UT139E and UT139S Digital Multimeters - no discussion?

[DavidA]

Many people here seem familiar with the UT139C digital multimeter, however Uni-Trend show a UT139E and UT139S model on their website. However searching for these models on EEVblog returns no results. Not a mention of either of them.

This surprises me, because I'm curious about whether they might be newer than the UT139C, which has been around for a few years now. I'm wondering how the UT139C might stack up against either of these, or indeed other new DMMs like the BSIDE ZT301, which is about 30-60% of the price of a UT139C.

Does anyone know what DMM IC these UT139E/S models use?

[hli]

For the BSIDE ZT301: I did not find any specifications whatsoever, so you don't know its accuracy. It might be cheap, but I would not trust it.
For the UT139E/S: when compared to the 139C, it has the same accuracy. But it comes with Low-Z mode and a LPF for AC measurements. This might be interesting depending on your needs. Apart from that I would assume any review of the 139C with regards to quality would still apply to the 139E/S.

[rsjsouza]

For the BSIDE ZT301: I did not find any specifications whatsoever, so you don't know its accuracy. It might be cheap, but I would not trust it.
For the UT139E/S: when compared to the 139C, it has the same accuracy. But it comes with Low-Z mode and a LPF for AC measurements. This might be interesting depending on your needs. Apart from that I would assume any review of the 139C with regards to quality would still apply to the 139E/S.

I saw the same when comparing the two, with the addition that all models claim to be ETL verified, which gives some added confidence. The UT139C, however, has a "VFD" mode that is usually a LPF on AC measurements.

Regarding quality, it is plausible they are comparable but ideally they should be independently checked by an unsuspicious third party with a random purchase. The E/S models certainly seem newer and are a category on their own - Uni-T bundles them together while separating from A/B/C variants.

[Maxlor]

Mmh, not that interesting, the new models. NCV and AC-LoZ aren't that useful for electronics, and the added bar graph isn't worth the $10 extra (-E vs -C). The -S goes for $70, seems a bit much? I like those EBTN displays, but I don't think I'd pay so much extra just for that? Not to mention that while it looks nice, it also requires more power. I reckon that battery life on the -S model will be 50-100 hours.

[Fungus]

For the BSIDE ZT301: I did not find any specifications whatsoever, so you don't know its accuracy. It might be cheap, but I would not trust it.

The specs are listed in many places, eg. here. It's basically a 0.5% meter, the same as those Uni-Ts. 6000 counts on screen is down in the noise level for meters of this spec (6000 counts is 0.016% accuracy - easily enough for 0.5% readings).

I'd trust one of those as least as much as anything made by Uni-T.

The new wave of low cost meters from China has been extensively discussed here and no problems found. Of the two I own I prefer the ANENG AN860B+ (but that's just me).

Mmh, not that interesting, the new models. NCV and AC-LoZ aren't that useful for electronics, and the added bar graph isn't worth the $10 extra (-E vs -C). The -S goes for $70, seems a bit much? I like those EBTN displays, but I don't think I'd pay so much extra just for that? Not to mention that while it looks nice, it also requires more power. I reckon that battery life on the -S model will be 50-100 hours.

Bar graphs can be useful.

I certainly wouldn't pay extra for a power-sucking screen, no matter how pretty.

[Hydrawerk]

LoZ is shit on UT139E or S. See the page 9 of user manual.
https://drive.google.com/file/d/0B4Jyby-tjH5oOUNDZTREUjdhbDQ/view

[hli]

The specs are listed in many places, eg. here. It's basically a 0.5% meter, the same as those Uni-Ts.

The UT139E is, apart from the DC voltage ranges, more accurate than the ZT301 (e.g in DC amps its 0.7% vs. 1.5%)

6000 counts on screen is down in the noise level for meters of this spec (6000 counts is 0.016% accuracy - easily enough for 0.5% readings).

I think you are confusing accuracy with precision. None of the meters is 0.016% accurate.

I'd trust one of those as least as much as anything made by Uni-T.

I would not trust a $25 meter that claims a 600V CAT III rating. AFAIR the verdict on the UT139 series was that they are OKish for mains voltage (in contrast to the chinese version of the UI61 series which was lacking all the needed input protection). For low-voltage electronics it doesn't matter, however.

[Fungus]

The specs are listed in many places, eg. here. It's basically a 0.5% meter, the same as those Uni-Ts.

The UT139E is, apart from the DC voltage ranges, more accurate than the ZT301 (e.g in DC amps its 0.7% vs. 1.5%)

Resistance is more accurate on the ZT301 (0.5% vs. 0.8% on the Uni-T), so...  Both are accurate enough for ordinary work.

I was really just pointing you to a place to find the specs (you said you couldn't find them).

6000 counts on screen is down in the noise level for meters of this spec (6000 counts is 0.016% accuracy - easily enough for 0.5% readings).

I think you are confusing accuracy with precision. None of the meters is 0.016% accurate.

No, I'm referring to the fact the 6000 counts displayed is enough for 0.5% meters (it's even enough for a 0.05% meter).

[Fungus]

As far as safetyrobustness goes, a UT139C wasn't anything special in Joe's tests:

https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/

It's a little bit better than most of the new Chinese meters but not much.

It's not in what I'd call the "safe" zone, and it's not what's printed on the front (CAT III 600V).

[Maxlor]

It's not in what I'd call the "safe" zone, and it's not what's printed on the front (CAT III 600V).

The safety standards don't require the meters to survive HV spikes, they only require them to protect the user. Joe's tests aren't about safety (which the CAT ratings are.)

[Fungus]

It's not in what I'd call the "safe" zone, and it's not what's printed on the front (CAT III 600V).

The safety standards don't require the meters to survive HV spikes, they only require them to protect the user. Joe's tests aren't about safety (which the CAT ratings are.)

I know joe's tests aren't about safety, that's why I crossed out the word "safety" above. Joe doesn't even test the amps ranges, which is where most of the sparks usually fly.

The first PTC in his Uni-T blew apart at 2/3 of the CAT rated voltage and a small amount of energy. I wouldn't like to be holding it in my hand at 6000V with the full CAT energy levels (which are far higher than joe's little box can manage).

FWIW the video is here for people to decide:

[rsjsouza]

Mmh, not that interesting, the new models. NCV and AC-LoZ aren't that useful for electronics, and the added bar graph isn't worth the $10 extra (-E vs -C). The -S goes for $70, seems a bit much? I like those EBTN displays, but I don't think I'd pay so much extra just for that? Not to mention that while it looks nice, it also requires more power. I reckon that battery life on the -S model will be 50-100 hours.

Bar graphs can be useful.

I agree as well; bargraphs can be quite useful to detect if the meter is set to DC on a line that also has an AC component - especially because this meter does not have AC+DC mode. However, this is only useful if the update rate is fast. Does that warrant the extra $10? YMMV.

I'd trust one of those as least as much as anything made by Uni-T.

I would not trust a $25 meter that claims a 600V CAT III rating. AFAIR the verdict on the UT139 series was that they are OKish for mains voltage (in contrast to the chinese version of the UI61 series which was lacking all the needed input protection). For low-voltage electronics it doesn't matter, however.

Uni-T claims the UT139 line has the ETL seal, which gives confidence it was at least tested at a certain point in time. However, trust is only warranted if the manufacturing process stays the same across the years - Uni-T does not have a stellar reputation in this regard, that is probably Fungus' point above. 

[HKJ]

No, I'm referring to the fact the 6000 counts displayed is enough for 0.5% meters (it's even enough for a 0.05% meter).

I would say that is 10 times to good for a 6000 count meter. It has to measure precise from 600 to 6000, not only at 6000, i.e. the worst precision is always just after a up range shift, that is a 600 reading.

[Fungus]

No, I'm referring to the fact the 6000 counts displayed is enough for 0.5% meters (it's even enough for a 0.05% meter).

I would say that is 10 times to good for a 6000 count meter. It has to measure precise from 600 to 6000, not only at 6000, i.e. the worst precision is always just after a up range shift, that is a 600 reading.

https://en.wikipedia.org/wiki/Benford%27s_law   

I agree though, all meters should be 999, 9999, 9,9999 counts (or whatever). I don't know why they aren't.

[Fungus]

I'd trust one of those as least as much as anything made by Uni-T.

I would not trust a $25 meter that claims a 600V CAT III rating. AFAIR the verdict on the UT139 series was that they are OKish for mains voltage

...'ish'.

All I'm trying to say is that "safety" doesn't belong on a list of reasons to buy a UT139. If you've got it on yours, think about taking it off.

For once-in-a-blue moon checks: If you triple check that the meter's in AC mode and all the cables are in the right holes then I'd trust one of those cheapo meters as much as a UT139.

nb. The type of fuses, etc., aren't really a factor in correct use of the meter, ie. You shouldn't ever be connecting it to AC mains in any of the amps modes.

[Mr. Scram]

Okish isn't ok at all. Anything used for mains should be plenty good and reliable.

[hli]

...'ish'.
All I'm trying to say is that "safety" doesn't belong on a list of reasons to buy a UT139. If you've got it on yours, think about taking it off.

It isn't (thats what my U1252 is for).

For once-in-a-blue moon checks: If you triple check that the meter's in AC mode and all the cables are in the right holes then I'd trust one of those cheapo meters as much as a UT139.

Yes, thats my definition of 'OKish' - be careful, and it will not kill you.

nb. The type of fuses, etc., aren't really a factor in correct use of the meter, ie. You shouldn't ever be connecting it to AC mains in any of the amps modes.

According to https://www.eevblog.com/forum/beginners/opinion-on-a-bside-zt302-multimeter/25/ the ZT302 has no input protection at all (whereas the the UT139C has at least some MOVs and PTCs, even though it could be better). The clearances could be better, and I have not found images of whats happening under the battery holder. To me this is not even 'OKish' (its about as bad as the original UT61E)
So I would not connect the 301/302 to mains, even after triple checking. To me there still is a difference between an $20 and a $40 meter, even if its not that much.

[Fungus]

According to https://www.eevblog.com/forum/beginners/opinion-on-a-bside-zt302-multimeter/25/ the ZT302 has no input protection at all (whereas the the UT139C has at least some MOVs and PTCs, even though it could be better).

None apart from the big yellow thing in the middle labelled "PTC1".


... and those two black things in front of it, which are clamping transistors. That's protection, too.


Also those blue MELF resistors near the fuse:


 

[DavidA]

Does the ZT301 have similar protection components? However I can check for myself soon, as I ordered a ZT301 as I'm curious about it.

EDIT: oh, sorry, those are pictures of a ZT301. I thought we were discussing a ZT302 in the earlier post though. Sorry for the confusion!

[gwojew]

LoZ function suggest that UT139E/S has different input than in UT139A/B/C.
Has anyone got it and is willing to share some photos?
I’m curious if Uni Trend improved this model robust-wise?
I’ve seen Joe’s Smith tests on UT139C, which was very informative, but results were rather average..

[gzfelix]

UT139E.

[gzfelix]

And the fuses UT139E uses.

600V 600mA


600V 10A

[fkfaraz]

hi gzfelix

did u make any video of that e-model or can u make it..... i am really interested in this meter 

even just turning it on and showing some basic measurement will help me a lot to decide..........

[gwojew]

Here’s my UT139S
Board looks pretty much the same - Rev08.1
As far works fine, but I haven't used LoZ function.

[fkfaraz]

hi gwojew

hope u will be doing well.....

can you make any video of that meter..... i am really interested in this meter 

even just turning it on and showing some basic measurement will help me a lot to decide..........
how about the battery life? can u do some basic test?

your help will be really appreciated.