UNI-T UT204 Clamp Meter review and tear-down

[Cpx]

Wytnucls, please test true RMS capabilities of ut204  at higher frequencies like 1 khz, 5 khz and 10 khz. Thanks.

[Wytnucls]

Wytnucls, please test true RMS capabilities of ut204  at higher frequencies like 1 khz, 5 khz and 10 khz. Thanks.

Those requested frequencies are way out of the published limitation range (400Hz max).
Nevertheless, I ran a test with a 10Vpp ramp wave at 90% asymmetry, at 50Hz, 500Hz, 1KHz, 5 KHz and 10KHz.
Here are the results, with  the 71D and Rigol DSO as reference:
(As you can see, accuracy deteriorates rapidly above 1KHz)
The user booklet also says that the published AC true RMS voltage accuracy of 1%+5 is only valid for a sine wave (crest factor 1.4).
With a peak or crest factor between 1.4 and 2.0, the accuracy decreases to 2%+5. (A triangular wave has a crest factor of about 1.7)

[Wytnucls]

Hi all,

I bought a Uni-T 204 a couple of weeks ago but it was very disappointing from my point of view.
The theoretical resolution below the 1 Amp range is not really usable due to the high fluctuation around the last (2) digits.
I was not able to measure a DC current around 100mA  and sent back the unit 

Any recommendation for a decent clamp meter that can measure down to 10mA without having the feeling just to read some random numbers on the display...

Regards Arne

The accuracy on the DC 40A range is 2%+5 with a resolution of 10mA. So, if you're measuring 1A, you can expect fluctuaction of 70mA either side of the real value.
If your conductor is not exactly in the middle of the jaws, you should increase that amount by 1%, giving you a fluctuation of 80mA.
These predictions are derived from tests done in a controlled environment.
As the Hall sensors are sensitive to magnetism, shock, heat and machines nearby, your measuring experiences coud fall outside these figures.
I find that if I respect the published procedure, I usually get readings within these limits.
For instance, measuring 100mA with the clamp, gives me readings fluctuating betweeen 70 and 130 mA.
If you need more accuracy, there are dedicated clamp meters for milliamp measurement, with much narrower jaws and better specs on the market.
Here is one of them (more expensive at 130$ and not true RMS):

[Cpx]

Those requested frequencies are way out of the published limitation range (400Hz max).
Nevertheless, I ran a test with a 10Vpp ramp wave at 90% asymmetry, at 50Hz, 500Hz, 1KHz, 5 KHz and 10KHz...

Ok..i am gratefull for your effort.

[kallileo]

Happy New Year!
Since it is stated that it's a TrueRMS (is it both AC and DC???) meter does that mean that it can be used to measure accurately the current of a dc motor driven by a PWM signal at 100Hz ?

[Wytnucls]

TRMS AC only. It should work fairly accurately, if the crest factor of the waveform is not too high. I'll run some tests when I get home in a couple of days.

[Wytnucls]

I have some DC motors, but they only draw about 50 mA, so the test is inconclusive, as the meter is not accurate enough with that current. Above 1A, you might get some meaningful readings, but I'm not very optimistic. You may have to read DC and AC separately to work out true RMS. Rather use a more expensive AC+DC clamp meter, like the UT222, but the lowest range is high at 200A.

[Red Squirrel]

I hope it's ok for me to bump this, found through google search as I'm debating on buying this meter.  It's on sale at Amazon right now.

http://www.amazon.ca/UNI-T-UT204-True-RMS-Auto-ranging-Clamp/dp/B005G4VKFY/

I just want to be clear this can measure both AC and DC currents using the clamp right? And the AC reading will be true RMS, so if I times by voltage I get the true wattage?  I want to use this to measure usage of various loads around the house, among other things.  I have an Ideal clamp meter already but I'm not sure if it's true RMS or not, I'm guessing it's not, as it would probably say on it.  The ability to measure DC is also very useful, for battery banks and stuff of that nature.

In general is this a good meter?  This would be for higher voltage/current.  For lower/precision I still want to buy a fluke or something later down the line, but I have a cheapy Canadian Tire one for now.

[Lightages]

Yes, the U204 is TRMS, and it will read DC current too. It is an OK clamp meter for the money. I have the 204A which is not TRMS. I also have a UT211B which I need to do a review of. IMHO, even for much more money, is worth the extra cost over the 204 series. This is my opinion and you might not think it worth the extra dollars.

I would give you more information and would ave done a video a long time ago, but health reasons have put me way behind work and I am going in for surgery tomorrow morning.

[Red Squirrel]

Thanks for the info!  I went ahead and ordered it.  I have to stop spending so much money and toys, but it's a good deal. 

[mzzj]

Yes, the U204 is TRMS, and it will read DC current too. It is an OK clamp meter for the money. I have the 204A which is not TRMS. I also have a UT211B which I need to do a review of. IMHO, even for much more money, is worth the extra cost over the 204 series. This is my opinion and you might not think it worth the extra dollars.

I would give you more information and would ave done a video a long time ago, but health reasons have put me way behind work and I am going in for surgery tomorrow morning.

UT210E would be another option and a bit cheaper. 35 to 40 eur/usd or so.  I have been reasonably happy with mine.
https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/msg560006/#msg560006

[npk]

Hi,

I am new here.

I have this UT204 which I seldom use. Recently, it started to give me a problem.

When I turn it on, it ran OK. As soon as I press SELECT, the screen went blank.

Is there anything that I can do to fix this problem? It is a pretty new unit.

Thanks in advance.

NPK
Malaysia

[Mkdsime]

Hi i have UT204A clamp meter it fell softly and now when i press the select or rel or hold button it beeps sometimes display goes crazy and shuts down. I have cleaned the connections on the pcb, measured the transistors with diode test directly on the board all 'Y1' SMD transistors have short between 2 pins. What could be the problem if someone knows please help somehow thanks and take care.

[Mkdsime]

Hi,

I am new here.

I have this UT204 which I seldom use. Recently, it started to give me a problem.

When I turn it on, it ran OK. As soon as I press SELECT, the screen went blank.

Is there anything that I can do to fix this problem? It is a pretty new unit.

Thanks in advance.

NPK
Malaysia

same problem tried cleaning the connections nothing i tested the transistor directly on the pcb with diode test the all with Y1 marking have short between two leads is that how it supposed. Can you test the transistors ??