Brymen BM789

[joeqsmith]

Hi Joe,
...
Depending on where your lab is, it may worth checking around.
...

In my house, in a spare room.  It's not a business.

But if you have not had yours done in 10-15 years, it may worth the effort if absolute accuracy is important to you, or if your DMMs are required to have current cal due to the type of work you do.

My hobby doesn't require any of my equipment to be in cal.  When I had it calibrated, it was more out of curiosity of how much it drifted.  No alignment was performed.   So it's never been aligned since shipped from the factory.   That's true for my other HP bench meter as well.   

[J-R]

We're definitely off topic at this stage, but another reason the references being discussed are popular is because calibration is easy and inexpensive.  Maybe $5 each way for shipping plus the calibration fee which is only charged after the 2nd year.  So you don't need to ship out your precious.

[joeqsmith]

We're definitely off topic at this stage, but another reason the references being discussed are popular is because calibration is easy and inexpensive.  Maybe $5 each way for shipping plus the calibration fee which is only charged after the 2nd year.  So you don't need to ship out your precious.

 

It would be very naive to think one data point even if it was NIST traceable is considered calibration.  When I had my HP meters calibrated, the reports are lengthy.  They have to check every mode, every range, several points per range, in controlled environment,  after it has warmed up.   For the HP meters, its all automatic using their software but for the BM869s, I suspect it would all be manually performed.  When I had the HP's cal'ed I think it was around $150/ea.  That was with the report.  I assume the costs have gone up over the last 10 years.   The next problem is your cheap standards are not going to be near good enough, even for that one data point.   Part of what I am paying for is the lab's equipment.  The calibrator required for a free harbor freight meter is not the same that is required for the HP34401A.   

Again, if I need the accuracy, I'm have them done by an accredited lab.  I'm not going to waste any time fooling myself.

[Veteran68]

When I had the HP's cal'ed I think it was around $150/ea.  That was with the report.  I assume the costs have gone up over the last 10 years.

When I last checked with a local calibration facility a couple of years ago to have my newly acquired Agilent 34401A calibrated, I was quoted $492 for an A2LA Certification. That was local drop-off & pickup, no shipping included.

I'm a hobbyist and couldn't care less about A2LA or NIST traceability, I just wanted to know for sure that the almost 20 year old meter I'd bought was as accurate as it was capable of, but that price was double what I paid for the meter. So I satisfied myself with my little cheap Chinese references (more than one though, to at least give me a better sample size).

I received my new SDM3065X yesterday and compared it to my warmed-up 34401A, and for DCV and resistance they were identical to the last digit in most cases, in the other cases they were off by 1 count. I was really surprised as I have no clue when the 34401A was last aligned/calibrated, but they are legendary for their stability. The BM869s was used for capacitance comparison since the 34401A doesn't have it, and while it didn't have as many digits it also matched exactly.

I'll take that as plenty good enough for my purposes, and save the calibration money for another piece of test gear.

[joeqsmith]

I can believe five bills on the 34401A today.   

I picked up a used Agilent PNA and looked into having it checked at Keysight for much the same reason you looked at having your meter calibrated.  In my case, I didn't get to a quote as it was so old they no longer offered any service for it.       

The white box I use makes for a decent quick sanity check.  It has a fair number of low temp co decent tolerance resistors, decent APEX voltage reference and a few other bits.   Guessing I have about $500 in that.  The reference IC alone would be over $100.   Not good enough for calibration but that was never the intent.   As you say, plenty good enough for my purposes.

[GuidoK]

I note you haven't quibbled about the chemical resistance, and missed off your list of PE uses "bottles for hydrofluoric acid", which I'll grant is a fringe case, so perhaps "fuel can" is more mainstream.

You think the display glass on the fluke meter is made from PE?
I'm pretty sure it isn't. And I think that is also the part of the meter which will be the part most likely damaged and the part where damage is most visible.

[GuidoK]

Hi,

Are you saying that from your professional experience Brymens don't maintain calibration for long(er) periods of time?

Maybe my Brymen was a one-off, I was just surprised that a brand new factory calibrated multimeter had to be readjusted in a few areas during external calibration to get within its own specifications.
I don't know that at all from the Fluke models at work.
I've been employed there in the testfield since 2003 and am now the manager and jointly responsible for the measuring equipment used.
We have a database for this measuring equipment, where all calibrations since procurement are stored and of course also failures.
No Fluke has ever failed in these years.
Even an ancient Fluke 8060A (100khz TRMS !!!) has survived every calibration until its "natural" retirement.
This is a quality that Brymen must first prove over the decades.
That is why I personally do not let anything come on Fluke meters, it is simply professional quality that has its price and they are simply the industry standard.
Still, I like my BM869s, it has many good approaches and is hard to beat for the money.
And you can buy almost 3 BM869s for the nominal price of an 87V, so it wasn't hard for me to decide for personal use.

Where did you send it to be calibrated (if not in-house?). Thanks 

Welectron offers a calibration service, not only for multimeters (you can choose) and either according to ISO or even DakkS.
They don't do it themselves, they then send it on to the lab.

https://www.welectron.com/Brymen-Multimeter-BM780-BM850s-BM860s-ISO-Calibration

I think this service is good, as a private person you usually can't get it so easily.

I have my Brymen BM869s ISO 17025 calibrated every year, for about 5 years now, and it always passes.
And in those years I've used different labs, including the one that welectron uses.
Also DakkS is an ISO calibration (ISO 17025) so it is a bit confusing that you use ISO without a number (you're probably refering to ISO 9001 if I were to guess).
BTW, the lab that Welectron uses (Esenwein) can't calibrate all functions of the BM869S according to ISO17025. I don't know if Welectron communicates that, but if you seek direct contact with Esenwein they'll tell you that in advance. I think it was capacitance and temperature, but don't hold me to that. For those parameters you get an ISO9001 calibration (so non traceable to national standards).
For me, that wasn't important, I need the calibration purely for DCV and DCmV. For the rest, their service is fine and their price is good.

I don't know why your meter failed calibration, but I'd say based on my own yearly experience that it's not normal.
For me, the BM869S is a very stable multimeter based on 5 years of annual calibrations. You can also see that in one of Dave's recent video's where he pointed out that the specs on DC current on his 786 were better than on the BM869S. However while he was saying this, in his test setup his 786 measured exactly the same value as his 10+ years old BM869, to the last digit. I call that a win for the BM869 no matter what the manual says!
So to me, the BM869S is a very accurate and stable multimeter. Is it more stable than a Fluke? Fluke also makes very good and stable multimeters. However, Fluke doesn't offer a multimeter that is that accurate or has that high of a resolution on the electrical parameters that I use (DC mV and the lower DC V ranges). So hard to say if Fluke would offer such a handheld meter, that it then would be that stable and accurate 

All I can say is that for my use, so the BM869s with interface cable of which I log with 200ms interval (I'm basically measuring electric charge, coulomb), is a setup that costs basically about €270, with the leads, pouch, usb interface etc (that's including VAT). If I were to go to fluke, only the 289 FVF package (basically the same content as the €270 brymen package) could do the same. That package costs about €1120 (incl vat). That's over 4 times as expensive. For that I get a multimeter with lesser factory accuarcy specs, lesser resolution and I think a slower logging interval (I think the 289 can only log every second, so 5 times as slow as the BM869s can).
That is a very easy choice to make for me.

[GuidoK]

especially when you consider the 869 is more designed as a precision high count lab meter than a field test meter.

The BM869S has rubber seals on each seam, including the input jacks. I don't call that particularly a designfeature for a lab meter.
For me, that's something useful for in the field.

[joeqsmith]

.. I need the calibration purely for DCV and DCmV.

Good suggestion so here is another data point.

It appears I purchased the my first BM869s in October 2016 from TME.  So its almost seven years old now.  Again, this meter was damaged during my transient tests.  I performed the repairs using OEM parts (unlike the other meter).  Outside of that, this meter hasn't seen a lot of abuse.  It is however the most used meter I have.   Like the other BM869s, it has never been aligned.   

Brymen specs 0.02% +2d, so 500mV +120uV

Again, using the Fluke 731B reference with a divider trimmed to 0.5V with my HP34401A, the Brymen is 30uV offset.  Again, nothing is in cal and I make no claim about the absolute accuracy.   Still, it's hard not to draw the conclusion that both of these meters would most likely pass calibration if I sent them in.   

[joeqsmith]

For a sanity check of the setup, let's look at one other meter.  This is my Gossen Metrawatt M248B Ultra which is six years old.  While I never damaged the meter, I did have to make several modifications to the German design to get it to perform to American standards.     Really a shame as this meter has the potential.   This meter has never been aligned but it was put though my battery of tests.   

I was going to show the last 121GW meter I purchased that was never modified or abused in any way.  That meter just bounces all over the place.   

Anyway, maybe this provides a bit more confidence in the setup.

[AVGresponding]

I note you haven't quibbled about the chemical resistance, and missed off your list of PE uses "bottles for hydrofluoric acid", which I'll grant is a fringe case, so perhaps "fuel can" is more mainstream.

You think the display glass on the fluke meter is made from PE?
I'm pretty sure it isn't. And I think that is also the part of the meter which will be the part most likely damaged and the part where damage is most visible.

If you take but a moment to actually think about it, the most likely parts of the meter to come into contact with such substances in a lab or workshop are the holster/back, range switch, and buttons.

[GuidoK]

If you take but a moment to actually think about it, the most likely parts of the meter to come into contact with such substances in a lab or workshop are the holster/back, range switch, and buttons.

How so?
If your meter gets splashed with acid, it always miraculously misses the display?
Anyway, for PC to get affected by hydrochloric acid and PE not, that's usually a matter of days if not weeks. You'll have time enough to clean the housing of your meter.
Where the real danger lies is ingress. Both the Fluke 87V as the Brymen BM869s have some ingress protection by having internal seals around the jacks etc.
But by then the acid probably also already got into the jacks, eating away at the metal.
If getting splashed by acid is a real scenario for your DMM use, you should pick your meter based on whether or not it's IP67 rated with sealing plugs on the open jacks, not based on if the housing is made from PE or PC imho.

[AVGresponding]

If you take but a moment to actually think about it, the most likely parts of the meter to come into contact with such substances in a lab or workshop are the holster/back, range switch, and buttons.

How so?
If your meter gets splashed with acid, it always miraculously misses the display?
Anyway, for PC to get affected by hydrochloric acid and PE not, that's usually a matter of days if not weeks. You'll have time enough to clean the housing of your meter.
Where the real danger lies is ingress. Both the Fluke 87V as the Brymen BM869s have some ingress protection by having internal seals around the jacks etc.
But by then the acid probably also already got into the jacks, eating away at the metal.
If getting splashed by acid is a real scenario for your DMM use, you should pick your meter based on whether or not it's IP67 rated with sealing plugs on the open jacks, not based on if the housing is made from PE or PC imho.

That's not a good example imo. Splashing is unlikely unless you're pretty clumsy,  and if you are I don't want to work in the same lab or workshop as you.

A far more likely scenario is contact via contaminated gloves,  which is going to be common in any busy workshop.

[GuidoK]

Well than it's only very minor quantities and you'll have plenty time to clean the meter before the acid actually starts eating away at the plastic.
Maybe it would be more useful to test the ink from the lettering to test it's resistance to acids. I can't imagine that the ink will be more resistant to acid than the plastic, being either PC or PE, let alone eating away that the meter becomes unuseable but with the lettering still on it.

So if that's the only thing you worry about in choosing a meter and want a definitive answer, you'd have to wait until Joe Smith adapts his destructive tests to include various acids in various strength to the lettering, display, plastic and rubber boot.
Or do the testing yourself, as I doubt Fluke or Brymen do these tests with various acids in various strengths.

I works with acids and other corrosive anorganic chemicals all the time (I work in galvanics so highly concentrated acids (in very very large quantities) are no stranger to me), and generally plastics getting attacked by corrosive anorganic chemicals isn't a real problem. Not during the timespan we're talking about. If you're constructing a tank were acids sit in for years, sure, you'd want a tested HDPE or HDPP, but that's a completely different situation.

Besides, if you're handling acids in the concentrations and quantities we're talking about, that could actually start eating away at PC if left over time, you're not working with your standard nitrile doctors gloves anymore.
You'll be wearing really thick synthetic gloves that go up sleeves, and those are usually not the kind of gloves that make operating a multimeter very easy. Certainly not that easy that only the knob is touched and never the display. At least that's my experience when I work with electronic equipment and galvanic chemicals at the same time (and yes, that happens. Not the use of a dmm, but the use of specialized rectifiers and other specialized tools)
So I just don't really see the real world scenario that you have in your head.

The chance that the meter falls of a desk or cabinet is much more likely, so impact resistance of the plastic the housing is made of is way more important. So I guess that is why manufacturers test that and give a spec on that, and not it's chemical compatibility to acids.

Besides if these situations occur in a lab, anorganic chemicals that are that potent that they affect plastics, will only be used under a fume hood. If some worker walks away from that still with his gloves on drenched in the stuff to a bench where a dmm is set up, he'll be denying a lot of H&S regulations, risking his co workers way more than a potential DMM. And if the DMM is set up in the fume hood, it becomes a specialized piece of equipment that probably will be tested in advance if it is suitable for that space and there'd be a protocol how to use it.
The most likely situation of a DMM being exposed to a fairly strong acid is I think in a garage, where some amateur is tinkering away with battery acid (37% sulfuric acid) and is getting it over his multimeter. Althoug I don't think it'll attack the PC plastic unless it's a fair amount and left to dry in for days. I imagine the lettering being gone long before that.
Can't fix stupid, can you?

[joeqsmith]

I bought a couple of used Fluke 97s from an garage.  Both meters have damage from splash or over spray.  When I work on the bikes, the worse chemicals are gasoline (some cocktail of ) and methanol.   I expose the meters I review to these and it's pretty amazing the difference I see between manufactures.  The two problems areas seem to be the screen and lettering. 

If you are interested in seeing how unstable my 121GW is compared with the other two, I made a short clip.  Note, this is the 121GW that was never exposed to any of my testing.  From what I remember, Dave was selling old stock which is what I received for the review so it is not the latest hardware.  The firmware of the day was 2.02.  They were playing a lot with the filters and maybe there is a version that is more stable but slower response??   

 

[GuidoK]

If you are interested in seeing how unstable my 121GW is compared with the other two, I made a short clip.  Note, this is the 121GW that was never exposed to any of my testing.  From what I remember, Dave was selling old stock which is what I received for the review so it is not the latest hardware.  The firmware of the day was 2.02.  They were playing a lot with the filters and maybe there is a version that is more stable but slower response??   

Wow thats just crazy. Thanks for that video.
If a meter keeps hunting around for a certain stable value, what's the point of having a high resolution meter?
Especially in my situation, where I want to log from the meter at a reasonable speed because the value I'm measuring is gradually creeping up or down. The faster the logging, the more accurate the calculated value that's using this input.
I can't imagine how that would look like with a meter that keeps wandering around in such a measuring session. Probably just a very hazy graph line 

And it's quite a bit too, I see 499,78 and 500,19. So 0,41mV uncertainty. Over 0,08%
If you'd only see the one meter and not knowing its measured source, you'd say it's an unstabilized rectified ac transformer or something like that. Certainly not a DC reference standard!

[joeqsmith]

The second one was damaged beyond repair during my evaluation of it or I would repeat the stability test using it.   I do have that prototype 121GW that Dave graciously provided but being a prototype and then my hacking the crap out of it, I don't think we would learn anything by looking at it.   Someone else with a 121GW would need to look at theirs.  Maybe the newer ones are more stable.

However, this thread was really about the BM789 and it only seems fitting that I show mine.  Again, this meter (along with all of my BM78x meters) was provided by Brymen during the development of the meter.  This particular one was after the final changes.  I have never changed anything with the hardware or touched the alignment.   

[AVGresponding]

Well than it's only very minor quantities and you'll have plenty time to clean the meter before the acid actually starts eating away at the plastic.
Maybe it would be more useful to test the ink from the lettering to test it's resistance to acids. I can't imagine that the ink will be more resistant to acid than the plastic, being either PC or PE, let alone eating away that the meter becomes unuseable but with the lettering still on it.

So if that's the only thing you worry about in choosing a meter and want a definitive answer, you'd have to wait until Joe Smith adapts his destructive tests to include various acids in various strength to the lettering, display, plastic and rubber boot.
Or do the testing yourself, as I doubt Fluke or Brymen do these tests with various acids in various strengths.

I works with acids and other corrosive anorganic chemicals all the time (I work in galvanics so highly concentrated acids (in very very large quantities) are no stranger to me), and generally plastics getting attacked by corrosive anorganic chemicals isn't a real problem. Not during the timespan we're talking about. If you're constructing a tank were acids sit in for years, sure, you'd want a tested HDPE or HDPP, but that's a completely different situation.

Besides, if you're handling acids in the concentrations and quantities we're talking about, that could actually start eating away at PC if left over time, you're not working with your standard nitrile doctors gloves anymore.
You'll be wearing really thick synthetic gloves that go up sleeves, and those are usually not the kind of gloves that make operating a multimeter very easy. Certainly not that easy that only the knob is touched and never the display. At least that's my experience when I work with electronic equipment and galvanic chemicals at the same time (and yes, that happens. Not the use of a dmm, but the use of specialized rectifiers and other specialized tools)
So I just don't really see the real world scenario that you have in your head.

The chance that the meter falls of a desk or cabinet is much more likely, so impact resistance of the plastic the housing is made of is way more important. So I guess that is why manufacturers test that and give a spec on that, and not it's chemical compatibility to acids.

Besides if these situations occur in a lab, anorganic chemicals that are that potent that they affect plastics, will only be used under a fume hood. If some worker walks away from that still with his gloves on drenched in the stuff to a bench where a dmm is set up, he'll be denying a lot of H&S regulations, risking his co workers way more than a potential DMM. And if the DMM is set up in the fume hood, it becomes a specialized piece of equipment that probably will be tested in advance if it is suitable for that space and there'd be a protocol how to use it.
The most likely situation of a DMM being exposed to a fairly strong acid is I think in a garage, where some amateur is tinkering away with battery acid (37% sulfuric acid) and is getting it over his multimeter. Althoug I don't think it'll attack the PC plastic unless it's a fair amount and left to dry in for days. I imagine the lettering being gone long before that.
Can't fix stupid, can you?

Yes, vehicle workshops are a good place to get your meter in contact with sulphuric acid, also oil, grease, and solvents of various types. The aggressive cellulose thinners aren't used any more afaik, but brake cleaner for example is a great way to ruin your meter casing (don't ask me how I know     ).

[GuidoK]

However, this thread was really about the BM789 and it only seems fitting that I show mine.  Again, this meter (along with all of my BM78x meters) was provided by Brymen during the development of the meter.  This particular one was after the final changes.  I have never changed anything with the hardware or touched the alignment.   

Yes I saw your video and how fast they fixed that bug you found in the firmware. Very interesting to see them having such a pro-active approach to improve their products.

I'm sure the 78x series will hold up in time just as well as the 86x series and 23x/25x series have. Very well thought out designs and quality materials. On par with Fluke, only for a fraction of the price.
Especially since early this year, Fluke has increased their prices quite a bit here in europe. A BM869S costs €209 (incl tax) with the silicone leads, or more on topic, the BM789 costs €192 with the silicone leads, whereas the Fluke 87V now costs €650 (incl tax) with the crappy pvc leads... 

[joeqsmith]

Someone asked about the Fluke 289's stability.  Personally, don't own one but do have a cheap knock off from UNI-T.  Current price on Amazon is $400 USD.   This meter had the ass blown out of it with my little gas grill igniter (like pretty much every UNI-T product I have looked at).   After repairs using OEM parts, I chopped up the PCB.  I then exposed the meter to much worse transients.   Guessing a brand new one would be as stable (and as easily damaged).     

[joeqsmith]

However, this thread was really about the BM789 and it only seems fitting that I show mine.  Again, this meter (along with all of my BM78x meters) was provided by Brymen during the development of the meter.  This particular one was after the final changes.  I have never changed anything with the hardware or touched the alignment.   

Yes I saw your video and how fast they fixed that bug you found in the firmware. Very interesting to see them having such a pro-active approach to improve their products.

I'm sure the 78x series will hold up in time just as well as the 86x series and 23x/25x series have. Very well thought out designs and quality materials. On par with Fluke, only for a fraction of the price.
Especially since early this year, Fluke has increased their prices quite a bit here in europe. A BM869S costs €209 (incl tax) with the silicone leads, or more on topic, the BM789 costs €192 with the silicone leads, whereas the Fluke 87V now costs €650 (incl tax) with the crappy pvc leads... 

The 87V isn't something I would want for electronics work.  I do like the Fluke 187/9 but but that's really the only handheld meter they offered that I like.  Just a simple no frills high end meter.   I can't argue with how electrically robust all of their products are.   Even their lowest end $50 meter is one of the more robust meters I have looked at.  Mechanically, I am not so sure.  The boot molding on that new 87V I bought looked poor.  When the function switch was tested to 50,000 cycles, it sounded like some dying critter and when I inspected it, the contacts were cutting into the PCB.  Not at all what I would expect from Fluke.     
 
From my testing, Brymen has proven to be right there with the name brands.  Not only some of the most electrically and mechanically robust products on the market but also are withstanding the test of time.    Then there is the fact that they actually make products that I have a use for!  There is a reason I use the BM869s. 

[dseyst]

I have a 121gw serial number 001307 with firmware 2.02 and when reading 500 millivolts from a PDVS2 mini it is perfectly stable and reads 500.00 millivolts exactly.

[dseyst]

My mistake, my 121gw is running firmware 2.05.

[joeqsmith]

I have a 121gw serial number 001307 with firmware 2.02 and when reading 500 millivolts from a PDVS2 mini it is perfectly stable and reads 500.00 millivolts exactly.

Interesting as mine has a nine digit SN.  So I was curious and pulled out the prototype.   It also has 9 digits.  Wanders about the same.  AGAIN TO BE CLEAR, THIS IS A PROTOTYPE AND HAS BEEN HIGHLY MODIFIED TO SURVIVE MY TRANSIENT TESTING!!

The only test equipment running is what is use for the test along with my PC which is maybe a meter away.   Both sets of cables were twisted.   I added some ferrite to both cables and saw no difference.  I did not attempt to shield the 121GW and it's cables.   It's certainly possible it is picking something up but odd that all of the other meters tested have been stable.   


   

[Caliaxy]

Someone else with a 121GW would need to look at theirs.  Maybe the newer ones are more stable.

Mine is as stable as it an be (one count). Bought in 2021, IIRC.