Handheld meter robustness testing

[joeqsmith]

Yes that was the test, I frequently use this function and wondered what the result would be from a meter which was unable to settle or stabilise for the capture to occur. 

I am not sure we are still talking about the same video as the problem I am showing in that last video appears not to be related to settling time but rather some problem with the autorange. 

If this is really what you are asking about,  for example, you would like to see the 121GW old hardware placed into its DC function with the Max selected.  Apply the DC biased 60Hz AC waveform and see if the 121GW can detect the DC value?   

[joeqsmith]

I've started looking at the 121's filter response for a few different modes.   As before, I'm doing a sweep from 0.1Hz to 10Hz.    Looking at the older firmware and comparing that with data I collected from the prototype, there appears to be no difference.  I wasn't expecting there to be but its good see reproducible results.  I've also looked that the noise levels of the two meters and nothing odd shows up.    Time to have a look at the newer versions of firmware.   

[CDaniel]

The filter was changed in successive firmware updates for resistance just because we complained that is very sensitive to mains noise ( and still is ) , maybe you should test this , injecting some AC 50/60Hz and compare with other meters .
From my tests is at least 10 times more sensitive than a Fluke ...
The main entry point for noise are the long leads , so a bad designed meter appears to be good when tested with a short testing jig ... that's why some "engineers" hate that people have hands and use them when measuring 


 

[joeqsmith]

The filter was changed in successive firmware updates for resistance just because we complained that is very sensitive to mains noise ( and still is ) , maybe you should test this , injecting some AC 50/60Hz and compare with other meters .
From my tests is at least 10 times more sensitive than a Fluke ...
The main entry point for noise are the long leads , so a bad designed meter appears to be good when tested with a short testing jig ...

It's interesting to see how the filters for the various modes, not just the resistance, have evolved.  This is basically going to be the focus of the next video.   I like your idea of testing the 50/60Hz notch with a direct injection.   I've haven't done much outside of showing the effects of the 60Hz tape eraser. 

Are you proposing mixing a 50/60Hz test signal with another signal (for example, measure 1VDC modulated with a 100mV AC signal), or just injecting the AC?    Did you post any data from your tests?  If so, please provide a link.  I would like to go over it.   

[CDaniel]

Nothing complicated , for resistance inject AC across the test resistor , for every range .
For voltage maybe is enough just to inject an AC voltage and see if the 0 V DC fluctuates .

That tape eraser is a good indication that a meter is sensitive to noise , but you don't know for sure if the noise is entering through inputs or has a problem with the shielding inside , or other issue .

[joeqsmith]

Nothing complicated , for resistance inject AC across the test resistor , for every range .
For voltage maybe is enough just to inject an AC voltage and see if the 0 V DC fluctuates .

That tape eraser is a good indication that a meter is sensitive to noise , but you don't know for sure if the noise is entering through inputs or has a problem with the shielding inside , or other issue .

When you ran this test, did you use a constant voltage for all resistance ranges?   What level?  Both 50 and 60Hz?  Did you center the resistance on each range?   Did you test all the various versions of firmware?   Which Fluke meters did you use as a comparison? 

I am interested in seeing your data if you don't mind along with as much details as you can provide about your setup.   I may attempt to just replicate your testing to see how our results compare.

*****
Also, I am interested in knowing more about your coupling network.   Please fill in some blanks and we can discuss. 

[joeqsmith]

Yes that was the test, I frequently use this function and wondered what the result would be from a meter which was unable to settle or stabilise for the capture to occur. 

I am not sure we are still talking about the same video as the problem I am showing in that last video appears not to be related to settling time but rather some problem with the autorange. 

If this is really what you are asking about,  for example, you would like to see the 121GW old hardware placed into its DC function with the Max selected.  Apply the DC biased 60Hz AC waveform and see if the 121GW can detect the DC value?

Finished looking at the filters.   Attempted using the Max as I described above.   Shown with all 4 meters in parallel.  121 is attached to the Fluke 187.   189 and 187 are connected to the supply.  Note that that DC value for the Fluke 189 matches with the Fluke 187 as it should.   121GW with Max selected showing 5VDC.  The autorange for  AC and AC+DC both appear fine.    Hope this answers your question. 

[Muttley Snickers]

Thanks Joe for your efforts. I could not find any mention of this meters min/max operation anywhere else and as you already had it alongside some other trusted meters I figured it was a good opportunity to ask if this feature was in agreement with the others.

[joeqsmith]

Oh, you just wanted to see how the min/max compared with others, not if it was able pick up the high voltage in this particular test case.   It was your mentioning that last video that threw me off. 

The 121GW has that 1ms peak detect as well as the auto and manual hold.    These are all covered in the manual. 

[Muttley Snickers]

Sorry, I probably could have worded that request a bit better, it was more the meters ability to capture rapidly changing readings and how it compared against the others in that particular mode.

[joeqsmith]

Now that I believe I understand what you are looking for, I've shown similar tests in the past.   I'll just follow that same sort of format.   I suspect the software video will be a little short so maybe I can include it with part 5.   

******
For those of you that joined my poll, you voted to see this meter ran by a large margin over the Gossen and Hitachi.    If you feel something is missing, now is the time to speak up.   This following is the order that I plan to run these tests.   

Part 6 will include the drop test, chemical  exposure, temperature things of that nature where I am not expecting to see any problems. 

Part 7 will be the transient tests.   Per Franks posts, the first thing I plan to do is have a look at the front end and see what they have done.  Then we can do some DC checks to try and get a feel for what to expect.   This test will include the typical AC line tests,  my grill starter, the large ESD gun and then the higher energy transients.   The prototype had not problems surviving the gas grill starter test but with the new improved front end, it may be worth having another look.  I didn't have the gun built back then, so that will be a new test.  The latest manual states "Transient Protection6 kV 2 Ω, Pulsed Source".   If the meter is still alive at the 5.8KV, I think we need to celebrate.       

Part 8 life cycle the switch.  No spit shine, no cleanups, no yellow post it notes,   just 50,000 full cycles.   I'll compare the contact resistance with other meters and we can have a look with my new used microscope head.   

After this, I would say anything goes. 

[CDaniel]

We all wait that switch test 

Meantime , my setup was simple , signal generator , constant voltage in parallel with the DUT resistor , I cranked up the voltage untill the value displayed fluctuates . I didn't choose the resistor to be in mid range or something ... of course you can standardise the setup as you wish .
The Fluke used were an 187 and an 867B graphical multimeter . So at 1Vpp 50Hz/60Hz 121GW fluctuates like mad but in a Fluke I could inject up to 10Vpp with minimal fluctuations , maybe 2-3 counts .
For Volts DC I didn't found to be a lack of filtering , the results were similar , of course I my test was mainly qualitative , not to measure exactly . You can go as deep as you like 

[joeqsmith]

I hope to get a part done each week, so in about 4 weeks I hope to show the results of the switch test.   

We all wait that switch test 

Meantime , my setup was simple , signal generator , constant voltage in parallel with the DUT resistor , I cranked up the voltage untill the value displayed fluctuates . I didn't choose the resistor to be in mid range or something ... of course you can standardise the setup as you wish .
The Fluke used were an 187 and an 867B graphical multimeter . So at 1Vpp 50Hz/60Hz 121GW fluctuates like mad but in a Fluke I could inject up to 10Vpp with minimal fluctuations , maybe 2-3 counts .
For Volts DC I didn't found to be a lack of filtering , the results were similar , of course I my test was mainly qualitative , not to measure exactly . You can go as deep as you like 

Very odd.   This is pretty basic stuff,  so lets try and clear up what you are asking.   Anything I have that works down to 50Hz is DC coupled and will have a 50ohm source. These are meant to drive a 50ohm load.  Let's ignore that and say you plan to go directly across the test resistor.    I would expect placing that 50ohm source in parallel with a 50ohm test resistor for example will yield somewhere around 25ohms.     Placing it in parallel with a 20Meg will yield something around 50ohms.  You could add a large blocking cap (reason I asked about the coupling network) to strip the DC but you never mention it.   

Let's just ignore all of that basic detail and assume your generator is DC coupled and is capable of driving 20Vp-p, with a 50ohm source.    Now run that to a 50ohm thru terminator.  Again, I would expect 25 ohms with the generator output set to 0V.   At least we are in the center of the 50 ohm range.   Assuming this setup is what you are doing, I would fully expect both meters to be effected as you turn up your generator to 20Vp-p.   Maybe an offset.   

With the 121GW, I suspect it will depend on the firmware that is installed.   If you installed 2.02 for example, with your generator set to 2 volts (for your 1V test case), I wouldn't be surprise to see that meter still be all over the place.   As Dave's speed test video shows, in that 50ohm range we can guess that they have continued to move the cutoff higher.  From the tests I show, we could see the 1.00 firmware provided a much more stable display than 2.02 which also backs up what I am suggesting.

We know the meter is sensitive to the 60Hz from the tape eraser.  I can only imagine what directly injecting a 1Vp-p signal will do to it. 

[barjammar]

I can’t find suggestions for improvements for the 121GW but Dave should certainly adjust the bottle opener. (See Video).

[CDaniel]

I hope to get a part done each week, so in about 4 weeks I hope to show the results of the switch test.   

We all wait that switch test 

Meantime , my setup was simple , signal generator , constant voltage in parallel with the DUT resistor , I cranked up the voltage untill the value displayed fluctuates . I didn't choose the resistor to be in mid range or something ... of course you can standardise the setup as you wish .
The Fluke used were an 187 and an 867B graphical multimeter . So at 1Vpp 50Hz/60Hz 121GW fluctuates like mad but in a Fluke I could inject up to 10Vpp with minimal fluctuations , maybe 2-3 counts .
For Volts DC I didn't found to be a lack of filtering , the results were similar , of course I my test was mainly qualitative , not to measure exactly . You can go as deep as you like 

Very odd.   This is pretty basic stuff,  so lets try and clear up what you are asking.   Anything I have that works down to 50Hz is DC coupled and will have a 50ohm source. These are meant to drive a 50ohm load.  Let's ignore that and say you plan to go directly across the test resistor.    I would expect placing that 50ohm source in parallel with a 50ohm test resistor for example will yield somewhere around 25ohms.     Placing it in parallel with a 20Meg will yield something around 50ohms.  You could add a large blocking cap (reason I asked about the coupling network) to strip the DC but you never mention it.   

Let's just ignore all of that basic detail and assume your generator is DC coupled and is capable of driving 20Vp-p, with a 50ohm source.    Now run that to a 50ohm thru terminator.  Again, I would expect 25 ohms with the generator output set to 0V.   At least we are in the center of the 50 ohm range.   Assuming this setup is what you are doing, I would fully expect both meters to be effected as you turn up your generator to 20Vp-p.   Maybe an offset.   

With the 121GW, I suspect it will depend on the firmware that is installed.   If you installed 2.02 for example, with your generator set to 2 volts (for your 1V test case), I wouldn't be surprise to see that meter still be all over the place.   As Dave's speed test video shows, in that 50ohm range we can guess that they have continued to move the cutoff higher.  From the tests I show, we could see the 1.00 firmware provided a much more stable display than 2.02 which also backs up what I am suggesting.

We know the meter is sensitive to the 60Hz from the tape eraser.  I can only imagine what directly injecting a 1Vp-p signal will do to it. 

This was not meant for the 50ohm range , low resistors , so you kill the generator , that's other story . Use 1K , 10K , 100K , 1M or any values you wish .
Some generators have internal output caps , you can add one , and a voltmeter to measure the actual AC voltage  . Anyway this was not suposed to be an exact voltage test , just to find the root couse why is more sensitive to noise than other meters and ...   the fluctuating reading is what you  see and not something precise to corelate with the input voltage in milivolts 

[joeqsmith]

Normally, I wouldn't use a bottle cap opener on a twist off.   

I hope to get a part done each week, so in about 4 weeks I hope to show the results of the switch test.   

We all wait that switch test 

Meantime , my setup was simple , signal generator , constant voltage in parallel with the DUT resistor , I cranked up the voltage untill the value displayed fluctuates . I didn't choose the resistor to be in mid range or something ... of course you can standardise the setup as you wish .
The Fluke used were an 187 and an 867B graphical multimeter . So at 1Vpp 50Hz/60Hz 121GW fluctuates like mad but in a Fluke I could inject up to 10Vpp with minimal fluctuations , maybe 2-3 counts .
For Volts DC I didn't found to be a lack of filtering , the results were similar , of course I my test was mainly qualitative , not to measure exactly . You can go as deep as you like 

Very odd.   This is pretty basic stuff,  so lets try and clear up what you are asking.   Anything I have that works down to 50Hz is DC coupled and will have a 50ohm source. These are meant to drive a 50ohm load.  Let's ignore that and say you plan to go directly across the test resistor.    I would expect placing that 50ohm source in parallel with a 50ohm test resistor for example will yield somewhere around 25ohms.     Placing it in parallel with a 20Meg will yield something around 50ohms.  You could add a large blocking cap (reason I asked about the coupling network) to strip the DC but you never mention it.   

Let's just ignore all of that basic detail and assume your generator is DC coupled and is capable of driving 20Vp-p, with a 50ohm source.    Now run that to a 50ohm thru terminator.  Again, I would expect 25 ohms with the generator output set to 0V.   At least we are in the center of the 50 ohm range.   Assuming this setup is what you are doing, I would fully expect both meters to be effected as you turn up your generator to 20Vp-p.   Maybe an offset.   

With the 121GW, I suspect it will depend on the firmware that is installed.   If you installed 2.02 for example, with your generator set to 2 volts (for your 1V test case), I wouldn't be surprise to see that meter still be all over the place.   As Dave's speed test video shows, in that 50ohm range we can guess that they have continued to move the cutoff higher.  From the tests I show, we could see the 1.00 firmware provided a much more stable display than 2.02 which also backs up what I am suggesting.

We know the meter is sensitive to the 60Hz from the tape eraser.  I can only imagine what directly injecting a 1Vp-p signal will do to it. 

This was not meant for the 50ohm range , low resistors , so you kill the generator , that's other story . Use 1K , 10K , 100K , 1M or any values you wish .
Some generators have internal output caps , you can add one , and a voltmeter to measure the actual AC voltage  . Anyway this was not suposed to be an exact voltage test , just to find the root couse why is more sensitive to noise than other meters and ...   the fluctuating reading is what you  see and not something precise to corelate with the input voltage in milivolts 

Even with a shorted output, I wouldn't expect it to kill a generator.   That would be a pretty poor design.    I would expect 1K to read around 47.6 ohms.   As you go higher in values, you will be closer to 50 ohms.  Again, just the basics.    So, no I wouldn't expect a change using the values you mention but it would allow you to get your 20Vp-p with a 10Vp-p generator. 

If your generator is AC coupled, provide the value that it uses, or a brand and model number for yours and maybe I can sort it out.   Again, I am interested in knowing exactly what test you ran and their results.  The more details you supply, the better. 

For testing the filters, as I mentioned, I just expanded on the tests I ran on the prototype over a year ago.  It paints a very clear picture of how the firmware has evolved over the last few years.   

[CDaniel]

Just test it if you want , it takes 2 min ... I doubt you will see different results because of the generator brand and output cap . Even if you apply an offset it is not important for lack of filtering . This is a comparative test after all , if you test all meters with the same generator and the same conditions should be fair enough .

[3db]

Hi Joe
Just a wee note to thank you once again for the time,effort,expertise and MONEY you put into testing these meters.
Best regards
3db

[joeqsmith]

Hi Joe
Just a wee note to thank you once again for the time,effort,expertise and MONEY you put into testing these meters.
Best regards
3db

Thanks.   Good to hear you are still enjoying them after all these years.   

Next segment may be a little late as I am hoping to add more to the mix for Muttley.   

[bc888]

Ditto what he said. Just so you know joe, I've read every post at least once, learned a LOT. Thank you for that too.

[Cliff Matthews]

Ditto what he said. Just so you know joe, I've read every post at least once, learned a LOT. Thank you for that too.

Ditto here too. I'm too old to read every post but dang it, the testing's great! (I still miss the earlier fireworks fun) 

[joeqsmith]

Ditto what he said. Just so you know joe, I've read every post at least once, learned a LOT. Thank you for that too.

Ditto here too. I'm too old to read every post but dang it, the testing's great! (I still miss the earlier fireworks fun) 

Thanks again for all the comments. 

One downside to looking at higher end products is we don't see a lot of fireworks.   Maybe the 121GW will put on a show. 

Still waiting on parts... 

[Kosmic]

Ditto what he said. Just so you know joe, I've read every post at least once, learned a LOT. Thank you for that too.

Ditto here too. I'm too old to read every post but dang it, the testing's great! (I still miss the earlier fireworks fun) 

I also echo those comments. Watched most of your videos, good stuff 

[joeqsmith]

Thanks.

It's looking like the part I am waiting for to run the test for Muttley is due this coming Monday.  Hopefully I can get things rolling again soon.   The 121GWs are starting to look a little too comfortable.    Rest while you can boys...

[joeqsmith]

My parts made it in early, so I ran some tests for Muttley Snickers and finished things up.