Desired frequency coupling circuit having undesired frequency cancellation trap located at voltage null point for desired frequency

Claim 1

IN A TELEVISION RECEIVER, APPARATUS COMPRISING THE COMBINATION OF A BANDPASS NETWORK INCLUDING A PAIR OF MUTUALLY COUPLED INDUCTANCES, SAID INDUCTANCES BEING DIRECTLY CONNECTED TO EACH OTHER AT A COMMON JUNCTION POINT, AN RF SIGNAL SOURCE, AN OUTPUT CIRCUIT, MEANS FOR CONNECTING SAID PAIR OF INDUCTANCES IN SERIES WITH SAID SIGNAL SOURCE AND SAID OUTPUT CIRCUIT, MEANS INCLUDING A CAPACITOR INSERTED IN SERIES BETWEEN SAID SIGNAL SOURCE AND SAID PAIR OF INDUCTANCES FOR CAUSING SAID JUNCTION POINT TO EFFECTIVELY COMPRISE AN RF NULL POINT IN SAID BANDPASS NETWORK, A RELATIVELY SHARPLY TUNED PARALLEL RESONANT CIRCUIT, AND MEANS FOR COUPLING SAID PARALLEL RESONANT CIRCUIT BETWEEN SAID JUNCTION POINT AND A POINT OF REFERENCE POTENTIAL.