:01:46 pm
content: Quote from: G0HZU on June 12, 2014, 06:56:22 pmYeah... this sounds boring.

author: wiss
author_rank: Frequent Contributor
timestamp: June 12, 2014, 08:43:07 pm
content: Quote from: caall99 on June 12, 2014, 12:55:58 pmThe loading problem could be handled by hooking up both meters simultaneously?Parallel for volts and series for current. Might not work for resistance thou...

author: KJDS
author_rank: Super Contributor
timestamp: June 13, 2014, 09:30:21 am
content: I've now had a chance to check the Clarke Hess calibrators that I have and they are ok as a transfer standard up to 4.5 digits.

author: Marco
author_rank: Super Contributor
timestamp: June 13, 2014, 10:35:29 pm
content: Quote from: caall99 on June 12, 2014, 12:55:58 pmIt's almost certainly AC ...The most common low current HV supply hack usesCCFL inverters.Add a Pi filter and a amplifierand you might get something decent (just picked a jellybean opamp, the first high voltage fast diode and MOSFET I saw in the library, some eyeballed values for the filter and feedback capacitors ... needs some real engineering but just to give an idea ... goes to 7 digits in simulation, fat chance of course).

author: jcbottorff
author_rank: Newbie
timestamp: July 07, 2017, 01:59:55 am
content: I know this is an old thread, but just did a self calibration of my HP 3478A against my calibrated HP 34401A, and generating the 300V DC voltage for the 3478A was problematic. I used a little charge pump HV supply gadget powered from my lab supply, which was not especially stable and was very fiddly to adjust to about 300V, but worked well enough for me to get the 3478A reading the same as the 34401A.A little Internet hunting suggests you can buy A23 (12 volt) batteries in bulk for about a dollar each. And you could buy some pieces of PVC pipe (3/8" schedule 40 looks about the right internal diameter) and load a bunch of them in series. So 1000V / 12V is about 83, so for $100 or so in parts, it should be possible to build a 1000V supply. An A23 is 28.5mm long x 10.3mm, so 83 would be about 8 feet long. A chunk of pipe cut into four 2 foot sections sounds easier to work with. One could stack some of the individual LR932 cells, or you might want some sort of voltage divider to adjust the multiple of 12V to something rounder, which if adjustable, might also be used to compensate for battery run down over time. I'm guessing a battery is not too temperature stable, but for short term transfer use might be ok. Perhaps someone here could calculate how rapidly the battery voltage would drop, due to aging, due to load. At 1000V the 10M input impedance of typical DMMs would be drawing 100 uAmps. An alkaline A23 is rated at 55 milliamp-hour capacity.Just an idea, haven't tried this myself.

author: alanambrose
author_rank: Frequent Contributor
timestamp: July 07, 2017, 04:28:31 pm
content: very nice

author: alm
author_rank: Super Contributor
timestamp: July 07, 2017, 05:16:40 pm
content: And now on to the 280V / 100 kHz that you need for ACV.

author: saturation
author_rank: Super Contributor
timestamp: July 07, 2017, 07:40:36 pm
content: For kV precision voltage seehttps://www.eevblog.com/forum/testgear/power-designs-3k10b-supply-info/

author: ConKbot
author_rank: Super Contributor
timestamp: July 08, 2017, 12:24:38 am
content: No mention of TIs take on a 1kv reference here?http://www.ti.com/lit/an/sbaa203/sbaa203.pdfI know 3ppm/C is probably a bit high for meter calibrations, so the whole thing would probably have to in an ovenized bath, but should hopefully be stable enough for a transfer?

author: 2N3055
author_rank: Super Contributor
timestamp: July 08, 2017, 08:39:31 am
content: Take a look at answer #9 up there ..

author: ConKbot
author_rank: Super Contributor
timestamp: July 08, 2017, 10:11:27 am
content: Derp, somewhere between where where I stopped reading what the original topic was and stated skimming. The stacked references is interesting though, once you stabilized it, if you had a scan card with enough inputs, and the output impedance of the reference stack was low enough, you could measure segments on a 100V or 300V range, and calculate the 1kv value directly rather than using a precision divider to transfer up a lower voltage calibration.

author: saturation
author_rank: Super Contributor
timestamp: July 08, 2017, 11:19:46 am
content: Depending on what country you are from for availability and export issues, buying a used industrial or commercial grade precision power supply or voltage source is your best bet, its stable enough to use as a transfer reference between say a calibrated DMM compared against a DUT DMM with both on the same bench. I waited for some years to get the 3K10B. Its been tested, characterized, defined, plus old models have full service data and schematics, you can keep them alive for a very long time.Granted if you get one damaged some of those parameters will be changed after repair you can retest it to insure its spec'd, but its better than rolling you're own from scratch using stand alone modern references with an untested design. Others sources you can find on eevblog archives includes the Krohn Hite MV106 or the HP 6114/5 and variant models before and after the model line I mentioned, see their pdf manuals. Then their are Keithley source meters, again get obsolete models for the cheap.

author: Zero999
author_rank: Super Contributor
timestamp: July 08, 2017, 06:55:45 pm
content: Probably not accurate enough for you but you can use a TL431 with a cascode to get 1kV. A similar technique can be used with a precision reference plus an op-amp to get a more accurate HV reference.