An Experimental Transistor Personal Broadcast Receiver

This paper describes a laboratory-model AM broadcast receiver which used nine alloy-junction transistors and two compensating diodes. Six of the transistors were of the laboratory p-n-p type, designed for radio-frequency amplifiers, and three of the transistors were of the conventional p-n-p type selected for Class B audio driver and output service. The use of Class B output permitted a total battery drain below 12 milliamperes from six 1.5-volt type C cells in series. The battery life was approximately 500 hours, and the battery cost relatively small. The maximum audio-power output was 150 milliwatts into a four-inch by six-inch oval speaker. The sensitivity and signal-to-noise ratio were comparable to that of conventional battery-operated receivers and conventional ac-dc receivers. The receiver may be used in the place of ac-dc receivers without the necessity of a power outlet or a connecting power cord at a battery cost approximately the same as the cost of power for an ac-dc receiver.