Just did another drift comparison between meters. The UT61E seems to be getting worse, whereas the UT71s are pretty much together. The 71s have 5ppm/c precision film 0.02% resistors, hence less drift I assume.
The table lists the LSD differences, with the 71D as the standard. All readings were very steady, down to the last digit, with a linear power supply from 2 to 14V DC.
Thanks for the info! From your post, it looks like I am looking at about 10 count drift. My requirement (with accuracy) is not high. 10 count drift doesn't please me, but it is (unhappily) acceptable to me.
The drift problem is probably why I never replaced my blown UT61E. I liked it at first but I found I had to keep tweaking it and that really isn't the way a good meter should behave.
While I am curious about the drift, at the same time, I feel a little silly spending $62 (DMM Check Plus) to check on my $60 DMM. You "tweak it" and get it back in line. Are you tweaking VR1 alone?
Thanks, both for the info. You are very helpful.
Let me rephrase the question this way:
The DMM Check Plus gives me a +5v +- 0.1% to 5 digits. If I can re-calibrate VR1 (alone) with the 5V reference, I am hoping to bring it back to say reduce the error by 1/2 (say from 10 digit off to 5 digit off). Am I dreaming or is that realistic?
I still feel a little silly spending $62 to adjust a $60 DMM, but that would be at least more than merely satisfying my curiosity...
Thanks again, both Mr Wytnucls and Mr Lightages. I appreciate your help.
Rick