Author Topic: EEVBlog 121GW Discussion thread  (Read 503062 times)

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Online Brumby

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Re: EEVBlog 121GW Discussion thread
« Reply #1075 on: August 29, 2018, 12:03:40 pm »
Exactly right.

Some time ago there was a discussion about naming the meter and the "121GW" proposition took an unbeatable lead in its support.
 

Offline IanB

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Re: EEVBlog 121GW Discussion thread
« Reply #1076 on: August 31, 2018, 02:59:26 am »
I have not ran a test like this with any of the other handheld meters I have.  None of them can capture data this fast.

Last night I ran a crude test on my BM869s by driving the data interface cable as fast as possible with a test program. I was able to obtain readings over the cable at a rate of about 200 ms per sample. This was done by starting the next read as soon as the previous read was completed and measuring the interval. I may post more on this in another thread after I do a few more experiments.
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Offline MiroS

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Re: EEVBlog 121GW Discussion thread
« Reply #1077 on: September 06, 2018, 10:03:38 am »
Dr Frank was suggesting a higher test current for the low ranges.

I do  not have this metter, but majority of multimeters I touched have always problem with low and high margin of ranges, especialy for lowest  range is a good test for mesuremant capabilities, e.g. current like 100nA, or 1nA.  Even if spec is claiming 0.5 % or so at marginal values for ranges  this might be quite high like 10% for lowest range and test current like 10nA, or 1nA , or 1uA at 1000V etc.

I wonder if GW121 is much different from other mutimeters?  I would think that it might be  actually worst than others due to low burden volatege (?)

 

Online HKJ

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Re: EEVBlog 121GW Discussion thread
« Reply #1078 on: September 06, 2018, 10:22:47 am »
Even if spec is claiming 0.5 % or so at marginal values for ranges  this might be quite high like 10% for lowest range and test current like 10nA, or 1nA , or 1uA at 1000V etc.

You have to look at the full specifications. A tolerance may be 0.5% + 4, the 4 is a very important part of the tolerance specification when measuring low values.
There is also a detail about AC, there the tolerances is usual not valid below 5% to 10% of the range.

I wrote a bit about it here: https://lygte-info.dk/info/DMMTolerances%20UK.html
 

Offline MiroS

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Re: EEVBlog 121GW Discussion thread
« Reply #1079 on: September 06, 2018, 10:27:56 am »
I wrote a bit about it here: https://lygte-info.dk/info/DMMTolerances%20UK.html

Nice article, thanks for sharing. Btw, I know rules , but  I wonder how is doing 121GW comparing to others by tests.
 

Online HKJ

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Re: EEVBlog 121GW Discussion thread
« Reply #1080 on: September 06, 2018, 10:38:58 am »
I wonder how is doing 121GW comparing to others by tests.

When I tested it, it was inside the specified tolerances (with one exception).
https://lygte-info.dk/review/DMMEEVBlog%20121GW%20UK.html
 

Offline MiroS

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Re: EEVBlog 121GW Discussion thread
« Reply #1081 on: September 06, 2018, 10:54:04 am »
I wonder how is doing 121GW comparing to others by tests.

When I tested it, it was inside the specified tolerances (with one exception).
https://lygte-info.dk/review/DMMEEVBlog%20121GW%20UK.html

I can  not find  test with nA test current. Did I missed this?
 

Online HKJ

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Re: EEVBlog 121GW Discussion thread
« Reply #1082 on: September 06, 2018, 10:59:39 am »
I can  not find  test with nA test current. Did I missed this?

My lowest test current is usual 1uA, I did mention that you need to use REL mode.
 

Offline MiroS

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Re: EEVBlog 121GW Discussion thread
« Reply #1083 on: September 06, 2018, 11:31:40 am »
.....range and test current like 10nA, or 1nA , or 1uA at 1000V etc.

Are you trying to apply 1000V with a supply that is limited to a uA and measure the voltage?  If you are trying to measure current, where does the 1KV fit in?   I am not sure what you are asking.

Not uA and not like this, as simple as that:
- 100nA at any voltage (better 10 or 1nA, no idea how 121GW sensitive is)
- 100nA (better 10 or 1nA, no idea how 121GW sensitive is) at 1kV (1kV relative to ground , not accross multiemer)


 

Online HKJ

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Re: EEVBlog 121GW Discussion thread
« Reply #1084 on: September 06, 2018, 11:57:46 am »
Not uA and not like this, as simple as that:
- 100nA at any voltage (better 10 or 1nA, no idea how 121GW sensitive is)
- 100nA (better 10 or 1nA, no idea how 121GW sensitive is) at 1kV (1kV relative to ground , not accross multiemer)

That would be outside the specifications for the meter, it is only rated for 600V to earth.
 

Offline MiroS

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Re: EEVBlog 121GW Discussion thread
« Reply #1085 on: September 06, 2018, 02:14:17 pm »
That would be outside the specifications for the meter, it is only rated for 600V to earth.

I would  not care for specifiation for such tests, but other hand I cannot ask anyone for potentialy destructive tests.
I would also not buy 121GW at this moment for own  tests, it looks not mature to me.
 

Offline Seppy

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Re: EEVBlog 121GW Discussion thread
« Reply #1086 on: September 10, 2018, 12:11:09 am »
That would be outside the specifications for the meter, it is only rated for 600V to earth.

I would  not care for specifiation for such tests, but other hand I cannot ask anyone for potentialy destructive tests.
I would also not buy 121GW at this moment for own  tests, it looks not mature to me.

Are you looking to find leakage current of the voltage range? If so, the leakage at 1kV isn't likely to fit on a straight line curve down to zero, so we would need a few different points.
 

Offline Visitor

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Re: EEVBlog 121GW Discussion thread
« Reply #1087 on: September 16, 2018, 04:03:24 pm »
Hi!

Got my 1.21GW a few days ago.
My first impression was like  :palm: when i saw the glonky springs trying to hold the batteries in place.
Oh my god, what a bad quality battery holder for a 240 EUR Multimeter.
Without aranging the Springs after puting the batries in  the holder they would almost jump out of it.

But the Multimeter itself looks pretty god  :-+
Some measurements in relatve mode makes no sense for me, but i need some more practice.
 

Offline chronos42

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Re: EEVBlog 121GW Discussion thread
« Reply #1088 on: September 16, 2018, 06:34:21 pm »
Hi,
that is true, the battery holders are terrible. That was also my first impression.
The worst springs of all my battery powerd instruments. I have aligned the springs with a small tweezer, so now it lookes a bit better.
Beside of this a great meter with some room of improvement in the firmware.
 

Offline 1anX

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Re: EEVBlog 121GW Discussion thread
« Reply #1089 on: September 16, 2018, 09:51:39 pm »
Hi,
that is true, the battery holders are terrible. That was also my first impression.
The worst springs of all my battery powerd instruments. I have aligned the springs with a small tweezer, so now it lookes a bit better.
Beside of this a great meter with some room of improvement in the firmware.
I think all of us who bought this meter were shocked at the springs fitted in the battery holder. A well made battery holder fitted with springs which are simply too long.

To use a "Dave" expression when reviewing products the springs are a "FAIL"!

Good meter fitted with the wrong length battery springs, how did this get into the production run?
 

Offline stig

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EEVBlog 121GW Discussion thread ESR of capacitors measurment
« Reply #1090 on: September 17, 2018, 07:32:39 am »
Was just wondering if it would get ESR in the capacitance measurment aswell :)
 

Offline CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1091 on: September 17, 2018, 10:36:48 am »
This multimeter has in theory an 50000 counts display , than range switching upward  at 55000 counts but downward at 40000 counts  is supposed to be a feature ?
I find this rather annoying ... lets say  I want to adjust a 5.0000V voltage refference , if I go up beyond 5.5000V I lose the last digit of resolution because is switching the 50V range , but then if I adjust downward I can't get it back since it remains in 50V range until it reaches 4V

« Last Edit: September 17, 2018, 11:21:48 am by CDaniel »
 

Offline Cliff Matthews

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Re: EEVBlog 121GW Discussion thread
« Reply #1092 on: September 17, 2018, 12:20:07 pm »
@CDaniel - Why not use the provided range switch?
 

Offline CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1093 on: September 17, 2018, 12:32:54 pm »
@CDaniel - Why not use the provided range switch?

Because it has autorange ...  |O
 

Offline Cliff Matthews

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Re: EEVBlog 121GW Discussion thread
« Reply #1094 on: September 17, 2018, 02:54:51 pm »
@CDaniel - You said you can't get it back after you turned down V-ref.. go manual to desired range, then flip it back to auto.
 

Offline CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1095 on: September 17, 2018, 04:27:11 pm »
Sure I could , but I don't think is normal to be 2 thresholds , that is my point .
And that was just an example .
« Last Edit: September 17, 2018, 04:28:55 pm by CDaniel »
 

Online newbrain

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Re: EEVBlog 121GW Discussion thread
« Reply #1096 on: September 17, 2018, 04:28:50 pm »
This multimeter has in theory an 50000 counts display , than range switching upward  at 55000 counts but downward at 40000 counts  is supposed to be a feature ?
I find this rather annoying ... lets say  I want to adjust a 5.0000V voltage refference , if I go up beyond 5.5000V I lose the last digit of resolution because is switching the 50V range , but then if I adjust downward I can't get it back since it remains in 50V range until it reaches 4V
I would consider this quite normal, though the hysteresis is a bit on the wide side.

This is what happens with my Fluke 87V:
Counts
Up at
%
Down at
%
6000
6.600
+10
5.40
-10
20000
19.999
+0
16.80
-16(Of course, it can't display > 19999)

The 121GW does it at +10% and -20%.

Sure I can , but I don't think is normal to be 2 thresholds , that is my point .
It's definitely normal! Without hysteresis you would have continuous range change at the threshold, a much worse experience.
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Offline darik

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Re: EEVBlog 121GW Discussion thread
« Reply #1097 on: September 17, 2018, 04:40:49 pm »
Sure I could , but I don't think is normal to be 2 thresholds , that is my point .
And that was just an example .

I have 4 meters. They all have two thresholds like that. I would imagine to prevent excessive autoranging when taking measurements near the threshold value. I believe it's called hysteresis.
 

Offline CDaniel

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Re: EEVBlog 121GW Discussion thread
« Reply #1098 on: September 17, 2018, 04:45:54 pm »
Ok , you are wright , I cheked my other multimeter who has 6,6V up and 6,2V down , which is much smaller and I never noticed since is not around 5V ( I don't think that's random design )
« Last Edit: September 17, 2018, 04:51:31 pm by CDaniel »
 

Offline IanB

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Re: EEVBlog 121GW Discussion thread
« Reply #1099 on: September 17, 2018, 06:19:56 pm »
Sure I could , but I don't think is normal to be 2 thresholds , that is my point.
And that was just an example.

There will always be two thresholds to prevent "hunting" of the auto-range circuit when close to the switch point.
I'm not an EE--what am I doing here?
 


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