Author Topic: DMM versus temperature comparison  (Read 691 times)

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Offline rigrunner

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DMM versus temperature comparison
« on: November 26, 2017, 04:21:19 AM »
It's the time of year when my lab temperature gets to wander about at the chillier end of things and i thought it would be interesting to see how the different DMMs compare with lab temperature change.  All i've done is set the EDC to 10V and take a measurement at 30 minute intervals with NPLC at 100 for the HP meters.  Both of the 3457A are soft calibrated when the temperature change is  +/- 1C.

The 3456A is remarkable and the Datron 1071 would make a pretty good thermometer :)

 
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Offline Andreas

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Re: DMM versus temperature comparison
« Reply #1 on: November 26, 2017, 04:36:35 AM »
Hello,

as comparison:

My K2000 has around 0.5ppm/K in the 10V range.

http://www.eevblog.com/forum/metrology/project-pimp-a-keithley-2000/msg1106839/#msg1106839

And no significant correlation to temperature in the 100 mV range.

with best regards

Andreas
 

Offline rigrunner

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Re: DMM versus temperature comparison
« Reply #2 on: November 26, 2017, 05:02:43 AM »
Using the down temperature slope from reading 89 onwards the DMMs here show:

3456A: -0.5ppm/K
3457A-1:  +0.83 ppm/K
3457A-2: -1.16 ppm/K
D1071: -2.0 ppm/K

I'd expect the 3457As would be slightly better in their 3V range. I wasn't going to check any other ranges but now that you've mentioned it i might flip the EDC to 100mV and log a little data there too.


 

Offline HighVoltage

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Re: DMM versus temperature comparison
« Reply #3 on: November 26, 2017, 05:18:12 AM »
How do you know that your 10V reference supply was stable during the change of temperature?
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline rigrunner

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Re: DMM versus temperature comparison
« Reply #4 on: November 26, 2017, 05:37:57 AM »
How do you know that your 10V reference supply was stable during the change of temperature?

For this set of measurements i don't know the stability of the 10V. All i was interested in was a comparison of the meters,. Whatever drift the EDC has is included in the measurements. Before i switch my 1271 over to the new build LTZ i can measure the 10V over a temperature range and get an idea of it's drift.

 

Online maxwell3e10

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Re: DMM versus temperature comparison
« Reply #5 on: November 26, 2017, 05:45:52 PM »
I looked at temperature sensitivity of Keithley DMM7510A and 34470A for periodic temperature changes on a timescale of 1000 sec:
http://www.eevblog.com/forum/metrology/dmm-adc-noise-comparison-testing-project/msg1330643/#msg1330643

For 34470A the measured sensitivity for these relatively fast temperature changes was about 0.8 ppm/K, while for DMM7510 it was 0.4 ppm/K. The specs for steady-state temperature change are 2 ppm/K for 34470A and 0.15ppm/K for DMM7510.

Someone must have done this for a 3458A?
 

Offline 3roomlab

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Re: DMM versus temperature comparison
« Reply #6 on: November 26, 2017, 07:03:37 PM »
It's the time of year when my lab temperature gets to wander about

how about sticking the VREF in a wine box?
http://www.eevblog.com/forum/metrology/dmm-adc-noise-comparison-testing-project/msg1136604/#msg113660
sometimes i understand, sometimes i don't. so i will post nonsense, likely i will spew more nonsense and not even know about it.
 

Offline Dr. Frank

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Re: DMM versus temperature comparison
« Reply #7 on: November 26, 2017, 11:13:51 PM »
I looked at temperature sensitivity of Keithley DMM7510A and 34470A for periodic temperature changes on a timescale of 1000 sec:
http://www.eevblog.com/forum/metrology/dmm-adc-noise-comparison-testing-project/msg1330643/#msg1330643

For 34470A the measured sensitivity for these relatively fast temperature changes was about 0.8 ppm/K, while for DMM7510 it was 0.4 ppm/K. The specs for steady-state temperature change are 2 ppm/K for 34470A and 0.15ppm/K for DMM7510.

Someone must have done this for a 3458A?

Well, yes, it's described here: http://www.eevblog.com/forum/metrology/ultra-precision-reference-ltz1000/msg1336575/#msg1336575, how to determine the 3458As T.C., and how to design a reference which is relatively independent from temperature changes, serving as a fix point for such measurements.

I've got a 3458A which has +0.4ppm/K, and Tins both 3458As are less than 0.1ppm/K.

Frank
 

Offline rigrunner

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Re: DMM versus temperature comparison
« Reply #8 on: November 27, 2017, 04:10:24 AM »
how about sticking the VREF in a wine box?

I've got a wine cooler similar to the thing Dave showed in episode #101 but the EDC is too large to fit inside :(
I will redo the measurements with an LTZ in the cooler when i've put the next one together.

 
 

Offline Mickle T.

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Re: DMM versus temperature comparison
« Reply #9 on: November 27, 2017, 05:49:43 AM »
R6581T: +1...+1.2 ppm/K (w/o selfcal)
D1271: +0.5 ppm/K (w/o selfcal)
S7081 #1: +0.06 ppm/K (20K span, LTZ mod + Cu mod)
S7081 #2: +0.03 ppm/K (20K span, LTZ mod + Cu mod)
S7081 #3: -0.55 ppm/K
HP 34401A: +0.1 ppm/K
K2100: -1...-1.5 ppm/K
D1071: +0.8 ppm/K
« Last Edit: November 27, 2017, 05:58:34 AM by Mickle T. »
 
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Offline e61_phil

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Re: DMM versus temperature comparison
« Reply #10 on: November 28, 2017, 07:33:22 PM »
I've attached a measurement from a Solartron 7081 I had some time ago. It was measured against my Fluke 5440B (10V). It gives a bit less than 0.8ppm/K
 
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