Broadband klystron input and output cavities

A report is given on a method of design of individually broad-banded input and output circuits for use on an experimental broad-band klystron. Multiple-cavity filter design techniques are applied to achieve a bandwidth of seven percent in L-band. The input circuit is comprised of a low Q coaxial cavity tightly coupled to the input cavity. It has a double humped response of ± one db amplitude variation across the band. The output circuit consists of three direct-coupled synchronously tuned cavities and produces a triple-peaked response with less than ± 0.5 db variation in the band. A refined cold-test procedure, using simulated beam loading in the output interaction gap, insures a proper impedance match between beam and load. An output coupler of this type has been used on a tube of known characteristics and hot test data indicate no degradation of efficiency compared to a tunable output cavity. The output power response of the output coupler agree within ± 0.3 db.