Abstract: Herein disclosed is a new and improved pulse modulator comprisng first current gating means for applying a current through a first primary lead of a current transformer during the duration of an applied control signal pulse and second current gating means for applying an oppositely directed current through a second primary lead of the transformer. The current flow through the second primary lead commences at the trailing edge of the control signal pulse and produces a flux which cancels the flux produced by the current through the first primary lead; whereby a high voltage output pulse is produced across the secondary winding of the transformer which accurately reproduces the duration of the applied low voltage control signal pulse.