Design, construction and characterization of a line-type pulse modulator for driving high power magnetron

In this work, the results of design, construction and characterization of a line-type pulse modulator for driving high power magnetron are reported. The sub-assemblies of modulator are: a high voltage supply, a charging reactor, a diode blocking, a pulse-forming network (PFN), a hydrogen thyratron model 5C22 and a pulse transformer. The PFN design approach is based on the Guillemin network synthesis theory, Foster´s and Cauer´s theorems. Using this approach, a 31 Ω of impedance level and 11.4 nF of capacitance PFN was simulated and then assembled to supply 9 kV and 0.7 μs voltage pulses in a pulse transformer primary circuit, at a pulse recurrence frequency (PRF) of 2 kHz. The pulse transformer was designed to impedance matching and d-c isolation between the PFN to magnetron, with transformation ratio 1:7, supplying 30 kV voltage pulses with 93% of efficiency and 9 A of filament d-c current through of a bifilar winding.