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DMMCheck Plus Multimeter Reference(and other References) - Experiences..

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J-R:

--- Quote from: bdunham7 on July 07, 2023, 03:16:21 pm ---
--- Quote from: J-R on July 07, 2023, 08:19:40 am ---The "recalibration" of the DC voltage references from VoltageStandard.com is also the same.  All the references are tweaked to be as close to the desired value as possible before being sent back to the customer.

--- End quote ---

FWIW, Doug puts the as-received value on the certificate as well.

--- End quote ---
Yes, that is correct.  My statement was aimed at the point that "calibration" included an adjustment, unlike the strict definition from the VIM.

bdunham7:

--- Quote from: jchw4 on July 08, 2023, 01:51:32 am ---The attention to details is what built trust in this product. Now it is different. And I feel that the new owners are basically reusing old product reviews (see the happy Doug customers above).
I would not apply Doug's reputation to the new product. It's not what it used to be.

--- End quote ---

I don't want to pile on or suggest the DMMCheck+ is a bad value or inadequate for it's obvious intended purpose (which IMO doesn't include calibration or precise checking of meters past the 4.5 digit mark), but as for the detail part here's the link to the calibration certificate for their 3458A.

https://img1.wsimg.com/blobby/go/c544540f-524c-4b38-8d0c-cbfda88bf37a/downloads/2022%203458A%20Calibration.pdf?ver=1688384167316

J-R:
I have the original calibration cert from the DMMCheck Plus I purchased from Doug in 2018 and it only has the DCV listed to the 100uV, no further.  I would make the guess that by that point he decided the extra digits can provide a false impression to the customer, so he reduced the resolution to make it clear what can be reasonably trusted and what can't, especially in between calibrations.

The voltage references are designed to be adjusted, that is why there is a trimmer pot installed.  If you want something different, the metrology forum is full of folks running references and tracking standards for years straight, noting every tiny fluctuation.  The DMMCheck Plus is just not a good solution for this.  The passives aren't good enough and nothing is sealed so you can bump things with your fingers, probes, etc.  The PDVS2mini is the superior voltage reference, but you'll pay $400USD for it.

I am not seeing the point of an "as-received" for the passives!

If Doug thought the current owners of the DMMCheck Plus were no good, I'm confident he would not have their web site address plastered across the top of his own web site.  But I don't see the point in idolizing Doug either.  At the end of the day, Doug and Russ are selling hobby products.  If you want to be serious, then buy the serious stuff for tens of thousands of dollars and forget these "toys", relatively speaking.


When I received my L/C board I did notice the fact they were using the BK 891 and wasn't super-impressed.  But on the flip side DMMs and LCR meters are known to use different test methods so it's already going to be a tricky situation to get useful numbers.

100% agree with regard to the "all tested to within .05% of their value" on the L/C board description.  I think there was just a misunderstanding on their part.  Now that the issue is out in the open, I'm sure it will be addressed.

jchw4:

--- Quote from: J-R on July 08, 2023, 04:24:07 am ---I have the original calibration cert from the DMMCheck Plus I purchased from Doug in 2018 and it only has the DCV listed to the 100uV, no further.  I would make the guess that by that point he decided the extra digits can provide a false impression to the customer, so he reduced the resolution to make it clear what can be reasonably trusted and what can't, especially in between calibrations.

--- End quote ---

My original cert is from 2018 too. And it lists DCV to the 100uV too. But later recalibration certificates are more precise. So I would guess the opposite.


--- Quote ---But I don't see the point in idolizing Doug either.

--- End quote ---

Sure. I just demonstrated the two certificates that present attention to details.


--- Quote ---When I received my L/C board I did notice the fact they were using the BK 891 and wasn't super-impressed.  But on the flip side DMMs and LCR meters are known to use different test methods so it's already going to be a tricky situation to get useful numbers.

100% agree with regard to the "all tested to within .05% of their value" on the L/C board description.  I think there was just a misunderstanding on their part.  Now that the issue is out in the open, I'm sure it will be addressed.

--- End quote ---

To me the main issue is ignoring the tool specification that they base their claim on. I wonder what Martin's cerificate says about the meter though.


--- Quote ---Now that the issue is out in the open,

--- End quote ---

Are you serious?

J-R:
My first cert is from December 2018 (Doug), next cert is from March 2020 (Russ), neither have more than 100uV, nor do subsequent ones.

Not sure about your comment regarding my comment to the issue being out in the open.  You said you e-mailed them but they blew you off or whatever, but now you've pointed it out in the forums for everyone to see and we agree with you.  So we should expect them to have to deal with it at some point.

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