Abstract: An actuator and programmable amplifier is operative for use with an expanding plug gage head operated by an axially movable plunger having a tapered operating end and an opposite cross head end. The cross head end of the plunger is releasably received and secured through a slot in a retracting lever which is pivotably mounted in the actuator/amplifier housing. A compression spring normally urges the plunger to a fully extended position within the gage head. The retracting lever is actuatable for withdrawing the plunger from the gage head. The actuator/amplifier device includes a transducer having a core which is coupled to the crosshead end of the plunger. The transducer is operative for measuring an axial position of the plunger within the gage head. The programmable amplifier includes a memory for storing a plurality of sets of configuration data for a plurality of different gage heads.