A slide screw tuner control mechanism uses linear actuator movement with numerically controlled PITCH (number of threads per inch). The PITCH is adjustable using the concept of a differential screw, implemented by independent control of the rotation of the actuator built-in ACME screw, yielding a numerically controllable overall effective PITCH. Tuner calibration and tuning can use dynamically adjustable horizontal movement increments increasing tuning speed at low frequencies without loss of fine-tuning resolution at high frequencies.