Abstract: A modular modulator having a high voltage supply source and a separating circuit connected at its input to the high voltage supply source. The output of the separating circuit is connected to a pulse generating circuit which is itself connected by a coupling circuit to a transmission tube. The pulse generating circuit contains a plurality of elementary delay cells. The delay cells are each connected to the coupling circuit by means of at least one switching circuit and the electrodes for triggering the switching circuits are connected to a control circuit which emits signals in sequence at different predetermined times. Triggering the switching circuits enables thus by the discharge of the elementary cells a resultant signal made up of elementary pulses of predetermined length to be generated.