Author Topic: UNI-T UT-61E  (Read 29195 times)

iloveelectronics

  • Full Member
  • ***
  • Posts: 227
UNI-T UT-61E
« on: October 13, 2012, 12:13:26 AM »
Hello all and hi Martin, Franky here :) I just got myself a UT61E and I must say that I'm really pleased with it thus far!

Despite it being VERY cheap, it is very fast, both in terms of auto ranging (it's lightning fast!!) and its continuity test. Screen update rate is reasonable (about 3 times a second I reckon). It has decent build quality inside and out, obviously not Fluke quality when it comes to input protection and so on but at <20% of the price I wouldn't expect that.

The DCV accuracy was slightly out of spec when I first got it (about 0.15-0.18% low consistently) but after fooling around with some trim pots it's almost spot on now, based on my only references of the DMMCheck Plus and the PentaREF anyway. I have no clue how to adjust the resistance readings as I'm very much a noob but they are within specs out of the box. Can't tell how long it's going to stay accurate though with a cheap meter like this.

It also comes with the software and RS232 cable to connect to the PC. I haven't got a Rs232 to USB converter yet so haven't tested that, but I don't expect any drama there.

Overall for its price I believe it's very hard to find competition!
« Last Edit: October 13, 2012, 04:46:15 AM by iloveelectronics »
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

Kiriakos GR

  • Full Member
  • ***
  • Posts: 208
  • Industrial Electrician - IT
    • ITTSB.EU
Re: UNI-T UT-61E
« Reply #1 on: October 13, 2012, 02:37:59 AM »
Tinkering and calibration adjustment  just few minutes out of the box ?

Franky all those manufacturers have serious equipment as calibration standards,
personally I think that you did a major mistake about tweaking a fresh meter with those devices which are made for hobbyists.   

iloveelectronics

  • Full Member
  • ***
  • Posts: 227
Re: UNI-T UT-61E
« Reply #2 on: October 13, 2012, 03:35:31 AM »
Tinkering and calibration adjustment  just few minutes out of the box ?

Franky all those manufacturers have serious equipment as calibration standards,
personally I think that you did a major mistake about tweaking a fresh meter with those devices which are made for hobbyists.   

You're probably right...LOL! As I mentioned, I'm a newbie and half the time I don't know what I'm really doing :p In any case, it just makes me feel better seeing the readings get closer to what I expect. The meter is so cheap (less than $40 shipped for me) I'm willing to risk messing it all up. I don't really need another meter to be honest, it's another one of those "multimeter addiction" syndrome things! I still have a Brymen 867 to go to in case I want a bit more accuracy and confidence.
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

Kiriakos GR

  • Full Member
  • ***
  • Posts: 208
  • Industrial Electrician - IT
    • ITTSB.EU
Re: UNI-T UT-61E
« Reply #3 on: October 13, 2012, 09:15:27 AM »
In my youth I also took apart one Police car (toy) so to find about their internals,
the problem is that at the age of seven, you are unable to reassembly it.  LOL

MJLorton

  • Administrator
  • Hero Member
  • *****
  • Posts: 817
Re: UNI-T UT-61E
« Reply #4 on: October 15, 2012, 01:06:45 AM »
Hello all and hi Martin, Franky here :) I just got myself a UT61E and I must say that I'm really pleased with it thus far!

Despite it being VERY cheap, it is very fast, both in terms of auto ranging (it's lightning fast!!) and its continuity test. Screen update rate is reasonable (about 3 times a second I reckon). It has decent build quality inside and out, obviously not Fluke quality when it comes to input protection and so on but at <20% of the price I wouldn't expect that.

The DCV accuracy was slightly out of spec when I first got it (about 0.15-0.18% low consistently) but after fooling around with some trim pots it's almost spot on now, based on my only references of the DMMCheck Plus and the PentaREF anyway. I have no clue how to adjust the resistance readings as I'm very much a noob but they are within specs out of the box. Can't tell how long it's going to stay accurate though with a cheap meter like this.

It also comes with the software and RS232 cable to connect to the PC. I haven't got a Rs232 to USB converter yet so haven't tested that, but I don't expect any drama there.

Overall for its price I believe it's very hard to find competition!

Hello Franky!

Hats off to you for getting it....and for Tinkering!!!! I love it!

Now then, someone else warned my about accuracy issues on the UT61E so this is something I will take a close look at that.

Chat soon,
Martin.
Play, discover, learn and enjoy! (and don't be scared to make mistakes along the way!)

Mr Eastwood

  • Sr. Member
  • ****
  • Posts: 271
Re: UNI-T UT-61E
« Reply #5 on: October 15, 2012, 05:25:22 AM »
The DCV accuracy was slightly out of spec when I first got it (about 0.15-0.18% low consistently) but after fooling around with some trim pots it's almost spot on now, based on my only references of the DMMCheck Plus and the PentaREF anyway. I have no clue how to adjust the resistance readings as I'm very much a noob but they are within specs out of the box. Can't tell how long it's going to stay accurate though with a cheap meter like this.

I can't honestly see them on the production-lines messing around trying to really fine-tune these; so long as they are within spec, they probably just pack them in the box.   So you might well be able to squeeze a little bit more out in some cases.   It's always good to have 2 meters just to cross-check though. 
Hey! Frisbee! Far out!

ModemHead

  • Newbie
  • *
  • Posts: 16
    • Mr. ModemHead
Re: UNI-T UT-61E
« Reply #6 on: October 15, 2012, 11:02:02 AM »
I think I'm the one Martin referred to about warning of UT61E accuracy issues.  I have a UT61E here that I purchased early 2012.  The first thing I noticed after opening the box was that it drifts quite a bit on DCV, and resistance is on the low side.  For example, my 5V reference (stability verified with better equipment) may read 4.993V now and 5.002V later.  Most of the time but not always, the excursions are within its specified accuracy.  The most annoying thing is that this drift seems to be accentuated by using other functions. Example, take a DCV reading, then measure a resistance or a capacitor, then go back and take the same DCV reading, and it will be several counts different. It usually drifts back to the original reading within a minute or so.

I have thought about 'tweaking' the DCV calibration pot, but it would be difficult get actual improvement.  The best result I could hope for is to try to center the excursions symmetrically around the actual reference value.  Too much trouble for too little gain.

Given this behaviour, and considering that everything except DCV is specified at +/- 10 counts or more, the last digit is not particularly significant.  My conclusions are that this UT61E is an acceptable 2200-count DMM, but as a 22000-count device, the last digit is just there for entertainment.  I would not trust it even in the short term for relative measurements.

I realize that I'm looking at a sample size of one, which is why I brought it to Martin's attention.  Maybe I have a dud.  Perhaps his sample will act better.  Looking at teardowns and so forth, it does appear that this model has evolved internally.

iloveelectronics

  • Full Member
  • ***
  • Posts: 227
Re: UNI-T UT-61E
« Reply #7 on: October 15, 2012, 01:13:38 PM »
The first thing I noticed after opening the box was that it drifts quite a bit on DCV, and resistance is on the low side.  For example, my 5V reference (stability verified with better equipment) may read 4.993V now and 5.002V later.  Most of the time but not always, the excursions are within its specified accuracy.  The most annoying thing is that this drift seems to be accentuated by using other functions. Example, take a DCV reading, then measure a resistance or a capacitor, then go back and take the same DCV reading, and it will be several counts different. It usually drifts back to the original reading within a minute or so.

My unit doesn't seem to have the problem you described, the DCV settles at a consistent reading very quickly every time, well, in the last few days since I've got it anyway. The warranty card that comes with it says the date of manufacture is 18 July 2012 so they may have had a few more mods since your batch. I do notice that it takes a while for the ACV reading to climb and settle though, but at least it's consistent. I have attached 2 pictures of the PCB in case anyone's interested in taking a look. Sorry about the lighting, I'm not a very good photographer.

One strange phenomenon I encounter though is that if I put the meter in ohm measurement mode, with leads plugged in but the probe tips not touching each other, display showing OL, and then unplug the positive lead swiftly from the socket, most of the time the bargraph would show a drop in reading, and the numerical display would sometimes capture values typically in the range of 1xx to 2xx M Ohms. Depending on which pair of leads I use I can sometimes even get the same fluctuation in readings simply by jiggling the leads! And I'm certain that the probes are not touching each other or any part of my body during the process. Normal resistance measurements are all within spec otherwise though.

Another issue I just found out is that in using the DMMcheck Plus for both DC and AC current measurements, if I use the mA range, the readings are pretty spot on (2-3 counts out or so on a 1.0000 mA reference). However, if I switch to the uA range, it would read 570-580 uA only instead of the expected 1000! I tried the same mA and uA comparison on my not-so-precise Chinese power supply, set it to a current limit somewhere between 1-2 mA, and the readings on both ranges do match each other for the most part. So is it because the DMMcheck's power being too low and the 61E's burden voltage too large on the uA range that it gives such hugely inaccurate reading?
« Last Edit: October 15, 2012, 01:15:39 PM by iloveelectronics »
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

Kiriakos GR

  • Full Member
  • ***
  • Posts: 208
  • Industrial Electrician - IT
    • ITTSB.EU
Re: UNI-T UT-61E
« Reply #8 on: October 15, 2012, 02:45:54 PM »
So is it because the DMMcheck's power being too low and the 61E's burden voltage too large on the uA range that it gives such hugely inaccurate reading?

Test with the Brymen too, and post a picture.

ModemHead

  • Newbie
  • *
  • Posts: 16
    • Mr. ModemHead
Re: UNI-T UT-61E
« Reply #9 on: October 15, 2012, 03:30:50 PM »
My unit doesn't seem to have the problem you described, the DCV settles at a consistent reading very quickly every time ...
Thanks for the report.  It may well be that I have an outlier on the performance curve.

Quote
One strange phenomenon I encounter though is that if I put the meter in ohm measurement mode, with leads plugged in but the probe tips not touching each other, display showing OL, and then unplug the positive lead swiftly from the socket, most of the time the bargraph would show a drop in reading, and the numerical display would sometimes capture values typically in the range of 1xx to 2xx M Ohms. ...
Mine does not do that at all.  In any case, it does not sound like a serious problem.

Quote
Another issue I just found out is that in using the DMMcheck Plus for both DC and AC current measurements, if I use the mA range, the readings are pretty spot on (2-3 counts out or so on a 1.0000 mA reference). However, if I switch to the uA range, it would read 570-580 uA only instead of the expected 1000! ...
Same reading here, about 578uA.  You are correct, it is due to the compliance voltage on the DMMCheck Plus being about 0.54V, which is not enough to overcome the burden voltage of the UT61E, which is roughly 1mV/uA, ie, a 1K-ohm shunt.

iloveelectronics

  • Full Member
  • ***
  • Posts: 227
Re: UNI-T UT-61E
« Reply #10 on: October 15, 2012, 09:04:54 PM »
So is it because the DMMcheck's power being too low and the 61E's burden voltage too large on the uA range that it gives such hugely inaccurate reading?

Test with the Brymen too, and post a picture.

The Brymen doesn't have the problem at all. mA and uA readings agree with each other on the DMMcheck Plus. What picture would you like me to post?
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

Kiriakos GR

  • Full Member
  • ***
  • Posts: 208
  • Industrial Electrician - IT
    • ITTSB.EU
Re: UNI-T UT-61E
« Reply #11 on: October 16, 2012, 07:17:13 AM »
The Brymen doesn't have the problem at all. mA and uA readings agree with each other on the DMMcheck Plus. What picture would you like me to post?

None, I believe you  :-)   



MJLorton

  • Administrator
  • Hero Member
  • *****
  • Posts: 817
Re: UNI-T UT-61E
« Reply #12 on: October 16, 2012, 08:03:49 AM »
I think I'm the one Martin referred to about warning of UT61E accuracy issues.

Yes...so thanks for posting your findings here as well as it will be a handy reference for others.

Cheers,
Martin.
Play, discover, learn and enjoy! (and don't be scared to make mistakes along the way!)

iloveelectronics

  • Full Member
  • ***
  • Posts: 227
Re: UNI-T UT-61E
« Reply #13 on: October 17, 2012, 01:41:56 AM »
Oh, I forgot to mention another issue about the probes. Out of the box they seemed to have poor contact surfaces, not very responsive during the continuity test. Initial tests I did were mainly with other pairs of leads I have around. However, after giving the tips a good round of cleaning with some rubbing alcohol the problem is now solved.
My eBay store: http://www.99centHobbies.com
Email: franky @ 99centHobbies . com

DaveXRQ

  • Newbie
  • *
  • Posts: 15
Re: UNI-T UT-61E
« Reply #14 on: October 27, 2012, 12:56:34 PM »
I see none of the problems you are having though, the +/- 10 counts might seem like it's going to be out of the box but WAIT, it's spec'd by UNI-T for 1 year drift. Frankly, 10 counts doesn't mean the last 10 counts are useless
BUT WAIT! That's on the AC voltage range.
A dear 87v is +/- 1 counts from 6V onwards (not sure about the "high-res" mode), this is 0.1% +/- 2 counts from 2 to 220V rated.
Point in point, 2 counts is pretty good for a meter that actually costs 30-35$ back in china. 35USD$? WOW
BTW, the MS8218 only costs 125USD back in china.
So now you know who's overcharging now? I can get the MS8218 on aliexpress for 150USD and frankly, that's a bit of a cheat but that's global shipping prices
as i can get the MS8218 sent to singapore for the first 500g at 5$ with the following 500g at 3$ and that's the 3 day shipping service (OF course, i have no idea who my china agent is shipping with), not the overpriced EMS rubbish

But really what's wrong with this meter? It's able to measure 220MHz! IT'S AWESOME.

Many things UNI-T got right with the meter itself,
Solid, doesn't creak when you turn it, some meters creak badly especially the BK 2709.
Doesn't slip around on a laminated surface when placed flat, i have a laminated surface right here
You can turn the rotary switch around without the meter rocking left and right
Well ... the LCD has oddly better contrast than the 87v, as well as a big display
when you do open it up, you can notice the design that went into the battery slot, as well how tightly it mates up with the body
as well when you look at how the shell on the bottom part goes right in between the front part, making a good blast shielding
They mount the LCD and it stays on the board and i have seen 50$ meters with the LCD gingerly hanging off the board
Solid feeling soft buttons
Fantastic rotary switch, frankly the only reason to love this meter is for the wonderful rotary switch, nice satisfying CLACK when you turn it off or the Amps range
and only a click on the other ranges
Lightning fast autoranging
Very fast continuity
Beeper is always on BUT the frequency is just about right.
Fast capacitance measurement, trust me, most 4000 count meters get this VERY wrong.

I just feel like the physical design team are 1000 times more competent than the design team of the electronics ...
Decent probes! They only cost 2-3 bucks back in china ... Only need to clean it when new but watch out, in a humid environment a layer of oxide can grow, i've seen even on my Wavetek (Very high quality!) probes
Also to note, the wall of the meter is pretty thick, as with the thickness of the back itself, physically this thing is a beast, sort of.
But i have seen flukes with worser physical qualities, did they hire building designers or what?
I'll say the integrated holster is a nice thing (easier to access battery and fuses), as with the battery + tilting bail
And ... this is the first meter i had that smells VERY nice, the plastic's smell if both of mine do fade away, i am tempted to buy another one ... just for the smell