EEVblog Electronics Community Forum
Electronics => Metrology => Topic started by: perdrix on January 14, 2018, 01:40:01 pm
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I'm currently running the Service note 18 drift test, and am already way out of bounds after a few days :'(
(https://www.eevblog.com/forum/metrology/oh-dear-another-drifty-3458a/?action=dlattach;attach=386490)
The error bars on the CAL72 values are set to 3.4E-5 percent of the reading which I think is the 0.34 ppm magic number.
The meter was powered on after a long period in storage on the day before the first reading in the graph.
Is this a definite case of "you need a new A3 board", or is there some hope that it can be fixed or will stabilise after a few more days?
Thanks
Dave
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I'd leave meter to run a week or two after storage and then do the test. You may have got just long storage stress.
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Keep measuring before spending money :)
My Solartron 7081 has an interesting maintenance procedure after being in storage: wrap it in insulation and keep it powered for 24 hours to raise the internal temperature.
I used a blanket, and the internal temperature rose to, IIRC, around 40C. It was noticeably better thereafter.
I make no comment about the relevance or otherwise to your 3458.
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Doh! It's nowhere near as bad as I initially thought - the limits are 0.43ppm per DAY, not 0.34 per week which is what I had misremembered! :palm:
I've since updated the spreadsheet to set the errors bars at 4.3E-5 percent.
The only period in which the limit was exceeded was the first one where the delta was 0.9ppm.
The next 24 hour drift was 0.13ppm.
So fingers crossed!
Dave
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It's probably fine, and you'll probably see it settle down a bit more. Let it run for -at least- a few weeks after a long power-off storage period before gathering any serious data.
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fingers crossed!
(https://wacowla.com/wp-content/uploads//2012/05/finger_crossed.jpg)
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My 3458a despite having a jumpy reference with a horrible temperature coefficient A9 has a very good "resistor switch/chip".
23/12/2016 35.20 997.876849
09/01/2018 35.20 997.876575
0.3ppm per year seems to qualify as "good enough" also for the 0.34ppm per week (but also month or year) :-DD
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My 3458a despite having a jumpy reference with a horrible temperature coefficient A9 has a very good "resistor switch/chip".
23/12/2016 35.20 997.876849
09/01/2018 35.20 997.876575
0.3ppm per year seems to qualify as "good enough" also for the 0.34ppm per week (but also month or year) :-DD
This looks impressive - has it been powered on for the entire time(it is only legit if powered on).
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My 3458a despite having a jumpy reference with a horrible temperature coefficient A9 has a very good "resistor switch/chip".
23/12/2016 35.20 997.876849
09/01/2018 35.20 997.876575
0.3ppm per year seems to qualify as "good enough" also for the 0.34ppm per week (but also month or year) :-DD
This looks impressive - has it been powered on for the entire time(it is only legit if powered on).
No not 24/24, let say 20% ... anyway still impressive. It has the new analog board.
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