VHF FM receiver with low component count - incorporates frequency-selective RF amplifier deriving power supply from emitter of crystal-filtered IF amplifier

摘要

An RF amplifier (10) with a single tuned circuit (12) fed from an antenna (1) is based on a bipolar transistor (Tr1) which has a tuned collector circuit (16) coupled to a mixer (20). The local oscillator (30) contains a crystal and a transistor (Tr3) with tuned emitter and collector circuits (32,34), providing the ninth harmonic of the crystal frequency. The power supply for the RF amplifier (10) is taken from the emitter of the transistor (Tr4) in the first IF stage. USE/ADVANTAGE - Wireless microphone system. Simpler and more reliable receiver. Contains all necessary components of superheterodyne circuit.