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All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
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HighVoltage:
Maybe some parts have changed in new production runs and older models still hold the older specs?
Kleinstein:
For the current ranges there could be a change of parts. The shunts are a bit special and expensive parts, where it could happen that if the original one go EOL that they didnot get a good replacement.
For the noise part there should not be a problem in getting equivalent parts with the same low noise. The OPA140 is still available and even a OPA141 or OPA1641 would not give much different noise performance.  For the resistors there should also be low noise ones available. I doublt that they would change the reference - though possible.

With the noise specs part there may be the point of including reference noise, so not just give the noise with a shorted input, but the noise for a FS input. Most noise specs are for a shorted input, but to be real honest they should also give the reference noise in some way (ideally as seprate noise at FS input for a hypothetical noise free input). Especially with the relatively good LTFLU ref. there is no good reason not to show it.

If the old meter still hold the old specs is a good question.
E-Design:
We work hard to make sure no specs are affected adversely if at all possible. If specs must change, we strive to at least minimize the impact.  However, we also value making sure they reflect the performance of the instrument accurately.

Some of the causes of spec adjustments:

1) Part changes - inevitable outcome of procurement issues and obsolescence of key components - its a never ending battle.
2) Improved testing and predictive methods.
3) Statistics / much more run time of units in the field.

If you feel some specification is now detrimental to your measurement needs, please describe in detail and I am happy to take the feedback so we can consider it next time.
We can always improve specs, but we need justification for that -- and having customer feedback is a nice way to do that.

There is no reason to believe older instruments in the field do not hold their specs.

Many thanks!



MegaVolt:
Thank you for staying with us :)


--- Quote from: E-Design on November 21, 2023, 10:10:14 pm ---There is no reason to believe older instruments in the field do not hold their specs.

--- End quote ---
I don't really understand this phrase.

To evaluate the capabilities of an old device, should I use the old specification? And for new devices, a new specification?
From what date is the device considered new?

P.S. After the new changes, my account was banned and I lost the ability to download new software :(
E-Design:
There is no reason to think older instruments do not meet those original specifications. Newer specifications will reflect closer to the newer builds and remain compatible with older instruments. (older specs tighter).
No specs were improved for newer instruments (some are worse as was pointed out). So you should be able to refer to either specification without worry. In general, we instruct everybody to use the latest released specifications. No need to worry about what date is newer vs older etc.. Hope it make sense.

@ Megavolt, I dont think you were "banned" - perhaps your account was disabled due to inactivity? You can surely sign up again if you are looking for newer software.
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