Extended bandwidth high fidelity, S-band coupled-cavity traveling wave tube

The design and test of two recently developed 150 kw peak power S-band coupled-cavity TWTs, one solenoid focused and the other ppm focused will be presented. The solenoid focused tube operates at 15% duty factor, one millisecond pulse length and provides a 21%, 1 dB bandwidth. The ppm focused tube weighs only 110 1b and operates at 6% duty factor over a 16% 1 dB bandwidth. Both tubes have low noise and excellent amplitude and phase characteristics. They employ the same high mu non-intercepting shadow gridded electron gun and single stage depressed collector. The wide operating band is obtained by a unique circuit design with in-band frequency dependent loss which yields sufficient stability, and permits an operating hot band to exceed the cold circuit bandwidth. No resonant loss is employed in the tubes. The electrical performance and circuit parameters of the tubes will be described.