High-power television transmitters for Bands IV and V

To increase the number of channels available for television broadcasting, it is now becoming increasingly necessary in several countries to utilize the ultra-high-frequency bands (Band IV, 470¿585 Mc/s, and Band V, 610¿960 Mc/s). The paper considers some of the factors concerning the relatively restricted coverage on ultra-high frequencies and the power requirements of transmitters to offset this disadvantage. This leads to a discussion on the choice of valve types for use in u.h.f. television transmitters. The choice of a high-gain klystron output amplifier for a 10 kW transmitter enables a relatively low-power modulated amplifier to be used in the penultimate stage. The paper describes the fully engineered transmitter installed experimentally at the B.B.C. television transmitting station at Crystal Palace for propagation and television reception tests in the u.h.f. band covering both the 405-line and 625-line television systems.