Quality Magazine

Portable 4-20mA Calibrator

November 26, 2007
The model 420 is for calibration/test of DPMs, PLCs, transmitters, sensors or any other device requiring a 4- to 20-milliampere current loop signal. The 4- by 2.5- by 4-inch housing comes with a belt clip for ease of operation. Powered by a 9-volt transistor-type battery, this unit operates down to 6 volts and can drive up to 300-ohm loads or sustain up to 7 volts burden of the load. The built-in display will only turn on if the loop is closed (connected), which is useful for troubleshooting loops.


The model 420 is for calibration/test of DPMs, PLCs, transmitters, sensors or any other device requiring a 4- to 20-milliampere current loop signal. The 4- by 2.5- by 4-inch housing comes with a belt clip for ease of operation. Powered by a 9-volt transistor-type battery, this unit operates down to 6 volts and can drive up to 300-ohm loads or sustain up to 7 volts burden of the load. The built-in display will only turn on if the loop is closed (connected), which is useful for troubleshooting loops.