The Type 1398-A Pulse Generator is a general- purpose pulse source intended primarily for laboratory use. The repet i t ion rates of the pulse s may be ei ther internally control led, at f requencies from 2.5 c / s to 1.2 Mc/s, or external ly controlled at f requencies up to 2.4 Mc/s. In addition to the main posi t ive and negat ive output p u l se s , the instrument a l so suppl ies synchronizing pulse s that correspond to the beginning and end of the main pulse. The early sync pulse ( prepulse ) is intended chiefly for synchronizing an osci l loscope while the late pulse ( delay pulse ) is in tended to make the instrument an accurate time-delay generator.