Wondering if there is a way to modulate fan speed based on ambient temperature. This will help keep temperature more stable.
But than we have the problem that when speed is slow there will be more temperature gradient inside the meter.
So even if done who can prove things get better? You need a 3458a into a thermal chamber a do calibration verification every few degrees.
Inviato dal mio Nexus 6P utilizzando Tapatalk
That is:
.. or more politely, it's the wrong approach..
It's well known, that the 3458A definitely has to be used in a temperature stable, laboratory grade environment, say about 23°C +/-2°C nominal and +/-0.2°C change during the run of your experiments.
Only then, you will get reproducible and stable measurements.
The specified T.C.s for the different modes and ranges will tell, what you might expect, with ACAL, and w/o.
It's a fact, that with ACAL, DCV has about 0.15°ppm/C, and Ohms about 1.. 0.5ppm/C, as latter lacks an ovenized or compensated, or more tightly T.C.-selected 40k reference.
The T.Cs w/o ACAL add about 0.5..2ppm/°C.
These rough figures apply for mostly all other long range DMMs in a very comparable manner, as they all use more or less similar technologies and components.
The Fluke 8508A only is much more stable wherever resistors are involved, especially on 1yr. stability spec., as it has to rely on this stability over one year, due to the lack of the 3458As ACAL feature.
Anyhow, both instruments are in the same ballpark, and trying to additionally temperature stabilize their interior, is not the effective way.
Again, all these instruments are in no way DCV or Ohm standards, exactly due to these described restrictions.
So I propose, that you instead maintain external temperature stable DCV and Ohm standards, so that you can do stable absolute measurements.
Frank
Home
Help
Search
Login
Register
