Keithley 2100,2000, etc or Chinese bench multimeters? - Page 1
Forum section: electronics / testgear

author: djsb
author_rank: Super Contributor
timestamp: October 27, 2024, 09:02:10 am
content: I'm looking to buy a 6.5 digit bench multimeter. I've been looking at the Siglent SDM3065X, Hantek HDM3065 and similar. But I'm also drawn to the Keithley/Tektronix 2000 series. I've read here that the keithley has this scanner card project availablehttps://www.eevblog.com/forum/circuit-studio/example-project-relay-scan-card-for-k2000-dmm/?allNow I'm thinking maybe a Keithley would give me more upgrade options via community add ons etc.Are the Keithley multimeters a better investment and can spares still be bought (IE display etc) for them. What is your favourite Keithley model and why? Thanks.

author: ch_scr
author_rank: Frequent Contributor
timestamp: October 27, 2024, 09:57:07 am
content: Take care, Keithley 2100 & 2110 are actually Picotest M3500A/M3510A. Not that they are bad meters per-se, but one wouldn't necessarily pay "Keithley money" for them.For the data-logging / switch card capabilities, this has to be seen in context: it usually necessitates a semi-permanent setup (of the stuff "to be measured"), usually one that's powered on for a long(er)-ish time and connected to some kind of computer running for that time as well, and the software setup to log / display that data.In my experience, the "general bench" is not a good place for that, as it will be in the way there, and blocking the use of the bench meter to boot!So at least I wouldn't advocate to restrict the "general bench DMM" selection by that capability.Which brings us to that, capabilities - e.g. if you do audio stuff, maybe look at the Keithley 2015 THD.But more generally, what do you (want to) use it for? Answer that, and people will be able to give better advice.Edit: For the Keithleys, the VFD's are usually unobtanium. Look at the venerable HPAK 34401A,the"general recommendation" 6 1/2 digit used market DMM, and replacement VFD's are available (except for the very early, all-red input jack model) for it, too.

author: BeBuLamar
author_rank: Super Contributor
timestamp: October 27, 2024, 10:02:52 am
content: Keithley is an American company but don't they make their meters in China too?

author: coromonadalix
author_rank: Super Contributor
timestamp: October 27, 2024, 10:32:14 am
content: 34410a 34411a vfd's clones can be bought they are very good meters to, you have the vfd less of them the L4411a ...but oldies like them, vfd age is often a problem ... check have to be done for caps and vfd's looks, if a seller shows it and you see pass testsand prices has gone bonkers ... repairability too in more recent stuff / models, no schematics etc ... i would go to 34401a 34410 and 34411, some k2000 models have been reversedi'm waiting for a Siglent sdm3065 well see .... but the reference voltage used is no par with the oldies with lm399 or the ltz1000 (3458a)For the Siglent well design capture software and automate tests with itKeysight has lost, in their benchvue softwares or "the old dmm utility was better", K2000 ?? unless you do Labview and other softwares ??For scanners cards, you do have open projects who could help lower purchases costs if you need multiples inputs, like the posted project link34970a was good too ... but the problems for all of them (cards options) is card costs ... some are unobtanium and very expensive, they where reversed too if i recallevaluate your need for the very long time you may need them ... and mostly calibrations, you can or could have big surprises ...I don't thrust any of the 34461 or 65 models, some reliability problems with them, give me one i'll get rid of it.DMM6500 7500 have good commentsunless you go pxi / pxie mainframes meters ?? calibration prices are way to excessiveEDIT this software is very good :https://www.eevblog.com/forum/testgear/program-that-can-log-from-many-multimeters/

author: 2N3055
author_rank: Super Contributor
timestamp: October 27, 2024, 02:40:20 pm
content: Quote from: coromonadalix on October 27, 2024, 10:32:14 amRigol DM3068 and Siglent SDM 3065 also use LM399...

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 27, 2024, 02:49:28 pm
content: I have the SDM3065X, and it's great. If you want to make good comparisons, and you care about a scanner card, look at the SDM3065X-SC version that comes with the card.Besides that, if you want Keithley, look at their DMM6500 model.Siglent also has a new model coming out - the SDM4065A which appears to compete more directly with the DMM6500.Whatever you choose, I would make sure it's compatible withTestController, as that will be better than most logging software, and it's free and made by EEVblog user HKJ.Thanks,Josh

author: coromonadalix
author_rank: Super Contributor
timestamp: October 27, 2024, 03:56:29 pm
content: test controller support a tons of meters, his maker is in this forum too, witch is a very good thingyou can email him ...I'm not so sure when you add scanner cards ... check in it's supported models / option ...

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 27, 2024, 04:10:56 pm
content: Quote from: coromonadalix on October 27, 2024, 03:56:29 pmYou could possibly add support for that sort of the thing by editing the device definition file (if it's not already supported).When I'm more ambitions and/or smarter, I'll try adding my IM3570 to it.

author: nctnico
author_rank: Super Contributor
timestamp: October 27, 2024, 06:23:10 pm
content: Quote from: djsb on October 27, 2024, 09:02:10 amTest equipment is never a good investment. And don't get to excited about having schematics and/or the really old stuff with crappy displays and very little functionality. Repairing equipment takes time which eats in to getting more useful things done.As ch_scr wrote: what do you want to do with a 6.5 digit DMM? What measurements do you want to make? Which features are important to you? With that, people can give useful recommendations instead of throwing random model numbers against the wall and see what sticks.

author: djsb
author_rank: Super Contributor
timestamp: October 28, 2024, 04:08:37 pm
content: Thanks for all of your replies.I'm going to take some time to do some research into what my essential requirements are. I will wait for the Siglent SDM4065A to arrive at my local distributor (Telonic) and read up on a few reviews. Will also give me time to get the cash together.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: October 28, 2024, 05:03:28 pm
content: Quote from: 2N3055 on October 27, 2024, 02:40:20 pmBut not aged, allegedly (at least not in Siglent SDM3065), which makes them prone to drift in time, requiring more frequent re-calibrations.

author: Zucca
author_rank: Unknown
timestamp: October 28, 2024, 05:15:16 pm
content: Quote from: djsb on October 27, 2024, 09:02:10 amA K2001 with schematics and service manual available, it makes automatically on the top on the list.The most hackable 7.5digit DMM on the planet!I am almost finished with the restoration of one unit, soon I will be selling it... stay tuned.

author: 2N3055
author_rank: Super Contributor
timestamp: October 28, 2024, 05:30:32 pm
content: Quote from: Caliaxy on October 28, 2024, 05:03:28 pmWhat do you mean "more frequent" calibrations?If reference is aged all you get is less drift on first calibration after a year.After DMM is a year or two old, they all drift the same from that point on.Aging is only accelerating initial drift, it does not make device better long term.If you are aging and sorting you can pick best ones and then it would make the slight difference.Which is not what happens for entry level 6.5 digit instrument even on big brands. For KS 3458 they will do it. For 34461 not really. Only some pre-aging.Maybe KS 34465 has aged and selected LM399 because it claims better specs than 34460/61.

author: zrq
author_rank: Frequent Contributor
timestamp: October 28, 2024, 05:46:56 pm
content: K2001 (and M) sometimes appear on ebay for a bit less than $800 so it's indeed a great value meter, but the voltage range noise as tested by myself suggests it's rather disappointing for reading the 7th digit (the noise can hardly be averaged down to 0.1ppm of range).

author: nctnico
author_rank: Super Contributor
timestamp: October 28, 2024, 05:55:03 pm
content: Quote from: Caliaxy on October 28, 2024, 05:03:28 pmTony Albus shows that in a review of a GW Instek GDM-9061.Around 16:00 he compares the GDM-9061 against the Siglent SDM3065 and the Siglent does seem to drift a bit.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: October 28, 2024, 06:44:20 pm
content: Quote from: 2N3055 on October 28, 2024, 05:30:32 pmAs needed to keep it on par with the ones with aged references (if precision matters that much).Quote from: 2N3055 on October 28, 2024, 05:30:32 pmYes, the drift slows down with time, until a point when it's not relevant anymore. SDM3065X only provides data for the first year (on par with 34461, indeed). Looking at the KS datasheets (for 34461 and 34465), the drift slows down a bit in the second year (by 25%). DMM6550 is more impressive, in two years drifts as much as the others in one. But they are all very small numbers.

author: 2N3055
author_rank: Super Contributor
timestamp: October 28, 2024, 06:47:34 pm
content: Quote from: nctnico on October 28, 2024, 05:55:03 pmI don't think what he shows is relevant in any way.He stacked 10 instruments , including SDM3065, so close that air passages are blocked and instruments are heating each other in addition to not having any airflow. GDM-9061 is on desk with normal air flow.So any "drifting" relative between these two instruments is irrelevant as a data point.And you know that...

author: nctnico
author_rank: Super Contributor
timestamp: October 28, 2024, 06:49:54 pm
content: Quote from: Caliaxy on October 28, 2024, 06:44:20 pmI don't think that will work. For as long as the drift hasn't made the readings go out of specification, there is no reason to adjust. A reference just needs to age to get rid of the initial drift.

author: 2N3055
author_rank: Super Contributor
timestamp: October 28, 2024, 06:54:09 pm
content: Quote from: Caliaxy on October 28, 2024, 06:44:20 pmI am afraid you misunderstood what some of these specifications mean in datasheets.1 year and 2 year columns do not mean drift in 1st and 2nd year. These are maximum errors with 1 year and 2 year calibration intervals.Drift basically drops exponentially with time. After reference is 2-3 years old drift will be in low ppm range.Other components will settle too.

author: temperance
author_rank: Super Contributor
timestamp: October 28, 2024, 07:18:44 pm
content: Also check the price for extra PC software if you need that. Tek's Kickstart software will cost you €177 annually or over €500 for a perpetual license. EasyDMM for a Signlent is free.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 28, 2024, 07:21:46 pm
content: Quote from: nctnico on October 28, 2024, 05:55:03 pmYeah, and the Siglent only had 5 minutes of warm up time. That's not enough for either of the meters to be perfectly stable.Next questions: Which reading was more accurate? What's the certified value for his ref? Is it in cal still? Is that reference really that stable?That Instek looks pretty nice though. Might look good on my bench next to my SDM3065X. 😉Quote from: temperance on October 28, 2024, 07:18:44 pmYes, but EasyDMM sucks compared to TestController, which is also free.

author: temperance
author_rank: Super Contributor
timestamp: October 28, 2024, 07:34:49 pm
content: Quote from: KungFuJosh on October 28, 2024, 07:21:46 pmI never tried EasyDMM.

author: djsb
author_rank: Super Contributor
timestamp: October 28, 2024, 08:06:43 pm
content: The dual measurement function of the GDM-9061 could be useful. It also has the GPIB option but no multiplexer option. The better displays on the Siglent and GW-Instek are a plus over the limited Keithley displays. I have an Instek GPP-4323 which it would sit nicely alongside.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 28, 2024, 08:25:59 pm
content: Quote from: djsb on October 28, 2024, 08:06:43 pmThe Siglent and the Keithley DMM6500 all support dual measurements. I think you should consider a modern model from those 3, and then it's hard to go wrong. Siglent is the least expensive, then the Instek, and most expensive (of course) is the Keithley. Personally, I want all 3. 😉

author: tautech
author_rank: Super Contributor
timestamp: October 28, 2024, 08:30:43 pm
content: Quote from: KungFuJosh on October 28, 2024, 07:21:46 pmYet EasyDMM is easier to use should you not have any programming skills.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 28, 2024, 08:33:48 pm
content: Quote from: tautech on October 28, 2024, 08:30:43 pmYes, EasyDMM is easier to use. It still sucks by comparison, and TestController doesn't need any programming skills if your device is already supported. Youcanprogram stuff/functions, but you don't need to.

author: Caliaxy
author_rank: Frequent Contributor
timestamp: October 28, 2024, 09:58:53 pm
content: Quote from: 2N3055 on October 28, 2024, 06:54:09 pmI understand thatI just inferred that if those maximum errors guaranteed by the manufacturer at delivery embed the drift of the reference (which, whatever it is, gets smaller with time) the lower degradation of accuracy in the second year after calibration reflects a one year longer-aged reference, right-shifted on its exponential curve. In turn, this would show a longer-aged reference in DMM6550 than in KS34665, for instance.Of course, this doesn't mean I am not wrong. There must be other factors/components that make DMM6550 better than KS34465 and KS34665 better than KS34461 and SDM3065. And no instrument gets better by just aging...What specs in the data sheets made you infer that KS34465 might have an aged reference (as opposed to KS34461 or SDM3065)?

author: Caliaxy
author_rank: Frequent Contributor
timestamp: October 28, 2024, 10:01:20 pm
content: Quote from: nctnico on October 28, 2024, 06:49:54 pmAgree, I might make wrong assumptions. A 100 ppm drift would alter those specs, a 5 ppm would not.

author: nctnico
author_rank: Super Contributor
timestamp: October 28, 2024, 10:12:31 pm
content: Quote from: Caliaxy on October 28, 2024, 09:58:53 pmProbably by selection. Keep in mind that Keithley / Fluke and Keysight have decades of know-how where it comes to making high precission multimeters and how to age / select references to meet specifications.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 28, 2024, 10:17:55 pm
content: Quote from: nctnico on October 28, 2024, 10:12:31 pmIt's not that simple. All these major brands know how to do that. The same question also applies to different meters within the same brand(s).In theory, Siglent keeps the price of their bench DMMs lower by not spending the investment pre-aging the references. I don't know to what degree that's true, but that's what I've read. My SDM3065X has excellent stability, especially for it being so young. 😉

author: nctnico
author_rank: Super Contributor
timestamp: October 28, 2024, 10:26:46 pm
content: Well, you don't learn how to make samurai swords in one day. It takes decades of training and devotion.BTW: do you have a good enough reference to back the claim that your SDM3065X has excellent stability? You'd need some really sophisticated gear to determine stability for a 6.5 digit DMM.In general most people / labs don't. You'd need a metrology grade voltage standard.

author: Martin72
author_rank: Super Contributor
timestamp: October 28, 2024, 10:28:13 pm
content: I bought a handful of SDM3045Xs for “my” test field. We don't need more than 3 decimal places of accuracy and as long as the annual external calibration “says” that the Siglent meets its own specifications, everything is fine.The same applies to my private SDM3065X.

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 28, 2024, 11:38:13 pm
content: Quote from: nctnico on October 28, 2024, 10:26:46 pmHa! That's a silly analogy. Making swords is a significantly higher level skillset. I have no experience selecting or aging ref chips, but I'm sure if I was working with somebody who was experienced, I'd be fine, and refer to them for confirmation. Electronics = measurable specs. Sword making is an art that takes hundreds or thousands of hours to be mediocre at. 😉Quote from: nctnico on October 28, 2024, 10:26:46 pmAbsolutely! For my needs. Actually, for better than my needs. 🤣I tested with a VREF10-001 r9 and posted the results from TestController in the Siglent DMM thread. I also shared the results with Doug (the maker of the VREF) and he was impressed with the Siglent's performance, and said the noise seen in the results is right on with the specs of the reference chip itself.Thanks,Josh

author: coromonadalix
author_rank: Super Contributor
timestamp: October 29, 2024, 12:25:02 am
content: for the based lm399 ltz 1000 and such, aging will make them better and less drifty ...i had proof of that with oldies like 34401a and their replacement L4411a and 34410a, theses later where as good ...even old Keithley 196 and Tek DM5120 based on lm399 where darn good too, but 300 volts, not 1kvsurely other in the k2xxx series would be as goodI'm not bashing Siglent or others but ... they will age in a sense ... all electronics do age, but temp controlled zenner will stabilize over timebut now all comments including mine are derailing the @op thread, he'll decide whats best for him, not us lollNow other brands tries to get the best bang for the buck, but some will never be as good as the past or actual main actors ... see the top end 8.5 digitsNothing as really changed over the years, just some black"ish" phenomenonFluke / Wavetek, Advantest, Keysight, Keithley, Datron, Prema, Solartron ... some of them haven't got any successor or extended models, just a black 3458a ...Or the ones we find on fleabay, that can be repaired and saved ...Now there is the new REF xxx series who seem's good, pretty good ?, well see how they evolve ...

author: KungFuJosh
author_rank: Super Contributor
timestamp: October 29, 2024, 01:03:29 am
content: I just watched the rest of Tony's video. The Siglent was not warmed up in Tony's video, but it was more accurate according to the outdated cal sheet. 😉 Then I watched a couple reviews of the DMM6500.Now I'm even more interested to see the SDM4065A when it comes out.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 29, 2024, 11:03:15 am
content: Quote from: Caliaxy on October 28, 2024, 09:58:53 pmFor the 10 V DC range the 34465 specs are 10 ppm for 24 hours, 20 ppm 90 days and 30 ppm for 1 year. So only 10 or 20 ppm of room for drift over 90 days / 1 year.The specs for the LM399 allow for a typical drift of 20 ppm for the frist 1000 hours. If not preaged this drift part alone would add at least 20 ppm for the first 40 days. To reach the tighter specs it would need some preaging / burn in and possibly also some selection.A good 6 digit DMM should have some burn in or at least pre-aging of critical parts to get the typical 35 ppm accuracy specs. Without it the LM399 ref. is barely stable enough for this. The meters based on a SD ADC chip have the additional drift part from dividing the reference down for the the ADC and scaling the input signal from 10 V to some 2.5 or 5 V range of the ADC.

author: Zucca
author_rank: Unknown
timestamp: October 29, 2024, 12:55:59 pm
content: Quote from: zrq on October 28, 2024, 05:46:56 pmCarefull with cheap K2001 on ebay, they are often corroded by the leaking caps.Yes it is a bit noisy for a 7.5, but the noise is not due to the HW but for the SW/DAC quantization algorithm.That said you don't buy the K2001 because of the low/high noise, but for all the rest.

author: djsb
author_rank: Super Contributor
timestamp: November 04, 2024, 07:17:05 pm
content: Thanks everyone for your replies and general interest.It looks like I'll be buying a Keithley DMM6500. I'll post back here later when it arrives.PS, It arrived yesterday morning. I bought a Certified Pre Owned DMM6500 from TestEquity in the UK. It has 3 years guarantee and the calibration runs out June 2025. It came with a cal certificate and still had the plastic screen protector. The instrument was shipped to me from their warehouse in Germany via the UK office in St Asaph in North Wales. The cost was £984 inclusive of VAT and postage. I'm going to be very happy with it.