Uni-T UT181A, professional multimeter and data logger

The idea of finding the perfect multimeter has been on my mind for quite a while.
I've already reviewed several multimeters and will link to those reviews; one of them will also feature in this review. But I wanted something good, accurate, and relatively inexpensive.
In this review, I'll show you the multimeter I liked and compare it with its smaller sibling.

Before getting to the review, I'd like to wish all radio amateurs a happy Radio Day.
And by “radio amateur,” I don't just mean people who can contact the other side of the world without the internet or a phone, but also anyone who's simply passionate about electronics.
In short, may you have fewer burned-out components, more new devices, and only the smell of rosin—not magic smoke.
73!

I ordered this instrument back in February, but by the time it arrived and I finally got around to it—partly on foot, too—a lot of time had passed.

Before buying it, I searched online for reviews of this instrument, but unfortunately couldn't find any. There are no reviews on our sites or even on foreign ones.
The only mention, with some tests and a teardown, is on Dave's forum; otherwise, there are only videos that are almost entirely advertising.
So you could say this is the first full review of this instrument.
Although, knowing what Dave thinks of cheap instruments, I suspect his review would have been a little biased.

I'll say up front that this review won't include huge numbers of tests comparing it with other multimeters, but I'll mention the ones I did compare it with.
I've reviewed the following instruments:
VC921 — a compact multimeter that works almost perfectly; it even still has its original batteries.
MS8910 — not quite a multimeter, since it serves a fairly specialized purpose, but it's convenient nonetheless.
ACM04 — a clamp meter with very good accuracy. I liked it, but rarely use it.
MS8240D — a very accurate multimeter; its main downside is probably its large size.
MS8216 — small, simple, and accurate, but it can't measure current.
HK68B — probably the worst value of all the multimeters I've tried. Its specs are quite good, but the price is high.
UT61E— in my opinion, the best-balanced model. Its price, accuracy, and build quality are all excellent, so I can recommend it without hesitation.

I've also reviewed various other measuring instruments.
DS203— if you're a beginner radio amateur with an extra $120–130 in your pocket and want a simple but decent oscilloscope, the DS203 is a good choice.
DSO138 — its main advantage is probably the price, although this oscilloscope probe can also be used to make some pretty good measurements that you can't always make even with “full-size” instruments. And it's a kit, so it's fun to build the instrument yourself.
RLC and ESR meter — one of the most disappointing instruments; I expected more from it.
Universal tester for electronic components — a kit. I hardly ever use it, but it's definitely handy and ideal for beginners.
Another universal tester — the simplest model for those who aren't afraid of the LUT abbreviation.
Second version of a homemade universal tester — it has plenty of features, almost as many as this device can offer, but you'll have to etch, tin, and solder the board again.

I won't mention little things like voltmeters, since they're very simple instruments.

But let's get to the subject of this review.
When I bought it, the multimeter cost $278.62, but the seller had two coupons: one for $5 and another for $3 off orders over a certain amount. I chose the $5 coupon and placed the order, but the second coupon got applied as well, so I got $8 off and paid $270.62. I didn't know before that you could use two coupons.
This multimeter costs about $100 more here. I figured, what's the difference where I buy it? In theory, the instruments should be identical.

And yes, I fully understand that this instrument costs about as much as nearly a hundred cheap 830-series multimeters. But even 1,000 cheap multimeters can't do what this instrument can.

Uni-T is a fairly large company. It's not Fluke, of course, but it does make decent instruments at affordable prices.

The instrument's stated specifications.


The seller shipped the item fairly quickly, but I have serious complaints about the packaging.
It was packed in a plastic bag, with no bubble wrap, and wrapped in tape.


The day the package was delivered to my post office, there was a very heavy rainstorm, which did a lot of damage to the packaging :(
The only consolation was the instrument's protection rating and the bag the kit came in.


Yes, a bag. Quite handy and pretty large.


Unfortunately, there's no shoulder strap, just a carry handle. They're cutting corners :(


Everything inside was packed well; no complaints there. No water even got into the bag, let alone the instrument.




Everything inside is held in place with elastic straps. Though I think a pocket would be useful, since small items could fall out.




Here's everything included in the kit:
1. UT-181A multimeter
2. Set of test leads
3. Two temperature probes
4. Adapter for connecting the temperature probes
5. Power supply
6. Adapter for connecting the power supply
7. USB adapter for connecting the instrument to a computer.
8. Instructions in Chinese and English
9. CD with the software and its instructions.
10. Bag.


Let's take a look at what comes with the instrument.
Along with the manual, they also included a warranty card, which shows that the instrument was made about a year ago.


The power supply is tiny, and outputs a non-standard 10 V.
The adapter for connecting to a computer. One advantage is that it doesn't need drivers. I considered getting the Bluetooth version of this adapter, but the $30 price is holding me back for now.


Temperature probes. They're useful in principle, especially since they can be used simultaneously, but I don't really need them yet.
The test leads are above average quality, with a stated safety rating of CATIII-1000V, CATIV-600V. As far as I can tell from their construction, they meet those ratings.
They even have protection on the ends of the plugs that go into the multimeter.


Adapters.
The first one is for connecting two temperature probes. It's quite convenient, which unfortunately can't be said about the adapter for connecting a power supply.
The thing is, to connect the power supply you have to disconnect the probes and plug in the adapter. In other words, the meter fundamentally cannot measure and charge at the same time.
This is because practically all meters lack galvanic isolation between the battery and the input terminals.
You could add an extra socket, but that would immediately lower the meter's protection rating and cause problems during measurement.


And here he is, in all his glory. The first thing I thought when I took him out of the bag was, “Wow, he's big—but beautiful :)”


I mentioned the well-known Fluke brand at the very beginning for a reason. The meter under review is almost an exact copy of their Model 287 multimeter.
The only external difference is that two buttons have swapped places. Of course, there are actually more differences than you might think.
If anyone still thinks this meter is expensive, I'll point out that it's four times cheaper (at local prices) than the equivalent Fluke, which costs us anywhere from 600 to 1600 dollars. So I think 270 dollars is genuinely cheap.


A few more photos.


The stand locks in the open position.


A nice bonus is the non-slip rubber inserts. Since the multimeter itself has a rubber casing, it's not easy to slide it off the table—a plus.


The multimeter has a 3.5-inch color display with a resolution of 320x240.
The controls are below.
Top row — function buttons; their functions change depending on the operating mode.
Four middle buttons — navigation buttons: left/right/up/down.
Hold — holds the readings.
Range — manual measurement range selection; press and hold to return to automatic mode.
Max/min — displays the maximum and minimum values recorded since the button was pressed, in addition to the current reading. Whenever a value changes (gets even higher or lower), a short beep sounds.
Select — selects additional operating modes, marked next to the mode selector in the same color as the label on the button.
The white button on the left turns the meter on and off. It responds with a delay of about 1 second to prevent accidental switching on or off.
The blue button on the right adjusts the display brightness. The display starts at full brightness when powered on; press the button once for minimum brightness, and again for medium brightness.
Press and hold to turn off the backlight. The power button's backlight then starts flashing to show that the meter is still running.


Operating mode selector:
Compared with the popular UT61, this meter has some obvious differences.
The selector is also divided into two ranges, for high and low voltage.
But it has four positions instead of two, since AC and DC voltage are selected with the switch rather than by pressing the mode button.
Another difference is that AC voltage comes first, rather than DC as on the UT61.
In order, the positions are:
1. AC voltage measurement up to 1000 V.
2. AC voltage up to 6 V
3. DC voltage measurement up to 1000 V
4. DC voltage up to 6 V or temperature measurement.
5. Resistance, audible continuity test, admittance measurement
6. Semiconductor junction test or capacitor capacitance measurement
7. Frequency, duty cycle, and pulse width measurement
8. DC or AC current up to 6 mA
9. DC or AC current up to 600 mA
10. DC or AC current up to 10 A
11. Battery charging mode


The terminals are laid out in the conventional way: the high-current input is on the left, followed by the low-current input, then common, and finally the input for all other measurements.
The two left-hand terminals are a little unusual: they have sensors that detect when a lead is plugged in.


First power-up—or almost the first :)
A small splash screen appears while the meter boots. The power button lights up during startup, then goes dark.
Boot time is about 4–5 seconds.


One great thing about this multimeter is that it turns on with a button, not the mode selector. Besides saving wear on the selector, it’s simply convenient: the meter starts in the mode you used last.
For example, I got used to turning on my old Mastech this way. On newer models with auto-ranging, you have to click through half the selector just to turn them off.
Speaking of the selector, it’s excellent. It turns smoothly, with soft but distinct clicks—none of the familiar rattling you get from cheap meters.
The display looks washed out in the photo, but it’s actually quite bright. You don’t even need to set it to full brightness, and the viewing angles are excellent. I have no complaints.


The back cover has warnings in two languages, along with certification information.
As far as I know, this multimeter is listed in the State Register, at least in Ukraine. So you can have it officially calibrated. And given what it can do, you could even give the power company a hard time if the mains voltage is outside the permitted limits.
There are probe holders above, but they didn’t make it into the shot—and I doubt anyone is particularly interested in them anyway.


To give you a better idea of how much larger this meter is than the popular UT61, I took a few photos of them side by side.
I think the pictures speak for themselves.


Even so, I like both meters, each in its own way.


Next comes a long, tedious description of all the meter’s operating modes.
But since it’s really long, I’ll hide it under a spoiler instead.

That covers the main modes. Now for the additional ones, which were partly why I bought this particular multimeter.
There are fewer of them than the main modes, but I’ll hide them under a spoiler anyway.

After that, of course, I wanted to take the instrument apart. What else would I do?
I’d already seen photos of the internals on blogger Dave’s forum page, but it’s always more interesting to take it apart yourself :)
The bottom cover is removable, but getting it off turned out to be very difficult. At one point I started to think it wasn’t meant to come off, but the photos said otherwise.
The cover is held on by FIVE! screws—or, more precisely, three screws and two small self-tapping screws.
The screws are very well designed. Not only do they thread into metal nuts molded into the case, they also stay in place when you remove the cover.
The two middle self-tapping screws act as additional fasteners. I think they were added during testing of the multimeter, since logically those should be screws too.
As I mentioned above, the cover fits very tightly. This is partly due to the instrument’s stated IP65 protection rating. According to the description, this protection rating means:
6 — Dust cannot enter the device. Complete protection against contact
5 — Protection against water jets from any direction


The multimeter is powered by a rechargeable battery. Capacity: 2200 mAh, voltage: 7.4 V.
Considering that the multimeter may need to run for hours at a time, this is a much more convenient option than batteries.
The battery is removable, but it’s not very convenient to take out. Mine arrived with a good battery, although Dave mentioned on the forum that one buyer received a faulty one and ended up modifying the instrument to use a camcorder battery.


When I removed the cover, I wondered how you were supposed to get the fuses out, but it soon became clear that it’s actually quite easy. The manufacturer molded notches into the plastic beside one end of each fuse, so you can pry it out with a screwdriver. I tried it—it works quite well.
There’s just one downside: why not include at least a couple of spare fuses?


Since what comes next isn’t for the faint-hearted, I’ll hide this part behind a spoiler.

I didn't test the temperature probes because I don't have any accurate sensors at home to compare their readings against. But even from a quick check, the readings seemed quite reasonable. Though I don't think there's much that can go wrong here.
They show roughly the same temperature.


The temperature difference display function. I warmed one of the probes a little with my fingers, and the meter showed the resulting difference. If you warm the other probe, the reading will be negative.


In charging mode, the display shows an animation of the charging process and the current charge level as a percentage.


The software included with the multimeter deserves a section of its own in this review.
It looks a bit like the software that comes with the better-known UT61E, but it's much more capable.
For starters, the software works both ways: it can not only receive live data, but also control the meter.


There were too many screenshots, so I put the rest under a spoiler.

The first tests I ran used a precision voltage reference, which I described in one of my reviews. At the time, I also checked its actual output voltage so I could be confident it was working properly.
A table of the reference's actual output voltages. The first column shows the specified voltage, and the second the actual voltage.


The results were a pleasant surprise—I'd even say they amazed me. The difference from the reference voltage was within the last digit, which can quite legitimately fluctuate.
I was also pleased because I didn't spot a single adjustment control when I took the instrument apart. Most likely, everything is calibrated in software, but I think the chances of finding the necessary software are close to zero.


Now let's move on to the main part of the testing.
Since the multimeter has impressive specifications, I couldn't really test it using whatever components I had on hand, even relatively accurate ones.
So I arranged to go with a friend to the metrology institute.
I didn't photograph the entire testing process because I didn't want to distract people from their work, but I did manage to take a few pictures.

5 V AC.


1. 50 V DC
2. 500 Ω resistance
3. I also checked the UT61E at 20 kΩ.
4. I ran into some difficulties checking the new multimeter's frequency measurement accuracy.
The instrument showed the same error across all ranges.
There are two possible reasons:
1. The tests were run with a sine-wave signal (if I remember correctly), at 1 and 10 V, and the result was the same. The signal generator for the built-in frequency counter may be at fault. I don't know how to fix that.
2. The built-in crystal oscillator's frequency is not set accurately. It might be possible to adjust it, fortunately this doesn't affect the other modes.


5 V DC. You can see that the accuracy is more than excellent, and definitely better than the specified 0.025%.


I put the test results in a table. The only suspicious range was 60 MΩ, but I was told that this can happen near the limits of the range.




While I was at it, I checked the ADC's linearity. The meter was set to the 6.0000 V range and gave the following readings over the 500 µV–5 V range:
0.0004
0.0050
0.0500
0.5000
5.0000 (4.999)

I also tested the Uni-t UT61E, which was featured in this review.
It's a fairly well-known meter that really impressed me with its measurement accuracy despite its low price. I think this will now be my new bench meter, replacing my old 20-year-old M890G.


Just in case, here are the specified specifications.


And the results I got:


The only time the meter behaved inexplicably was when measuring AC voltage at 10 kHz, even though it gave an excellent result when measuring current under the same conditions.


A little more information.
A photo in my hand—the multimeter is hard to call compact :)




That seems to cover everything. Time to sum up.
Pros
Accurate
Feature-rich
Protected
Inexpensive
And simply good-looking

Cons
There’s a problem when measuring frequency :(
No wrist strap for the carrying case

My opinion: I really liked this meter. It’s genuinely well made—well, as well made as a Chinese instrument can be. Of course, it may have more features than many people need, but there are simpler versions, the UT171 and UT71.
The frequency counter issue was the only real disappointment; I didn’t expect that. After all, the function itself isn’t all that complicated (relatively speaking), especially since the UT61 performed brilliantly in this test.
But considering that the meter cost me $265, I’m willing to live with it. I’ll think about fixing the defect, or at least try to figure out what’s causing it.
The UT61 didn’t let me down either. The only thing that raised suspicion was the AC voltage measurement mode at 10 kHz. Otherwise, it’s excellent.

By the way, this multimeter is listed in the state register (at least in Ukraine), but under a different name.
The multimeters listed in our register have different names. The standard model is called the UT181A, but in the register it’s listed as the UTM1181A. This can cause some confusion, since the UT81A multimeter is called UTM181A here, but it’s not the 181A—it’s the 81A, a completely different instrument. Keep that in mind when choosing.

As additional materials, here’s an archive from the instrument’s original disc.

That’s all. I hope you found the review useful.