The effects of variations in transistor parameters on the overall performance of a radio receiver

The purpose of the paper is to show that, despite wide variations in the characteristics of currently available transistors, fully transistorized radio receivers, of an acceptable performance standard, can be mass-produced without using special techniques.An indication is given of the variations in transistor parameters which occur in production, and a typical factory test specification for a small receiver is outlined.The circuit of a 6-transistor portable radio set is used to demonstrate how the effects of variations in transistors on receiver performance can be minimized. The various factors affecting the a.f. and r.f. sensitivities, image rejection and i.f. bandwidth are discussed.