Abstract: By providing a hand-held remote controller capable of controlling, at a low voltage level, all operational functions of an X-ray generating module with all high voltage lines contained within the main housing, a portable X-ray unit is achieved having both mobility and flexibility. This is chiefly attained by employing kVp line selection in the remote controller with high speed solid state switching in the main housing for energizing the desired windings in the high voltage transformer, and digital control of the current in the remote controller for delivery to the filament transformer of the X-ray tube. The filament current to the X-ray tube, which is automatically varied as a function of the kVp level and exposure time selected, is controlled by changing the frequency of the pulse delivered to the filament transformer. The particular current level being employed is automatically determined by the system, to assure maximum power utilization of the X-ray tube within its heat dissipation capabilities.