Some developments in high-power modulators for radar

Modulators which depend upon the discharge of a pulse-shaping network, involve also the action of charging. These two component actions are inter-rclatcd but separate events, each with its set of characteristic problems. In dealing with these problems the paper first describes the principle of alternator charging, as it is applied to thyratron and to spark modulators, and compares this with a.c. rectifier charging. It then discusses means, apart from the use of a pulse transformer, for generating higher pulse voltages than are possible by the discharge of a single pulse-shaping network. These include the Blumlein cable circuit, and the Marx connection of cables, with its auxiliary charging problem. Two forms of four-electrode air-blown triggered spark-gap are introduced, together with an account of the mechanisms of their triggering and of jitter. The paper outlines a theory for the series peaking transformer, which is an important component in triggering, and concludes with a description of modulators embodying these features, together with a reference to fault protection and to measures for the suppression of radar interference.