I just picked up a nice, used Fluke 8840A meter on eBay. Looks like I got lucky as the display is in really good shape and nice and bright. Really nice unit - like it so far. Help me understand one thing please:
Overall, the unit seems to be very well calibrated (last calibration sticker from 2012). Compared to my DMMCheck and any other reference I have, any reading is well in spec. Specifically the resistance.
For example, in 2 wire mode with the leads zeroed out, the meter reads 0.99981kOhm for the 1k reference, which according to the calibration sheet of the DMMCheck is spot on to the exact digit - nice.
However, in 4 wire mode with Kelvin clips, the 100k reference reads 100.066k vs the 100.096k of the actual reference. In 2 wire mode that same resistor reads 100.095k.
So, could it be that the meter was only calibrated for 2 wire measurements?
Is there a separate adjustment for 4 wire? Or am I missing anything else?