This is a quick overview and initial impressions of the Tenma 72-9380A72-9380A multimeter. A comparison is made to other multimeters I currently own and use.
Background
I currently own 4 multimeters that I frequently use, one of which has been on the blink. So when I won a recent Project14 contest it was an opportunity to replace it at the right out of pocket cost (no out of pocket cost). I am an electronics enthusiast and my criteria for instruments differs from those who work professionally and especially those working with high voltage. My projects are usually 5V or less and never more than 12V. I sometimes do experiments where high resolution is useful and recently have become interested in automating data collection and look for USB connection. So when I spotted the 40,000 count 4.75 digit Tenma 72-9380A for $135.05 on Newark, normally $258.44, I decided to get it with my Project14 winnings.
Datasheet
Datasheet from Newark website: 72-9380A.xls (farnell.com)
First Impressions
The multimeter came nicely boxed and undamaged. The meter itself has a nice zip up case also containing probes, alligator clips, K-type temperature probe, optically isolated USB connector, manual and CD.
Right off it appeared that the supplied software probably wouldn't meet my needs because it was on a CD which was dated 2004 and I no longer have a computer with a CD reader. The meter is quite large and feels sturdy. When turned on it responds with a nice loud beep. The display is large but the numbers while readable are the smallest of any of the multimeters I currently use. There is backlighting which works well enough. There is an analog bar graph that updates around 10 Hz. It can store min and max values when in manual range.
The rotary switch clicks through the settings nicely and snaps to the desired function with authority. The buttons are a bit squishy but OK.
I'm not going to comment on the high voltage aspects of the probes and meter because that is not something I deal with and I don't feel qualified. The leads on the probe are stiff and the points not particularly sharp but I have better probes when needed. Response of the continuity tester is quite slow with the supplied leads.
Moving around to the back there is a tilting stand, access to the battery compartment and connection for USB. The tilting stand does not hold the meter upright but rather just lifts it off the surface at maybe a 30 degree angle. I would prefer a more upright position or adjustable to a more upright position.
The meter takes a 9V battery which is less preferable than the AAA batteries my other meters use. The battery is accessed through a cover that is secured with a screw into a brass insert. The battery is a bit fiddly to replace.
USB is through an optically isolated connection that slides into the upper back of the meter.
The back cover comes off when 4 more screws plus the battery screw are removed. All 4 of these screws are self tappers. Two are hidden by little rubber feet. This is as far as I will disassemble the instrument.
The fuses are huge and accessible. The PCB is tidy and no flaws were spotted in the soldering. However, note the sheathing that covers the power from the 9V battery is nicked open. That wasn't done by me and must have happened when the case was originally assembled. There are lots of interesting bits but I didn't spend much time inside and reassembled it without issue. Again I won't comment on high voltage due to lack of knowledge and it is not my use case.
A quick thumb through the manual showed it to be comprehensive and it appeared to be well written.
Time to Try It Out
This is not a comprehensive review and I don't have precise standards for comparison. Instead I will be comparing it to other multimeters in my possession, none of which have calibration certificates. If they are all in decent agreement I figure the readings are good and the manufacturers have not somehow conspired against me and sent instruments which all have major error by the same amount.
The Contenders
The four meters being compared are starting from the left a Tenma 72-1020 bench multimeter, the Tenma 72-9380-A which is the instrument under review, an Extech EX330, and an Aneng AN8008.
The Tenma 72-1020Tenma 72-1020 bench multimeter is my favorite and remains so. It never leaves my bench, is plugged into AC power, has a bright display with good resolution and so far has never let me down. It is a 40,000 count meter and sells for $261 on Newark. I also got this after winning a Project14 contest and my recollection is that the price was closer to $200 at the time I got it.
The Extech EX330Extech EX330 was my first "good" meter and I have had it a number of years. They can be purchased for a bit over $50 and this model was the winner in an under $100 shootout on the EEVBlog a few years back. They were more expensive at the time I purchased it. From time to time the rotary switch doesn't click into the Vdc setting securely now and the resolution is only fair at 4000 count.
I have two of the Aneng AN8008 meters and one of them doesn't work in the capacitor setting and the switch may be wonky. Now that I have a replacement I may open it up and see if I can spot the issues. The construction is not up to the others reviewed here and I certainly wouldn't trust it on mains. However, they can be bought for $27 on Amazon in the US and shipped with 2 day delivery. I paid less for mine several years back but they shipped from China. They are 10,000 count meters and actually work pretty good (when they work :-). For the price they aren't bad for a hobbyist on a budget.
In all the following tests the results in the table are in the same order as the meters are shown in the image above. All meters are in auto mode. The voltage source is my Tenma 72-2685Tenma 72-2685, the resistors and capacitors are just components I have at hand. This is crude testing at it's finest.
DC Voltage
It is obvious that my bench power supply settings are off a bit.
| PSU Set Voltage | Tenma 72-1020 | Tenma 72-9380A | Extech EX330 | Aneng AN8008 |
|---|---|---|---|---|
| 0.01 V | 0.0072 V | 0.0071 V | 0.0073 V | 0.0074 V |
| 0.1 V | 0.0942 V | 0.0944 V | 0.0946 V | 0.0945 V |
| 1V | 0.9939 V | 0.9948 V | 0.994 V | 0.9953 V |
| 3V | 2.9896 V | 2.9919 V | 2.988 V | 2.992 V |
| 5V | 4.987 V | 4.994 V | 4.99 V | 4.997 V |
| 10V | 9.972 V | 9.979 | 9.98 V | 9.985 V |
AC voltage not tested.
Current
I don't measure current directly much on the DMM. I'll just test some low values on two better meters and see what I get.
| PSU Set Current | Tenma 72-1020 | Tenma 72-9380A | Extech EX330 | Aneng AN8008 |
|---|---|---|---|---|
| 10 mA | 12.670 mA | 12.678 mA | ||
| 100 mA | 102.52 mA | 102.66 mA |
Those were closer than I thought they would be. There was some movement in the readings at the lower current.
AC current not tested.
Resistance
I have a milliohm meter if I need really low values so will start the testing at 100 ohms. I'm using the same set of leads on all meters.
| Various 1% loose resistors | Tenma 72-1020 | Tenma 72-9380A | Extech EX330 | Aneng AN8008 |
|---|---|---|---|---|
| 100 Ohm | 100.10 | 100.20 | 100.4 | 103.0 |
| 1 kOhm | 0.9968 | 0.9982 | 1.000 | 1.005 |
| 10 kOhm | 9.955 | 9.992 | 10.00 | 10.01 |
| 100 kOhm | 98.97 | 99.22 | 99.4 | 99.6 |
| 1 MOhm | 0.9922 | 0.9938 | 0.999 | 0.999 |
Capacitance
I won't do much testing here either as I have a decent LCR meter now. I may post a test on it in future.
| Various loose capacitors | Tenma 72-1020 | Tenma 72-9380A | Extech EX330 | Aneng AN8008 |
|---|---|---|---|---|
| 1 uF | 1.1551 | 1.1679 | ||
| 100 nF | 99.2 | 99.3 | ||
| 4.7 uF | 4.746 | 3.89 uF |
Note that according to user manual the accuracy above 4 uF is not specified for the 72-9380A and indeed the reading was way off.
Continuity
Continuity works but it is slow. There is a nice loud beep.
Diodes
According to the manual the open circuit voltage is around 2.8V. It was able to light a blue LED. A silicon diode showed just over 0.6 V forward voltage as expected.
Frequency / Duty Cycle
Not tested.
4-20 mA Loop Current
Not Tested.
Temperature
Using the temperature probe that came with the 72-9380A it reads 20.0 C on the bench multimeter and 21.5 C on the 72-9380A. The bench multimeter is closer to the actual temperature. At room temperature the manual states the accuracy is +/- 3% so it is in spec.
USB
I don't have a reader for the CD that came with the kit and probably wouldn't use the software anyway if I did. I tried talking to it from a terminal with SCPI and couldn't get a response. I knew this was a risk when I selected it as I couldn't find anywhere in the documentation online at Newark that it could communicate with SCPI.
The Verdict
This wasn't comprehensive testing - I just wanted to make sure things worked more or less as expected and get a baseline. I didn't analyze it too carefully but it seems to be within specification. When used in experiments or critical measurement I will do a quick test against another meter first but I normally do that with all my meters.
Despite my criticisms it is entirely useable and a major upgrade from the much less expensive Aneng 8008. I also prefer it to the Extech EX330. It seems sturdy and for $135 it was a good deal since I value the high resolution. Thanks for reading - happy to answer questions.
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