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Abstract

A circuit arrangement for a wide band superheterodyne radio receiver for receiving wide band FM, narrow band FM, and AM modulated radio signals between 25 and 550 MHz. The first LO is a phase locked loop controlled VCO, with central processing unit control of the phase locked loop circuitry. The first IF frequency is higher than the highest received frequency and the output frequency of the first LO is higher than the first IF. A second LO and second mixer convert the signal to a second IF lower than the first IF. Separate third and fourth IF band pass filters are provided at the second IF for WFM and for NFM/AM, respectively. The output of the third IF filter (WFM) is converted by a third LO and third mixer to a third IF lower than the second IF. A WFM demodulator is provided at the third IF. The output of the fourth IF filter (NFM/AM) is converted by a fourth LO and fourth mixer to a fourth IF lower than the second IF frequency. A fifth IF band pass filter is provided at the fourth IF. The output of the fifth IF filter is received be separate NFM and AM demodulators. Each demodulator is followed by its own audio amplifier, each selectively connectable to a speaker.

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