Any low cost multimeter calibration services? - Page 1
Forum section: electronics / general

author: LogicalDave
author_rank: Regular Contributor
timestamp: October 23, 2021, 12:04:00 am
content: I have a few old multimeters (Fluke 8840A, Advantest R6552) that still work well, but are many years past their last calibration. There's not much point in using 5.5 or 6.5 digits if you can't trust the last few digits. Are there are any US-based calibration services that are low enough in cost to make these worth calibrating? If so, recommendations would be much appreciated; thanks!

author: bob91343
author_rank: Super Contributor
timestamp: October 23, 2021, 01:31:59 am
content: All you need is one meter with a lot better accuracy. Cheaper to buy used than to pay for a calibration. I use my HP 3456A for sanity checks on all my dc meters.

author: LogicalDave
author_rank: Regular Contributor
timestamp: October 23, 2021, 01:34:35 pm
content: Thanks @bob91343. I'm not just looking for a sanity check, but to calibrate the meters so that when I use them, I know the readings are accurate. Buying another meter that is in calibration and has enough additional digits to properly cal 5.5 digit meters is going to be pretty expensive and would still leave me needing to read the service manuals and perform the calibration. Cal services will have high accuracy standards and a good tech will have calibrated many of these meters so they can do it quickly. I could certainly do it myself given enough time and high quality standards (I calibrate my OCXO counters using rubidium and GPSDO sources), but I'm interested in finding out whether there are US-based services that could cal these meters at a price that makes sense; if you hear of any, please let me know; thanks again!

author: ogden
author_rank: Super Contributor
timestamp: October 23, 2021, 03:03:52 pm
content: I'm afraid that calibration is not what you think it isQuotehttps://soluzionesolare.com/news/difference-between-calibration-and-adjustment/

author: LogicalDave
author_rank: Regular Contributor
timestamp: October 23, 2021, 04:58:37 pm
content: @ogden "calibration service" is EXACTLY what I think it is.When it comes to multimeters, and most electronics equipment, "calibration service" is pervasively understood to mean the process of comparing a DUT to a reference standard AND adjusting it so that its measurements match the standard within the equipment's specifications. Every sticker on lab equipment indicates "Calibrated MM/YYYY", not "Adjusted MM/YYYY". If I asked for "Adjustment Service", no one would know what I was talking about.Fluke (a company with some familiarity with multimeters) offers "Calibration Services":https://www.fluke.com/en-us/support/calibration-servicesKeysight (another company with a modicum of electronics experience) also offers "Calibration Services":https://www.keysight.com/us/en/products/services/calibration-services.htmlSo again, I'm looking for a US-based test lab that provides Calibration Service for older multimeters at a price that makes sense.

author: bdunham7
author_rank: Super Contributor
timestamp: October 23, 2021, 05:44:28 pm
content: Quote from: LogicalDave on October 23, 2021, 04:58:37 pmWell, it probably should be--but if you are going to shop for low cost calibration service, make sure you know exactly what you are getting.No comment on the Advantest, but the Fluke 8840A is very unlikely to be 'out of cal' on the DC and R ranges unless it is broken. The only part that may need attention is the AC board, especially at the higher frequencies. For those saying get another meter, you can't calibrate a DMM with another DMM. You need stable--if not necessarily accurate--sources for all of the relevant voltages and frequencies, and then you need stable resistors as well.A calibration service on the 8840A should not be difficult for a conscientious, well-equipped cal lab. The question is what is the price that you think 'makes sense' and will the lab competing on price do a good job. A mediocre no-data calibration certificate may make you feel more accurate, but the actual result may be the same or even possibly worse than it was when you sent it in. For example, the calibration procedure on the Fluke Recirculating RemainderTMA/D converter is iterative and fussy, so a low-cost quickie once-through may actually degrade performance over a decades-old factory calibration.So, IMO, you need to make sure any prospective cal lab is appropriately equipped and that you are getting a calibration with before and after (as-found and as-left) data. Anything less is just paper.

author: bob91343
author_rank: Super Contributor
timestamp: October 23, 2021, 05:50:41 pm
content: I still feel that adequate 'calibration' of a 4 or 5 digit meter can be made from a once-calibrated 6.5 digit meter. Said meter doesn't have to be expensive; my 3456A was around $200 if I recall correctly and has paid off greatly in giving me assurance that my bench meters are accurate.Perhaps you are expecting too much from your everyday meters. By today's standards, they are commonplace and not in the high end category. Further, for the cost of sending it to a service you can probably buy a new one.

author: ogden
author_rank: Super Contributor
timestamp: October 23, 2021, 06:33:02 pm
content: Quote from: bdunham7 on October 23, 2021, 05:44:28 pmRight. Even Fluke can calibrate your DMM w/o adjustment:https://eu.flukecal.com/support/calibration-services#Calibration_Levels

author: bdunham7
author_rank: Super Contributor
timestamp: October 23, 2021, 06:33:50 pm
content: Quote from: bob91343 on October 23, 2021, 05:50:41 pmFirst, you still need stable sources, which may be easy for 1V or 10V DC, but becomes more difficult for the actual calibration points of the meter in question. 200VAC @ 100kHz? Second, lumping the meter in question into the "4 or 5 digit" category isn't too helpful in this case. Your 3456A is only twice as accurate as his 8840A by the specs--at 90 days. The 3456A doesn't have a 1-year spec, the 8840A does. If I was comparing one of each and their last calibration was a decade ago, there's no way I would assume the 3456A was more likely to be accurate.As for the cost of replacing it, there's not a meter I know of under $1K that would completely exceed the capabilities of the 8840A, although obviously newer meters have more features. The 6.5-digit models from Rigol and Siglent come close, but their reputation for drift would keep me from agreeing that they are better in every way.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 23, 2021, 06:38:39 pm
content: Quote from: bob91343 on October 23, 2021, 05:50:41 pmAnd this is the essence of the problem. I don't know what LogicalDave thinks makes sense, but my guess is that it is a modest fraction of the cost of a new meter. That is what would make sense to me as a user. But if the calibration process takes an hour or two of technician time (likely that or more when unpacking, stabilization, adjustment, documentation and repackaging are included) and you add overhead costs and profits the price that makes sense to the calibration lab is likely to be a large fraction of the cost of a new meter. While a high volume calibration lab may get some economies of scale from seeing multiple copies of a given model meter, they will never come close to the manufacturer who is only dealing with a single model at a time, and has the whole sales volume to work with. Even the highest volume lab will have only a portion of the production run with competing labs and those who don't bother calibrating drawing volume down.It is possible that calibration still would make sense if the user takes advantage of the increased stability of an aged meter and uses that to increase calibration interval, but the cost advantage is unlikely to be overwhelming.

author: bdunham7
author_rank: Super Contributor
timestamp: October 23, 2021, 07:33:33 pm
content: Quote from: CatalinaWOW on October 23, 2021, 06:38:39 pmI don't think its quite that dire, except for lower-cost meters where calibration is only reasonable if you need the paper. The process is usually semi-automated and a 'standard' calibration of ordinary bench meters like the 34401A, 8842A and even the 8846A (!) can be had for as little as $80. I'm not endorsing or panning this particular cal lab, but they do list a bunch of prices for their no-data service.https://www.custom-cal.com/TypeInfo.aspx?kn=156&srv=Multimeter_DMM_Calibration_Repair

author: CatalinaWOW
author_rank: Super Contributor
timestamp: October 24, 2021, 12:56:19 am
content: Quote from: bdunham7 on October 23, 2021, 07:33:33 pmTheir page is a little confusing. Not saying they are a bad service, but OP would have to discuss what they do before knowing whether it is a good deal. The note under the table you referenced says that measurement data is not provided, but NIST traceable calibration is provided along with a seal. If they are indeed saying that will adjust as required to certify that the meter meets original specs I am very impressed that they are able to make money providing the service at the advertised prices. In the US it costs in the neighborhood of $100 an hour to employ modestly paid individuals (various taxes, health insurance and so on usually triples wage paid to the technician.) Even with automating the measurement process getting one of these meters through in a fraction of an hour is tough. It is also interesting that they don't provide the data if the process is automated. The extra ink on the paper can't be that expensive.Looking at their list of used meters provides similar confusion. The summary at the top of the page says that all of their meters are provided fully calibrated, but then the price list shows calibration as a separate charge.

author: Denny Wa
author_rank: Newbie
timestamp: October 24, 2021, 06:03:11 am
content: I think that is why you see so many really nice DMMs on ebay, the folks that own them don't want to pay the calibration costs or send it out for calibration, only to get hit with additional adjustment fees. Even the round trip shipping is expensive. And then the calibration labs wants extra for the data. My last calibration cost on a 5 1/2, was USD$65, but that's here in Taiwan, and that is NIST traceable with data.I know you don't want to hear it, but I would consider sending the instrument to Mexico for calibration. I would think there are some reputable calibration labs south of the border. Where do Mexican manufactures send their instruments, doubt they send them to the US. The question is, can they make adjustments if needed.Just had a look, yes there are calibration labs in Mexico, that are certified. Maybe you will start a trend of sending instruments south of the border for cost effective calibration.

author: exe
author_rank: Unknown
timestamp: October 24, 2021, 11:55:01 am
content: I'm jealous! Here in the Netherlands I can't even find a calibration service at all that would work with individuals. It seems my best options is to post it to Germany, where prices start at 100+euro (+shipping) to calibrate my 6.5digit K2000. At this price point it's about 50% of the price I paid for the meter. I'm also concerned something may happen to the DMM in shipping.So, my "solution" is I'll just probably calibrate everything to my K2000. For me absolute values are not important, I mostly care about drift.Anyway, if you are only interested in low voltages and happy with just some basic verification of performance of you dmms, then something like a (recently calibrated) DmmCheck (or a similar project) might work for you.

author: mendip_discovery
author_rank: Super Contributor
timestamp: October 24, 2021, 05:15:06 pm
content: Quote from: LogicalDave on October 23, 2021, 04:58:37 pmSorry but calibration is the act of doing the comparison. Adjustment is an adjustment. Manufacturer's have confused the matter over the years so don't wave them about as being the pillars of the rules. I calibrate mechanical and electrical items and its generally understood in the rest of the "World" what is meant by the term calibration.If you were to ask a lab to calibrate the device and adjust it if required and provide measurements before and after then you would get plenty of nods from labs.Quote from: LogicalDave on October 23, 2021, 04:58:37 pmGood luck in your search. Have you tried asking a local electronics company who they use or who they would recommend? I would be careful of cheap labs as they may not have the uncertainty to satisfy your needs.

author: Jwalling
author_rank: Unknown
timestamp: October 25, 2021, 08:49:57 am
content: I use Global Test Equipment.https://4gte.com/They charge about $100 to calibrate andadjustAgilent 34970A units for me, and it comes with data as well.EDIT: And the last time I used them, return shipping in the lower 48 was free.

author: Denny Wa
author_rank: Newbie
timestamp: October 25, 2021, 10:05:26 am
content: That's a very good deal, and that's also a nice instrument. I demo-ed one of those. Made a simple ATE system, in under an hour. It's a little pricey new though, in the secondary market it is a steal.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: October 25, 2021, 04:42:16 pm
content: I find an uncalibrated 6.5 digit meter quite useful and one mostly does comparisons at that level, or is looking for very small changes, not worrying about absolute accuracy. Buy any decent calibration standard off eBay, or a very close tolerance reference, than match all your meters. In your own world everything will be consistent. Who else matters? In 40 years of design and production work, I've never once had need to match an absolute standard better than a couple digits, though it's often been necessary to resolve a dozen ppm.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 25, 2021, 05:01:04 pm
content: For private / hobby use one can get away without calibration quite a bit. The main function of the calibration is to check if the meter is performing correct. With modern digital meters it is very rare that an adjustment is needed. This would be mainly after a repair that changed critical things. For most meters if they drifted out of spec and would need adjustment, this indicates that there is something wrong. A new adjustament hardly makes it better as it would still be a meter to not really trust.With higher resolution meters a CAL history with readback values may make sense - mainly if one plans to send it to cal regularly (e.g. 2-3 times at least).Higher resolution without a NIST or similar tracable link is still usefull and in ones own bubble it does not really matter if all readings are off by 0.5%.One can do quite a few test on the meters without much special instruments. With an old meter it may be a good idea to do a few checks yourself before sending it out to an expensive calibration.

author: bdunham7
author_rank: Super Contributor
timestamp: October 25, 2021, 05:18:34 pm
content: Quote from: Kleinstein on October 25, 2021, 05:01:04 pmYes and yes. And that's one of the two main reasons you need data with the calibration service. The best deals in old, used bench DMMs are closed-case calibration models, like the Fluke 8842A and HP 34401A, that have 19 calibration stickers all stacked on top of each other but still have the factory calibration constants. You can be pretty confident that they aren't going to drift into the weeds anytime soon.

author: LogicalDave
author_rank: Regular Contributor
timestamp: October 25, 2021, 08:14:12 pm
content: Thank you thank you thank you @bdunham7 and @Jwalling, that was exactly what I was looking for. I had actually used CustomCal in the past (for an old HP 3478a); they did a great job and were quite reasonable, but I'd forgotten their name! I'll check out GTE as well.@DennyWa the idea of using a Mexican lab is interesting; I'll look into that too, but I'd be worried about shipping costs (and risk of equipment loss) exceeding any savings. I'm jealous of your Taiwanese cal costs! If I find anything good, I'll post it here for folks scanning this thread in the future. @mendip_discovery, asking my CM who they use is a good idea too!@bdunham7 questions whether cal/adjust of older DMMs is necessary for them to retain their specified accuracy. I'm very interested in the answer to that question if anyone has worked in a cal lab or at a DMM manufacturer. What I want is confidence that the value on the display is accurate (within the specifications of the meter). I have a precision voltage source (like DMMCheck) and high tolerance resistors and I check my meters periodically (once a year or so) to make sure they aren't wildly off, but I don't have the standards (or knowledge and time) necessary to do proper calibration and adjustment of my older meters. If someone really knows how to do this for older DMMs, without spending hours or thousands on standards, it might be worth avoiding the hassle (and risk) of sending older gear out to a lab; in which case I (and surely others who find this thread) would appreciate the details of your process (notably equipment used).For those who replied without offering any solutions: while I appreciate you taking time to share your thoughts, I'd ask you to consider whether replies to a specific question that don't offer specific answers are really a good use of everyone's time. As you can see, there are indeed US companies that provide calibration (and adjustment) services for reasonable prices: a fairly small fraction of what you could purchase a decent calibrated 5.5 or 6.5 digit DMM for. I am super busy and will happily spend $80-100 per meter to have someone else do the calibration/adjustment. What makes EEVBlog so great is that people can post questions and getusefulanswers...anyone coming to this thread in the future will find it far more useful if it contained less questioning of motives, language, and feasibility...at least without also including answers to the question.

author: bdunham7
author_rank: Super Contributor
timestamp: October 25, 2021, 09:14:44 pm
content: Quote from: LogicalDave on October 25, 2021, 08:14:12 pmI feel compelled to ask: How do you know that? Was there data and a list of equipment used?QuoteSurely you mean 'hoursandthousands'?

author: engineer_in_shorts
author_rank: Regular Contributor
timestamp: October 27, 2021, 08:36:16 am
content: Quote from: LogicalDave on October 25, 2021, 08:14:12 pmI have to say I disagree. I think a number of forum users have hopefully pointed out that anyone looking for "low cost calibration" should be beware and really understand what they want to achieve.In the old adage of 'Fast, good, or cheap – pick two.' applies here.Things to check before sending off for calibration:1. If you want adjustment you should explicitly ask for it, and not assume.2. If you are have adjustment on a UUT that you must ask for before and after. Otherwise how do you know your previous use of the UUT was potentially different readings?3. Establish the UUT specification that will be used to determine if the instrument needs adjustment.4. Does the calibration house have adjustment procedures?5. Is the calibration house using manufacturers recommended verification points (if available) ?6. What quality standard is the calibration house performing the procedures under?7. Verify the equipment used for the calibration and uncertainties for the measurements.You will be surprised about how calibration houses cut corners or are just plain ignorant. Remember there is no 'right way' to perform a calibration, just an agreed way between two parties. Therefore without agreement explicitly in place the calibration house can do what ever they feel right, and hence room to cut corners.Sorry to cast a dark shadow on all calibration houses, but with competition down to $100 precision DMM calibration something has to give. The trade-offs might be OK for your application.

author: LogicalDave
author_rank: Regular Contributor
timestamp: October 27, 2021, 03:29:45 pm
content: @bdunham7I believe they did provide a detailed (automated) report that included equipment and standards used, but it was a long time ago and I no longer recall; I'll see if I can find the report. You're correct that with any such service, a certain level of trust is required; for verification, the best I can do is check it against a precision source like a DMMcheck.@engineer_in_shortsYou are, of course, welcome to disagree and thank you for taking the time to respond. In my defense: the reason for my last comment is that many of the responses in this threaddid not make any attempt to answer the question. The OP was a request for recommendations for a low-cost US cal service for older mid-range DMMs. If you are aware of problems, it would be helpful to share shops to avoid or recommend good shops. Merely pointing out that theremightbe incompetent calibration houses adds FUD, but doesn't help me find a good shop. For DMMs with closed case calibration, a shop with proper equipment (e.g. Fluke 5080 for HH DMMs) can fully automate the calibration and adjustment process such that it takes just a few minutes and not much expertise...this may make it perfectly reasonable and even desirable (to maximize ROI) for them to offer a low cost cal and adjustment service that verifies/restores equipment to OEM spec and doesn't cut corners.

author: bdunham7
author_rank: Super Contributor
timestamp: October 27, 2021, 05:06:10 pm
content: Quote from: LogicalDave on October 27, 2021, 03:29:45 pmIf it gets you to realize that you can't just send it anywhere and expect an excellent result, then it does help. I still think you may still be a bit optimistic about how good a cheap calibration service is likely to be.QuoteSure, an automated process run by minimally skilled labor. What could possibly go wrong?Although I don't agree withCatalinaWOW'sdire estimate of labor costs (and I've had employees, I know what they cost) there are still plenty of expenses. The calibrator you cite, the 5080, would not even be good enough for better HH DMMs and you probably don't want to know the cost of even that basic unit plus MetCal 'Lite'. Then you have the building, insurance, yada yada. I think it would be tough to properly do even calibration checks on basic clamp meters for less than $40 or so.When it comes to something like a 8442A, 34401A or, at the upper limits of any conceivable 'low cost' cal, the 8846A, getting that done properly for $80 does seem a stretch. You can't do it in a 'few minutes' because the meter has to be acclimatized, warmed up for several hours, then each reading has to be given enough time to stabilize and so on. You need a very expensive high-performance multifunction calibrator, a matching power amplifier, a climate controlled room, etc etc.I've posted a graph of the warmup performance of an HP 34401A. How long would you like your cal lab to let it warm up before they run the procedures? The HP manual (p. 61-64) states that you need a 2 hour warmup, then a 5 minute thermal settling time after handling any connections. It also says that an automated calibration can be done in as little as 20 minutes. I'd imagine if the lab was organized and the tech was quick, they could do 2 per hour without any shortcuts--at the very best. And that's assuming they have a separate area to store them for the 72-hour acclimatization period and room on the bench to keep a stack of them warming up.

author: MadTux
author_rank: Frequent Contributor
timestamp: October 27, 2021, 08:52:59 pm
content: Stack of Fluke 5440B/AF that agree with each other, my totally own 10V, who cares about the NIST volt ;-) for DC standard and don't care about the rest, as long as not totally out of whack.I like/need high resolution DMMs mostly for resolution and convince/speed, like to measure voltage drop to find short circuits, resistance/voltage drop over high power rails, RDS in power Mosfets, measure linearity in ADCs....Doesn't matter a bit in these applications if the reference is off by a few ppm, I certainly won't feed any of my precious cash to Keysight suckers for that. I rather invest in a nice stack of Fluke 5440s ;-)

author: engineer_in_shorts
author_rank: Regular Contributor
timestamp: October 27, 2021, 09:04:10 pm
content: Quote from: LogicalDave on October 27, 2021, 03:29:45 pmTo be absolutely clear, what i am saying is that they did answer your question, but not in the way you expect. You are asking for good, cheap calibration service but have not defined what is good, or cheap. Take a little look at my list and define what you expect for what money.Quote from: LogicalDave on October 27, 2021, 03:29:45 pmI did not say incompetent. I said ignorant. What i mean is that calibration houses will perform there 'standard' service either ignorant that this might NOT be the service you want. Or in the absence of agreement cut procedures, calculations and traceability information where it wasn't requested.Here is an example:Calibration company A is one-man-band, picked up a calibrator on Ebay and then start advertising to do DMM calibration.Calibration company B is a team working to accredited standard (assume some national or international standard).You ask both for "Calibration and Adjust, Before and After Results. Use manufactures spec x for adjustment and either manufacturer verification or suggested points y"..... which one has the cheapest quote? Which one do you want to use?