|First let me say that you dont normally buy a DC clamp meter for ultimate accuracy. Its more of a convenience thing for measuring circuits quickly.|
I also bought because multimeters even Flukes can not measure currents accurately at low voltages. There is a thing called the burden voltage which destroys even the accuracy of the best fluke and agilent meters. I bought this clamp meter to overcome this "burden voltage" error. Now I have a beautiful Fluke 376 which is perfect. But the problem with the fluke is its lower 100ma resolution and poor resolution. Step in the CEM337 meter. Now there is 2 versions, a blue version and a yellow version. The blue version is the high resolution with a claimed accuracy and resolution of 1 ma. The yellow versions is the same meter, but is autoranging from below 4a to the 80amp range. It however is not as good as the blue at resolving low current ranges like below 4 amps. Anyway I bought the Blue DT337 for its supposed ultimate 1ma accuracy. You will find numerous reviews on the internet and youtube by promoters and sellers of this Chinese equipment. These reviews are hardly independent since they are selling these meters.
There is no doubt that the DT337 can resolve 1ma but its repeatability is very poor. Its so poor when connected to Agilent bench power supply and a calibrated resistor the unit drifts all over the place as you move the clamp to different portions of the test leads. The ZERO while it works has a lot of drift. You can zero the unit and 10 seconds later the unit has drifted and the display not set too zero. This drift can be as much as 10 to 50 ma. I found that its best to turn the clamp meter off, then on again and do the zero. And then by some miracle it will read exactly what the exact current is. Unclamp and move to a different spot on the test jig and the current reading is different. THERE IS JUST NO REPEATABILITY for measuring current with the confidence of a multimeter. So the bottom line is that while they can claim to have 1ma resolution you can have no confidence that what you measuring and reading on the meter is the actual current value. The various sellers and promoters on Youtube seem to get samples from the factory that are stable. I bought two of these meters and both meters have such poor stability which is typical of the Chinese Clamp meters. If I ZERO my Fluke clamp meter and process calibrators they stay zeroed while the meter is on. It does not matter how many times I open the clamp over a load its accurate. This is not the case with the Chinese Junk clamp meters and these DT337 meters in particular. Its a shame Fluke or some other reputable company does not make a decent low current clamp meter. These meters are handy when working on switch mode power supplies and other DC electronics.
In short dont waste your money thinking anything from China that is a clamp meter with a claimed resolution of 1ma will be accurate and reliable. If it was possible Fluke or Agilent would have offered a reliable solution by now. Dont waste your money and beware of Youtube sellers who pass their reviews off as in depth non biased reviews. They always positive about the products that they sell. We all know this but, you can have your judgement rattled by some of these reviews and various other blogs.
CEM DT337 dont waste your money!
A good conception that is poorly executed in the final product. Back to wiring the Fluke into the circuit!