desired position the catheter 12 may also include mechanical stops or detents located internally within the handle 22 that provide the user with tactile feel as to the positioning of the needles 27 and 29 when they are manually advanced for example such tactile feel may be provided by a spring plunger with a ball detent built into the handle 22 wherein the spring loaded ball would ride along a smooth wall of an i inner handle recess or detent locations would be calibrated along the inner handle to deploy the array a predetermined diameter alternatively a tab or o ring connected to the inner surface of an outer handle could be used to locate recesses or detents formed on the inner handle another alternative may include radial grooves on an inner or outer handle that enables the probe to be rotated and held in place after the array have been deployed a predetermined diameter t the control system 14 preferably comprises a rf power source 38 such as a generator a drive controller 42 coupled to the power source 38 an impedance and or temperature monitoring module 40 coupled to the power source 38 and the drive controller 42 and a variety of displays to indicate temperature impedance needle position elapsed time and the like the drive controller 42 may be built into the rf generator or may be a stand alone unit a first cable 32 interconnected to the power supply 38 extends from the control system 14 to the proximal end.