UNI-T UT60BT Multimeter

[Dave_g8]

I don't know if this is specific to the UT60BT, but I have noticed that there is a sort of dead spot in the measurements.

Example: DC Current

On the DC Current ranges, there is a minimum value before a reading is registered.
- The minimum value before a reading is registered on the 999.9µA range is +/-0.8µA.
- The minimum value before a reading is registered on the 999.9mA range is +/-0.8mA.
- The minimum value before a reading is registered on the 9.999A range is +/-0.005A.

This is not covered by the specification.


This does not seem to be related to the resolution, since the readings are correct when above these minimum values.

[Caliaxy]

Well, this is actually specified indirectly in the accuracy numbers. For instance, 0.8% accuracy on the 999.9µA range hints you not to trust any reading under 8.2µA (0.8%+3), because the instrument can display any random number there. In these instances, some manufactures choose to display "0", others just trust you that you won't take seriously those very low readings.

On top of that, as a general rule, as you know, no measurement at the bottom of any given range (say under 5%) should be considered very accurate.

[Dave_g8]

Hi,
Understood, but is the calculation only valid for a reading of 999.9uA.
On the 999.9uA range, the reading is zero when less than +/-0.8uA, not 8.2uA as indicated from your calculation.
If the current is 1uA for example, I would expect an accuracy +/- (0.008 + 3digits) = 0.3uA.

Using another DMM as a reference (which may not be accurate), these are the measured readings.

[electr_peter]

A% number in +-(A% + Bd) specification means % from full range, B means digits in least significant digit. Thus +-(0.8% + 3) on 999.9uA range is +-(8uA + 0.3uA) = +-8.3uA.
And as mentioned by OP, some DMMs show 0 on purpose when actual reading is close to zero (your measurements indicate that UT60BT is in this category).

[Dave_g8]

Hi,
Thanks for the information.
My understanding was that the A% was % of the "reading" rather than a % of the full range.
With the 0.8% specification, for reading 999.9uA, %=8uA, for 100uA, %=0.8uA etc..
Calculation based on specification +/-(0.8%+3) attached.