Anyone played with a Uni-Trend UT81B ? - Page 1
Forum section: electronics / general

author: PeterG
author_rank: Frequent Contributor
timestamp: September 10, 2010, 10:52:39 am
content: This Scope-meter seems to have good specs. But i don't know much about this brand apart from them being a China based company and have a considerable range of test gear.Regards

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 10, 2010, 08:08:48 pm
content: Well if the 1969 its your born date , I have the same actually 10 May at 1969.So my current experience with UNI-T, its just great , its my first choice if I need something reliable at the most sweet price.Not all models are build equal , but thats your part about exploring them.

author: nyo
author_rank: Contributor
timestamp: September 10, 2010, 09:14:45 pm
content: I've had one for a couple of years now, never used it that much but I have no problems with it. I'm a firm believer you get what you pay for, it was my first oscilloscope and I think it was worth it. On a side note I think the software used with the usb connection is just crap, very slow and unreliable.

author: saturation
author_rank: Super Contributor
timestamp: September 11, 2010, 09:42:52 pm
content: I think as a hand held scope its not bad. There are not too many between what Dave calls 'toys' and usable hand held scopes. If all you need is a DMM, you can get one cheaper with the same specs, so the extra cost is for the scope part.I don't own one, but had to choose between it and the Velleman HPS40. The 40 is on closeout at Tequipment for $200, and the 81B is available to USA buyers only via eBay for about $180 S&H included, from HK or China.There are a couple of youtube videos reviewing it looking at old analog TV waveforms, and likewise there are a few reviews of the HPS10. The both the 10 and 40 has been around for ~ 10 years, and was popular as a budget automobile scope, but the frequency response for such work is under 1 MHz.The 81B review is very revealing, because old PAL or NTSC color burst signals require a scope in the 10-20 MHz range. Those signals in the video look good enough, and they are typically 4 MHz bursts. The 81B specs state it has a 40Msa/s rate, which suggests its only useful to 4 MHz, which means its should roll off thereabouts, but the signal on the video looks pretty good.The HPS40 is a competitor, and I've tested it to 4 MHz with distortion, 2 MHz is clean, so its more like a 3 MHz scope. Its sold as a "12" MHz handheld, and does 40 Ms/sec too.http://www.amazon.com/review/R2A7O3DS27XQVA/ref=cm_cr_pr_cmt?ie=UTF8&ASIN=B000WCCVBC&nodeID=&tag=&linkCode=#wasThisHelpfulThe only problem is having to buy the Uni-T from China, vs from the US, if it breaks within warranty, tequipment has a very solid reputation.I think the Uni-T is a better bang for buck in paper, if it could be purchased locally and if I could really see it at work.What do I use it for?You have a high risk of damage to your scope or injury to yourself if you read AC line voltage, or any portion of it even if stepped down [ unless its fully isolated first] or what you think might have AC line voltage as a contaminant, using a AC line powered scope like the popular Rigol 1052E. Battery powered hand held scopes are not physically grounded, but float, so its ground is relative not earth ground.The Velleman is built very much like a Fluke 80 series DMM, and rubberized. I've looked at waveforms as high 1kV DC using it [which surprised the jeebers out of me, as I wasn't expecting to see it nor did the Fluke 87V pick it up, except it was suspicious because the readings never settled down to a solid number], and while it doesn't have the best screen for examining waveforms, it tells you that it is there, riding on the DC or low voltage AC. Its easily to lug around, and very easy to see in sunlight, the HPS40 LCD is old type the HPS10 is sharper and clearer but not as fine as the Uni-T [particularly a version sold with deep blue pixels], but the HPS10 is only rated to 1Msa/s, that just 100kHz response.Anytime you want to take a quick peak and see what type of a waveform could be in a test circuit, the Velleman or even the Uni-T if I had one, can deliver; the only question is accuracy of the shape because of its frequency response, but once I identify something else exists in a test circuit, I have the option of setting up a better scope and taking the DUT for a better exam.

author: saturation
author_rank: Super Contributor
timestamp: September 12, 2010, 05:31:57 pm
content: Here's a sample of the HPS40 looking at the output of an old variable power supply capable of 600Vdc. The DMM showed erratic readings, but the waveforms are more revealing, even if they could have a lot of anti-aliasing errors.

author: PeterG
author_rank: Frequent Contributor
timestamp: September 13, 2010, 08:00:22 am
content: Many thanks to everyone who responded. I have looked at the HS10 and 40 and decided the UT81B will be best for me as i like having the DMM functions and from what i have seen, the UT has a better screen. I will post my impressions when i receive it and have played with it a bit.Regards.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 13, 2010, 08:55:38 am
content: Congrats ...As soon it arrives , test it and post an complete mini review here ..https://www.eevblog.com/forum/index.php?board=9.0

author: saturation
author_rank: Super Contributor
timestamp: September 13, 2010, 08:28:39 pm
content: Welcome, please do review it. We don't hear much about that particular model.Quote from: Darkman1969 on September 13, 2010, 08:00:22 am

author: PeterG
author_rank: Frequent Contributor
timestamp: September 16, 2010, 02:17:00 pm
content: I am waiting impatiently for it to arrive. Aussie customs are probably siting on it now. Should have it one day next week.On a side note, my VC3165 Counter arrived today, seems good enough for the $100 price tag.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 16, 2010, 03:06:22 pm
content: Quote from: Darkman1969 on September 16, 2010, 02:17:00 pmAfter an quick search , found negative words about it, longevity & accuracy .Test it, in comparison with another one , so to check accuracy at list.

author: Unknown
author_rank: Unknown
timestamp: September 16, 2010, 04:56:56 pm
content: Quote from: shafri on September 16, 2010, 01:59:36 pmAlmost any scope can do that with the right probe: a current probe, or a (makeshift) differential probe + shunt.I flipped through theUT81B manual. I don't think you can use the current input in scope mode, although you could of course use an external shunt (it's floating anyway). The Scope input is the volts/ohms input. The manual refers to the multimeter part for info about ACV/DCV/HZ/ACA/DCA, the only option for scope is DC or AC coupling. The manual is in Engrish, as expected, and not very good (compared to the Flukes and Agilents of the world). It seems to use the soft keys (F1-F4) for everything. No advanced features like XY mode as far as I see. It seems like you can get an optional BNC probe (can't parse the Engrish about how this connects to the UT81B), bandwidth and noise with banana leads will probably be pretty bad.

author: Unknown
author_rank: Unknown
timestamp: September 16, 2010, 08:17:02 pm
content: Quote from: shafri on September 16, 2010, 07:32:02 pmDon't think Rigol makes them, all major scope vendors make them, but most of the recent designs are vendor-specific (they need active power, and the manufacturer doesn't mind forcing you to use their scopes).AC only is relatively easy and cheap, and usually passive (basically a transformer with the primary winding consisting of the wire you clamp it around). Usually a split core so you can clip it around a wire. Fluke has some, like the i5S (40Hz to 5kHz) and i200s (40Hz to 10kHz), most are for high currents. Tektronix has the P6019/P6021 (low frequency, about 120Hz to 60MHz with passive termination and 12Hz to 35MHz or so with Type 134 active termination) and P6020/P6022 (higher frequency, 935Hz to 120MHz with passive termination and 100Hz to 60MHz or so with Type 134 active termination), they are regularly available on the used market, make sure to get some sort of termination with it (passive has better high-frequency response, Type 134 much better LF response and better sensitivity). They are for relatively low currents (from a few mA to 20A or so, you need the 134 for the low end). There are larger probes available for higher current. They work with any scope with 1Mohm BNC input. There are also smaller probes, tuned for high frequency, that have a fixed core (need to feed the wire through it, as opposed to clipping it around a wire).For DC probes, you need an active Hall sensor, and if you want frequency response beyond a few kHz, you need to combine this with a transformer (not easy). Tek P6302/A6302 is (was?) the best, it's pretty expensive, even used, and fragile, and needs a dedicated amplifier (AM503/A/B/AM5030, with proper power supply mainframe for most), they are usable with almost any scope, DC-50MHz. A6312 is DC-100MHz, rarer, also needs amplifier. Any newer models won't work with non-Tek scopes without expensive power supply, model 1103/1104, only available used). Fluke also has the 80i-110s (DC-100kHz) and i50S (DC-50MHz, probably rebadged and expensive).Agilent, Lecroy, Iwatsu and Yokogawa also sell current probes, I don't know any model numbers of the top of my head, or if they're usable with scope from other vendors.An AC-only current probe with decent bandwidth (eg. Tek P6019/P6021 w/ termination) should be available on eBay for around $100+S/H if you wait for the right offer, though the two recent auctions went for around $200. DC current probes will be more expensive (more expensive than the scope), especially those from DC to several MHz. New will obviously be much more expensive.

author: PeterG
author_rank: Frequent Contributor
timestamp: September 17, 2010, 12:17:46 am
content: Kiriakos-GR, can you put up a couple of links to reviews on the VC3165?I looked it up before i purchased it and didn't find anything to bad about it. I will be doing more testing now you mention its possible faults.Regards.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 17, 2010, 06:53:45 pm
content: I did an quick search by curiosity , and the first link that popped out was this.. Read ithttp://www.eham.net/reviews/detail/7839

author: PeterG
author_rank: Frequent Contributor
timestamp: September 18, 2010, 06:03:42 am
content: OK, i just ran some basic tests on my VC3165 using my DG1022 Function Gen. It seems accurate enough. it shows what the DG1022 says its generating. However i can only test up to 20Mhz.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 18, 2010, 06:46:34 pm
content: Well , if this is the range that you will work with it , then you have nothing to worry ..

author: PeterG
author_rank: Frequent Contributor
timestamp: September 21, 2010, 04:12:42 am
content: The UT81B arrived today, and i have to say first looks are impressive. Comes complete with USB lead,software and all the usual connectors and leads. There are no "Optional extras". The Scope works on Hz, Volts and Amps(uA and mA as well). The screen is amazingly clear and easy to read for a meter in this class. I am yet to do any real tests on the meter, however, i am expecting it to perform well enough to be well worth the $200AUD. I will be testing out the software as well eventually, but i am not expecting much from the software due to it being China based. China is not known for making great software.If anyone wants a specific test run on this meter, let me know and if i can do it i will. NO i won't be doing a drop test. Thats Daves specialty.I have not posted any pics yet, there are enough of them on the net already, but i will post test result pics later.Regards

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 21, 2010, 09:39:02 am
content: Quote from: Darkman1969 on September 21, 2010, 04:12:42 amDo not be confused .. China its an very very large spot on the map .With a Billion of people on it ..UNI-T its currently an leading company down there ,that had choose to offer quality products at an reasonable pricing.The software application for data logging of multimeter 's ,its not that special because its not needed to be.By the same skeptic ( logic ), any software about smart uninterruptible power supply ,that do logging and diagnostics , never was looking that " shiny " and high tech .Oups ... one minute ...I have an idea . Dave ..I found the reason for the existence of an new Video blog ." An review - presentation of the currently supplied software of multimeter 's "Dave is that possible ?Quote from: Darkman1969 on September 21, 2010, 04:12:42 amThe best and only test, are to measure reference sources .There is no other way !!https://www.eevblog.com/forum/index.php?topic=1032.0https://www.eevblog.com/forum/index.php?topic=1148.0

author: PeterG
author_rank: Frequent Contributor
timestamp: September 21, 2010, 10:14:33 am
content: I would really like to see how it goes up against a real reference voltage/current setup. All i have at the moment that is reliable is the Rigol DG1022 FG. The rigol provides more than enough range to test the UT81B Scope functions, but i don't have a solid ref power supply.I know Uni-Trend have a solid refutation in Asia and am impressed so far for the price.Regards

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: September 21, 2010, 10:25:22 am
content: No problem ..Take your time , and take good pictures of it