Extech prc20 thermocouple calibrator extech prc20 the extech prc20 thermocouple calibrator can source and measure 8 types of thermocouple j k t e c r s and n with one meter that provides a precise output in deg c deg f or mv applications include lab and field calibration and verifying the operation of sensors thermocouple probes controllers panel meters and testing tools it is useful for engineering research and design manufacturing and test engineering hvac and temperatur