uCurrent - wrong gain/shunt on 1mV/1mA range

[JohnnyMalaria]

Hi,

I've noticed that the apparent gain for my uCurrent Gold is wrong on the 1mV/1mA range (10m shunt). It should be 1000 but seems to be 3X that.

Attached are plots of some resistors I measured (I capture the source voltage and uCurrent output via a DAC at 16kHz using a 1Vpk sinewave anywhere between 1 and 500Hz.)

The left plot for resistors ranging from 220R to 5.5K using the 1mV/1uA. The values calculated using the uCurrent output are the expected values.

The right plot is for resistors ranging from 5R to 220R using the 1mV/1mA range. The values calculated using the uCurrent output are a third of the expected values.

The 220R was tested with both ranges.

So, my unit is behaving as if the 10m shunt is actually 3.3m.

Thanks.

Has anyone else come across any discrepencies at the 1mV/1uA 1mV/1mA setting?  (Sod's Law it's the one of most importance to me.)

EDIT: typo - wrong range

[JohnnyMalaria]

Thanks.

I copied/pasted incorrectly (see edit). I meant the 1mV/1mA range is where my problem is showing up.

[JohnnyMalaria]

Did you accidentally measure in the "On & Short" position? I can repeat this with only 1/3 as a result.
I only measured with direct current, 15 Ohm and 30 Ohm as resistance, the result is exactly 1/3.

Peter

I don't think so because I made all the measurements on both ranges without changing the off-on-short switch. But I'll check since you got 1/3 that way.

Thanks.