The SRT-422 E-Beam Source Indexer provides accurate, reliable rotation control of multiple-crucible electron beam sources. The standard unit is designed to work with a variety of e-beam sources with internal 4 to 1 rotation reduction. Crucible pocket location patterns are provided which cover the majority of e-beam source designs. The unit consists of two components: 1) a remotely-mounted control panel and power supply and 2) a compact stepper motor drive unit.