Design of a 150-magacycle Pocket Receiver for the BELLBOY Personal Signalling System

This paper will describe the electrical and physical features of the 55A radio receiver and certain associated apparatus, which were designed for use in BELLBOY personal signaling systems operating in the 150-megacycle common carrier hand of frequencies. The receiver is pocket-sized and provides, in effect, an extension of the telephone hell to the customer's pocket so that he may be alerted while away from his office, home, or base location. An incoming signal, bearing the customer's specific code, triggers the receiver. The receiver then emits a continuous tone, in response to which the customer calls his base telephone to receive his message, or responds in some other prearranged manner. The requirements and applications of this service have been covered 527 528 THE BELL SYSTEM TECHNICAL JOURNAL, MAY 1963 in a previous paper. 1 In the present paper, discussion is concerned with the requirements placed on size, cost, and performance of the receiver, and the various circuit and equipment features which were used to achieve these ends. Major problems encountered in both the electrical and mechanical design are discussed in some detail, and an analysis of the circuit performance is included. The 55A radio receiver is a ten-transistor superheterodyne circuit packaged in a molded plastic case. It has a self-contained antenna and is powered by a battery mounted in a detachable case. When a rechargeable battery is used, a charger is provided, which will accept the battery case and permit the battery to be charged by placing the assembly in any convenient 117-volt ac outlet.