New TRMS Uni-T UT139C DMM is available now

[adrianf88]

Yeap... I would most definitely do some mains stuff... Testing live wires mostly... But not just sticking the probes in the outlet for the kicks    Hence the need for NCV but anything more than that, i don't think so.

But still some questions remain...

How reliable is it for bench operation only?

How much drift should i expect after 1 year? What about 5?

[adrianf88]

Guess what... I bit the bullet and i bought it... I'm the proud owner of a brand spanking new Uni-T UT139C and i love it. I'll just have to see if it was worth the money in the long run...

[john_p_wi]

Adrian, I'm sure it will be fine as long as you don't do something stupid with it.

I bought one from Franky over the Holidays and it seems to be a great little meter for general bench use.  So far I have only used it in concert with other meters in the development of a low voltage tube filament soft start supply with LED go - no go indication.  The only complaints that I have so far are 1) It shuts itself off too quickly and 2) the resistance reading update time is slooow.  That is OK, I'll just use one of my Flukes for resistance measurements.

Actually, I'll probably order another with a set of mini clips - it is just too handy for general bench use.

[Simon1983]

I also got an 139C some month ago. I already had an Ut81B (the scopemeter) ansd it worked well, but was replaced with a Rigol DS1054z. The 81B is still in use for work at cars, where a scopemeter is handy. On the bench I only use it because it runs from mains over the power plug.

But I really love the UT139C. Is has fast display update speed, good continuity tester, ans its the first UNI-T I own thas really has input protection and big fuses. The only small drawback (as already mentioned) is the auto-off feature. Yes, and if you would want to calibrate it and adjust it to your reference, you can't: No pots in there, just an eeprom which (possibly) stores the calibration data. The UT81B has pots and I trimmed them to match the UT139C so I would have matching meters (good when using both meters in one circuit).

[mos6502]

You can disable the auto-off feature. Hold select while turning the meter on.

[Martini]

Hey!

I'm probably going to pull the trigger on a UT139C in the coming days. I found it listed at 33 € shipped and that seems very reasonnable compared to a Vichy VC99.

I don't think I'll miss the bargraph. One thing I'll miss, though, is the carrying pouch. Any advice on where to find one? Or keywords for the eBay/aliexpress search?

[iloveelectronics]

Hey!

I'm probably going to pull the trigger on a UT139C in the coming days. I found it listed at 33 € shipped and that seems very reasonnable compared to a Vichy VC99.

I don't think I'll miss the bargraph. One thing I'll miss, though, is the carrying pouch. Any advice on where to find one? Or keywords for the eBay/aliexpress search?

I sell one in my eBay store which fits the UT139C rather well: http://www.ebay.com/itm/Double-Layer-Zipper-Carrying-Case-Bag-for-Multimeters-Fits-UT61E-Fluke-87V-/171047385726

[freebil]

  Hello. I would like to buy the ut-139 but I saw that it can measure frequency up to 10Mhz. The ut-61e can measure up to 220Mhz I think. The difference is big but maybe I will go with ut-139c because of the protection and its nvc.
  As I read here its board has different versions and the last version is the fourth. Are there any differences between the versions? May I assume that the last version is better? Thanks

Hello there!
I just got this meter, and well it is quite good for the price. Mine is also the 4.th revision.
I wonder if anyone read the chip's datasheet? It says that there are serial output.
There are also connections on the PCB for communicating(sda,scl) and for calibration 
Apparently the "cal" traces do not lead to the mcu, but the RMS chip if i am correct

I think this link is useful:
http://www.kerrywong.com/2016/03/19/hacking-dtm0660l-based-multimeters/

[Tainer]

  Hello. I would like to buy the ut-139 but I saw that it can measure frequency up to 10Mhz. The ut-61e can measure up to 220Mhz I think.

I can't tell you about different versions, but if you're planning to buy this meter then keep in mind that frequency measurement will only work if the signal has no DC offset. For instance, you won't be able to measure a 0-3.3V PWM from microcontroller and so on. You'll have to AC-couple the signal with an external capacitor.

[freebil]

  Hello. I would like to buy the ut-139 but I saw that it can measure frequency up to 10Mhz. The ut-61e can measure up to 220Mhz I think.

I can't tell you about different versions, but if you're planning to buy this meter then keep in mind that frequency measurement will only work if the signal has no DC offset. For instance, you won't be able to measure a 0-3.3V PWM from microcontroller and so on. You'll have to AC-couple the signal with an external capacitor.

Thanks for the answer. Can ut61e measure it if it has DC offset?

[Tainer]

Can ut61e measure it if it has DC offset?

I don't have a 61E, but user manual says "Input amplitude: (DC electric level is zero)", so I presume the answer is no.

[freebil]

Ok! I pulled the trigger and I ordered one! Are there any alligator clips that can be used with the probes? Maybe these? Thanks.

[pmason]

Ok! I pulled the trigger and I ordered one! Are there any alligator clips that can be used with the probes? Maybe these? Thanks.

I just received mine from China yesterday. I don't know of any alligator clips that are going to work with the probes.  Just buy a set of alligator test leads.

The UT139c feels very good in the hands, and I really like the ability to snap the probes into the back of the case.     The probes are not sharp though. 

[hugatry]

Ok! I pulled the trigger and I ordered one! Are there any alligator clips that can be used with the probes? Maybe these? Thanks.

Those need leads that have 4mm banana plugs on both ends. I haven't tested, but these should work with the probes that came with the meter.

[freebil]

Anyone with 5th revision of the board? Or the last revision is 4?

[electrifying]

What about the current clamp? Does anyone of you have a current clamp for this meter? And if so, where did you buy it? I have been looking around ebay now but the current clamps I can find cost more than the multimeter itself and mostly have a BNC connector. Am I just using the wrong search phrase? The link to a clamp on Amazon from earlier in this thread sais "currently not available". What's the purpose of the clamp connection if it's cheaper to just buy a complete clamp meter instead of an external clamp for the multimeter? 

[crazyguy]

MS3302 Digital AC Clamp Meter
http://www.p-mastech.com/product/detail/392

[electrifying]

That one would probably work, but only for AC by the looks of it. I would like to have a clamp that can also measure DC. I think it must have hall-effect sensors to measure DC. Strange that UNI-T does'nt offer any clamp at all when they advertise that the meter can be used with a "optional current clamp". I bought the meter thinking that I would just buy a clamp for it as soon as I need one... Maybe they are afraid that offering a reasonable current clamp for the UT139C could ruin the sale of their clamp meters...?

[classical]

Sensitive DC clampmeters are not cheap and have to be "calibrated" directly before andin the place of the measrement to compensate the magnetic field of the earth.
Some years ago a bougt a CA 60 from German ELV.de for about 70 EUR. It is "just" a converter i-> u with 1 mV/10 mA: up to 2 A or 1 mV/100 mA for i> 2 A. You need an additional Multimeter or a scope.
If you need 10 times higher resolution next would be Chauvin Arnoux E3N or K1 about 400 to 500 EUR. 

[freebil]

Hello. The 2 fuses are blown now. Where I can find cheap alternatives? I see that the one is 6X32mm(600V, 600mA) and the other 6x25mm(600V, 10A). I found some 250V and maybe I will go with them. The glass fuses are far inferior to ceramic?

[cpalha]

Hi friends

Recently I buy one UT139c from ebay.
But has a problem with temperature measurement, when I compare teperature measuremente, the UT139c, gives less 8ºc from reality.

I check with other k thermocouple, but the difference are the same, and there is no polarity change.

What I can do with this problem? The guy from ebay sais that can refund, but it is only the temperature.
Any ideas to resolve this problem? This ut139c has some temperature sensor inside that can be damaged?

I would prefer try to resolve the problem or change for a newone, but from ebay seems the only solution will be the refund, and this way is no fair to the seller.

Best regards
cp

[Macbeth]

Hi friends

Recently I buy one UT139c from ebay.
But has a problem with temperature measurement, when I compare teperature measuremente, the UT139c, gives less 8ºc from reality.

I check with other k thermocouple, but the difference are the same, and there is no polarity change.

What I can do with this problem? The guy from ebay sais that can refund, but it is only the temperature.
Any ideas to resolve this problem? This ut139c has some temperature sensor inside that can be damaged?

I would prefer try to resolve the problem or change for a newone, but from ebay seems the only solution will be the refund, and this way is no fair to the seller.

Best regards
cp

There is likely a trimmer inside to calibrate the temp. In fact I've found many DMM's with 2 trimmers, 1 for each scale C or F, which is absurd. (Oh are you sure you are reading the correct units C or F?)

If all the other functions on the meter appear in good calibration then a twiddle of one of these trimmers while your K probe is in the vicinity of a known good thermometer is probably all you need to fix it.

eta: Measuring temps using thermocouples requires a cold junction compensation. In a lot of hand helds this will just be hard-coded to a typical 25 celcius lab temp. If your environment is hotter or colder than this then that is why you have a problem.

[cpalha]

Hi Macbeth

Thanks for the answear.
I compared the measure in degrees celcius with a good thermometer from my lab.
In page (6) of this thread we can see the pcb board inside the ut139c and i dont see the trimmers, but i will open it.

best regards
cpalha

[Kbird]

Hi , new Member here but I have been reading the Forums for a while and Ordered a Uni-T 61E, for playing around with small projects at home and measure the odd line voltage thing at work, but at least to me it was doing strange things like when auto ranging while measuring AC voltage of an outlet and getting stuck in Manual mode, so I returned it and replaced it with the UT-139C having read about it here too and knowing it was safer for AC measurements anyway since it has 600v Fuses not 250v  like the UT-61E . However I am sure the 61E was able to do the Red LED test as can my Old POS DMM I have had for 15-20yrs, but my new 139C doesn't seem to be able too ...or I am doing something wrong ?

Is there a good Tutorial on Testing a DMM , incase this one needs to go back too while it can, it seems okay autoranging on AC unlike the 61E ...thanks.

Also I always seem to have an issue measuring AC at an Outlet easily , so my thought was to splice a polarised Lamp cord ( so you can't get it wrong) into a set of cheap DMM leads I still have hanging around in the Shop , and use that instead of the probes?.

Thanks for your help/comments

KB
.

[totalnoob]

Not really a tutorial, but if you go to Youtube and look for, I believe its, MLorton he tested a boat load of meters a few years ago and he uses a multimeter test board that he purchased online and goes through each test in those reviews.  I believe in one of his videos, or in the comments he tells you where he purchased it from.  It contains known values for the various functions that you can test your multimeter against.  Without something like that, you are really just guessing as to whether your meter has a problem or not, although you can probably get close enough if you have multiple multimeters that give approximately the same reading.