The television performance of the klystron amplifier

The paper describes the electrical behaviour of multi-cavity klystrons, now extensively used as high-power amplifiers in u.h.f. television transmitters. The factors affecting the frequency response are reviewed, with descriptions of the particular conditions required for output coupling and cavity tuning. The response of the klystron to the television tests for non-linearity is discussed in detail, and it is suggested that (a) differential phase shift is produced by the basic a.m.-p.m. characteristic of the tube; and (b) the discrepancy between observed results of line-rate linearity and differential gain tests is due to differing amplification of single and double sidebands, to be expected with any non-linear transfer characteristic. This discrepancy can be removed by suitable signal processing in the transmitter.