UNI-T UT-181a – what am I doing wrong? (BIG bandwidth on AC Volts range ?)

[evava]

Hello folks,
I noticed lately too optimistic (IMHO) bandwidth of UT-181a meter on ACV range (TRMS).
For -3dB (in comparison with 100Hz signal): sine 1.474MHz, square 1.240MHz, triangle 1.462MHz.
Incomparably larger than on any handheld Fluke?!?

Can someone explain this to me?
(Although I don't even know whether -3dB attenuation is feasible for meters, or just for filters)

[Matje]

Hello folks,
I noticed lately too optimistic (IMHO) bandwidth of UT-181a meter on ACV range (TRMS).
For -3dB (in comparison with 100Hz signal): sine 1.474MHz, square 1.240MHz, triangle 1.462MHz.
Incomparably larger than on any handheld Fluke?!?

Can someone explain this to me?
(Although I don't even know whether -3dB attenuation is feasible for meters, or just for filters)

The -3dB limit is really only used for filters, amplifiers etc.

No meter manufacturer would want to write an accuracy spec of -30% (what -3dB pretty much is) into their manual, and they wouldn't want to guarantee this for a standard DMM.

Have a look into the manual of your meter, there will be a much better accuracy spec than 30% for AC, albeit at a much lower frequency. For measuring HF voltages there are special built meters.

[Wytnucls]

The Fluke 87V has better specs actually:

At 20kHz, the error is within 2%+20.
At the same 20kHz, the 181A error is 3%+40.

[evava]

Thank you both for your answers.
First I was astonished and did not trust my measurements.
Inbetween I assured myself that my measurements are what they are, nothing wrong with them.

I see that -3dB is too inaccurate for meters, yet I think it characterize various meters in some way.

In following table there are results for -3dBV = 0.707Volts RMS from 1.000Volt RMS at 100Hz at three signal shapes (AC Volts range):

frequency for -3dBV	sine	square	triangle
UT-181a	1.474MHz	1.240MHz	1.462MHz
UT-61e	210kHz	211kHz	209kHz
Fluke 187	210kHz	186kHz	208kHz
Fluke 289	200kHz	178kHz	199kHz
Fluke 87V	114kHz	86kHz	111kHz
Minipa ET-997TR	6.6kHz	5.5kHz	6.5kHz
UT-210e	2.93kHz	2.66kHz	2.91kHz

(Minipa is low end meter with probably very slow TRMS converter.)

Fluke vs UNI-T duel is presumably caused by input protection circuit, which lacks on UNI-T.
Interesting enough for me, although I do not know whether it's good or bad to have such "input bandwidth" on UT-181a   

Edit: added UT-210e for comparison..

[skander36]

Hi @evava !
I can confirm such a difference between UNI-T 181A and Fluke 289. Plus Agilent U1252B show -3dBV at 330 KHz.
For other waveform, the measurement does not have a practical value. I will not use a DMM to measure but an oscilloscope instead.
Why do you say that UNI-T lacks a input protection circuit ?

[evava]

It is a known fact that UNI-T meters have weak protection against HV surge, sometimes is enough to walk with meter in hand on a carpet 
High static voltage with low energy can damage your meter..

Joeqsmith could tell you more

[skander36]

I know Joeqsmith experiments and tests from some time ago, but even he cannot say that this meter lack input protection . Maybe is not like Fluke, but there is a good input protection on it . If you will look to inside photos attached there are more MOV's and PTC in UT181A that in Fluke 289 . In fact I have seen until now 2 FLuke289 blown , and one with motherboard changed on Fluke service in Holland, but no one UT181A. Sure number of Fluke 289 sales is bigger than UNI-T 181A.
I have measure mains with UNI-T and done logging for ore than 24h and nothing bad has happened.
In fact in my experience with electronics no DMM has been damaged by such transient voltages.
Even at my beginnings (30 year ago) when I have done on cardboard a DMM with a C520D and 3 digit LCD from a slot machine (don't ask how  ) nothing bad has happened . Next DMM (cheap chinese yellow 10$) and also nothing bad was happened . Those things does not have any kind of input protection on them.
I think that if you will not measure at general mains or 380 V equipments , you will not have problems. For this kinds of measurements you must use other protection class tools . Non contact recommended .
Nobody put a grill starter on a DMM inputs  except @Joeqsmith .
Don't forget that this meter has passed UL and Intertek certification.
So to summarize they have a good protection input but nor for grill starters ...
If were looking for troubles I suggest putting a wire outside along a courtyard when is a storm and connect the Fluke to  it . Let see how good it is ...
 

[joeqsmith]

I know Joeqsmith experiments and tests from some time ago, but even he cannot say that this meter lack input protection . Maybe is not like Fluke, but there is a good input protection on it .

It's not a good subject for the beginner.  Obviously I have indeed said that this meter has a problem with input protection and will continue to do so as long as the data supports it.   I will also continue to say that there is a trend for UNI-T brand products to not be very robust when it comes to their front ends.  This isn't my personal feelings.  It's based on the many products that I have tested to their limits when compared with many other products.   You may not like it, but that's how the data looks.

If you will look to inside photos attached there are more MOV's and PTC in UT181A that in Fluke 289 . In fact I have seen until now 2 FLuke289 blown , and one with motherboard changed on Fluke service in Holland, but no one UT181A. Sure number of Fluke 289 sales is bigger than UNI-T 181A.

No doubt you will find specific cases where meter X has been damaged in the field.  So what.  Again, the tests I run are repeated over and over, for each meter I look at.  I ran them using the same conditions to see how they compare.  Sadly, when if comes to UNI-T, they don't perform very well.   

Could I stress a Fluke (pick a model) to failure.  Sure, and I have.   The data is all on-line and free to download.

I have measure mains with UNI-T and done logging for ore than 24h and nothing bad has happened.
In fact in my experience with electronics no DMM has been damaged by such transient voltages.
Even at my beginnings (30 year ago) when I have done on cardboard a DMM with a C520D and 3 digit LCD from a slot machine (don't ask how  ) nothing bad has happened . Next DMM (cheap chinese yellow 10$) and also nothing bad was happened . Those things does not have any kind of input protection on them.
I think that if you will not measure at general mains or 380 V equipments , you will not have problems. For this kinds of measurements you must use other protection class tools . Non contact recommended .

Nobody put a grill starter on a DMM inputs  except @Joeqsmith .

Your ignorance is apparent.  While I took the time in that second video to show how I characterized that grill starter along with how it compares with the IEC 61326 standard, it seems to have escaped you.  Again, it's not a beginner subject but I would expect someone who worked for 30 years to have some basic knowledge of ESD. 

Don't forget that this meter has passed UL and Intertek certification.
So to summarize they have a good protection input but nor for grill starters ...
If were looking for troubles I suggest putting a wire outside along a courtyard when is a storm and connect the Fluke to  it . Let see how good it is ...

Provide the UL report number.   

While their website does show that the 181A was certified for both 61010 and 61326, it's through Intertek.  The same organization that approved the 121GW that has a problem with the autorange and will not always show when possible lethal voltages are present.   I hold less and less stock in these certifications as we see more shit get approved. 

The 61326 standard, which I talked about in that second video is not a safety standard.  In there you will find information on ESD testing and how it compares with that little grill starter.  That particular grill starter puts out hardly anything compared with what the standards call for.  I'm surprised it has damaged any meter. 

You may not understand the basics of transient testing and you may feel the need to defend your purchases.  You may not like that I have sent what many may consider great products to the recycle bins.   You may see the whole thing as a big waste of time and even take offense to it.   In the end, none of that will have no bearing on the data I have  presented.   I suggest you at least try to learn some of the basics.  Then if you have questions about the tests I have ran (after you have read the FAQ),  feel free to ask. 


BTW,   I have heard Gossen actually changed their Ultra but I have yet to confirm it.  Again, there is product that had been through testing and was approved.  While it was VERY robust, it had/s some major issues.   I was told I was on a witch hunt over that meter.   

[skander36]

Hi JoeqSmith ,
It seem that you take personally every reference to your work without read carefully what is written . You are beginning to be sensible to anyone that may have doubts about "your truth " .

1. I write above, in response to idea that the UNI-T is lacks input protection which is false and you cannot deny . "They do not perform very well" doesn't mean that they lack input protection . That I am saying.
2. I believe more in engineers that design UNI-T meters than in your knowledge . At least you can design such a thing ? Or you ignorance cannot help to do this ? You think that you are more clever that they  ?

3. I was not invalidate your experiments, even if they don't have a practical value for me , is your right to do and say anything you like about this domain . I am not offend by the fact that you sent to recycle bin some DMM . Keep it going. I am not considering UNI-t 181A the best DMM. For me Brymen are by far better and my 867s has better accuracy than 181A and Fluke 289. Also logging capability on 181A is nearly useless compared with Fluke 289 , even that the last is displaying graphs more slow.
So I don't have any problem to criticize my DMM's. I don't defend my purchase . Fluke 289 is also my purchase . I defend one and other I condemned ? What are you thinking ?
4. My experience (and the vast majority of people here ) prove that one can use DMM's with weak input protection in electronics area and be safe . This model (181A) is not for power electronics . If you read thorough,  I said that. You cracked a 181A with a grill starter . So what ? That this mean that I cannot use it to measure Volts/Amps  mV AC/DC mA AC/DC , ohms , capacitance and other values ?
To sumarize,  what I am saying is that UNI-T 181A doesn't lack input protection, and can be used safely in electronics . Your experiments and "grill starter characterization" are not engineering breakpoints .

Finally I am not consider @evava user a beginner that do not understand  the danger of electricity . From what is doing and is said in his post I have put him in a category that can understand what I am saying and can discern by itself . 
But I'm considering exaggerated opinion that this meter lack input protection . That's all , and I have exposed my opinion .

[joeqsmith]

Hi JoeqSmith ,
It seem that you take personally every reference to your work without read carefully what is written . You are beginning to be sensible to anyone that may have doubts about "your truth " .

1. I write above, in response to idea that the UNI-T is lacks input protection which is false and you cannot deny . "They do not perform very well" doesn't mean that they lack input protection . That I am saying.

My truth??  I just collect and present data.  Again, you may not like the findings, but that's not my problem.

As I stated during the video, the 181A has some decent parts.  As far as protection is concerned, it's only as good as the weakest part.  The PCB makes up part of that.  And to be clear, when I am talking about protecting, I am not talking about safety.   As I have stated many times, I suspect the font ends of these meters is there to make them robust, to extend their life.  As far as safety, I would guess it has more to do with the mechanics.   But I am not a safety expert and have little interest in that subject.  I am far more interested in a meters ability to survive some basic transients.  This is again why I test at very low energy levels.   

2. I believe more in engineers that design UNI-T meters than in your knowledge . At least you can design such a thing ? Or you ignorance cannot help to do this ? You think that you are more clever that they  ?

Hard to say.  It took very little effort on my part to see the problem with the UT181A and correct it.  I didn't add any cost and could have caught it in the design review.  After repairing mine, I repeated the test that had damaged it and proceeded to run some decent transient through it with no problems.   

I have no interest in designing a handheld DMM. 

3. I was not invalidate your experiments, even if they don't have a practical value for me , is your right to do and say anything you like about this domain . I am not offend by the fact that you sent to recycle bin some DMM . Keep it going. I am not considering UNI-t 181A the best DMM. For me Brymen are by far better and my 867s has better accuracy than 181A and Fluke 289. Also logging capability on 181A is nearly useless compared with Fluke 289 , even that the last is displaying graphs more slow.
So I don't have any problem to criticize my DMM's. I don't defend my purchase . Fluke 289 is also my purchase . I defend one and other I condemned ? What are you thinking ?

I am thinking you know little about what you commented on which is why I suggest you learn more about it. 

4. My experience (and the vast majority of people here ) prove that one can use DMM's with weak input protection in electronics area and be safe . This model (181A) is not for power electronics . If you read thorough,  I said that. You cracked a 181A with a grill starter . So what ? That this mean that I cannot use it to measure Volts/Amps  mV AC/DC mA AC/DC , ohms , capacitance and other values ?
[/quote]

The little grill starter is just one test.  It's not much of an ESD event as I have shown but again, it has damaged several UNI-T products.  It sounds like you have no understanding of ESD and what causes it.  Again, it's just ignorance on your part.  You could fix this if you wanted.  I've certainly damaged things with ESD.   Normally I am careful as a fair bit of my equipment is very sensitive to it.  A handheld meter is the last thing I would expect to be weak in this area. 

To sumarize,  what I am saying is that UNI-T 181A doesn't lack input protection, and can be used safely in electronics . Your experiments and "grill starter characterization" are not engineering breakpoints .

Finally I am not consider @evava user a beginner that do not understand  the danger of electricity . From what is doing and is said in his post I have put him in a category that can understand what I am saying and can discern by itself . 
But I'm considering exaggerated opinion that this meter lack input protection . That's all , and I have exposed my opinion .

ESD is common.  It does not matter if you work in electronics.  If you are ignorant about it, it will more than likely get you at some point.  It's best to educate yourself so you understand how to prevent it.   In the case of the hand held meters, we expect them to survive some basics which is why I test them.   UNI-T as a whole has done very poorly compared with other brands.   I mentioned how we picked up 8 or so UT210Es a couple of years ago and how three of them have now failed due to their switch not being well designed.   It's a cheap meter but I find it useful.   I would have paid triple the cost to get a better product. 

[skander36]

It seem that you missed the point of this thread.
You are so busy to make others to accept your opinion,  that you forget how the discussion was started.
While I am not an expert I am not ignorant in ESD . My experience prove me that with some precautions measures you can avoid more troubles. But this is not a guarantee, obviously.
I was saying that UNI-T does not lack input protection. It is not on the level you test it . But as I can measure anytime in the range they specified is not a problem for me . ESD events can appear and destroy even a Fluke .
As you said you can stressed any meter to failure . So what is you point then ? Some meters are better than others . We all know .
You cannot guarantee that a Fluke, Brymen or any meter that has pass you test will not get blown if an ESD event will happened . So again what is your point ? You can guarantee that my Fluke will not be blown, because on your test it pass ?
The UNI-T can measure mains without any problems unmodified . I don't care if you are not happy with this or not .

My truth??  I just collect and present data. ...

Your ignorance is obvious .
You defend your findings .  You are so identified with this so you begin a crusade against every man that even just touch your work .

Forgive me for disturbing your ego .
Forgive me that I am not granting you the importance that you deserve .
I am so sorry that I've been upsetting you Master, the keeper of all ESD knowledge in the world 

[joeqsmith]

It seem that you missed the point of this thread.
You are so busy to make others to accept your opinion,  that you forget how the discussion was started.

My opinion?? Again, I am running meters to a somewhat standard and presenting the data I collect.  My opinion has nothing to do with it. 

While I am not an expert I am not ignorant in ESD . My experience prove me that with some precautions measures you can avoid more troubles. But this is not a guarantee, obviously.
I was saying that UNI-T does not lack input protection. It is not on the level you test it . But as I can measure anytime in the range they specified is not a problem for me . ESD events can appear and destroy even a Fluke .

What you did is you made a claim about what I personally could say.  You based your claim on your feelings about what you see inside of a meter when you looked at it with your unprofessional eyes and formed your opinion about it.    In your ignorance, you failed to understand that the layout is part of that system.   While I have demonstrated time and time again how poorly UNI-T products perform in these conditions compared with many others,  you only offer your opinion.   

Obviously, if you are going to be posting about me and what I can and can't claim, I am going to call you out.   It's not my ego, it's yours that can't expect that you don't understand what you are looking at.   You can't believe that you have 30 years experience and don't understand the basics.    Again, that's not my problem.  You could correct this but your ego will not allow it.   

As you said you can stressed any meter to failure . So what is you point then ? Some meters are better than others . We all know .

Your sentence following your question IS the point!!!  You follow with, we all know.  In my case, I will certainly claim my own ignorance on this subject which is why I started running these tests in the first place.   I was pretty vocal, stating my opinion about Fluke before I started testing and I was wrong.   I have no problems admitting that.  It was an opinion, based on a very small data set of one very old meter.

You cannot guarantee that a Fluke, Brymen or any meter that has pass you test will not get blown if an ESD event will happened. So again what is your point ? You can guarantee that my Fluke will not be blown, because on your test it pass ?

Again, this is your ignorance on testing.   Of course I can not predict all individual cases.    What I can and have done is show how my grill starter and later my gun compare with the IEC standards.  I can capture how I perform the tests on video and make it available free to the public.  I can record my findings into a spreadsheet that is easily and freely viewed by anyone who cares to learn from them.    I can subject many (I think there were over 70) products to the same ever increasing levels of severity to see how they compare.   I can see trends in this data and point them out.   

The UNI-T can measure mains without any problems unmodified . I don't care if you are not happy with this or not .

I've been upfront that my testing has NEVER been about safety.  If you need a product to work on mains in CAT III and up, I expect you are well educated.    Personally, I am not an electrician.  I seldom have a need to poke around the AC lines.  When I do, I have the proper equipment for it.   I am fine with other people doing what ever they please as long as it doesn't effect me.   I tell people all the time, I am not selling meters and could care less what people buy or how they use their products. 

My truth??  I just collect and present data. ...

Your ignorance is obvious .
You defend your findings .  You are so identified with this so you begin a crusade against every man that even just touch your work .

Forgive me for disturbing your ego .
Forgive me that I am not granting you the importance that you deserve .
I am so sorry that I've been upsetting you Master, the keeper of all ESD knowledge in the world 

I expected no less from you.     

As for evava's original post on BW, I normally measure the 3dB point as part of my reviews now.  UNI-T and some of the other lower end meters are typically faster in this area.  The same with the frequency counter.  Having this higher BW appears to come at a price (or lack of it).   I made a series of videos about a UT61E because it is such a popular meter.  I had damaged them with the grill starter (no surprise) and decided to show the reason why this particular meter is so easily damaged.  As part of this, I changed a few circuits.  One of the things I showed was how it effected the BW.  It was certainly not what I consider optimum, but was more just to try and educate people that may want to understand a basic problem like this and how to solve it.   Personally, I don't consider a handheld meter when looking at >> 100KHz signals.  I would rather give up BW to have a electrically robust product.   

[skander36]

Yeap ... 
You have so much right dear Joe ... 

[joeqsmith]

Yeap ... 
You have so much right dear Joe ... 

Yours it a typical response.  You want to argue with your opinion but have no data  to back it up.   I let the data stand on its own and try to explain it.  You digress to name calling.   

I don't mind spending the time trying to help people understand what is being shown but there are people that can't get beyond their egos and strong feelings about what they believe.   You believe UNI-T designs meters with robust front ends and I doubt there is anything anyone could do to get you to understand otherwise. 

[skander36]

It seem that you live from argues ... not a good principle of life . I'm sorry for you .

Please reread what I am saying :
https://www.eevblog.com/forum/beginners/uni-t-ut-181a-what-am-i-doing-wrong-(big-bandwidth-on-ac-volts-range-)/msg3049824/#msg3049824
You lost the tread trying to punish me  because I was daring to mention your name in this post .

[tooki]

It seem that you live from argues ... not a good principle of life . I'm sorry for you .

Ummm, yeah, one of you two definitely lives to argue, but it’s not joeqsmith...

(And I say this as someone who has had arguments with him.)

[skander36]

It seem that you live from argues ... not a good principle of life . I'm sorry for you .

Ummm, yeah, one of you two definitely lives to argue, but it’s not joeqsmith...

(And I say this as someone who has had arguments with him.)

So you agree with the Joeqmsith aproach , calling me ignorant , and misinterpret every sentence .
Maybe I'm wrong myself , I was try to end this discussion , but I don't know what this guy want from me .
I have argumented my post but I don't want to argument forever with a guy that do not want to understand what I am trying to say and misinterpret my words . L.E.
 I will stop posting here .

[rsjsouza]

Wow... Interesting discussion.

As Joe always said, safety is tested in any other way via the 61010 and other standards, but robustness is indeed quite well covered in his videos. One is very different than the other. Also, if I am not mistaken, the standard cares for the survivability of the operator, not the meter - obviously that, if the meter survives, the operator will probably be fine as well.

Hello folks,
I noticed lately too optimistic (IMHO) bandwidth of UT-181a meter on ACV range (TRMS).
For -3dB (in comparison with 100Hz signal): sine 1.474MHz, square 1.240MHz, triangle 1.462MHz.
Incomparably larger than on any handheld Fluke?!?

Can someone explain this to me?
(Although I don't even know whether -3dB attenuation is feasible for meters, or just for filters)

I just finished shooting a video test of the peak detect mode on several of my meters, which can have a correlation with the bandwidth. Of all my meters, the UT61E won over 87V, 189, BM857, U1282A and U1273A - not surprisingly, it is the one with the least protection of the bunch.

In the past, I also tested the same UT61E in frequency and it's bandwidth is very wide.

This shows to me that a meter with minimal input protection has its place in the lab. My biggest beef is with the fact they claim to meet so and so CAT rating and when they simply don't know or deliberately skimp on input protection (case of my UT61E, which has unpopulated parts).

[tooki]

It seem that you live from argues ... not a good principle of life . I'm sorry for you .

Ummm, yeah, one of you two definitely lives to argue, but it’s not joeqsmith...

(And I say this as someone who has had arguments with him.)

So you agree with the Joeqmsith aproach , calling me ignorant , and misinterpret every sentence .
Maybe I'm wrong myself , I was try to end this discussion , but I don't know what this guy want from me .
I have argumented my post but I don't want to argument forever with a guy that do not want to understand what I am trying to say and misinterpret my words . L.E.
 I will stop posting here .

There's no "joeqsmith approach". He called you ignorant because, well, you have shown your knowledge to be spotty. And you have rejected every bit of information others have provided. So you have low knowledge, yet are acting as though you were some world expert on the subject. It's the tone of your posts, above all else, that are really obnoxious.

To be clear and repeat what others have told you, which is the crux of the problem: input protection isn't about protecting the user (i.e. safety), it's about protecting the meter. So you keep coming back saying that the Uni-T is safe to use… well, yeah. The claim wasn't that it was unsafe, it was that it was not resilient. Joe made it perfectly clear that safety isn't what he is concerned with.

[rsjsouza]

(...)
While their website does show that the 181A was certified for both 61010 and 61326, it's through Intertek.  The same organization that approved the 121GW that has a problem with the autorange and will not always show when possible lethal voltages are present.   I hold less and less stock in these certifications as we see more shit get approved. 

Joe, the issue may also be rooted in the spec itself - the test procedure may have been followed to the "T" by the company but it may not cover the specific scenario (or scenarios).

Not having studied the standard with the depth it deserves, I can only speculate. However, I can imagine that the cert company will better follow the standard or take the brunt of a lawsuit in case some claim is unsubstantiated.

[joeqsmith]

(...)
While their website does show that the 181A was certified for both 61010 and 61326, it's through Intertek.  The same organization that approved the 121GW that has a problem with the autorange and will not always show when possible lethal voltages are present.   I hold less and less stock in these certifications as we see more shit get approved. 

Joe, the issue may also be rooted in the spec itself - the test procedure may have been followed to the "T" by the company but it may not cover the specific scenario (or scenarios).

Not having studied the standard with the depth it deserves, I can only speculate. However, I can imagine that the cert company will better follow the standard or take the brunt of a lawsuit in case some claim is unsubstantiated.

The body that governs the standards may be too large to be effective.   Take the case of magnetic interference.  The standards cover it but they never consider the field that can come from a hanging magnetic strap.   Gossen and now we suspect a French company, decide to release products with latching relays.  With the Gossen, we can see how the magnet from a strap can change their state.  We have also seen how this can cause the meter to be unable to display potentially lethal levels.    Gossen engineering and marketing should have NEVER created such a product but it's not a problem as far as meeting that magnetic part of the spec.

If the company makes a product and knows of such a weakness but doesn't disclose it to the company doing the cert and the person assigned to run the tests does what they are told to the "T", this is what you get.   I agree, the standards ARE lacking. 

These guidelines are not a gold standard.  The companies designing and marketing their products should be taking steps to make sure their products are safe  (FMEAs, FMETs....)   
They are the experts in their field. 

In my case, I'm not being paid by the government or anyone for that matter.  I'm free to spend time learning the product and seeing how it handles some basic conditions.   You don't want some hobbyist, playing in their home with homemade test equipment finding your problems and pointing them out.  Then again we saw where the AVE channel had dumped all over Fluke all the while showing how ignorant they were.   Just crazy someone could be that dumb and claim to actually work in that industry.    Then again, it created lots of views and it's obvious they didn't give a shit about the corporation they were defaming.  So smarter than I give them credit for.   

My goal has never been to defame anyone (though I am sure Dave and others see it otherwise).  It was more just an independent small scale study of the various brands.  If Gossen or UNI-T felt they had their problems solved and wanted me to repeat the test, I would have no problems doing it. 


 

[rsjsouza]

(...)
While their website does show that the 181A was certified for both 61010 and 61326, it's through Intertek.  The same organization that approved the 121GW that has a problem with the autorange and will not always show when possible lethal voltages are present.   I hold less and less stock in these certifications as we see more shit get approved. 

Joe, the issue may also be rooted in the spec itself - the test procedure may have been followed to the "T" by the company but it may not cover the specific scenario (or scenarios).

Not having studied the standard with the depth it deserves, I can only speculate. However, I can imagine that the cert company will better follow the standard or take the brunt of a lawsuit in case some claim is unsubstantiated.

The body that governs the standards may be too large to be effective. 

And would that be anything new?

Keep in mind that standards are committees of folks from the industry and I expect that some compromise is bound to happen - UL themselves has created several internal standards that had become universal/american ones. Heck, and we are not even talking about aeronautics and their latest scandals. 

Take the case of magnetic interference.

Fully agree. 100% shameful for the two companies you mentioned to not acknowledge their mistakes (or alledgedly changing their designs silently).

If the company makes a product and knows of such a weakness but doesn't disclose it to the company doing the cert and the person assigned to run the tests does what they are told to the "T", this is what you get.   I agree, the standards ARE lacking.

My point exactly. Test. Pass. Go.

Despite I am not deeply familiar with the 61010 or 61326 applied to multimeters, I can tell the manufacturer can provide several operation modes and boundary conditions to exercise the DUT. Things such as "which range tests this feature", or "which buttons to press to put the DUT in such and such mode", etc. In the aforementioned case, I can only speculate, but what if the manufacturer simply said that "this meter is a complete product and testing with any accessories is void - if anything, we solve this with a remark in the documentation" or "this meter is not rated for mechanical impact / drop test. All testing shall be performed with the meter on a stable surface", which we all know is BS given the product is portable and the accessories are official.   

These guidelines are not a gold standard.  The companies designing and marketing their products should be taking steps to make sure their products are safe  (FMEAs, FMETs....)   
They are the experts in their field. 

You don't go out much, do you?  This is all a CYA op!

In my case, I'm not being paid by the government or anyone for that matter.

I am still not convinced...
 

Then again we saw where the AVE channel had dumped all over Fluke all the while showing how ignorant they were.   Just crazy someone could be that dumb and claim to actually work in that industry.    Then again, it created lots of views and it's obvious they didn't give a shit about the corporation they were defaming.  So smarter than I give them credit for.   

I agree, the video to me was somewhat alright while he was unsuccessfully trying to use the meter (just data), although I wouldn't jump as quickly as he did to the assumptions when trying such unconventional product for the first time. However, it quickly becomes cringy when he opens the unit (spark gap as diode, resistive network as capacitor... or something ceramic).

[joeqsmith]

These guidelines are not a gold standard.  The companies designing and marketing their products should be taking steps to make sure their products are safe  (FMEAs, FMETs....)   
They are the experts in their field. 

You don't go out much, do you?  This is all a CYA op!

I am guessing is has just as much to do with import/export laws. 

In my case, I'm not being paid by the government or anyone for that matter.

I am still not convinced... (Attachment Link)
 

 

I agree, the video to me was somewhat alright while he was unsuccessfully trying to use the meter (just data), although I wouldn't jump as quickly as he did to the assumptions when trying such unconventional product for the first time. However, it quickly becomes cringy when he opens the unit (spark gap as diode, resistive network as capacitor... or something ceramic).

I cringed as soon as they pulled out that Klein current clamp breakout adapter.    I understand why so many people had written me and I am amazed the guy never recanted.   One funny fact, they were a subscriber to my channel.  No big deal.  But after I called them out, they left.      The fact you could go on a rant like that, feel it's just fine but can't take a little heat when presented with some data with an opposing view, it say's something about your character.   

[rsjsouza]

Joe, who are "they"? AvE?

If so, you got me confused with the gender neutral ling-o-ma-jig...

[joeqsmith]

Joe, who are "they"? AvE?

If so, you got me confused with the gender neutral ling-o-ma-jig...

I was referring to the AVE host.   

[skander36]

...  If Gossen or UNI-T felt they had their problems solved and wanted me to repeat the test, I would have no problems doing it.  ...

It seem that UNI-T has tried to improve the PCB layout on UT181A . Photos from my unit (2020) and from the unit tested(2016) . Maybe is an attempt to address the problem you found.

[joeqsmith]

The areas you are pointing to are for the high current measurement.   I don't keep any metrics for the current.  All of the transient testing is performed between the common and voltage inputs.     Normally if I do anything with current, I will connect them to a bench supply with a few other meters in series.  Sometimes I will run the open fuse test that the IEC standards call out but I use a much lower power supply than what is called for.   

[skander36]

Ok.

[rsjsouza]

Even still, if they did a PCB review to acommodate this change, hopefully they took your video in consideration and modified other sections as well. Without both meters to compare, we can only speculate.

[joeqsmith]

If UNI-T contacted me and said they had made the meter more robust,  I wouldn't be apposed to running another as long as they were willing to stand by their product like Brymen has done.   The same offer would go out to Gossen.   If they really feel they have improved their meter, send it and I will repeat the tests.   I don't hold any malice towards any of these brands and these two meter in particular would both be worth the effort in having another look.