The Meriam M334 loop calibrator is a state of the art, highly reliable, rugged and easy- to-use milliamp calibrator. It has the functions necessary to perform all the required maintenance and calibration tasks of virtually any 4-20 mA loop. It provides source and read milliamp functions along with power and measure, and two-wire transmitter simulations. In addition it can measure DC voltage for troubleshooting power supplies. The Meriam M334 loop calibrator is functionally equivalent to similar calibrators with many additional benefits. These improvements include better long term stability, accuracy, reliability and ruggedness including significantly improved battery life. The combined improvements allow the Meriam M334 to meet or exceed all of the expected performance and functions of similar products.