Design philosophy for the RF section of consumer AM radios

Abstract

The first basic requirement for the RF section of an AM radio for world-wide use is adequate sensitivity over a wide frequency range. It should also be easy to tune accurately, have a wide dynamic input signal range, be insensitive to interference and have low intermodulation distortion. Building such an RF section with conventional architecture and traditional circuitry requires a lot of electronic and electro-mechanical components. This, of course, leads to reduced reliability due to component ageing, distortion caused by the influence of variable-capacitance tuning diodes and increased cost. This presentation evaluates these problems and describes how they can be solved with particular emphasis on portable short-wave radios.<>