Products > Test Equipment
Review and tear-down of UNI-T UT612 LCR meter
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BravoV:
Wytnucls, thanks for the close up shot.

Yeah, don't think that kind of modding is necessary, but as a tinkerer this is an option for the future just in case if needed.  ;)
Wytnucls:

--- Quote from: alm on March 07, 2013, 10:13:05 pm ---The long leads you can compensate for, their resistance is constant. Kelvin connections are critical once contact resistance between the probe/clip and DUT becomes significant. This contact resistance often varies between measurements, and may be dependent on force. Kelvin connections can compensate for this variation.

--- End quote ---
Quite correct Alm. So, it is very important to have a good electrical connection to the DUT with a 2-wire system to measure small resistors of less than 1 Ohm. Whether the 2 connecting pressure plates on the UNI-T adapter are sufficiently adequate, I don't really know. Contact resistance is usually about 1mOhm.
I did run a test with a 30cm length of wire on the UT612, with the ends pushed through the blade connectors after calibration, which gives me repeatable measurements of 5milliOhms in Rs 1KHz mode. I don't have the instrument to measure the actual resistance of that wire, unfortunately.

Here is a sample of small 10% inductors measurements taken both with the UNI-T and the CEM 9935, using the pressure plates and also a sample of 1% resistors using a 1KHz frequency and short leads and clips (resistor legs are too thin to push through the plates), with the UT71D DMM as an extra reference:
Hydrawerk:

--- Quote from: Wytnucls on March 09, 2013, 03:29:49 am ---Here is a better PCB picture, with a close-up of the jacks. At first glance, it seems possible to modify for a proper 4-wire measurement system. You would need to investigate further, before you start hacking at your meter.

--- End quote ---
There is no doubt that UT612's PCB is better designed than DT-9935.
Wytnucls:
Here is a selection of small caps measured with both LCR meters again, using short test leads and clips and also some electrolytics:
Wytnucls:
Some inductor measurements, with short test leads and clips:
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