Citizens band broadcast band coupling circuit

摘要

A circuit for coupling a citizens band transceiver and a broadcast band receiver to a standard automobile antenna. The circuit is comprised of an impedance transforming network connected in series with the standard automobile antenna and a parallel-tuned circuit in series with the broadcast band receiver. The series-tuned network is comprised of a split capacitance for stepping the impedance down from the citizens band transceiver to the lower impedance of a standard automobile antenna. The series-tuned circuit also includes a tuning coil for matching the output of the network to the particular automobile antenna. In series between the automobile antenna and the broadcast band receiver is a parallel- tuned circuit comprised of a capacitor and a tuning coil. To prevent multiplication and excessive voltages in the event the broadcast band receiver should become disconnected, a limiting resistor connects the parallel-tuned circuit to ground. The tuning coil of the impedance transforming network has a novel molded plastic tuning knob for simplifying tuning of the circuit.