In my case, I am always referring to the data collected on the SD card. I have no desire to watch the LCD for 40 minutes and try to manually pick out any sort of trend.
OK, and I was referring to the stability on the display, where you need a couple of seconds only to see, that it's now stable to the last digit
The SD card logging, though, contains completely other data, 50 times more noisy, and a different average value, see graph.
That's not usable, analysis from disassembling by tpw_rules explains the whole story.
Again, keep in mind this is not the same hardware you are testing. I have damaged the meter three times and have changed some of the hardware in an attempt to make it more robust. I have also completely realigned the meter. Maybe there is some other difference.
I would expect with your setup you should easily replicate anything I show. If you are seeing something different there must be something we have not accounted for.
Well, I don't think, that this makes a qualitative difference, as I in fact see the same behavior.
I did make a short video for you. I start out with the modified 1.02 firmware. I just let it run for a few minutes. You can see the drift as the meter warms up. Again, I assume this is caused by the Hycon chip they chose. I always found it strange they used that part after Dave's review of the Keysight meter. Anyway, I then reprogrammed the latest firmware and let the meter run for 15 minutes or so to stabilize. I then captured some video while it continued to run for several more minutes.
Thanks a lot! Very instructive, and confirms that for recent firmware 1-25, the logged data is noisy, in contrast to the displayed data.
One point of interest is that I understood the kickstart to have roughly 2000 participants and that the vast majority have been delivered. I assume very few people have firmware 1.0 installed. Your recent post where you used the 1.9M was really brought my attention to this potential problem. It does not seem to be common. So, it's possible that people are just trusting the meter is fine. Perhaps they really have no need for a higher class meter and bought it for other reasons. Another possibility is they are not seeing the problem. If it's the later, then why.
Well, only few people of this Kickstarter project have the means to check the 121GW in depth, and even less might go into detail, and just trust the manufacturer, with Dave as the initiator in the background.
Nevertheless, it's very positive, that several members of the eevblog community take their time to make a deep analysis of the faults and traps of this eevblog DMM, and especially for me it's a great pleasure to cooperate with you and tpw_rules on this special problem.
Btw.: I signed up for this 121GW, because I wanted to have THE 'Dave-O-Meter', which is simply iconic.
Initially, I did not expect this instrument to be perfect.
So I also expected to have some fun in detecting errors in the instrument, and in the documentation.
Frank