Abstract: A steerable catheter comprising a resilient deflectable body member having an expandable electrode array at the distal end thereof, and a manipulation handle attached to the proximal end of the body member, the handle including an array deployment device. A mandrel is movable through the shaft of the catheter by control movements at the handle to deploy the array or collapse the array as selected. A displacement compensation system is operatively connected to the mandrel such that when the array is expanded, the compensation system biases the mandrel so keep the array expanded, even during instances of deflection of the distal end. Similarly, the displacement compensation system biases the mandrel to keep the array collapsed when that configuration is selected, even during instances of straightening of the catheter. The displacement compensation system also compensates for overturning the control device in the handle to protect the array and deployment systems.