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This paper describes the design and performance of a remote tuned FM receiver. Three voltage variable capacitance diodes are used to tune the RF amplifier, local oscillator and mixer stages. Either local or remote tuning is accomplished by means of a variable DC bias voltage giving performance equal to receivers tuned by mechanical variable capacitors. Tracking and temperature stabilization methods are described along with advantages and disadvantages of this tuning method with respect to those presently used. Possible applications include central home music systems and aircraft receivers where it is desirable to separate the tuning control from the receiver.

This report presents the results of a study of transistor mixer operation at high frequencies. A general analysis of mixer operation is developed based on the assumption that any device in which mixing occurs can be represented by a linear network with time varying components. From this analysis a general mixer equivalent circuit is developed. This may be applied in the transistor mixer case by proper modification of the Giacolletto equivalent circuit. In the theoretical analysis it is assumed that collector current can be represented by a square wave switched at the local oscillator frequency. In actual practice IC does not approach a square wave sufficiently for good agreement with experimental results. A constant correction factor is experimentally determined which when included in the equation allows calculation of conversion gains that agree to within 5% to 10% of those measured.