Siglent Bench DMMs SDM3065X, SDM3055 and SDM3045X

[slavoy]

Info for adjustment wasn't available until recently, first introduced in FW a few years back but an unwieldy process compared to the simple adjustment process that is available to any any user today.

That's what I'm also wondering about. The user calibration was introduced on April 25. Although I see on the website that esz AG have been collaborating with Siglent for several years on this matter, so perhaps they did perform factory adjustment.
In any case, during the calibration, the parameters were within the specified range. So, for me, it's strange that it "suddenly" went beyond the specification (slightly for that manner), and even in the opposite direction.
The warming up curve also looks different than what I have seen in another topic. The voltage value was increasing with time instead of decreasing. Maybe it depends on specific voltage reference?

[tautech]

Info for adjustment wasn't available until recently, first introduced in FW a few years back but an unwieldy process compared to the simple adjustment process that is available to any any user today.

That's what I'm also wondering about. The user calibration was introduced on April 25. Although I see on the website that esz AG have been collaborating with Siglent for several years on this matter, so perhaps they did perform factory adjustment.
In any case, during the calibration, the parameters were within the specified range. So, for me, it's strange that it "suddenly" went beyond the specification (slightly for that manner), and even in the opposite direction.
The warming up curve also looks different than what I have seen in another topic. The voltage value was increasing with time instead of decreasing. Maybe it depends on specific voltage reference?

skander36 Cal report doesn't show they did but maybe I missed it. 

[mawyatt]

Let things run for a couple hours, and then let each of the readings stabilize for at least 20 minutes using the same cable with our LTZ1000 stabilized 10V reference which has been running 24/7 for 2 years, each reading at least 1000 averages with 10 PLC, SD under 6uv in all cases, except 34401A these were slow 6 digit setting.

Deviation from ideal 10 volts, at 26C 42% RH with AC cycling On/Off.

New KS34465A reading +2ppm
1 1/2 year old KS34465A +1ppm
2 year old KS34465A +4ppm
1 1/2 year old DMM6500 +6ppm
HP34401A + 3ppm
AG34401A +2ppm
2 year old SDM3065X +9ppm

Good results for all the DMMs relative to each other IMO.

It's nice to see Siglent has introduced a self cal/adjustment routine, and Defpom has done a nice video on such. So the question for us is do we send this in, or just "wing it" here with the latest KS34465A as the "Reference" since we don't normally use the SDM3065X for any verified customer measurements. We''ll probably let the SDM3065X LM399 collect a few more hours before attempting any type of adjustment, or sending in.

Best,

[tautech]

Good info Mike and nice to see a ppm comparison. 

Defpom and I worked on the first version of SDM adjustment when still in beta development and it remained unchanged on release which was a shame as it was a PITA to complete needing spreadsheet values adjusting in a nonintuitive way before uploading into the SDM.
The latest adjustment procedure is where it should've been right from the start.

[Martin72]

It's nice to see Siglent has introduced a self cal/adjustment routine

Yepp, nice for the cal-lab, makes it easier for them.
Or for the one or two hobbyists out there who have a suitable reference for a calibration of a 6.5 digit meter.
My DMMChecker is already out there.

[TheDefpom]

And its rediculous into how many menus you have to go to to take a screenshot.

Yes a few instruments from that era of design are a pain to grab USB screenshots with.....
Maybe it's time for a new feature request to much improve that.

I'll give this some thought and forward a suggestion......something like pressing 2 specific buttons together saves screenshot to USB ?

Better ideas ?

Done.
Suggested a long press of Run/Stop for capturing a USB screenshot.

Had a SDM out and that just seemed to make the most sense.

I think pressing the OK button is a good option, if there are no half done setting changes it should do the job.

[TheDefpom]

And now I just became dissatisfied with my SDM3065X    I bought it new from a local distributor, and it turned out the factory calibration certificate was from 2019... I plan to send it for calibration soon and will let you know how it turns out (unfortunately, I don't have a stable reference source to check the drift.)

Are you sure it was 2019... they use that date as an EXAMPLE of checking the intervals on the cal verification sheet.

[Performa01]

- The drift itself does not cause the meter to go outside its own tolerance.

This depends on the initial adjustment...

- The drift will decrease over time, i.e. when the LM399 has aged "enough" ?

Of course. The drift will be worst during the first year, where you should be prepared for up to 20 ppm. It gets increasingly (and significantly) better in the following years.

The best strategy would be a single adjustment after two years and you'll never have to adjust the instrument again. The LM399 has excellent long term stability, once it is sufficiently aged. It's better to have a cost effective meter with an unaged high quality reference such as the LM399 than having an instrument with some well aged lower grade reference.

- You should have a high precision voltage reference in your house if you don't want to bring the meter for calibration every year.

Like 99% of all 5.5, 6.5 and 7.5 digit meters, the SDM3065X requires separate adjustment for every single range. Consequently, a simple reference wouldn't cut it anyway - you need a multifunction calibrator. There you could spend some real money getting one - not to mention the maintenance effort and cost to keep it in calibration...

[slavoy]

And now I just became dissatisfied with my SDM3065X    I bought it new from a local distributor, and it turned out the factory calibration certificate was from 2019... I plan to send it for calibration soon and will let you know how it turns out (unfortunately, I don't have a stable reference source to check the drift.)

Are you sure it was 2019... they use that date as an EXAMPLE of checking the intervals on the cal verification sheet.

I'm such an idiot. I only looked briefly at one side and throw it to the box. The calibration was done in 2021    Thanks for making me double-check 

[Martin72]

Is it a complete protocol ?

[slavoy]

It's only a certificate with date and used calibrator (FLUKE 5522A), one page. No values whatsoever.

[Martin72]

That is simply pathetic.
We're not talking about a $10 meter from the hardware store, but a precision meter with 6.5 digits....Incredible.

[tautech]

It's only a certificate with date and used calibrator (FLUKE 5522A), one page. No values whatsoever.

At Siglent EU ?

I suspect they run the same secret calibration/adjustment script as at HQ that doesn't give a detailed printout.....it's all about the script.....

[slavoy]

At Siglent EU ?

It's a factory certificate.

[tautech]

At Siglent EU ?

It's a factory certificate.

No doubt based on Performance verification spec on P12-16 in the service manual:
https://int.siglent.com/u_file/document/SDM3065X_ServiceManual_SM06036-E02F.pdf

[skander36]

and that will be a good ideea for Martin to think about.

Absolutely and thanks again for that.
I was not aware of that at all.
Nevertheless, I am waiting for an offer from Batronix.
And take the following for me:
- The drift comes from the unaged LM399
- The drift itself does not cause the meter to go outside its own tolerance.
- The drift will decrease over time, i.e. when the LM399 has aged "enough" ?
- You should have a high precision voltage reference in your house if you don't want to bring the meter for calibration every year.

Whereas the latter may become obsolete, because:
Such a reference will cost money, not a little money if you want to calibrate a 6.5 digit meter with it.
The reference must then of course be calibrated regularly, which also costs money.
From this point of view, you could calculate how often you can send a meter for calibration, until you have the money out, which you would spend for your own reference and regular calibration.

This is why I suggest to think to DMM6500. They have a two year specification along with many more advantages over SDM3065. It simply worth its money.

[alm]

- The drift itself does not cause the meter to go outside its own tolerance.

I'm not sure if this has been established yet. You would need data on a fair number of units.

- The drift will decrease over time, i.e. when the LM399 has aged "enough" ?

Probably, but since Siglent appears to not be doing any binning for drift or noise, you are to some degree depending on getting lucky with a good LM399 sample.

From this point of view, you could calculate how often you can send a meter for calibration, until you have the money out, which you would spend for your own reference and regular calibration.

I would also take into account how these expenses and effort compare to buying a meter from HPAK/Keithley.

[mawyatt]

One must consider the expected use of the DMM as well, and evaluate the relative cost of achieving the desired use/results.

The SDM3065X is a fine DMM, certainly capable for general purpose use, and a good value. However, it is not a replacement for the mentioned more expensive KS and Keithley DMMs, which have a long established pedigree and demonstrated long term stability. The aged, selected LM399s are likely only one of the reasons for the higher expense, some of the more critical components are probably selected or specified as well, and the final instruments may go thru a more rigorous test and burn-in before delivery.

If one must make precision, verifiable, repeatable measurements, then one must use an instrument capable of such, and in case of customer requirements be able to demonstrate measurements on demand. This is why calibration certification is important, it gives the user and customer confidence in the measurements at hand.

The metrology folks would have issue, and rightly so, with our approach of using 5 DMMs to verify a measurement, rather than the proper certification trail for each instrument (one instrument had such). Our customer verified our measurements with their instruments at a different location & time without our participation, so they accepted our approach.

Anyway, aging the SDM3065X LM399 is certainly an acceptable approach (we are doing so now), and ok for general purpose use, but not a substitute for the higher precision mentioned DMMs, especially in case of verifiable, repeatable precision measurements.

Best,

[Martin72]

Then I will have to live with the "little blemishes"...

[skander36]

The truth is that in 2021 when I have aquired DMM 6500 it was 1018 E on Welectron.
Now I see that it is 1559 E !!! 50% in two years ... not speaking of KS...
In this time Siglent has almost the same price ...

[Domitronic]

The truth is that in 2021 when I have aquired DMM 6500 it was 1018 E on Welectron.
No I see that it is 1559 E !!! 50% in two years ... not speaking of KS...
In this time Siglent has almost the same price ...

Another drawback of the DMM6500 next to the increased price is that it can't measure the resistance of inductors properly. Not sure if they fixed it in later versions but ours at work can not do that. This is related to a hardware bug. Shouldn't happen at a 6.5 digit meter from an A brand for that price. But otherwise a nice DMM.

[skander36]

The truth is that in 2021 when I have aquired DMM 6500 it was 1018 E on Welectron.
No I see that it is 1559 E !!! 50% in two years ... not speaking of KS...
In this time Siglent has almost the same price ...

Another drawback of the DMM6500 next to the increased price is that it can't measure the resistance of inductors properly. Not sure if they fixed it in later versions but ours at work can not do that. This is related to a hardware bug. Shouldn't happen at a 6.5 digit meter from an A brand for that price. But otherwise a nice DMM.

It depends. Is not a normal function. I have measured now 120uH inductor and it show 0,2 ohm on DMM6500, 0,24 ohm on 34465 and 0,1ohm on SDM 3065X, while on DE-5000 show 0,21ohm as ESR parameter and DCR.

[Martin72]

No I see that it is 1559 E !!! 50% in two years ... not speaking of KS...
In this time Siglent has almost the same price ...

And I would pay under 800 incl. VAT for the siglent, so I pulled my trigger now on it.
One day, when I need more, the cards will be reshuffled.
I will post my experiences with the SDM3065X here from time to time.
Thanks to all who opened my eyes (not as easy as I thought), especially skander36.

[mawyatt]

The truth is that in 2021 when I have aquired DMM 6500 it was 1018 E on Welectron.
No I see that it is 1559 E !!! 50% in two years ... not speaking of KS...
In this time Siglent has almost the same price ...

Another drawback of the DMM6500 next to the increased price is that it can't measure the resistance of inductors properly. Not sure if they fixed it in later versions but ours at work can not do that. This is related to a hardware bug. Shouldn't happen at a 6.5 digit meter from an A brand for that price. But otherwise a nice DMM.

Wasn't aware of this issue. Our DMM6500 is a couple years old and has firmware version 1.7.7b and serial number 0451XXXX. Just measured a few inductors laying around without issue, so maybe this is related to the older hardware.

Really like the 10 ohm range, one reason we acquired this DMM, the KS34465A has 100 ohm range, SDM3065X has 200 ohm range, and 34401A is 1000 ohm range. This supplements the low 0.1 ohm and 1 ohm ranges of our bench LCR Meters.

Best,

[Kleinstein]

Quite a few meters have problems with large inductors. The 120 µH may not yet cause problems. The typical tricky part is measuring the resistance of a tranformer primary - this can get to the 10s of H range. The usual countermeasure is to short a seconday for this test.
It can be different inductor that different meter can have problems with and it may depend on the range and auto-ranging / offset compensation that can be an additional difficulty.