A New Air-Cooled 5-Kilowatt Broadcast Transmitter

This papers gives details in design and construction of a new,5-kilowatt transmitter for use in the broadcast band of 550 to 1600 kilocycles. By the use of illustrations the arrangement of components in each cubicle is shown and the text refers to the various major details. One method of adapting a single blower to the cooling needs of an entire transmitter is described. The supervisory, sequence interlocked, control system is outlined and the placement of indicator lights, switches, and relays used in conjunction with this control system are oztlined. With the use of a simplified schematic several specialized adaptations of new audio circuits are shown and discussed. These circuits reduce distortion to very low values and a flat frequency response is obtained over wide limits. Distortion values at various percentages of modulation are plotted in a response curve of a typical 5-kilowatt transmitter. A means of reducing radio-frequency output power with split-second push-button control of a magnetic switch is also touched upon. The summary at the close of the paper outlines various performance characteristics such as power consumption at several modulation levels, audio response, radio-frequency stability, and power output.