DMM Volts/Ohm Calibration Club - anyone interested?

[Alex Nikitin]

Tempco of 3458A can be limited pretty much to one of 40K resistor, if you add code into logging script to run ACAL DCV&OHM on each 1C of TEMP? change. That to be expected <1ppm/K.
What is printed is one thing, but it's interesting to see actual curve and it's slopes. It may or may not match the "typical" specs.

The printed Alpha and Beta values are measured for each unit so aren't "typical". I was running the HP3458A and the Fluke for two hours, the lab temperature (and the internal temperature of the meter) went up by one degree C, the measured value decrised by about 0.7ppm. However when I've performed another ACAL OHM, the vealue went back to the measured just after the first ACAL earlier, within 0.1ppm. To get a reliable slope measurement in this situation I'll need a controlled temperature chamber (and a stable lab temperature).

Cheers

Alex

[enut11]

We need to get back on topic. Can this device be used as a roving standard for a forum calibration club?

[Alex Nikitin]

We need to get back on topic. Can this device be used as a roving standard for a forum calibration club?

No. But it can be used to calibrate a rowing standard - or several. Right now I have several wire-wound resistors that can be used as travelling standards. And I plan to make a travelling 1010 standard (10V/10K) soon.

Cheers

Alex

[CalMachine]

I would love to join this club!! 



I work and a 17025 accredited 3rd party cal lab and have pretty damn cheap electronic cal prices if anyone wants to send anything i to get calibrated.  Our price for 7.5 digit multimeters and lower is $85 (yes for an accredited cal).

I can list a lot of our standards we use and can even provide a copy of our scope if you'd like.

[enut11]

Hi calmachine. Please tell us more. Where do you live/work?

[CalMachine]

Hi calmachine. Please tell us more. Where do you live/work?

Hey Enut11!!  My name is Ryan and I work at ENI Labs in Ft. Wayne, Indiana!  Fully 17025 Accredited lab for most everything in the Metrology world!  I, myself, specialize in electronic calibrations and specifically 8.5 digit/dc/low freq.  Ever since I joined the Lab I've been pushing for better quality practices, procedures, and we are really have been investing a lot in upgrading our standards.   

If anyone has any questions, please feel free to ask

www.ENILabs.com
https://www.a2la.org/scopepdf/2147-01.pdf

[retrolefty]

Hi calmachine. Please tell us more. Where do you live/work?

Hey Enut11!!  My name is Ryan and I work at ENI Labs in Ft. Wayne, Indiana!  Fully 17025 Accredited lab for most everything in the Metrology world!  I, myself, specialize in electronic calibrations and specifically 8.5 digit/dc/low freq.  Ever since I joined the Lab I've been pushing for better quality practices, procedures, and we are really have been investing a lot in upgrading our standards.   

If anyone has any questions, please feel free to ask


www.ENILabs.com
https://www.a2la.org/scopepdf/2147-01.pdf

 What does it feel like to be paid to be a volt-nut? 

[CalMachine]

Hi calmachine. Please tell us more. Where do you live/work?

Hey Enut11!!  My name is Ryan and I work at ENI Labs in Ft. Wayne, Indiana!  Fully 17025 Accredited lab for most everything in the Metrology world!  I, myself, specialize in electronic calibrations and specifically 8.5 digit/dc/low freq.  Ever since I joined the Lab I've been pushing for better quality practices, procedures, and we are really have been investing a lot in upgrading our standards.   

If anyone has any questions, please feel free to ask


www.ENILabs.com
https://www.a2la.org/scopepdf/2147-01.pdf

 What does it feel like to be paid to be a volt-nut?

It's phenomenal and I am couldn't be happier this field. I wasn't a volt-nut / metrology-nut until about a year ago.  But I've been entrenched ever since!!  We've been making some big purchases to drastically increase our uncertainties and I am over here having the time of my life!  I'm pretty sure we're going to be snagging 1 of those Datron 4910s posted in the other thread.   

I plan on having a Quantum Hall Resistance system up and going by the middle of 2018.  And probably a Josephson Array shortly afterwards.  I'm so ecstatic for the future

[Dr. Frank]

We've been making some big purchases to drastically increase our uncertainties and I am over here having the time of my life!  I'm pretty sure we're going to be snagging 1 of those Datron 4910s posted in the other thread.   

I plan on having a Quantum Hall Resistance system up and going by the middle of 2018.  And probably a Josephson Array shortly afterwards.  I'm so ecstatic for the future

For sure you're ecstatic, I see.. But anyhow, you want for sure to decrease your uncertainty, aren't you? 

And obviously, you want to found another National Institute of Metrology.. I did not know yet, that any private company owns a QHR system, as it's yet more bulky and pricey than a JJA system, that huge dewar can and that strong superconducting many-Tesla-magnet..

Anyhow, if you succeed, especially in the year of 2018, you'd be well prepared for the new Si-2018! 

Frank

[CalMachine]

We've been making some big purchases to drastically increase our uncertainties and I am over here having the time of my life!  I'm pretty sure we're going to be snagging 1 of those Datron 4910s posted in the other thread.   

I plan on having a Quantum Hall Resistance system up and going by the middle of 2018.  And probably a Josephson Array shortly afterwards.  I'm so ecstatic for the future

For sure you're ecstatic, I see.. But anyhow, you want for sure to decrease your uncertainty, aren't you? 

And obviously, you want to found another National Institute of Metrology.. I did not know yet, that any private company owns a QHR system, as it's yet more bulky and pricey than a JJA system, that huge dewar can and that strong superconducting many-Tesla-magnet..

Anyhow, if you succeed, especially in the year of 2018, you'd be well prepared for the new Si-2018! 

Frank

Haha touche, I guess I mean't increase the greatness of our uncertainties! by lowering them.  But, turning our lab into a national standards institute is my end goal.  I would die a happy man.  I'm fairly young at 30, too!  So I've got plenty of time

But a QHR isn't too bad, especially now that graphene has been shown to be a viable medium.  You only need to get down to about 4K in about 5-10T to observe the QH effect.  There are multiple manufacturers we're looking at and so far some quotes have been ~ $250k for a cryogen free graphene QHR system...  which isn't TOO bad.

I have yet to look into a JJA system at all yet...  do you know a rough ballpark what one of those systems would run?

[Dr. Frank]

Commercial JJA systems are offered by hypres in U.S., the other is supracon in Germany.
They cost about 150-200k, a bit cheaper, as you don't need that magnet and big dewar.
The JJA may be produced by NIST or PTB, anyhow.

[CalMachine]

Commercial JJA systems are offered by hypres in U.S., the other is supracon in Germany.
They cost about 150-200k, a bit cheaper, as you don't need that magnet and big dewar.
The JJA may be produced by NIST or PTB, anyhow.

Awesome, thanks for the information!

[dr.diesel]

Hi calmachine. Please tell us more. Where do you live/work?

Hey Enut11!!  My name is Ryan and I work at ENI Labs in Ft. Wayne, Indiana!  Fully 17025 Accredited lab for most everything in the Metrology world!  I, myself, specialize in electronic calibrations and specifically 8.5 digit/dc/low freq.  Ever since I joined the Lab I've been pushing for better quality practices, procedures, and we are really have been investing a lot in upgrading our standards.   

If anyone has any questions, please feel free to ask

www.ENILabs.com
https://www.a2la.org/scopepdf/2147-01.pdf

WooHoo, this might be good news for me, I'm in Terre Haute!

[CalMachine]

Hi calmachine. Please tell us more. Where do you live/work?

Hey Enut11!!  My name is Ryan and I work at ENI Labs in Ft. Wayne, Indiana!  Fully 17025 Accredited lab for most everything in the Metrology world!  I, myself, specialize in electronic calibrations and specifically 8.5 digit/dc/low freq.  Ever since I joined the Lab I've been pushing for better quality practices, procedures, and we are really have been investing a lot in upgrading our standards.   

If anyone has any questions, please feel free to ask

www.ENILabs.com
https://www.a2la.org/scopepdf/2147-01.pdf

WooHoo, this might be good news for me, I'm in Terre Haute!

Sweet!!  Fairly close

[enut11]

Hi calmachine. Please tell us more. Where do you live/work?

Hey Enut11!!  My name is Ryan and I work at ENI Labs in Ft. Wayne, Indiana!  Fully 17025 Accredited lab for most everything in the Metrology world!  I, myself, specialize in electronic calibrations and specifically 8.5 digit/dc/low freq.  Ever since I joined the Lab I've been pushing for better quality practices, procedures, and we are really have been investing a lot in upgrading our standards.   

If anyone has any questions, please feel free to ask

www.ENILabs.com
https://www.a2la.org/scopepdf/2147-01.pdf

Hi Ryan. I should have guessed that you were in the USA! You are going to make a few American/Canadian voltnuts happy.
Maybe I could visit Indiana (from Australia) one day?

enut11

[TiN]

I have yet to look into a JJA system at all yet...  do you know a rough ballpark what one of those systems would run?

NIST SRI6000 10V PJVS system pricing is listed on  their site, 450K for compressor cooled all in one or 320K for LHe system. 10V JJA chip itself is 52.4K, 1V AC JVS - 26.3K .

Do you plan to calibrate DIY SSR/Resistance boxes, like LTZ1000-based/VPG foil 4W modules and such? Perhaps estimated ballpark pricing would benefit many of lurkers here, including myself.

[CalMachine]

I have yet to look into a JJA system at all yet...  do you know a rough ballpark what one of those systems would run?

NIST SRI6000 10V PJVS system pricing is listed on  their site, 450K for compressor cooled all in one or 320K for LHe system. 10V JJA chip itself is 52.4K, 1V AC JVS - 26.3K .

Do you plan to calibrate DIY SSR/Resistance boxes, like LTZ1000-based/VPG foil 4W modules and such? Perhaps estimated ballpark pricing would benefit many of lurkers here, including myself.

TiN, it would depend on the specs of the unit and the uncertainties in which you are looking for.  I'm sure we would have no issue providing accredited measurements on DIY equipment for $50-100 to hobbyists here at EEVblog!

[TiN]

I think specs would be in range <2ppm DCV, <8ppm Ohm (10k) so hopeless voltnuts with 3458 can benefit most, to have small reference box on 6/12 month rotation. You can also have a requirement for inbound SSR to be 0.5ppm stable within 7 days to ensure you not wasting time. So owner would need to do "pre-work" checklist on DUT reference to ensure this.

How about international shipment then? Small box with LTZ modules and resistors can be well below 5kg. Calibration for 1V, 10V, 10k, maybe 1 ohm. Usual procedure, similar to F732B and F742A can be used to make series of measurements over few days after 24h warmup. Such SSR box can have standard F732B ext battery DB9 connector port, to resolve PSU issues.

If you prefer, we can discuss over email details of such, but I think community can benefit a lot from having this info public. I'm not aware of any cal labs doing such service for hobbyists, esp. with international shipping.

[Nuno_pt]

I would join for calibrate my LTZ/10k box.

[CalMachine]

I think specs would be in range <2ppm DCV, <8ppm Ohm (10k) so hopeless voltnuts with 3458 can benefit most, to have small reference box on 6/12 month rotation. You can also have a requirement for inbound SSR to be 0.5ppm stable within 7 days to ensure you not wasting time. So owner would need to do "pre-work" checklist on DUT reference to ensure this.

How about international shipment then? Small box with LTZ modules and resistors can be well below 5kg. Calibration for 1V, 10V, 10k, maybe 1 ohm. Usual procedure, similar to F732B and F742A can be used to make series of measurements over few days after 24h warmup. Such SSR box can have standard F732B ext battery DB9 connector port, to resolve PSU issues.

If you prefer, we can discuss over email details of such, but I think community can benefit a lot from having this info public. I'm not aware of any cal labs doing such service for hobbyists, esp. with international shipping.

Unfortunately our DC/low frequency program isn't as robust as I would like it to be, that's why I am beefing up our procedures, standards, and getting some long-term data logging in place.  At the moment, we don't do long period temperature curves on resistances, which I also want to start providing to our customers.  All in due time

Also, if you're looking for those tight of specs, I can definitely give you some accredited measurements, however our *stated* uncertainties, depending on the range, could only yield a TUR as low as 2:1.  Once our next A2LA audit comes up, we will be seeking to lower our uncertainties significantly utilizing a lot of the new equipment we've been purchasing the last few months. 

As far as international shipping... I don't see that being much of a problem as long as you, the customer, is willing to pay for international shipping!

TiN, I've not seen any of these LTZ boxes you speak of... they sound pretty sweet!  I would love to give them a go...  and you say they have a 9pin DSub connector to plug into a F732B?

If you would like to discuss further, either on here or over email, don't hesitate to get ahold of me

[TiN]

At the moment, we don't do long period temperature curves on resistances, which I also want to start providing to our customers

I more meant that customer himself does "pre-test" before sending the box to you, and you just run it for few days (let box rest day 1, take 10 samples day 2, 10 other samples day 3, send unit back day 4, etc). Not necessary to have 24/7 longterm logging for calibration, you should expect already characterized reference at inbound. It's not the calibration lab job to do testing for the user, when asked (and paid for) only for calibration, which is measurement only, by the books. Hope this clarify things a bit, so we on same page.

As far as international shipping... I don't see that being much of a problem as long as you, the customer, is willing to pay for international shipping!

They'd better pay  . That sounds right, no problems. I just had different experience few years ago, when asked some cal labs to do same thing, with me paying shipping both ways, when I was looking to import DCV/Ohm into my homelab. I hand-carried standards and did own transfers since then, so it's less of an issue for me now, but I'd be looking for 3rd callab cross-check, and your service seem to fit great into the spot.

TiN, I've not seen any of these LTZ boxes you speak of... they sound pretty sweet!  I would love to give them a go...  and you say they have a 9pin DSub connector to plug into a F732B?

Well, the box I'm talking right now is not that refined, but I see no difficulty to prepare above-mentioned in Q3'2017 timeframe to perform a transfer. Since 2014 I was tinkering and had designed, built and tested compact 7V LTZ1000-based module following standard datasheet application almost exactly, and using bank of 4 modules as my homelab primary DCV standard, doing cross-checks from time to time. Design is fully open-hardware and covered in article on my site. One of latest modules was also tested in more detail covered here and discussed here and even got group of voltnuts to fab PCBs . For my first transfer in March'16 I've used standalone 3458A's A9 module to calibrate my first 3458A after repair. That got me to DCV within 6 ppm, which later in August was improved to <2ppm with bank of 8 x LTZ1000's (6 on my modules, 2 inside K2002's). For Ohms I use aged Vishay hermetic foils so far.

As of power port, it's easy to design in the enclosure to fit my references and provide DB9 interface, which can couple to 732B-7001 battery pack/charger. so you don't have to worry about finding power supply to power up the reference. International shipping is usually too long to have unit sent hot, and shipping large batteries require special permits/legalpapers anyway. So I'll have to test for hysteresis and stability after thermal shock first, before I have anything shipped. Surely other option to have regular mains PSU integrated as well, but that adds weight and size.

If you would like to discuss further, either on here or over email, don't hesitate to get ahold of me

Thanks for being transparent for hobby level things, this is rare thing in metrology market. We can keep discussion here for time being, as things covered are pretty generic. You will get line of voltnuts lineup with their boxes quicker than you realize 

[CalMachine]

At the moment, we don't do long period temperature curves on resistances, which I also want to start providing to our customers

I more meant that customer himself does "pre-test" before sending the box to you, and you just run it for few days (let box rest day 1, take 10 samples day 2, 10 other samples day 3, send unit back day 4, etc). Not necessary to have 24/7 longterm logging for calibration, you should expect already characterized reference at inbound. It's not the calibration lab job to do testing for the user, when asked (and paid for) only for calibration, which is measurement only, by the books. Hope this clarify things a bit, so we on same page.

Well, sometimes we do take special requests for testing parameters on a particular unit, if customers have them.  That can definitely up the price of the cal though.  But yes, you are correct... we generally only take measurements, and adjust if possible/needed.

As far as international shipping... I don't see that being much of a problem as long as you, the customer, is willing to pay for international shipping!

They'd better pay  . That sounds right, no problems. I just had different experience few years ago, when asked some cal labs to do same thing, with me paying shipping both ways, when I was looking to import DCV/Ohm into my homelab. I hand-carried standards and did own transfers since then, so it's less of an issue for me now, but I'd be looking for 3rd callab cross-check, and your service seem to fit great into the spot.

Ahh, sorry to hear about your past experiences.  And yeah, we purchase used test equipment internationally sometimes.  Like that Datron 4910 we might get from that German company you linked in the other thread (I believe it was you).

TiN, I've not seen any of these LTZ boxes you speak of... they sound pretty sweet!  I would love to give them a go...  and you say they have a 9pin DSub connector to plug into a F732B?

Well, the box I'm talking right now is not that refined, but I see no difficulty to prepare above-mentioned in Q3'2017 timeframe to perform a transfer. Since 2014 I was tinkering and had designed, built and tested compact 7V LTZ1000-based module following standard datasheet application almost exactly, and using bank of 4 modules as my homelab primary DCV standard, doing cross-checks from time to time. Design is fully open-hardware and covered in article on my site. One of latest modules was also tested in more detail covered here and discussed here and even got group of voltnuts to fab PCBs . For my first transfer in March'16 I've used standalone 3458A's A9 module to calibrate my first 3458A after repair. That got me to DCV within 6 ppm, which later in August was improved to <2ppm with bank of 8 x LTZ1000's (6 on my modules, 2 inside K2002's). For Ohms I use aged Vishay hermetic foils so far.

As of power port, it's easy to design in the enclosure to fit my references and provide DB9 interface, which can couple to 732B-7001 battery pack/charger. so you don't have to worry about finding power supply to power up the reference. International shipping is usually too long to have unit sent hot, and shipping large batteries require special permits/legalpapers anyway. So I'll have to test for hysteresis and stability after thermal shock first, before I have anything shipped. Surely other option to have regular mains PSU integrated as well, but that adds weight and size.

That module you designed is fantastic!  I love it.  I am definitely trying to get into the design side of things.  Do any of you here see a market for 10.5 digit multimeters?  I've been thinking about trying to design one in my off time.  First though, I was going to try to design a new way to get a more accurate voltage reference.  This is probably a few years in the making, however lol.... As I delve into it, it could very well be a thing that's not feasible.  I will definitely be looking to some of the great information I've found on this website when I get the go ahead.

If you would like to discuss further, either on here or over email, don't hesitate to get ahold of me

Thanks for being transparent for hobby level things, this is rare thing in metrology market. We can keep discussion here for time being, as things covered are pretty generic. You will get line of voltnuts lineup with their boxes quicker than you realize 

You are very welcome!  I try to be as transparent as possible, as I know a lot of the other cal labs I've dealt with can be pretty shady.  I've gotten multiple suspect cals from labs I thought were pretty reputable.

[TiN]

Unless one can design JJA which runs at LN2 temps, there is no possibility of 9.5 digit "DMM" smaller than few 42" tall 19" racks and taking few KW of power. Limitation of performance is the reference in most aspects. Conditioned LTZ1000 bank gives you noise/short-term stability in range 0.2-0.4ppm, so even if you pay few M$ to design and make ultralinear ADC you will be limited by this number.
For resistance it's bit better, as you can apply ratiometric measurements with DCCT bridge to get 9.5 digits, but thats still a 42" rack of equipment. Check Measurement International site, they have such system for sale.
JJA-based voltmeter also exists, made by Supracon ?G/PTB.

[e61_phil]

But even an ADC in the same class as the 3458A would be very interesting. CalMachine how would you like to realize that?

[CalMachine]

Unless one can design JJA which runs at LN2 temps, there is no possibility of 9.5 digit "DMM" smaller than few 42" tall 19" racks and taking few KW of power. Limitation of performance is the reference in most aspects. Conditioned LTZ1000 bank gives you noise/short-term stability in range 0.2-0.4ppm, so even if you pay few M$ to design and make ultralinear ADC you will be limited by this number.

Oh! That makes sense.  What if one was able to design something more stable with less noise than the tried and true LTZ1000 references?  The new DMM I have in mind would be very similar to the Datron 4950... where it can measure only in small bands, EXTREMELY accurately.  Mostly for metrology purposes, and not for general measuring applications.  One big thing I would like to incorporate into it is; referenced to quantum realization of the SI units as opposed to normal primary or secondary standards.

For resistance it's bit better, as you can apply ratiometric measurements with DCCT bridge to get 9.5 digits, but thats still a 42" rack of equipment. Check Measurement International site, they have such system for sale.
JJA-based voltmeter also exists, made by Supracon ?G/PTB.

Oh wow,  Thank you for showing me this company!  I didn't think there were many companies out there developing test equipment utilizing the new quantum standards. 

But even an ADC in the same class as the 3458A would be very interesting. CalMachine how would you like to realize that?

Can you elaborate a little bit on your question?