High-frequency 250kW broadcasting transmitter

In 1939, a paper by Hayes and MacLarty was published which contained a comprehensive review of high-power high-frequency broadcasting-transmitter-design techniques which existed at that time. Since then, high frequencies have continued to be used for worldwide broadcasting, and the paper describes the latest techniques used in the design of transmitters. A transmitter is described which uses evaporation cooling for the valve anodes, is rated ot 250kW carrier power, and is designed for `trapezium modulation¿ to raise the effective signal level.