Electronics > Metrology

Who Has The Best Home-Made 10Vdc Reference?

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CalibrationGuy:
Hello everyone! As some of you know, I have a calibration lab and I enjoy testing voltage references and have dabbled with creating my own. However, after perusing the threads here, I see that my efforts have been eclipsed by some epic efforts by the likes of Dr. Frank, Andreas, Branadic, TiN, et al. I have several Fluke 732 references. One of my older units, a 732a has an extraordinary drift history. I measured it once with a Keysight 3458a that was right back from a metrology lab calibration from Keysight (compared with their Josephson array) 20 months ago, and once again recently with the same meter back from another metrology grade calibration. The result: 0.3ppm difference! Yes, the temp/humidity was the same for both measurements, same cable connecting the units, RF field measured, ACAL ALL, 200NPLC, etc,, etc,, etc. An incredible result. Of course, if we apply all the uncertainties, a cynic can say that this is hardly definitive proof. Well, I concede that point, but now I have 2 more 732a units, a 732b, and 732c which will give me really good data points in the coming years.

So, sorry for the long winded intro, but my question is this: Who has the best reference here? I mean one that they've built. Also, you have to back up your claims by comparisons to a known voltage reference such as the 732. I have 4 3458a meters sitting on my bench right now and can see them drift over the course of 24 hours by 0.3 to 1.6ppm max difference between them.

Looking forward to your responses!

TomG.

My apologies for forgetting Kleinstein!

Grandchuck:
Here is a shot of one of my reference units.  3 copies of Dr. Frank's design.  My 3458A readings wander about +/- 1.5 ppm.  I have checked calibration using the standard designed and built by TiN (USA Cal Club).  I don't think I can achieve anything more as a voltnut without going into more expense and time than I am willing to invest.

CalibrationGuy:
That's a very nice looking project. If you have time, it would be nice to see the front panel with one of the outputs hooked up to your reference meter.

TomG.

Grandchuck:
Sure TomG.  Thanks for the kind words!

I added a 7 hour graph.

CalibrationGuy:
Thank you for that picture. I assume the panel meter is monitoring your power supply voltage. We are sending one of our Fluke voltage references to Keysight soon. It's part of our effort to get under the half part per million uncertainty certification @10Vdc. Once that happens we can characterize your home project if you are curious as to how close it is to 10.00000Vdc. You pay the shipping. The test is free, but I can't give you an official calibration report. Otherwise, my corporate clients would be really not happy.

TomG.

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