As you can see, the two meters match up well, better than I expected! I tested voltage and resistance too against some precision references and precision resistors. It read 0.4% high on average in voltage mode (worst: 0.47% or 5 counts) and was generally bang on in resistance mode (worst: 0.2% or 2 counts.) The circuit board has some input protection with two PTC's and 3 MOV's. The input resistors (R37A, R37B, R37C, R37D: 4x2.5Mohm) is split into 4 resistors, between these resistors and the input is a PTC.

Further it is possible to switch the selector on 20A, to press the ZERO button and to nullify indications. At the same time the instrument in hand not to hold, give time for that that indications calmed down, to place the instrument where least of all el./magn. noises and the more so far away from magnets.

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I've looked at many different clamp meters, and typically they come with one or more of these limitations:

This meter is nice for measuring 100's of mA or more without any voltage drop, using it for lower DC currents requires careful use of the zero button. There are no major transmission lines visible from my location, and local power is distributed via underground wires. I took the meter outside and tested in two different locations separated by 100 feet or so. Before being zeroed, the meter reads in the 320-430mA range. After zeroing the meter, I tested variability based on orientation. Slightly rotated and tilted up and it read 130mA . Tilted it down, -75mA. The variation was similar when tested in the other location. (Biggest change tends to happen when tilting up vs down.) So today, outside, the variation is around 210mA. I saw earlier in the thread that the meter could become magnetized and require degaussing. I understand this could cause an offset in the reading, but it's not clear to me if it could also cause the variation based on orientation that I'm seeing. Also, I'm not sure which of my power tools or appliances would leak enough EMF to use as a degausser. Changing the PROM will not impact the drift.I suspect you could run 100 of them an they would all drift roughly the same.I suspect you two main problem will be temperature and placement.When Maxlor posted 10mA in a minute, I can believe it.When I ran that test I was careful to try and hold the temperature as tight as possible and not move the clamp. Narrowed it down to two, UNI-T UT210D and the UNI-T UT204, just want to see if other guys have brought.

Screen update rate is unusually fast for Uni-T at around 4 updates per second. Unfortunately, other things are slow: the latched continuity tester is usable, but certainly not fast. Resistance autoranging is slow. Reading current with the clamp is also a tad slow, it usually a second or two for the value to come up to the right area, and then 2-3 seconds more for the last digit to stabilize, so current isn't instant.