Method and apparatus for fine tuning for a television set having both vhf and uhf ranges

Claim 2

In a fine tuning system for a television having a tuner with VHF and UHF ranges; said television comprising local oscillator means having a respective basic frequency for each channel in each of said ranges of the tuner for beating a received signal to a predetermined intermediate frequency signal, a frequency discriminator having an input responsive to said predetermined intermediate frequency signal so as to receive a signal which varies in frequency with variations in frequency of the television local oscillator means, said oscillator means comprising circuit component means the impedance of which is variable in responsE to an applied voltage, variations in the impedance of said component means being operable to change the frequency of said oscillator means, first means connecting the output of said frequency discriminator to said component means in both ranges of said tuner, and second means operable for reducing the voltage supplied from said frequency discriminator to said component means in the UHF range only of said tuner.

Claim 3

A fine tuning system according to claim 1 further comprising switch means having first and second contact means, wherein said first means includes a first resistor connected at one end to the output of said frequency discriminator and at the other end to said component means, and said second means comprising a second resistor connected at one end to the component means end of said first resistor and at the other end being connected to said first contact means, and said second contact means connected to ground and engaging said first contact means in the UHF range only of said tuner.

Claim 4

A fine tuning system according to claim 2, in which said television includes a UHF adapter, said other end of said second resistor coupled to said adapter and in which said adapter comprises a UHF antenna input network, said UHF antenna network having two terminals which are connected to opposite ends of a transformer coil in the UHF range of said tuner, said other end of said second resistor being connected to one of said terminals of said antenna network, said second contact means being connected to an intermediate point of said transformer coil.

Claim 5

In an oscillator for a television having a tuner with both VHF and UHF ranges, said oscillator comprising capacitance and being variable in frequency in accordance with changes in said capacitance, a diode forming at least a part of said capacitance and being variable in capacitance in response to changes in the bias thereon, a frequency discriminator having an output which is zero when the frequency of said oscillator is at such a value that an incoming signal is beat down to a prescribed intermediate frequency signal, said discriminator output voltage varying in one direction from zero when the oscillator frequency is above said correct value and in the other direction when the oscillator frequency is below said correct value, a resistive voltage divider having one end connected to said discriminator output and having an intermediate point connected to said diode thereby to effect corrective adjustments in the bias on said diode in conformity with variations in the oscillator frequency from the said correct value thereof, and switch means operated by said tuner being in the UHF range only for connecting to ground that end of said voltage divider remote from said frequency discriminator.

Claim 6

In an oscillator for a television having a tuner with both VHF and UHF ranges, said oscillator comprising capacitance and being variable in frequency in accordance with changes in said capacitance, a diode forming at least a part of said capacitance and being variable in capacitance in response to changes in the bias thereon, a frequency discriminator having an output which is zero when the frequency of said oscillator is at such a value that an incoming signal is beat down to a prescribed intermediate frequency signal, said discriminator output voltage varying in one direction from zero when the oscillator frequency is above said correct value and in the other direction when the oscillator frequency is below said correct value, a resistive voltage divider having one end connected to said discriminator output and having an intermediate point connected to said diode thereby to effect corrective adjustments in the bias on said diode in conformity with variations in the oscillator frequency from the said correct value thereof, and switch means operated by said tuner being in the UHF range only for connecting to ground that end of said voltage divider remote from said frequency discriminator.