EU - CalClub

[branadic]

Hi MiDi,

I noticed, that it seems your Guard is set "To LO" instead of "OPEN" on 3458A, while Guard is not connected to LO at the reference. Because of that we had quite some shifts during MM2020mini that were reproducable afterwards.
Has Frank measured the reference the same way you did, I mean the same wiring scheme?

Edit: I'm also curious about your uncertainty values, they seem a bit low. For comparison, Keysight Böblingen gives +/-2.5ppm on our 3458A calibration. Why you add only 0.5ppm/2 to your uncertainty? Maybe you can elaborate on that numbers?

-branadic-

[MiDi]

I noticed, that it seems your Guard is set "To LO" instead of "OPEN" on 3458A, while Guard is not connected to LO at the reference. Because of that we had quite some shifts during MM2020mini that were reproducable afterwards.
Has Frank measured the reference the same way you did, I mean the same wiring scheme?

I followed 2ppm hunt in MM thread 
The measurement for LTZ#2 was taken as shown on picture, Guard closed and connected to case of LTZ#2.
I have done comparisons between all possible configurations for guard open/closed and guard connected to case or to low on LTZ#2.
Afair there was no significant difference in the readings, unfortunatly I lost the notes, so nothing left as foundation 

Edit: I'm also curious about your uncertainty values, they seem a bit low. For comparison, Keysight Böblingen gives +/-2.5ppm on our 3458A calibration. Why you add only 0.5ppm/2 to your uncertainty? Maybe you can elaborate on that numbers?

For the reference values I used the mean values provided by Dr. Frank before and after return and added half of that drift to the uncertainty:

There is no added uncertainty for my measurements, I just used uncertainty Dr. Frank gave for his references.
After return, Dr. Frank told me that both references drifted by ~+0.5ppm.
As I said, I have no experience with this kind of calculations, if this is wrong, please push me on the right path.

[branadic]

Progress on EU Cal Club kit.
I finished my LTZ1000#9, it's tc compensated and the output adjusted. I measured:

10.0000537V (+5.4 ppm) over 16 values (~1 min) with a standard deviation of 366 nV and 10.0000535 V with a standard deviation of 360 nV over 781 values (~52 min), measurement taken with 100NPLC or 4s integration time with R6581D

The reference has been with Frank and he confirmed the results with his 3458A:

10.0000508 V (+5.1 ppm) with a standard deviation of 224 nV over 10 min, 302 nV over 1 h and 587 nV over 18 h

A hardcase with foam inlay has been ordered, to make it a kit. Unfortunately I didn't had the time yet to also set up a 10k resistance reference, which should have been part of the kit as well, but I'm working on it.

-branadic-

[Andreas]

Hello branadic,

do you plan to put a temperature data logger into the case?
E.g. something like this?

https://www.amazon.de/Temperatur-Luftfeuchtigkeits-Datenlogger-Rekorder-Digitaler-Temperatur-Datenlogger-Rekorder-Lebensmitteln/dp/B083JSL3DM/ref=sr_1_2_sspa?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=3DBNEWBS4WZL3&dchild=1&keywords=elitech+rc-5&qid=1604773291&sprefix=elitech%2Caps%2C178&sr=8-2-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExV1lNRDlESlo3V1VYJmVuY3J5cHRlZElkPUEwMDY3OTI2MzFQT0YxMDRIRTc2SSZlbmNyeXB0ZWRBZElkPUEwMzA4NTc2M0RERjczR1JQTkMxJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==


with best regards

Andreas

[Dr. Frank]

As promised, I'd offer one of my monitored 10k, VHP202Z resistors, with operational description.
Frank

[branadic]

Andreas,

a logger would be nice, agree, but I don't have one yet and boycott to buy from Amazon

-branadic-

[Sprock]

Hello Branadic

if one could have access to a PT100 or NTC 10k from outside.
Lemo B (Reichelt: EGGOB302CLL -2pol) or similar if place is there.
Just a idea.

best regards
Sprock

[Dr. Frank]

At least a temperature data logger is urgently required during transport!

Our 'secret' volt-nuts club uses a similar to AZ Corp. (Taiwan) 88163 AZ (T+ humid. + Press.) pdf logger inside the suit case.
That's especially important, as both non-heated references (V, R) will show a hysteresis of several ppm if they are exposed to temperatures below about 0°C.
Temperatures below -15°C might literally harm the LTZ1000 stability.

Transport should only be done, if environmental temperature is > 10°C, to be sure.  I have not seen any hysteresis on both, down to this temperature.

My VHP202Z reference assembly contains a precision NTC, which is sufficient to reproduce its T.C. behavior, and to calculate its correct resistance value at the given environmental temperature.

Andrés LTZ #9 reference is temperature compensated to a level being irrelevant to volt-nuts level comparisons, i.e. on the order of a tenth of ppm over +/- 10°C, or so. André for sure will specify that precisely.   

Frank

[Andreas]

Hello,

for a similar price I found the UT330C Humidity/Temperature/Pressure Datalogger @ Reichelt.
https://www.reichelt.de/datenlogger-temperatur-luftfeuchte-luftdruck-ut-330c-p147784.html?&nbc=1

with best regards

Andreas

[branadic]

Thanks for that hint Andreas, bought a used unit cheap, that already arrived today.

-branadic-

[branadic]

A test run on German ring comparison with LM399-PWM-DAC started today, final measurements happened yesterday, today the small pelican case clone with the reference, a linear wall adapter, cable for the internal temperature sensor (10k NTC) and UT330C ambient datalogger made its way to first participant.

"Each journey starts with a very first step."

-branadic-

[branadic]

So we have finished our test run and the results were already presented at yesterdays MM2022, here they are. Different to what was shown yesterday an additional and final measurement point was included.
Some lesson were learned and can help to improve future CAL runs within Germany or even EU.

Thanks to all the 13 participants that used the very short time very effective.

-branadic-

[Andreas]

Hello,

and the best of all:
there is virtually no change of the LM399-based 10V reference during transport if you compare the first Measurement (#1) with the last (#18) with the same instrument.

So it is a big success.
Thanks @branadic for organisation.

with best regards

Andreas