A lot of great information Eric, thanks for sharing the link.

Due to my ignorance in general on the subject of Metrology, I have the
following question for the list.

If one built a project with the LTZ1000, like the one described on xDevs
and could set it to a value of 7.15000000v at the NIST lab, and observed
stability to 7 1/2 digits, would using that device to calibrate your own 7
1/2 digit DMM be considered NIST traceable? Let's say your device is well
insulated and battery powered, and your calibration was done at the same
altitude and room temperature as at NIST, plus anything I left out that
would make the conditions ideal.

The above was not meant to be a trick question, and I may have asked it
incorrectly, but I view the answers as instructive - or I hope they are.

Russ

On Wed, May 25, 2016 at 10:27 AM, Eric Garner garnere@gmail.com wrote:

On 25 May 2016 at 19:24, Russ Ramirez russ.ramirez@gmail.com wrote:

As far as I can determine, as long as you can work out the uncertainties,
no matter how large they might b,  the measurement is traceable. If you use
a 3.5 digit multimeter that is NIST traceable to calibrate a 7.5 digit
multimeter, the calibration is still NIST traceable. The calibration will
be pretty useless, and you may not be accredited, but it is still NIST
traceable.

Or if you want to be accredited, get your mate down the local pub (bar) to
accredit you!

On a more serious note, if people felt that design was good, and wanted to
produce the PCBs. and/or make parts available, I'd be interested. I only
have a 6.5 digit meter, but feel sure I could find someone with a 3458A in
the UK who could measure the voltage for me.

Dave <not a metrologist>

As Dr K said, traceable and usefully calibrated are not necessarily connected.

I can calibrate to any arbitrary standard I like.  That standard need not be traceable if all that is important to me is consistency across all the instruments in my lab.

If I, on the other hand, want to be consistent with someone else's lab, then we need to be traceable to a common source. Thus NIST. I presume most countries have a NIST like organization. How often to they cross check each other?

Accreditation, on the other hand can be, as the good Dr. points out, pretty useless unless the accreditation body is, itself, held to some (professional) standard.

And I'd also love to build one of these if there is enough interest. While I'm sure we can't get enough orders to get the 100pcs discount on the LTZ1000, it would be a great group project and I'd be willing to participate in bringing it to fruition. I'm also sure I can find a calibrated, traceable, reliable 3458 in the area code.

The irony  is that while I'm less than 15Km from the New York State Bureau of Weights & Measures Metrology group, which has all the traceable standards for the state, they cannot do high accuracy for time or voltage. My personal house standards are better than theirs for those two. By a lot. Adding one of these would add a few more orders of magnitude...:)

Heck, if you’re going to make one, you might as well make one GREAT.

I would be interested in doing a 4910 version, so to speak.  Four in one thermal box and the ability to use them independently or summed and averaged.  Similar to the Fluke 730a, I think?  Oh, and one of them must be removable for transportation.  :  )

Of course, if properly designed one could build any number of them into whatever box they can podge together and use the boards as they please.  I’m in!!  I would find it difficult to believe we could not find 100 individuals that would buy at least one.  The challenge is buying the LTZ’s in enough QTY to grade them like Solartron did in the 7071 and 81’s.

David

If you build these you need to build several and age them together and see
how the members drift against the population. After 6 months or so you
should be able to tell which ones are stable and weed out any drifters.

On Wed, May 25, 2016 at 6:42 PM, bownes bownes@gmail.com wrote:

--

John Phillips

Hello,

there are further projects (including measurement results of Illya = TiN)

in this thread:

http://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/

and others in the metrology/projects section of eevblog

http://www.eevblog.com/forum/projects/project-kx-diy-calibrator-reference-sourcemeter/

With best regards

Andreas

Am 25.05.2016 um 17:27 schrieb Eric Garner:

What prices are you seeing for 100 LTZ1000s?
The main thing is they need to be cooked in then sorted for stability.
A good data acquisition system used to do stats on all the units would
really help.

On Wed, May 25, 2016 at 10:17 PM, Andreas Jahn Andreas_-_Jahn@t-online.de
wrote:

--

John Phillips

On 26/05/2016 06:59, John Phillips wrote:

You also need to factor the stability and ageing of all the other components in the unit, mainly about 5 other resistors
that need to be as stable as the ltz1000