The development results of low-noise tunable narrow bandpass filter used as input selector for short-wave receiver are presented. A filter construction scheme is proposed based on joint use of discrete variable capacitor and discrete variable inductor. The frequency range boundaries and maximum achievable overlap coefficient are determined for the circuit practical implementation, based on the capabilities of the modern element base. The frequency selectivity data and level of intrinsic noise were obtained in the course of practical research for various selector configurations. It is noted that the obtained characteristics exceed parameters of modern analogues. The selector is introduced into serial production and is supplied as independent product, as well as part of a short-wave receiver.
bandpass filter, shortwave receiver, low-noise selector, discrete variable capacitor, discrete variable inductor
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