I was living in Bangkok, and had resurrected my past interest in electronics, most notably through using Arduinos. After playing about for a few weeks I realised that I sorely needed a digital multimeter (DMM). I already own one, from my days at university, 27 years ago, a M-776 Precision Gold Autorange Digital Multimeter (with transistor tester and display hold) from Maplin. Cost me £20 at the time, which seemed like a lot of money back then (for a pound you could do the week’s shopping, have a night out on the town, entertain some ladies and still have enough money to get the bus home – not any more, eh?), although I seem to remember it being a top of the mid-range model, so it was worth it.
I have still got the box it came in!
Anyway, I digress… so the M-776 was no good to me back in the UK, when I’m in BKK, so I thought that I might as well splash out and get a new one, for two reasons:
- It is always handy to have two, so that you can simultaneously measure current and voltage, and;
- The newer models were bound to have better features than the M-776
Now, which one to buy?
Hunting down the prey
Before looking anything up on google, I remembered that, back in the day, Fluke were the be all to end all (indestructible, accurate, reliable etc. as well as being the industry standard), so that was the first stop. Looking up the Fluke 87V on eBay, they were going at about £150-£250 second hand. The 87 III seemed a reasonable alternative, but still over the top in price, plus it didn’t really over any new features over the M-778 that I already had, apart from the name and accuracy and what have you. I was slowly realising that I wanted a bells and whistles model.
So, I googles about, extensively, for weeks, obsessing over the details and models, taking notes, recording youtube videos, watching them over and over, noting down URLs… the usual shopping research for the serious connoisseur. Plus I did a bit of running around in the BKK heat to see what was on offer locally and comparing prices with eBay, in particular items originating from China. After all, that is where I had sourced every last piece of Arduino kit, discrete components and ICs. The lead time, post-wise, or EMS as it is known in Thailand was about a week from China, in lieu of the 4-6 week wait back in the UK. Thank Buddha for the Sino-Thai train link!
The BKK window shopping was hell, what with the heat, language barrier and general ineptness of Thai shopkeepers. However, four note worthy locations were:
- the “Amorn” chain of stores, full of (what seemed at the time) dodgy red Chinese UNI-T DMMs that seemed to be very cheap and ranging from pocket wallet DMMs for £10, up to handheld oscilloscopes for £150. These shops are dotted around BKK, with three in Ban Mo alone;
- A district known as Ban Mo, a bustling Thai street market full of electronic items and components, which had rabbit warren type markets leading off the road into derelict houses, with stalls on multiple floors. The heat was stifling in there, and, unlike most markets, was only open during the day, closing at 5pm, which meant that you couldn’t escape the heat by doing a bit of night shopping. There one can find lots of really dodgy looking Chinese clones for £20 that seemed to have some of the bells and whistles that I was after, but which would give spurious readings and/or fall apart as soon as you twisted the dial. I got shouted at a few times there for being a rude falang;
- A filthy store full of knowledgable staff, packed full of gear, at the end of a small soi in Ban Mo, on a corner, opposite a sewer. I have forgotten the name unfortunately, but here it is on streetview. It had many multimeters, especially Sanwa, a Japanese top notch brand, but they were over £200 for the good ones
- Electronics Source, a beautiful air-conditioned shop that sold Raspberry Pis, but also contained Flukes, but was too pricey.
Here is a video of Ban Mo, BKK, if you are interested:
There were plenty of other shops, too many to mention really, but Amorn was my favourite haunt, especially as there was one, a ten minute walk from my apartment, in Fortune Town, an air-conditioned mall, full of mobile phone shops and an enormous Tesco Lotus. Just next to the MRT at Phra Rama 9.
Anyway, as you shall see, the UNI-T brand kept on coming up as a potential candidate for features vs reliability vs cost.
Videos of note
So, focusing back onto the online research that I did, here is a list of the videos that I watched. They are predominantly a mix videos by my preferred tutor, Martin J. Lorton (mjlorton), of tester.co.uk and from the entertaining Dave of EEVblog.
Synopis: Input protection
Additional online text reviews
A great comparison of the Flukes: Fluke 87-V vs Fluke 87 and alike
This was a very useful review, and one that ended up helping me make my mind up: UNI-T UT71D review.
A short review listing the flaws in the UT71D, Multimeter UT71D from Uni-T flaws.
An extremely handy tip on how to get fast continuity on the UT71D: Fast continuity on the UNI-T UT71D.
More about the 71D, this time unwrapping it: Uni-T Multimeter UT71D unboxing and teardown.
A critique of UNI-T. Good for anyone, like myself, who thinks that UNI-T may be dodgy Chinese clones: Are UNI-T Multimeters any good?
An interesting comparison of the main UNI-T contenders: UNI-T meters, UT61E vs UT71E, UT33C, UT10A.
Building a high current adapter, useful for high current applications. Not specific to a particular mark or model of DMM, but an interesting read.
This mentions the UT61E: DMM specs needed for measuring in PWM and buck/boost surroundings?
Weighing up the candidates
- UT20 is a good throw away meter, for £15, but for the extra couple of quid, you had just as well go for the UT-120;
- UT120A/B/C would be a lovely pocket multimeter if you need one, for £20;
- The UT61 series was certainly very reasonable at about £30, and the video reviews stand testament to that fact, but they are lacking in the features that I hankered after;
- UT33C is nice low-end DMM, for 30 quid;
- UT71B had no logging and, for a few pennies more, you could have, in the shape of the UT71D;
- UT71D which seemed to have it all, and had a reasonable price tag;
- UT71E was no good because the current/voltage range, or frequency response, or error range wasn’t quite good enough or I didn’t need the power reading capability. I don’t quite recall exactly.
- UT81C a large screened scope multimeter, but it seemed extremely gimmicky, and for the high price was rather toy like. It seemed better to save the money and get a proper oscilloscope, which is what I did.
I also considered the following DMMs:
- 179 – Field
- 175 – Field
- 87V – Industry standard, Lab 12000
- 28-II – Robust
- 189 – Data logging 10000
- 187 – Data logging 10000
Why I chose what I chose
The following are among the reasons that I told myself why I needed the UT71D:
- I wanted the data logging capability – you never know when it might come in handy;
- I liked the temperature reading – again it could be useful one day;
- I wanted the high accuracy on the mV scale;
- I loved the analogue display along the bottom of the screen;
- The ability to test diodes;
- The ability to test capacitance;
- The frequency measurement was necessary and of a good accuracy;
- The safety, with respect to the input protection, and ability to change the fuses inside from the UK 240V type to the HRC fuses. If you watch the 61E teardown video (part 3) you can see that there are holes in the PCB for the larger fuse holders. Interestingly, some UT71D have the HRCs already fitted:
- The ability to measure transistor hFE was not required, as it is a gimmick, plus I already had that on the M-776, and;
- The ability to measure power was not necessary, after all, if you have two DMMs you can work it out anyway (P=IV).
Making the purchase
I finally plumped for the UNI-T UT71D, £90 on eBay. It was a Buy It Now, as it was new and no auction was available. The seller messaged me back promptly and asked how much I wanted him to say it cost on the customs slip, on the package. I said $25, but he ended up putting $45 as he said that $25 would look suspicious. Fair enough. I then sat back and waited. Well, actually I went out and had some Khao Pad Gai for 50 Baht, at the little street stall down the road. Very tasty. However, I digress once again.
Day of reckoning
It arrived not long after purchasing, three days I think. It also arrived direct to my door, without having to go to a random Post Office in Samsen Nai, next to BTS Saphan Khwai, and paying a customs tax, which is what I had to do in order to get my hands on my Motorola Lapdock, from Israel (but that is another story). Opened it up and everything was in order, all the probes and accessories were there. One thing to note was that it came with a USB opto-couple link. I had read “horror stories” of people receiving it with a nasty RS232 cable, but I was either fortunate or they had bought an older model/version.
I had to go and buy a battery from Tescos, as it has been sent via AirMail and batteries aren’t allowed. I got home with the battery, shoved it in and it worked. Brilliant.
Not a lot more to say, apart from I am very happy with it, and it has served me well.
I haven’t used the data logging function in anger yet, although I have connected it to the PC and tested it with UNI-T software, which is OK. Tom’s UltraDMM project wasn’t compatible when I first got the DMM, see the thread UltraDMM Software Project, but I have since seen that UltraDMM2 is now out. I’ve downloaded it, but not had time to test it yet. From this point in the thread , the UT-D04 cable is mentioned
This thread could be useful also, Multimeter software that workes with many brands?, as there is a brief discussion of software. It is from this thread, whence comes this image of the UT71D
From this video UNI-T UT-D07A BLE Adapter w/ UT181A DMM on Windows 10, for the UT181:
If it helps take a look at my USB-adapter console software for UT181A. It implements all functions and messages.
Possible bad quality
While this is not a review (it is quite hard, if not impossible, to find a review of this product), from New app for bluetooth Multimeter adapter
Sadly I’ve found the phone app pretty rubbish – on iOS it crashes, and on Android it seems to frequently disconnect. The PC app has no ability to connect over bluetooth, which I was really hoping to achieve.
The PC app that comes supplied it supposed to be rather basic, indeed someone noted that software is not Uni-T’s strong point, hence the UltraDMM.
How much is it?
- AliExpress: Uni-T UT-D07A bluetooth adapter module for UNI-T UT181A , UT171A and UT71E, £21.19
- Ebay: Uni-T UT-D07A Bluetooth Adapter Module for UNI-T UT181A UT171A UT71E, £19.99 + £2.50
Some addition links that someone may find useful, I did: