The Phase Variator's design is simple, yet unique. Each unit is comprised of the following major components: six chain sprockets, a piece of roller chain, a sliding yoke assembly and a control knob.

Sprockets A and B are keyed to the input and output shafts, allowing either to be used as the input. The other four sprockets serve as idlers. Idler sprockets C and D are mounted in a sliding yoke assembly which may be adjusted along its travel by rotating the control knob. An endless roller chain engages all six sprockets as shown in the diagram.

Assume that shaft A, and therefore sprocket A, are stationary. If the control knob is rotated in the counterclockwise direction, the yoke assembly will begin to travel downwards along the threaded control knob shaft. As a result, shaft B will change its position relative to shaft A, as the chain from sprocket C is taken up by sprocket D.

If shaft A is the input and the control knob is rotated in the clockwise direction, shaft B will then advance its position relative to shaft A. If shaft B is the input and the control knob is rotated in the clockwise direction, shaft A will retard its position relative to shaft B. In either direction, the yoke may reach the end of its travel and must then be reversed to make further phase adjustments.