EEVBLOG 121GW DC mV Stability Test, Conclusion
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- Опубликовано: 2 сен 2023
- Video showing my attempt to possibly explain the instability problems seen with my EEVBLOG 121GW when applying a 500mV source.
For context, please see the following thread on EEVBLOG:
www.eevblog.com/forum/testgea... 
Наука
LOL the gw looking like the little brother from “a Christmas story”. All bundled up
Good work finding the cause.
Certainly a clue but I don't think we have found the root cause just yet. It will be interesting to hear from Dave if they did indeed change the shield after the ones I purchased.
Thanks!!! As someone who owns one I had no clue about this problem. Important stuff to know.
Your older meter may not have the extra shielding. All production meters have had the extra PCB shielding for quite a few years now. There were also firmware improvements.
I posted a photo on EEVBLOG showing the internals of one of the production meters I purchased for the review. You would have to tell me if its current or not.
Confirmed. I have also confirmed this happens on the Keysight U1282A, Fluke 17B, and Brymen BM235 so far. Keysight is the worst one I've tested so far. So this does not seem to be an issue specific with the 121GW. I now recall that this is not new and has been discussed a few years back?
UPDATE: The Keysight U1272 also does this at greater amplitude than the 121GW but at 36MHz
I think this guy is jealous of Dave's channels success. He's repeatedly given the impression that his channel should be more successful because he's so much better and experienced. Be that as it may but half the likability of Dave is the personality. Just saying
EEVblog meters aint bad, need to remember some of them are rebranded Brymens
On EEVblog we usually talk about the FAFB when it comes to handheld multimeters, its the big 4 and what people are crawing.
Flukes, Anengs, Fnirsis, & Brymens... the FAFB backland.
some will argue that Keysight should be part of this elite group, and maybe in the past, perhaps they should, but Keysight aint what they previous were, samr with UniT and Gossen, but for now they aint, its the big four the FAFB and then there are these other secondary DMM makers that also makes okay handheld multimeters..
@@fly-luckydude is just testing meters. The meter will do what it does. Where did you get all of that other stuff from?
WOW this is fascinating (this vid, the last one and blog comments), and as I have the BM869s (164490215), BM786 (204520906) and a 121GW (180202062, from the crowd funder), I had to try this against a couple references I have (incl, Fluke 731b, 732A, 343A, 752A divider). My 121GW (U-2.00 updated) is reading high on mV range so I ended up using 100mV as a test voltage (I used shielded PTFE copper cables). Sure enough, noisy till I put foil around it and grounded, then stable as the other two. Unexpected, but nice work, definitely need to remember that.
Interesting. You're the first owner to reproduce what I am seeing.
PS: couldnt help it, also tried an Agilent U1253A (MY51400064), Fluke 189 (75240037), 289 (35740002), 8060a (7720020), Uni-T UT181a (C171835804), Tektronix DMM916 (144966) and even an Owon B41T+ (21340133), thankfully no other noise issues (even tried with a MHz noise generator transmitting in the background).
Now you're just showing off 😄But good work anyway. @@nikmilosevic1696
Good job 👍👏
Thank you.
Nice experiment
If a product's rotary encoder gives wacky results when turning it quickly, you know the engineers writing code at the heart of the UX handling processor just wrote in the naive algorithm for interpreting its couple of wires of output, rather than implementing the not-much-more-complicated state machine algorithm which checks for valid state transitions of the input sequences and produces much much more reliable increment/decrement values. Nowadays its a quick google + 5 minute read to find this info, yet still disheartening to see it not done in so many places. Always fun finding out if a car's volume or other knobs have the good implementation or not.
I was surprised to see modern test equipment having a basic problem like this.
Also might try some Mix31 or 61 on the leads if this is "instability" is an issue for you. My Fluke 189 is a good transmitter of RF.
👍👍
Did you notice, that, the "Internal Temperature measurement value" is 27C on that meter, but was about 19C on the "Production" meter?. I don't know how much of a difference that makes in that DC mV test, but the disparity between the 2 in the same environment seems strange to me. I am also wondering if ambient 60Hz power line noise, or a harmonic of it, might affect the reading as well. That clip on ferrite might not filter out that low a frequency. The 869S has shown it is sensitive to induced noise from an AC power cord near its leads, so, there's something to that issue in some meters.
For me, it's not strange at all. I think you missed that one is a PROTOTYPE, not production and not in cal. I did run a test on these meters using a tape eraser. Those tests are all available on-line if you're interested in watching.
At end of video, you have 4 DMM terminated in chamber. Are they terminated in SHORT or with a LOAD? If a load, what value?
50
It might be a bit off-topic but I'm really curious - is there an explanation why at 5:37 the prototype displays 19c, while the production 1 meter shows ~27c in the top right corner? I assume this is supposed to be the ambient temperature in °C.
As Dave had told me, it was never fully aligned originally and then I loaded newer firmware which I think the format had changed with further messed with the cal. Then, if that is not enough, I damaged the meter during my testing. Then I repaired it. Then to top it all off I changed the hardware to allow the meter to pass my transient tests. Then because it is a prototype, the design also changed. I went over some of that when I reviewed the production meter.
@@joesmith-je3tq I guess the torture the prototype went through would explain why it was off. Thanks for the quick response.
After greeting
I want to get program(labview ) open(vi) of ads1262
how can you help me
You have a website dedicated to LabView and I assume do it for a career. You started asking for my source code 9 months ago. Are you telling me that in 9 months as a professional LV programmer you couldn't figure this out on your own? I'm guessing I spent a day on it at most.
You probably could make a simple shield out of thin single sided PCB material made to fit the board and then tie it to common through a series/parallel R/C network and fix the problem permanently.
If you watched my series on the Gossen, I used a Mu metal (Netic). Still, wouldn't help if it comes in by the antennas I plug into the front.
I guess one has to dig deeper to find out the full path and then look at proposing fixes.@@joesmith-je3tq
@@ebayscopeman This is why I shotgunned it.
next time my meters jitter around i will try a foil wrap
What was that terrible rotating table in the end ? 😂
Turntable in the anechoic chamber. Not sure how many lbs we can put on it but it's fairly beefy.
121GW -> POS