Power System

The transmission equipment in the TD-3 radio system is designed to be powered from common, --24-volt battery plants. Where voltages other than --24 volts are required, for the traveling-wave tube, the IF circuits, the microwave generator, and the like, they are furnished by power supplies which are powered from the common --24-volt battery plant. An exception is the transmitter-receiver test set power supply which is powered from commercial 60 hertz ac. The stringent noise requirements of the TD-3 radio system dictated a precisely-controlled approach to dc power distribution. DC power feeders from the common --24-volt battery plant through a battery distribution circuit breaker board arc segregated into noisy, quiet, and undesignated groups. The noisy group, those feeders on which there is appreciable noise, feed primarily converter-type power supplies. The quiet group consists of feeders whose loads are susceptible to noise, such as the regulated --19-volt power supply. The undesignated group primarily feeds alarm battery supply loads which generally are not noisy, but will on occasion, such as when a relay drops out, produce noise. With rare exceptions, a separate ground return feeder of equal cross sectional area is run with each hot (off ground) feeder from the circuit breaker board to the equipment bays. This minimizes current flowing in the equipment bay frameworks and thus reduces system noise. In the TD-3 main and repeater stations of the initial installation, 1487