USA Cal Club Round 3.1

[CalibrationGuy]

First Voltage Reference Bank FX assigned value: +9.999956709. Less than 24 hours powered up.

Setup conditions: +/-12Vdc by 4x6Vdc AGM SLA batteries for lowest noise. Actual voltage was 12.8Vdc at start.

70.49 degrees F, 31.49% RH

Hope this is useful to the group. Batteries should last 4-5 days, so I'll update with daily readings and send it back by week's end.

Voltage Bank: 4x732A, 4x732b, 1x732c (characterized at Keysight's Standards Calibration Laboratory) with 34420a using NIST measurement methodology running custom data acquisition and mathematical regression script.

PS - Kudos to my friend Ilya at xDevs, truly remarkable performance!!!

TomG.

[CalibrationGuy]

Ok, the day 2 number is: +9.999955289Vdc. Temp and humidity within +/-1 of yesterday's values. Next update will be tomorrow evening.

TomG.

[CalibrationGuy]

I guess I should also point out that the difference between these numbers is nearing the noise threshold of all the devices involved.

TomG.

[CalibrationGuy]

OK, day 3 last reading: +9.999955144, day's average: +9.999954989.

TomG.

[bdunham7]

OK, day 3 last reading: +9.999955144, day's average: +9.999954989.

That's a lot of digits!  Is the final result going to be 9.999955 +/- 2µV?  That puts it at -0.9ppm from the previous calibration over almost 18 months and dozens of cross-country trips via USPS. 

One question about this--what is your educated opinion on how close your 10V is to xDevs 10V? 

[CalibrationGuy]

OK, day 3 last reading: +9.999955144, day's average: +9.999954989.

That's a lot of digits!  Is the final result going to be 9.999955 +/- 2µV?

The digits result from averaging samples over the hours, so we keep the digits for the math. Yes, the value looks like it's going to be +9.999955, well within +/-2µV.

TomG.

[CalibrationGuy]

One question about this--what is your educated opinion on how close your 10V is to xDevs 10V?

I just noticed your question. xDevs' and our 10V values are extremely close, probably +/-1ppm or less. The master 732c in our lab was compared to Keysight's primary JVS less than a year ago, so our confidence level is very high.

TomG.

[CalibrationGuy]

Ok, day 4 reading: +9.999955408. That's the average. Variations pretty small today.

TomG.

[CalibrationGuy]

You guys wanted to know how close I was to Ilia's value. Now you're going to have your answer because I dropped the FX reference off with him and he will characterize it. And then we'll see the difference.

TomG.

[CalibrationGuy]

So Ilya's first measurement of our 732b transfer standard is less than 0.18ppm away from our value. So very high level of confidence in our measurement setup as well as his. Hope this is useful information to you guys.

TomG.

[1audio]

Thats really reassuring, even though its well below anything I could confidently measure.  I now have some confidence in my 732A measured value.

[Rax]

Second 1audio's point. Many thanks, TomG, all this data is in spot on agreement with everything I've been able to assess across my bench standards (to a scary level of agreement, candidly).

[CalibrationGuy]

A request was made for final value and measurement uncertainty for this calibration/characterization. Here it is:

+9.9999554Vdc, uncertainty for this measurement is 0.2ppm.

TomG.