82 Detent manual varactor tuning system

In a television receiver tuner of the type having resistive means developing a nominal tuning voltage for supplying a capacitive network connected for tuning a varactor element to a selected television channel, the improvement comprising:

• switching means initially connecting said resistive means to said capacitive network for supplying said nominal tuning voltage and subsequently decoupling said resistive means from said capacitive network;
• automatic frequency control means in association with said capacitive network and operable for adjusting the voltage thereacross for tuning said varactor element to a received signal in said selected television channel;
• and
• control means operable for confining the voltage impressed across said capacitive network to a range of voltages including said nominal tuning voltage, said voltage range defining a restricted range of frequencies within said television channel.

A television receiver tuner comprising:

• tuning means including at least one varactor diode as the frequency determining element, the frequency determined being a function of the voltage presented to a terminal of said varactor;
• a voltage generating element connected for presenting a voltage to said terminal;
• means for establishing a plurality of DC potentials each defining a frequency range corresponding to a television channel;
• a control voltage divider selectively connectable across each of said plurality of DC potentials for deriving therefrom a nominal tuning voltage defining a frequency near the center of a selected channel and a pair of control voltages defining a restricted range of frequencies within said selected channel and about said center frequency;
• means initially supplying said nominal tuning voltage from said control voltage divider to said voltage generating element for tuning to said center frequency and subsequently decoupling said control voltage divider from said voltage generating element;
• means for confining the voltage developed by said voltage generating element between said pair of control voltages for maintaining tuning within said restricted range of frequencies;
• and
• automatic frequency control means for adjusting the voltage developed by said voltage generating element for tuning to a received signal within said restricted frequency range.