A 14 MeV, S-band linear accelerator has been designed and built by Beta Development for use in the MIDEP explosive detection program at Titan/Spectron Division. The explosive detection technique utilizes photoneutron activation of the nitrogen which is an integral component in most commercial and military explosives. The accelerator was designed to be a small, high power, light weight, and portable unit capable of operation from the bed of a moving vehicle. The accelerator produces 3 kW of beam power at an energy selectable between 12.5 and 14 MeV. The electron beam will strike a converter to give over 300 R/s bremsstrahlung radiation. This paper describes the accelerator system and the associated control features.