Circuit arrangement for changing the oscillator frequency of uhf tuners

Claim 1

IN A UHF TUNER INCORPORATING (A) A TANK CIRCUIT HAVING AN OUTER WALL AND A CENTRAL CONDUCTOR, (B) AN OSCILLATORO TUBE HAVING FIRST, SECOND AND THIRD ELECTRODES, SAID FIRST ELECTRODE BEING CONNECTED TO SAID OUTER WALL OF SAID TANK CIRCUIT AND SAID SECOND ELECTRODE BEING CONNECTED TO A REFERENCE POTENTIAL, AND (C) A CONNECTOR LEADING FROM THE CENTRAL CONDUCTOR TO SAID THIRD ELECTRODE OF THE OSCILLATOR TUBE, THE IMPROVEMENT WHICH COMPRISES FINE TUNING MEANS FOR CHANGING THE OSCILLATOR FREQUENCY BY USING THE VARIABLE BARRIER LAYER CAPACITANCE OF A CONTROLLED DIODE, SAID TUNING MEANS BEING A SERIES CIRCUIT COMPOSED OF SAID DIODE AND A CONDENSER, WHICH SERIES CIRCUIT IS INTERPOSED BETWEEN THE WALL OF THE TANK CIRCUIT AND A POINT OF THE CONNECTOR LOCATED APPROXIMATELY AT THE MIDPOINT THEREOF, IN CONSEQUENCE OF WHICH THE FREQUENCY DEVIATION IS SUBSTANTIALLY CONSTANT OVER T HE ENTIRE TUNING RANGE OF THE UHF TUNER.