Industrial 334A Loop Calibrator

Altek 334A Milliamp Loop Calibrator is a handheld, battery-powered instrument designed to check, calibrate, and troubleshoot 4-20 mA DC current loops in industrial instrumentation. The compact unit uses a rotary knob to set output current and mode-select toggles to switch between core functions such as sourcing, simulating, and measuring loop signals, enabling precise verification without external power. Intended for on-site calibration workflows, the 334A lets technicians insert the device into a live current loop to verify transmitter outputs, calibrate loop receivers, and diagnose issues within process-control circuits. In practice, it supports verifying transmitter span and linearity, validating PLC or DCS input channels, and performing quick fault isolation in field environments. Often described as part of the Transmation Altek family, this model is valued for its simplicity, durability, and direct, no-fuss operation when working with standard 4-20 mA loops. Overall, the 334A provides a practical, portable solution for maintaining accuracy across instrumentation loops, making it a go-to tool for maintenance technicians and control engineers performing routine loop checks and calibrations.