Generation of closely-spaced, doublet, CFA cathode pulses with a line-type modulator

It is noted that the radar system pulse format requirement for the generation of closely spaced, doublet RF pulses seems to preclude the use of line-type modulators. The author describes the dual channel, line-type modulators used to generate doublet cross-field amplifier (CFA) cathode pulses in a 1.25 MW peak RF power output master oscillator power amplifier (MOPA) transmitter chain. The high-power RF amplifier chain consists of a 20 kW peak power traveling wave tube (TWT) , a 150 kW peak power intermediate CFA, and the final CFA stage which amplifies the doublet RF pulses to the 1.25 MW peak power level. A comparison of a typical hard tube modulator circuit to the dual channel line-type modulator circuit is presented. The intermediate CFA stage modulator (22 kV and 14 A pk) and the final CFA stage modulator (35 kV and 77 A pk) are described with equipment photographs, test data, and results