The UNI-T UT81 is a multimeter-cum-oscilloscope meter aimed at those who are interested in better analyzing a given signal. It is entry level and comes with 8MHz capability, together with traditional multimeter measuring criteria like voltage, current and resistance. This portable scope meter would be ideal for someone just starting out in the data-center field or just for hobbyists.
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Main Features
- Test bandwidth: MAX 8MHz
- Sampling rate: MAX 40 MS/s
- Triggers: free run, single shot, normal
- Measures up to 1000V (DC), 10A (AC/DC)
- Measures resistance & continuity
- Measures frequency & capacitance
- True RMS accuracy
- Relative mode
- Screen hold
- 4000-count display resolution
- Size: 7.9″ (200mm) x 3.9″ (100mm) x 1.9″ (48mm)
- Weight: 1lb (498g)
Comes With
- Power adapter (6V)
- Probe adapter (scope probe optional)
- USB cable for PC connectivity
- Test leads
- Alligator clips
- X4 AAA batteries
- Carry bag
- CD
- Operator’s manual (online version)
Complete Review of the UNI-T UT81
In short, what we have here is the combination of a multimeter and an oscilloscope, commonly known as a scope meter. You practically get the full spec of a standard multimeter, with an oscilloscope mode tacked on. This can be used to look more closely at signals in voltage, current and frequency.
Nominal test bandwidth is to 2MHz, which will allow the user to analyze a range of signals. Constant sample rate is to 20MS/s. Peak sampling allows you to pick up spikes/over-signals. In addition are screen zoom and data storage.
The great thing about the UNI-T UT81 Scope Meter is that it ships with a power adapter, allowing you to test to your heart’s content on the bench and save battery power. In addition is a set of alligator clips – they’re not the best quality but screw onto the leads for a solid connection.
Scope meters tend to be on the bulky side due to the added onboard electronics, and the UNI-T UT81 is no exception. It’s a bit of a brick, but, then again, it’s fairly compact when compared with other meters of this nature, like some of the Flukes and Keysights (Agilents).
Models: There are several models of the UT81, running A through E. The B version the most common.
Accuracy Figures
| Range | accuracy | |
|---|---|---|
| DC voltage | 400mV / 1000V | ±(0.8%+8) |
| AC voltage | 4V / 750V | ±(1.0%+15) |
| DC current | 400uA / 10A | ±(1.0%+8) |
| AC current | 400uA / 10A | ±(1.5%+8) |
| Resistance | 400Ω / 40MΩ | ±(1.0%+5) |
| Capacitance | 40nF / 100µF | ±(3.0%+8) |
| Frequency | 10Hz / 10MHz | |
| Duty cycle | 0.1% to 99.9% | |
Interface
On quick glance, we have a typical multimeter with a large screen, a dial and four jack inputs, but with more buttons than usual. The various buttons and functions are self-explanatory. The dial is also uncluttered, though the labeling could be a bit clearer.
Display: The most obvious difference with a standard multimeter in the UT81 is its sizeable display. It is 160X160, 4000-count resolution in basic monochrome with controllable brightness and contrast levels. In addition are 10 screen positions and a real-time sample rate of 40MSa/s. Screen refresh rate is up to three times per second. Time-base range is 5s per division. The display is backlit but a bit washed out when read at an angle. Overall, it is okay for this price point.
Build Quality
Most reviews of the UniTrend UT81 have a reasonable quality device with a rubberized case. It may appear bulky but is a lot more manageable than many of its cousins. With this, it is easier to carry to the jobsite but is not built to industrial standard so one should not expect too much of it.
The test probes feature protective caps. On the bench with the tilting bail down, the dial is easy to turn. It also has an auto-power off and the battery case is easy to get at.
Functions and Performance
The auto-off is a very useful feature. It is configurable and can be set anywhere from one to 30 minutes. In addition are auto polarity, an over-range indicator and low battery warning. The relative mode on the UNI-T UT81 allows you to compare the results of a previously recorded value.
On the downside, the UT81 is a bit slow on the response side, but not having to lug around heavy equipment is a definite plus. It is also a lot cheaper than your average scope meter and boasts the general purpose multimeter ranges.
Safety Ratings
The highest category rating is CAT-III at 600V, which lets you test fixed systems to distribution; i.e. not above switch gear. Category II levels are up to 1000V, which applies to devices connected to the mains, but not the mains itself. The leads are rated to CAT-IV.
Note: Keep in mind that the Uni-T’s are not known for their high levels of input protection, so be mindful of high amperage situations.
UNI-T UT81 Pros and Cons
PROS
- Dual-use device: scope + multimeter
- Main multimeter test ranges
- True RMS
- Auto ranging
- Plugs into mains power
- PC connection
- Good value
CONS
- A bit slow & clunky
- Display washes out
- Can’t replace full range oscilloscope
- Bulky
Roundup
The UNI-T UT81 Scope Meter is a full range multimeter with limited oscilloscope options. Best for enthusiasts and hobbyists (as opposed to those in industry), it gives graphical representations of test signals. The multimeter side also works okay and has most ranges an electrician would need.
Of note; the Uni-T’s tend to be a bit temperamental; some work well, others not so well. It can sometimes be a lottery as to whether you get a good one. The beauty of shopping with Amazon is they allow no-quibble returns.
Alternatives: Another middle of the road meter manufacturer, Extech also makes half decent scope meters, albeit for around double the money. Fluke, on the other hand, typically puts out high quality oscilloscope meters that are in orders above this; $1,000 and up.