Review and tear-down of UNI-T UT612 LCR meter

[don.r]

Is this not true on other meters like the CEM? IIRC, it had the same issue.

[iloveelectronics]

Is this not true on other meters like the CEM? IIRC, it had the same issue.

I have not tried the CEM so can't comment on that. But the Mastech MS5308 definitely doesn't have that problem. It has a super big and clear LCD display.

[don.r]

Has the PSU issue on the Mastech been sorted yet? I can find the Mastech for about $180 so I may go for that instead since its true 4w.

[iloveelectronics]

Has the PSU issue on the Mastech been sorted yet? I can find the Mastech for about $180 so I may go for that instead since its true 4w.

Last I heard (a couple of months ago) from Mastech directly, they were only taking away the PSU from the package. No modification to the actual unit. They did mention about removing the DC jack altogether in the future, but not sure if they have taken any real action yet.

I may be biased (because I used to sell them) but I think the MS5308 is a very nice unit other than that power adapter issue. Its size makes it perfect as a bench equipment, though maybe not so much as a handheld device.

[Wytnucls]

I wouldn't call the LCD readability a major issue. Just a minor hindrance. The CEM meter has exactly the same display quirk, by the way. At right angle, the LCD is a bit blurred, but still readable. At about 15 degrees and more from vertical the readability is normal. The effect is slightly worse with the backlight on, as seen in the pictures. I got used to it very quickly and don't fret about it.
The main deciding factor should be about true 4-wire measurement requirement, at the same time evaluating the MS5308 own peculiarities, like the lack of a proper calibration button, for instance.

[don.r]

Too bad Uni-T didn't use split jacks like IET. What we really need is a shootout between these... c'mon Dave! 

[spurlte]

I wouldn't call the LCD readability a major issue. Just a minor hindrance. The CEM meter has exactly the same display quirk, by the way. At right angle, the LCD is a bit blurred, but still readable. At about 15 degrees and more from vertical the readability is normal. The effect is slightly worse with the backlight on, as seen in the pictures. I got used to it very quickly and don't fret about it.
The main deciding factor should be about true 4-wire measurement requirement, at the same time evaluating the MS5308 own peculiarities, like the lack of a proper calibration button, for instance.

Thank you for your nice review. I was looking at the EIT-5000, but the price is to high for this recently turned electronic hobbyist. The price for your Uni-T is just about right for my playing around. I am building the jim's audio on ebay Krell KSA-100 digital amplifier. I keep reading about impedance in and out of devices and this is what I really needed a LCR meter that has the impedance parameter. Does the UNI-T UT612 offer impence measuring?

[res1fen4]

I just purchased one but can't get the USB to work on the computer it does not recognize it.

[Wytnucls]

You're not forthcoming with details.
What steps did you follow?
What computer did you try installing it on?
What operating software do you use?

From an earlier post (post #2):
'Be aware that I found an incompatibility with my USB Logitech MX mouse, so I have to disconnect it while using the logging software, otherwise the meter is not seen by the PC.'

[res1fen4]

I Followed the steps outlined in the instruction manual for the install,  I am running windows 7 on an HP laptop I am using the touchpad no mouse. checked for conflicts with other drivers installed and could not find any.

[Wytnucls]

I'm running a Sony Vaio laptop with MS windows 7. Had to reinstall the UT612 software after I had to reformat the hard drive.
This is what I did:
Install the software from the mini disc.
Remove the USB mouse
Connect the USB cable to the meter then the laptop.
Switch the meter on for USB recognition.
Start the software
Connect any DUT to the meter
Press USB on the meter and 'connection' button on the logging software.
Measurements should appear and start filling the database in the software.

If it still doesn't work, I suspect a conflict on the laptop. I'm not sure how to fix that. I have the same problem as yours with the UT61E logging software. My laptop doesn't see the meter. It is still unresolved.
You could try contacting Uni-t, but I doubt they will be able to help you.

 

[torr032]

Can this meter be used for testing polyester capacitors ESR?

[Wytnucls]

Yes, but the values will be wildly different depending on test frequency.
Polyester capacitor datasheets usually quote a maximum DF (dissipation factor) at a specific frequency.

For instance, a new MKP15 220nF should have a DF below 0.003 at 10kHz, to be in tolerance. The batch I have all measure 0.001.
ESR for the same cap varies between 0.1 Ohm and 10 Ohm, depending on test frequency.

[torr032]

Nevermind I bought DE-5000 with both test leads. Still waiting for him to arrive, seamed like a much better value then this uni-t.

[Wytnucls]

What I said earlier applies to any LCR meter, not just the 612.

Prices for the DE-5000 have come down recently, especially from sellers in Japan. If you buy the whole kit though, the values aren't very different. The main advantage of the DE 5000 is its proper 4-wire resistance measurement capability.

[Wytnucls]

I ran a small test to see how the UT612 fared with 10 small 5.6 Ohms resistors and 2-wire measurements.
I did a fresh calibration and used the plug-in test gizmo provided, to eliminate test leads, with a 100kHz current, which provided the best results.
I used the Gossen 30M and Rigol DM3058 with 4W measurements as control DMMs.

The calibrated Gossen and Rigol are very much together, within 2 mOhms, with a 2 mOhms calibration offset taken off.
The UT612 has a large 22 mOhms offset, otherwise doesn't fare too badly, reading within 7 mOhms of the Gossen, after the 22 mOhms correction.
The offset on your meter could be different of course, depending on original manufacturer calibration.
The offset could also be partially attributed to the 2-wire losses in the blade contacts.

[MCCSolutions]

Great Review!

Based upon your review im either going to get this unit and add my own lithium and a recharge port or im going to wait for a better one to come along that is rechargeable and has a better display.

I really wish the big DMM's came with LSR/ESR.......

What do you think about this one in comparison to the UT601 or UT-50D, is it really worth the price difference?

[Wytnucls]

The UT601 and UT-50D are very basic meters, but depending on your requirements, may be all you need. They are not proper LCR meters though, lacking frequency selection and not measuring ESR, dissipation factor and Q. Their range is also much narrower.

[MCCSolutions]

K! Thanks! Yea I do mostly DC PSUs and TVs but im one of those people who would rather have the capability just in case. Looking forward to your next review! 

[HiTech]

Sold my UT-612 on fleaBay. Got tired of positioning the unit "just so" due to the funky display issue as well as a laggy response from one of the push buttons.... I suspect a buss commun. problem (was intermittent). I didn't like the bogus 4-wire clips either.... they shouldn't even be listed as being Kelvin on some of the internet ads selling them. There's no shielding nor proper wiring to the clip halves. I never felt solid about the meter after using it a few times. The Applent AT824 & AT825 cost several more $$ and the quality/performance is far above that of the Unit-T.  I now have an Applent AT825.

[Wytnucls]

The Applent AT825 is more expensive, doesn't power-up or charge from a USB 5V connection and lacks the all important 100kHz test frequency. Not a good trade-off in my book.
Of course, if measuring low value resistors is most of what you do, then a proper 4W system is better. Even then, as I have shown, errors are within 30mOhms on the UT612, which has a best resolution of 1mOhm on the 20 Ohm range.
Shielding is useful for measuring resistor values over 10M with long test leads, but not much else. The UT612 comes with shielded tweezers anyway.
The LCD screen is not an issue really, but if your meter was faulty then I understand your frustrations. I couldn't find your past eBay transaction where you presumably listed the problems with your meter though.

[MarkPalmer]

Take a look at the tables in the back of the Uni-T’s manual.  You will see that just like Agilent’s 100 kHz handheld LCR model it doesn’t have much to offer as far as ranges go at its 100 kHz test frequency, and even what it does offer is at a high percentage of error at 100 kHz.  The Applent AT's include a regular AC charger.  I don't consider a USB charger to be any sort of standard necessity with any test equipment myself or any form of a disadvantage without USB charging. As Applent manufactures a lot of sophisticated battery testing instruments, I imagine they felt it to be safest to not feature USB charging.

-Mark-

[HiTech]

The Applent AT825 is more expensive, doesn't power-up or charge from a USB 5V connection and lacks the all important 100kHz test frequency. Not a good trade-off in my book.
Of course, if measuring low value resistors is most of what you do, then a proper 4W system is better. Even then, as I have shown, errors are within 30mOhms on the UT612, which has a best resolution of 1mOhm on the 20 Ohm range.
Shielding is useful for measuring resistor values over 10M with long test leads, but not much else. The UT612 comes with shielded tweezers anyway.
The LCD screen is not an issue really, but if your meter was faulty then I understand your frustrations. I couldn't find your past eBay transaction where you presumably listed the problems with your meter though.

1.  In all practicality, how often does any hobbyist (or even the professional tech for that matter) need to test capacitance at 100KHz? Perhaps some esoteric switching power supply caps? 10KHz is plenty for the most part IMHO and I will quickly trade that seldom needed feature for the bright, color TFT display of the Applent - and a touch display at that!

2.  For my needs, 4-wire ohms measurement is better accomplished and trusted using my older Fluke 8085A or my Datron any day, before that from a Uni-T product. I didn't but the UT-612 to measure low value resistance.

3.  As for the laggy response of the meter, it's my overall "perception" of it compared to others I've tried. It seems to require more "communications" or measurement time before displaying the results.

4.  You have to admit it's peculiar and noteworthy about the viewing angle issue of the LCD display that seems to plague all production units of the UT612. Gosh, even the LCD display of cheapo $3 DMM that Harbor Freight Tools often gives away for free has good contrast at most any angle. So after some use, yes, the UT612's goofy display became an annoyance to me. I don't want to spend time positioning a meter to effectively view it.... especially when all the other test equipment on my bench needn't that silly bit of attention! Appears to me Uni-T decided to gamble and compromise rather than reject the whole lot of LCD displays. Given that, makes me wonder where/how else they may have compromised on that model?

5.  As for eBay, the meter isn't truly faulty. I simply don't like it's overall response and the bogus 4-wire clips that are sold under the premise as being Kelvin.

[Wytnucls]

Not quite.
The inductance measurement has an extra range at 100KHz (20uH), with a resolution of 0.001uH and the same accuracy of 1%+5.
The capacitance measurement range goes down to 200pF for both frequencies with an accuracy of 2%+5.
But it is not only a matter of low ranges, some components have to be tested at 100KHz to properly compare readings to datasheet specs.
That is why high-end LCR meters have a wide range of test frequencies. Some small thin film caps call for a test frequency of 1MHz.

As for the USB connection, it might not bother you to carry an extra wall wart, but it is hard to deny the inconvenience. The safety issue is probably worse for your AC wall charger.

[Wytnucls]

AFAIK, the UT612 was never advertised as being equipped with a Kelvin connection. The tweezers provided are shielded though and so are the UNI-T clips sold on the internet. Some unscrupulous sellers advertised them as Kelvin, but if you know your meter, it is easy to tell that it has no 4 wire connections: The middle jacks are clearly marked 'GUARD'.

The peculiar LCD screen has been discussed at length. The CEM LCR meter screen is just the same. I really don't think it matters that much, but I understand that some people may be unhappy with it.

I see that some UT612 are available for 120$ or less on eBay now, with free shipping:
http://www.ebay.com/itm/UNI-T-UT612-Multi-purpose-LCR-Meter-Inductance-Capacitance-L-C-R-DCR-Q-D-ESR-/221392747637?pt=LH_DefaultDomain_0&hash=item338c093c75

And yours of course, with the Kelvin clips  :
http://www.ebay.com/itm/Uni-T-UT612-digital-LCR-meter-/171457846139?pt=LH_DefaultDomain_0&hash=item27ebaf1b7b