Electronics > Metrology

Metrology Meeting in Stuttgart/Germany

<< < (61/61)

alm:
I had time to run one more test to continue the 3458A guard switch saga, which was to check if the same problem also occurs if I use a different voltage reference than the Fluke 7001. So now I used the same 3458A #1 DMM and cable, but I used a Fluke 732A running off mains power (it does not have batteries yet) instead of the Fluke 7001 running of battery I used for the previous experiments. I tried both with connecting the guard lead to the F732A guard terminal, which is isolated from the 10 V HI/LO terminals. Unsurprisingly the guard switch did not make a difference there, and the difference are way down in the noise (0.05 ppm). Note that the vertical scale spans 0.2 ppm here:


Then I connected the guard to the same terminal as the low input lead to the DMM (so 10 V LO when measuring positive polarity and 10 V HI when measuring negative polarity). Here I observed a very similar effect to what I saw on the F7001, -6 to -8 ppm for this meter. So clearly the effect isn't just that the setting upsets the F7001 output stage:


Error bars again indicate standard deviation, n >= 20.

Navigation

[0] Message Index

[*] Previous page

There was an error while thanking
Thanking...
Go to full version