> How accurate is it to % or ppm? I made some quick and dirty tests in the following conditions: 1) Solartron 7150+ not calibrated and turned on 15 minutes before measurements 2) Thommen 230 in battery mode (no external power supply) 3) I set the output voltage in mV (entered with the following format: xxx.xx) and I waited for the output to stabilize (from 6 to 12 seconds) 4) I used cheap tester leads to make the measurements 5) the ambient temperature was about 25 Celsius 6) I repeated several times the measures and the max difference shown on the 7150+ is no more than 2 units on the least significant digit (6 digit mode) here it is a small table with some of the measured values (columns: 1=Thommen, 2=7150+ reading, 3=delta%): [I padded the numbers with zeroes so I hope the formatting will not be disrupted] Thommen 7150+ delta% 0000.10 0000.099 -1.010 0001.00 0000.996 -0.402 0005.00 0004.996 -0.080 0010.00 0009.997 -0.030 0020.00 0019.998 -0.010 0050.00 0050.003 0.006 0100.00 0100.011 0.011 0123.45 0123.456 0.005 0200.00 0200.020 0.010 0500.00 0500.057 0.011 0900.00 0900.067 0.007 1000.00 1000.080 0.008 I know these measurements are far from what you are used, but not being a real Volt-Nut, I think 15 euros was a good price for this small portable calibrator... Now I have only to find some documents which explain me how to really use it!!! . ciao _ Elio.