Hi guys,
I'm new here, but happened on a useful feature for anyone with a UT81B scope meter. If you power the device up and hold the HOLD button down it takes you to a calibrate screen for the scope.
Press F1 to enter calibration, or F4 to Quit
You will then be asked for a password, 5 seconds of hacking solved it. Press F4, F3, F2, F1
Next it will ask you to short the leads and set the base level for the voltage ranges, press F4
Once it has cycled through that, you need to have a precise 600mV source ready, I used my PSU and a voltage divider to get it spot on, and left my reference meter in circuit. Press F4
This will cycle to the next 1.5v reference and finally the 3v reference. F1 at the end to save the new calibration and your done.
I gained a further 15mV accuracy doing this on my meter thats a few years old.
Joules