Author Topic: Easy way to test the calibration of a DMM (Fluke 45)?  (Read 227293 times)

0 Members and 2 Guests are viewing this topic.

Offline shapirus

  • Super Contributor
  • ***
  • Posts: 1721
  • Country: ua
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #25 on: March 30, 2024, 10:50:18 pm »
Is the DMM Check sufficiently accurate to calibrate a Fluke 45? No F**king way and you know it!
Yes of course it is, albeit only at a single voltage value (5V). It's accurate to ±0.007% (DCV output) and it's aged and then adjusted to exactly 5.0V as measured by a calibrated DMM with 0.0008% accuracy.

Quite obviously (on second thought -- maybe not so obviously; how much more accurate should the reference be compared to the DUT?) good enough for calibration of a 0.025% base DCV accuracy meter. But if we were to speak about adjustment (alignment), then it wouldn't be suitable, as you'd need more than one reference voltage, and probably more precise one than 0.007%.

I'm sick of your arrogant sideswipes about most of my posts as I try to be a good participant in this forum.
You see, the issue with your device is not the quality of the device itself -- it may very well be just fine and suitable for many applications -- but lack of information. To be better than the chinese sellers, you should at least specify what device was used to measure output voltage of each reference you sell (I believe you specified this in at least one post) and present a calibration certificate for that device. To be much better than the chinese sellers (and this will almost inevitably lead to a price increase), you need to measure and specify more data: long-term stability, temperature stability, noise level etc. Aging them will also be a plus.

The value of a voltage reference is not so much in its components and design, but in the reference to which its output voltage can be linked. This is an important aspect where the DMMCheck Plus is good and chinese references are poor.
« Last Edit: March 30, 2024, 10:53:26 pm by shapirus »
 

Online bdunham7

  • Super Contributor
  • ***
  • Posts: 8177
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #26 on: March 30, 2024, 11:54:15 pm »
assuming shipping is within the United States and available reasonably, which it should be through whatever freight forwarder service I use.  I can include the return label in the box....  I am curious about what equipment you have in your lab that you might test it with, so I can gloat about know to what standard it's been calibrated to.

I'm in California and I'd recommend UPS or USPS with good packing.  FedEx seems to be air-dropping stuff right from the plane from the looks of the packages.

As for equipment, not much to gloat about.  I use an assortment of things to get the stimuli needed and a Fluke 45 is at the beginning of the area where things get slightly challenging.  I've managed to calibrate 6.5-digit meters that later passed a 'real' calibration without adjustment, but in reality that's a stretch.  The ideal situation is to have a good enough uncertainty ratio (TUR) that you can adjust the meter to within the limits of its short term stability.  On your meter I would use:

Fluke 5100B multifunction calibrator, repaired and calibrated by me.  50ppm DCV basic accuracy, but no cert.

Fluke 8846A 6.5-digit DMM, calibrated by Fluke (cert attached below)

Fluke 5220A current amplifier, calibrated by Transcat (but more than a year ago) no cert available as I just have the sticker.

Fluke 8506A Thermal-RMS DMM, AC ranges informally calibrated by using a 5200A with an in-cal 3458A in parallel.  This meter has a 1-year basic spec of 200ppm on AC and it probably is within that, but it only needs to be somewhat close in order to be more than good enough.  In reality this is overkill, but I have it and need an excuse to use it.

A set of L&N NBS-style standard resistors from 1R to 1M.

Siglent SDG2042X signal generator

I use the calibrator as source for most ranges and then one of the DMMs in parallel (or series for current) to characterize the 5100B output.  IOW, I fine-tune the 5100B using the more accurate meter.  The Siglent AWG is for the 100kHz frequency test.  For resistance, the decade resistors in the calibrator are accurate enough for your DMM and I'd check them immediately beforehand with the 8846A.

I've also attached the calibration procedure for the service manual.  You can look at each test or adjustment point and see what the tolerances are and then compare them to the tolerances of the calibration equipment.  For example, the third peformance test point is 900.00mVDC and the tolerance is +/- 290µV.   If you look up and calculate the tolerance for the 8846A (1-year spec) at 900mV, it is +/- 30µV.   And so forth.  Those are good ratios, certainly good enough that I'm confident that your meter will be accurate, but probably no bragging rights.

« Last Edit: March 31, 2024, 01:13:07 am by bdunham7 »
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
The following users thanked this post: shabaz, Fried Chicken

Online bdunham7

  • Super Contributor
  • ***
  • Posts: 8177
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #27 on: March 31, 2024, 01:12:18 am »
But, you seem to have a bug up your ass about some of my devices that I offer on eBay.

I'm not claiming that you are dishonest or that your devices are overpriced, but rather that you don't seem to fully understand where they would be appropriate and where they aren't helpful.  You're starting with a 0.05% device and trimming it to some unstated uncertainty and not further characterizing it or indicating how stable it might be over time.  The descriptions and claims just aren't very precise.  Your listing says 10.000V in one spot and 10.0000V in another.  The maximal implied precision of first might be just adequate for a sanity check on the Fluke 45 if it were perfectly stable.  The second claim of 10.0000V is preposterous if you are implying that level of accuracy with that device.  If you trim it to that number using a particular meter or method, you should specify those particulars and give some idea of the actual uncertainty.  Otherwise your specs are misleading, even if you don't intend them to be.

The problem in the context of the OPs issue is that when you have a particular device that you have doubts about, checking it with another device of similar uncertainty and no independent verification just leads to more uncertainty--if they disagree you just have two things that you're not sure of.  In this case, your device is probably good for spot-checking the Hioki, but not adequate for the Fluke, IMO. 

That's about the whole issue I have in this context.  I realize it is a very inexpensive device and it would be silly to hold it to the same standard as a VREF10 or even a DMMCheck, but that also implies that its applicability is more limited.  If you want a better idea of how your device performs and aren't ready to start logging temperature vs voltage and so forth, send me one (I'll send it back) and I'll give you a chart.  Maybe it will do better than anyone thinks.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
The following users thanked this post: shabaz, edavid, KungFuJosh

Offline Fried ChickenTopic starter

  • Regular Contributor
  • *
  • Posts: 160
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #28 on: March 31, 2024, 01:25:27 am »
To be honest, if I have two units with agree with a calibrator, and a fluke that doesn't, that definitely points to the fluke being problematic.  It would serve to see if I need calibration... assuming my other voltmeter devices are accurate enough.
Google is spyware
 

Offline shabaz

  • Frequent Contributor
  • **
  • Posts: 574
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #29 on: March 31, 2024, 01:58:39 am »
Very kind, generous offer to unofficially calibrate.

Just to put some sample numbers out there, for the AD584 cheap references (sub-$10 on AliExpress), by chance, a friend and I have both measured these devices (one sample each, purchased separately at different times) using two separate DMM6500 meters.

The label on it, claiming to have been measured with HP 3458A, is, of course, completely untrue (unless it's a completely broken HP 3458A!). They probably used (at best) a 6.5-digit meter, perhaps not even calibrated, and even then, they have typos in the printed values (the label on mine had a noticeably erroneous extra digit for one of the values!).

However, on the plus side, it turned out that the nominal voltage values (2.5V, 5V, 7.5V, 10V, were actually close enough to the real values, that it's very likely that one would be able to tell if that 0.02V discrepancy you're seeing between multimeters is a problem with one meter or the other, or both. In other words, a 20 mV discrepancy should be identifiable if it's present at one of those four voltages (2.5/5/7.5/10V).

Beyond three digits, you can't really rely on it with no measurement with a known calibrated instrument. Nevertheless, for the price (under $10) with no further measurement, it is a crude finger-in-the-air type of check if absolutely nothing better is available.

Just in case this helps, this was my sample result:
Label              My measurement
-------            ---------------
2.49954            2.49963
4.999501           4.99964
7.39875            7.49899
9.99823            9.99854


 
The following users thanked this post: edavid

Offline Fried ChickenTopic starter

  • Regular Contributor
  • *
  • Posts: 160
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #30 on: March 31, 2024, 03:02:43 am »
Here's a guy with a Fluke 8842a and a cheap chinese voltage standard:

« Last Edit: March 31, 2024, 03:05:31 am by Fried Chicken »
Google is spyware
 

Offline Fried ChickenTopic starter

  • Regular Contributor
  • *
  • Posts: 160
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #31 on: March 31, 2024, 03:40:49 am »
assuming shipping is within the United States and available reasonably, which it should be through whatever freight forwarder service I use.  I can include the return label in the box....  I am curious about what equipment you have in your lab that you might test it with, so I can gloat about know to what standard it's been calibrated to.

I'm in California and I'd recommend UPS or USPS with good packing.  FedEx seems to be air-dropping stuff right from the plane from the looks of the packages.

As for equipment, not much to gloat about.  I use an assortment of things to get the stimuli needed and a Fluke 45 is at the beginning of the area where things get slightly challenging.  I've managed to calibrate 6.5-digit meters that later passed a 'real' calibration without adjustment, but in reality that's a stretch.  The ideal situation is to have a good enough uncertainty ratio (TUR) that you can adjust the meter to within the limits of its short term stability.  On your meter I would use:

Fluke 5100B multifunction calibrator, repaired and calibrated by me.  50ppm DCV basic accuracy, but no cert.

Fluke 8846A 6.5-digit DMM, calibrated by Fluke (cert attached below)

Fluke 5220A current amplifier, calibrated by Transcat (but more than a year ago) no cert available as I just have the sticker.

Fluke 8506A Thermal-RMS DMM, AC ranges informally calibrated by using a 5200A with an in-cal 3458A in parallel.  This meter has a 1-year basic spec of 200ppm on AC and it probably is within that, but it only needs to be somewhat close in order to be more than good enough.  In reality this is overkill, but I have it and need an excuse to use it.

A set of L&N NBS-style standard resistors from 1R to 1M.

Siglent SDG2042X signal generator

I use the calibrator as source for most ranges and then one of the DMMs in parallel (or series for current) to characterize the 5100B output.  IOW, I fine-tune the 5100B using the more accurate meter.  The Siglent AWG is for the 100kHz frequency test.  For resistance, the decade resistors in the calibrator are accurate enough for your DMM and I'd check them immediately beforehand with the 8846A.

I've also attached the calibration procedure for the service manual.  You can look at each test or adjustment point and see what the tolerances are and then compare them to the tolerances of the calibration equipment.  For example, the third peformance test point is 900.00mVDC and the tolerance is +/- 290µV.   If you look up and calculate the tolerance for the 8846A (1-year spec) at 900mV, it is +/- 30µV.   And so forth.  Those are good ratios, certainly good enough that I'm confident that your meter will be accurate, but probably no bragging rights.

I'll send you a PM tomorrow.  I think I'll take you up on this offer!  Would definitely be thrilled to see the process documented!  Happy Easter!
Google is spyware
 

Online J-R

  • Super Contributor
  • ***
  • Posts: 1319
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #32 on: March 31, 2024, 04:58:19 am »
The problem with the Chinese eBay references is that you can't really apply any trust to them.  Sure, one person might get one that is OK, but the next may not be.  Or you could have blatant fakes, as has been shown already with the copied calibration labels.

Also, a random video of someone showing how close their DMM is to a reference can be suspect because it's possible they used it to calibrate the DMM earlier and are hiding that fact.  You just can't be sure.

Compare this to the references from Doug and Russ where they have been active here for a while and their products are well regarded.  Although really the King of hobby DCV references is the PDVS2mini in my opinion.  Really hoping it comes back soon so I can get a second one.  I also plan to get a second 10V reference from Doug because his updated model has some great improvements.  I have quite a bit of equipment that can leverage a 10V calibration point.

But the bdunham7/Majorassburn conversation has got me thinking that what the hobby really could use right now is a budget-friendly calibration service.  There is a gap between getting a professional calibration and trying to do a DIY calibration with references on hand.  I don't see the USA Cal Club being a solution since it's more in the metrology space.
 
The following users thanked this post: Shock

Offline alm

  • Super Contributor
  • ***
  • Posts: 2903
  • Country: 00
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #33 on: March 31, 2024, 10:14:34 am »
But the bdunham7/Majorassburn conversation has got me thinking that what the hobby really could use right now is a budget-friendly calibration service.  There is a gap between getting a professional calibration and trying to do a DIY calibration with references on hand.  I don't see the USA Cal Club being a solution since it's more in the metrology space.
The problem I see that this is capital and time intensive. I would imagine buying all the equipment that bdunham7 listed now might cost you maybe $5k, if not more. And calibration of even just the 8846A (which will give you uncertainties that are plenty good for 4.5 digit like the Fluke 45 but not for 6.5 digit like HP 34401A) will be a few hundred USD per year. This figure can easily get into thousands per year if you need to have multiple pieces of equipment calibrated. And also, correctly if I'm wrong, I'm guessing that bdunham7 has not set up an automated calibration for the Fluke 45, so calibration, and particularly adjustment, might easily take hours in changing connections and settings, waiting for things to stabilize, etc. Expecting someone to do this regularly for a low fee is a lot to ask. Would you like to be spending every Saturday doing calibrations for say $100 per day?

Even the production of products like the Geller Labs voltage references, DMMCheck Plus and PVDS2Mini does not seem very sustainable given how often the stop production or change hands.
« Last Edit: March 31, 2024, 10:16:12 am by alm »
 

Offline robert.rozee

  • Frequent Contributor
  • **
  • Posts: 326
  • Country: nz
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #34 on: March 31, 2024, 01:28:15 pm »
one could probably go a long way with just a DIY hamon divider http://conradhoffman.com/HamonResistor.html and the raw output from a simple LM399 reference. first send the LM399 off to someone with a good 6.5 digit meter to measure it, then use the LM399 and hamon divider to calibrate low DC voltage ranges at 7v, 700mv, 70mv. if desired, 70v and 700v points can be calibrated using the same gear plus an adjustable HV supply and a little creativity.

i dare say resistance ranges can similarly be calibrated using similar methods to scale up/down and just a single precision resistor that has been measured with a good 6.5 digit meter.

sending off a small PCB (containing LM399 + CC source) and a single resistor through the post should be relatively cheap, and the time expended by the recipient making measurements relatively short.


cheers,
rob   :-)
« Last Edit: March 31, 2024, 01:31:45 pm by robert.rozee »
 

Offline Majorassburn

  • Regular Contributor
  • *
  • !
  • Posts: 95
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #35 on: March 31, 2024, 03:39:25 pm »
But, you seem to have a bug up your ass about some of my devices that I offer on eBay.
snip -
You're starting with a 0.05% device and trimming it to some unstated uncertainty and not further characterizing it or indicating how stable it might be over time.  The descriptions and claims just aren't very precise.  Your listing says 10.000V in one spot and 10.0000V in another.  The maximal implied precision of first might be just adequate for a sanity check on the Fluke 45 if it were perfectly stable.  The second claim of 10.0000V is preposterous if you are implying that level of accuracy with that device.  If you trim it to that number using a particular meter or method, you should specify those particulars and give some idea of the actual uncertainty.  Otherwise your specs are misleading, even if you don't intend them to be.
snip -
If you want a better idea of how your device performs and aren't ready to start logging temperature vs voltage and so forth, send me one (I'll send it back) and I'll give you a chart.  Maybe it will do better than anyone thinks.

OK, Thank You for that advice. Let me respond:
1) For your first comment about the 10Vref and trimming, the "10.0000" you refer to was a typo on an early eBay ad where that ad had both 10.000 and 10.0000 in the specs. That was corrected several ads ago to read "10.000". So, you are correct about the typo conflict.

2) I built a typical 10Vref, like my eBay ads, and that device is trimmed to an actual value of 10.0000 with a new DMM6500 that I have occasional access to. That device is then "compared" to my new Sig SDM3065 and the eBay devices are then trimmed to 10.000 based upon the Sig. Crude but very effective, so far. Read the eBay feedback from those who have bought them and tested them for accuracy.

I'm not saying that's the best way to operate but at this point, it keeps costs low and makes the low-end buyer happier than spending $250+ for a DMM Check, etc. if they are even in stock. Not knocking DMMChecks but whenever I wanted to buy one in the recent past they were never available.

3)  As for the SPECS issue, I agree with you that my devices are very short on "specs" but my devices are also very short on CLAIMED specs, like so many phony Chinese devices. I don't want a volt-nut to buy one of my devices and then scream that it missed listed specs by .0005ppm after it was lit up in an oven for 6 months.  :-DD 

The specs for my devices are the data sheet from Linear Tech (Analog Devices) for the AD1236-10 voltage ref IC that my device is based upon. I include the data sheet with every sale so that each buyer can decide how much faith he/she/it  :scared: should place on the long-term accuracy/usability of the device. Of course, I could list the fact that in the trim circuit, I use all selected 1% 15-25ppm metal film resistors but the Bourns trim pot blows that up into another spec argument, right? Or, I could hand trim each device with selected low-ppm resistors and eliminate the easy-adjust trimpot. Hmmmm.

Now, you may begin to appreciate why I purposely avoid "over-specifying" my devices. For those serious buyers, like yourself and myself, who eat & sleep specs before we buy stuff, my devices amount to no more than curiosity or novelty. But, to anyone who wants to simply and quickly and affordably verify the DC or AC or Resistance accuracy of their DMM, I honestly believe that my devices fulfil that kind of need.

Do I compare my devices to a DMMCheck or other superior engineered devices? NO, not at all. I'm not in that league. I'm making hobby-grade stuff for amateurs, homeowners, DIYers, students, hobbyists and guys like us that now have something new to talk about and slice and dice in forums.  :-DD :-DD

Here's what I would like to do:  I'd like to start a thread where I list reasonably concise specs for each of my hand-made devices and encourage fellow forum participants like you to evaluate, correct, criticize and comment on which would help me arrive at some happy medium in my ads.

Where in this forum should I do that?  What category?  Test Equipment? Metrology/ (I love that category because there are no sane individuals there at all - I feel at home there just browsing!)  :-DD

Let me know what you suggest and I'll do it.
Thanks and Happy Easter, all.
 

Online bdunham7

  • Super Contributor
  • ***
  • Posts: 8177
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #36 on: March 31, 2024, 04:05:28 pm »
Where in this forum should I do that?  What category?  Test Equipment? Metrology/ (I love that category because there are no sane individuals there at all - I feel at home there just browsing!)  :-DD

Just reuse this post with a little background added and post it in the metrology forum.  I'm sure you'll get comments and some might actually be helpful.  Include everything  you've written here as I'd like to respond without cluttering up this thread any more.
« Last Edit: March 31, 2024, 04:08:17 pm by bdunham7 »
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline shapirus

  • Super Contributor
  • ***
  • Posts: 1721
  • Country: ua
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #37 on: March 31, 2024, 04:12:01 pm »
...and I wish you good luck (without irony), because having yet another option for an inexpensive voltage reference is a good thing, especially if it comes with an honest specification which lists its parameters and allows to clearly understand the limits of its applicability.
 

Online Fungus

  • Super Contributor
  • ***
  • Posts: 17526
  • Country: 00
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #38 on: March 31, 2024, 04:21:05 pm »
Just to put some sample numbers out there, for the AD584 cheap references (sub-$10 on AliExpress), by chance, a friend and I have both measured these devices (one sample each, purchased separately at different times) using two separate DMM6500 meters.

Those cheapo references on Aliexpress are a mixed bag.

Some are genuinely measured, some aren't. Several people on EEVBLOG have ordered one and received the exact same "calibration"sheet.

https://www.eevblog.com/forum/metrology/are-cheap-ad584-units-worth-it/msg920924/#msg920924

 
The following users thanked this post: shabaz

Offline shabaz

  • Frequent Contributor
  • **
  • Posts: 574
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #39 on: March 31, 2024, 04:47:28 pm »
Hehe yeah zero trust there with that sticker : ) I had the access to be able to test it against a known DMM, but most people purchasing that won't.

I think it's fine as a quick check for those seeing large discrepancies (tens of mV) to try to narrow down which of the instruments is most in need of a health-check, and definitely expectations need to be low and not trust the device (at least not without confirming) much further than 3-digits (i.e. 2 decimal places) or so!
« Last Edit: March 31, 2024, 05:08:51 pm by shabaz »
 

Offline alm

  • Super Contributor
  • ***
  • Posts: 2903
  • Country: 00
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #40 on: March 31, 2024, 05:10:34 pm »
one could probably go a long way with just a DIY hamon divider http://conradhoffman.com/HamonResistor.html and the raw output from a simple LM399 reference. first send the LM399 off to someone with a good 6.5 digit meter to measure it, then use the LM399 and hamon divider to calibrate low DC voltage ranges at 7v, 700mv, 70mv. if desired, 70v and 700v points can be calibrated using the same gear plus an adjustable HV supply and a little creativity.

i dare say resistance ranges can similarly be calibrated using similar methods to scale up/down and just a single precision resistor that has been measured with a good 6.5 digit meter.

sending off a small PCB (containing LM399 + CC source) and a single resistor through the post should be relatively cheap, and the time expended by the recipient making measurements relatively short.
Yes, that could certainly work. That's how metrology labs did it before instruments like the HP 3458A and Fluke 5700A automated it. They would have 1.018V standard cells and 1 Ohm standard resistors and derive everything from those. There's no reason why you couldn't do the same artifact calibration by hand if you had ways of scaling voltage and resistance (note that the ratio of the voltage across two resistors in series is proportional to the resistance ratio). ACV and ACI is more tricky, though maybe there you could use a trick like ratio transformers. Solutions like the cal club could be useful for importing the cardinal points like 10V and 10k that you can scale to any other value.

Online J-R

  • Super Contributor
  • ***
  • Posts: 1319
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #41 on: April 01, 2024, 02:04:53 am »
Of course the calibration service I'm proposing is not going to be making the owner rich, and I'm confident Doug/Russ/Ian are not doing what they do for the money.  As long as you're close to breaking even then you are doing fine because you're investing in yourself and probably having some fun at the same time.

And I would suggest this basic service would be just a verification of the calibration points listed in the service manual.  There is no need to get carried away with the more mundane metrology aspects.  If you need that then go with an accredited lab.

$5k or even $10k plus hundreds per year for an external cal is really nothing for a dedicated hobbyist.  It just comes down to what you choose to spend your money on.
 

Offline BILLPOD

  • Frequent Contributor
  • **
  • Posts: 386
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #42 on: April 01, 2024, 05:52:21 pm »

Shamelessly self-promoting my products..... :-DMM

https://www.ebay.com/itm/285781907875

Plus, I have precision resistors, etc....
[/quote]

Good Morning Majorassburn, when I went to E-Bay to look at your module, it indicates it is sold and no others are available??? :wtf:
 

Offline Majorassburn

  • Regular Contributor
  • *
  • !
  • Posts: 95
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #43 on: April 01, 2024, 07:33:46 pm »
Removed listings:
Deleted

BTW, you can always do an advanced search on eBay for SQWARREL to see my listings.
« Last Edit: April 02, 2024, 02:06:16 am by Majorassburn »
 

Offline EEVblog

  • Administrator
  • *****
  • Posts: 39026
  • Country: au
    • EEVblog
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #44 on: April 01, 2024, 10:18:50 pm »
Here are a few of today's listings:

Please do not spam these in existing threads, use the Buy/Sell section.
 
The following users thanked this post: Shock, Martin72

Offline Majorassburn

  • Regular Contributor
  • *
  • !
  • Posts: 95
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #45 on: April 02, 2024, 02:04:47 am »
Thank you.  I should have known better. Sorry.
 

Offline CalibrationGuy

  • Supporter
  • ****
  • Posts: 103
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #46 on: April 02, 2024, 06:05:04 pm »
DISCLAIMER: I don't know Doug, just bought one of his 10V references from voltagestandard.com. Base cost is $140. I dusted the unit off and measured it. Attached is the picture.

Just to put things in perspective for those perusing threads like this one. First of all, I paid over $2,700.00 to calibrate that meter. The cable attached to the meter and the reference box costs more than the reference.

People measuring the Chinese/Asian boxes do NOT (most likely) have the capabilities that my lab has, so PLEASE take their observations with a grain of salt. They are well meaning, but measurement procedures/traceability DO matter. As a hobby, it is great to share experiences, but observations may be misleading without intending to be misleading.

Final thoughts, I'm impressed with Doug's device, I know it's out of the OP's price range, but I just thought I would show you how mine held up as measured with a calibrated, certified, accurate 3458A.

TomG.
 
The following users thanked this post: Kosmic, KungFuJosh, Vertamps

Offline shabaz

  • Frequent Contributor
  • **
  • Posts: 574
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #47 on: April 02, 2024, 07:44:10 pm »
It would be a complete waste of time and money spending $140 plus £2700, when the OP could simply send his meter in for a calibration check for under $100.

You'd need to be calibrating a _lot_ of equipment per year before that made any sense.

The OP observed a 20 mV discrepancy between meters. That doesn't require a 10.0000V standard to determine which instrument is faulty.

The OP could simply buy several calibrated meters, new, each year, and it would be cheaper than that.
 

Online KungFuJosh

  • Super Contributor
  • ***
  • Posts: 3166
  • Country: us
  • TEAS is real.
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #48 on: April 02, 2024, 07:48:42 pm »
It would be a complete waste of time and money spending $140 plus £2700, when the OP could simply send his meter in for a calibration check for under $100.

That wasn't his point at all. His point was that the reference for $140 is surprisingly accurate.

Also, where can he get his DMM calibrated for under $100? (besides bdunham7 that offered to do it for free)
"Right now I’m having amnesia and déjà vu at the same time. I think I’ve forgotten this before." - Steven Wright
 
The following users thanked this post: CalibrationGuy

Offline CalibrationGuy

  • Supporter
  • ****
  • Posts: 103
  • Country: us
Re: Easy way to test the calibration of a DMM (Fluke 45)?
« Reply #49 on: April 02, 2024, 07:50:01 pm »
I think you completely missed the point of my reply. As I said, it's out of range of the original poster's budget but I was just showing a contrast to the expense required to definitively get precision data.

TomG.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf