Review – Tenma 72-7222 Digital Clamp Multimeter - Page 1
Forum section: electronics / general

author: johnboxall
author_rank: Unknown
timestamp: October 11, 2011, 06:07:19 am
content: Element-14 offered me the chance to choose an item for review, so here we have the Tenma 72-7222 Digital Clamp Meter...Initial ImpressionThe Tenma arrives in a retail box, and generally nicely packaged. Naturally this has nothing to do with the performance of the meter at all, but at least they made an effort:Opening up we find a nicely rounded group of items: the meter itself, some no-name AAA cells, test leads, a thermocouple for temperature measurement, a surprisingly articulate and well-written user manual, and the unit itself – all within a nice pouch. Wow – a pouch. Agilent? Fluke? All that money for a DMM and you don’t include a pouch?Recent test equipment reviewers have made pulling apart the unit part of the review – so here goes… the back comes off easily:No user-replaceable fuses… instead a PTC. A closer look at the PCB:A very neat and organised PCB layout. There are plastic tabs that hold the PCB in along with a screw, however the case flexed too much for me to warrant removing the PCB completely. The spring for the clamp meter is locked in nicely and very strong, it won’t give up for a long time. Pulling the clamp base out reveals the rest of the PCB:Installation of the battery is two stage procedure, first you need to remove a screw and then slide out the rear door:… then insert the AAA cells into a frame, which is then inserted inside the unit:The physical feel of the unit is relative to the purchase price, the plastic is simple and could be quite brittle if the unit was dropped from a height. The user manual claims the unit can be dropped from up to a height of one metre. Onto carpet? Yes. Concrete? Perhaps not. However like all test equipment one would hope the user would take care of it whenever possible. The clamp meter is very strong due to the large spring inside the handle, which can be opened up to around 28mm. The included leads are just on one meter long including the length of the probe:The leads are rated to Category I 1000V (overkill – the meter can’t go that high) and 600 V Category II – “This category refers to local-level electrical distribution, such as that provided by a standard wall outlet or plug in loads (for example, 115 AC voltage for U.S. or 200 AC voltage for Europe). Examples of Measurement Category II are measurements performed on household appliances, portable tools, and similar modules” – definition from from National Instruments. Unlike discount DMMs from unknown suppliers you can trust the rating to be true – otherwise element-14 wouldn’t be selling it.Unit SpecificationsVoltage Measuring Range DC:200mV, 2V, 20V, 200V, 600VVoltage Measuring Range AC:2V, 20V, 200V, 600VCurrent Measuring Range AC:2A, 20A, 200A, 400AResistance Measuring Range:200ohm, 2kohm, 20kohm, 200kohm, 2Mohm, 20MohmTemperature Measuring Range:-40°C to +1000°CDMM Response Type:True RMSDMM Functions:AC Current, AC/DC Voltage, Resistance, TemperatureRanging:AutoDisplay Count:1999AC Current Range Accuracy:± (1.5% + 5d)AC Voltage Range Accuracy:± (1.2% + 5d)Accuracy:± (1.0% + 3d)Current AC Max:400ACurrent Range AC:2A, 20A, 200A, 400ADC Voltage Range Accuracy1:± (0.8% + 1d)Resistance Range Accuracy:± (1.0% + 2d)Temperature Measuring Range:-40°C to +1000°CThe only measurement missed out on is DC current, however there is the Tenma 72-7224 which has DC current and frequency ranges. Finally, all the modes and buttons can be selected while holding the meter with one hand – for both left- and right-handed folk.Measurement experienceNormally I would compare the measurements against my Agilent U1272A, however it’s out to lunch. Instead, a Fluke 233. First, AC voltage from the mains:Next, a few DC voltage measurements:Now for some resistance measurements. Higher values near the maximum of 20M Ohm can take around four seconds to measure:Forward voltage of a 1N4004 diode:Now off to the kitchen for some more measurements – first with the thermocouple:The boiling water test – 100 degrees Celsius (you can also select Fahrenheit if so inclined):And now to test out the AC current clamp meter function with a 10A kettle at boiling point. First, using the 20A current range:And then again on the 400A current range:As always, it’s best to use the multimeter range that more closely corresponds with the current under test. The meter also has a continuity test with a beeper, however it was somewhat slow and would often take around one second to register – so nothing too impressive on that front. The meter can record the maximum value with the grey button, or hold a reading using the yellow button.ConclusionThe Tenma 72-7222 works as advertised, and as expected. It is a solid little unit that if looked after should last a few years at a minimum. It certainly has a few limitations, such as the 1999 count display, lack of backlight, and the average continuity function. But don’t let that put you off. For the price – under Au$30 – it is a certified deal. If you need a clamp current meter for odd jobs or a casual-use multimeter and you are on a limited budget, the Tenma will certainly prove a worthwhile purchase. Full-size images are available here:http://www.flickr.com/photos/tronixstuff/sets/72157627736200005/.You can purchase a Tenma 72-7222 from element-14, Farnell and Newark.Original article -http://tronixstuff.wordpress.com/2011/10/11/review-tenma-72-7222-digital-clamp-multimeter/

author: saturation
author_rank: Super Contributor
timestamp: October 11, 2011, 11:51:46 am
content: Thanks a ton tronixstuff, it looks like a decent clamp meter, worth a buck. I like the move toward mores AAA in test equipment, makes for lighter devices and easier to acquire compared to 9v, particularly using LSD NiMH cells.On the side your comment, " Normally I would compare the measurements against my Agilent U1272A, however it’s out to lunch. Instead, a Fluke 233... " shows how its hard to beat the old guard.

author: johnboxall
author_rank: Unknown
timestamp: October 11, 2011, 12:02:15 pm
content: Quote from: saturation on October 11, 2011, 11:51:46 amThanks. The Tenma is very good value considering the price. My U1272A is heading back for a warranty service. It was always a little screwy in my opinion - even after the firmware update, so I hope the service centre gives it a good seeing to.

author: Unknown
author_rank: Unknown
timestamp: October 11, 2011, 01:20:01 pm
content: Quote from: tronixstuff on October 11, 2011, 06:07:19 amGreat review John and thanks for highlighting a perpetual gripe with the big brand. Given that the genuine pouches are mostly cheap garbage anyway they should be included in the freight.A year or two back somebody scored my old style Fluke 27, when somewhere between the Wentworth and the Opera House one very overpriced and near new Fluke pouch decided to part company with its carry loop. Wasn't impressed is an understatement.

author: johnboxall
author_rank: Unknown
timestamp: October 11, 2011, 01:30:52 pm
content: Quote from: Uncle Vernon on October 11, 2011, 01:20:01 pmThanks UV.You can't win some days. I left my new copy of "The Art of Electronics" on the train last month. D'oh. I hope whoever kept it now understands more about analogue electronics.The Wentworth ... ohhh that takes me back. Good times.

author: Unknown
author_rank: Unknown
timestamp: October 11, 2011, 01:48:30 pm
content: Quote from: tronixstuff on October 11, 2011, 01:30:52 pmOuch! Equally difficult to replace. Did you try City Rail lost and found, amazing what they do find and store. Slim chance but it's worth a penny for the call.QuoteI'm find good times and the CBD rarely coincide much anymore, and enjoying only having to be in Sydney for no more than a couple of days a month.

author: johnboxall
author_rank: Unknown
timestamp: October 11, 2011, 01:55:04 pm
content: Quote from: Uncle Vernon on October 11, 2011, 01:48:30 pmFunny that, as you get older the city becomes more of a pain.I lost the book on the Hunter line. Unfortunately people don't tend to hand things in up here. :| Such is life

author: Bored@Work
author_rank: Super Contributor
timestamp: October 11, 2011, 04:05:39 pm
content: Quote from: tronixstuff on October 11, 2011, 06:07:19 amWell, this is not how it is done. Your Tenma simply is a rebadged UNI-T, not something Farnell designed, build or tested by themselves.And the whole thing when known companies sell rebadged stuff is an exercise in ass covering. You establish a paper trail with your manufacturer that proves that you couldn't and didn't know about some bad stuff and had reason to believe the good stuff the manufacturer told you. You make sure that your ass is either covered by the manufacturer or your insurance if something goes wrong. And then it becomes a business decision. Financial risk if something goes wrong vs. money to be made. Potential loss of reputation vs. gain of reputation.

author: johnboxall
author_rank: Unknown
timestamp: October 11, 2011, 04:13:52 pm
content: Quote from: BoredAtWork on October 11, 2011, 04:05:39 pmYes, I realise that Farnell didn't have anything to do with the design. Turns out the meter is a Uni-T UT202. Thanks for that.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 11, 2011, 06:01:53 pm
content: Quote from: tronixstuff on October 11, 2011, 04:13:52 pmut201 doesnt have temp reading. this is ut202, and it looks very familiar to me...https://www.eevblog.com/forum/index.php?topic=500.msg53881#msg53881thanks alot for the review. please do more performace test and review

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 11, 2011, 06:39:31 pm
content: OupsAgain a red daemon hides under the Tenma clothing this time. LOLInteresting review tronixstuff, thanks mate.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 11, 2011, 07:14:00 pm
content: Quote from: Kiriakos-GR on October 11, 2011, 06:39:31 pmno need oups. orange certainly is more modern.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 11, 2011, 08:31:46 pm
content: In this category of products the color does not mater.Check out the price SonSimilarly priced clap meters, last in the field work about 6-8 months if you are lucky.The most common reason of damage is the plastic cover its not strong enough.If you put your hand on the Chauvin Arnoux clamp, you will spot the difference immediately.

author: Mechatrommer
author_rank: Super Contributor
timestamp: October 11, 2011, 09:30:05 pm
content: Quote from: Kiriakos-GR on October 11, 2011, 08:31:46 pmi got camera that will be damaged if got dropped even once. i've brought it frequently to fields for 3 years now, still ok. i think its how you handle it.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: October 11, 2011, 09:41:06 pm
content: Quote from: Mechatrommer on October 11, 2011, 09:30:05 pmTrue.. but up to a point it also haves to do with the environment that you work at.Usually I do not break apart tools, mainly the HVAC boys keeps the specific score high.The specific tool, belongs to the entry level category.And that's all about it.