Electronics > Metrology

Keysight 34465A intermittent wrong readout ?

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oz2cpu:
i am monitoring a 34465A DC voltage, about 4V
running constantly on, voltage is in parallel with other meters,
so i can easyly double check it is NOT the input that jumps !
but once every 2-4 days i see intermittent reading, it is even the last digit
but the 2nd last digits that is 1-2 counts off !!
when i push a button, the error goes away,
i did send it for firmware upgrade (was locked for upgrades) but still it does this !!

anyone else see this ??

Andreas:
Hello,

thats about 120 ppm deviation. This is clearly not within spec when the environment conditions did not change largely.

I would consider some "popcorn" noise up to 1 ppm as limit for a 6.5 digit instrument.

See a measurement of my K2000.

Is the going back to "normal" value only related to a "button push" or is there also a jumping back without actuation?
Is the "offset compensation" still active or did you deactivate it for the measurement? (this would give a contiouous slow drift).

with best regards

Andreas

oz2cpu:
you mean Auto zero ? see attached
i turned that off as you see, that is why i love to take pictures of the screens, this way i can remember better what is going on.
next time i see the problem, i better try record a video, and then press a button.
this is a sw bug, that no normal mortal will discover,
it takes days to show up, and goes away when i touch a button, very wierd
display update / refresh / saver ?
the unit looks like it is alive

bdunham7:
Turn autozero back on and then try it again for a few days. 

Andreas:

--- Quote from: oz2cpu on January 15, 2022, 12:58:48 am ---you mean Auto zero ? see attached

this is a sw bug, that no normal mortal will discover,

--- End quote ---

Yes  auto zero is what I meant.

Setting auto zero off is only intended to increase measurement rate for short measurements.
But also measurement error is increased.
For longer measurements you have to use the default setting with auto zero = on.
Accuracy specification is also with auto zero = on.

It is not a bug it is a feature (read the manual).

with best regards

Andreas

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