SOLID-STATE TUNED UHF TELEVISION TUNER

• US 3,643,168 A
• Filed: 07/07/1969
• Issued: 02/15/1972
• Est. Priority Date: 07/07/1969
• Status: Expired due to Term

• Current Assignee: Gert L. Manicki
• Original Assignee: Gert L. Manicki
• Inventors: Manicki, Gert L.
• Primary Examiner(s): Murray, Richard
• Application Number:
  US04/839,169
• Time in Patent Office: 953 Days
• Field of Search: 325/452,457,459,461,462,464,465,468,363 334/14 330/30 29/626
• US Class Current: 455/178.1
• CPC Class Codes: H03J 3/185 with varactors, i.e. voltage variable reactive diodes
• CPC Class Codes: Y10S 55/05 Methods of making filter

Abstract

A solid-state voltage-controlled capacitor (varactor or varicap) UHF television tuner is described which includes a varicap preselector tuned circuit, a varicap tuned RF amplifier stage inductively coupled to the preselector circuit, and a varicap tuned oscillator stage, both the oscillator stage and the amplifier stage being inductively coupled to the diode mixer stage from which an IF signal is derived. The tuner employs a single tuning voltage source to tune across the entire UHF range and also includes provision for AGC. Trimmer capacitors and inductance adjusting devices of unique and advantageous configuration are employed to align the tuner. Further disclosed are unique methods of assembly and alignment for the tuner.

Claims

1. A television tuner for tuning the American UHF television frequency band comprising:

a conductive shielding housing defining an interior volume;

an input into said housing for received UHF television frequency band signals;

a first voltage tuned circuit within said housing, coupled to said UHF television input and comprising first inductance and first solid-state voltage-variable capacitance coupled to said inductance, for selecting a channel signal from the UHF band;

an oscillator in said housing including an amplifier device and an oscillator frequency determining voltage tuned circuit comprising an oscillator inductance and oscillator solid-state voltage-variable capacitance coupled to said oscillator inductance;

a mixer in said housing coupled to said first voltage tuned circuit for receiving therefrom selected channel signals, and also coupled to said oscillator for receiving therefrom its oscillatory signals, for mixing the selected channel signal and the oscillatory signal to produce a modulated IF signal;

an IF output from said housing coupled to said mixer for receiving the modulated IF signal therefrom; and

a tuning voltage input into said housing for receiving a selectively variable tuning voltage, coupled to said solidstate voltage-variable capacitance of said first tuned circuit and coupled to said oscillatory solid state voltage-variable capacitance of said oscillator tuned circuit for controlling in common both of said tuned circuits whereby said oscillator is caused to track said first tuned circuit by a predetermined constant frequency difference to generate at said mixer a modulated IF signal of constant predetermined IF carrier frequencies for any channel signal in the UHF range;

said tuner including a RF amplifier device coupled between said first tuned circuit and said mixer for amplifying the signals selected by said first tuned circuit, and a third voltage-tuned circuit coupled between said RF amplifier device and said mixer for further emphasizing the selected and amplified channel signals and for deemphasizing and shunting out nonselected signals and noise, comprising third inductance and third solid state voltage-variable capacitance coupled to said third inductor; and

said third solid-state voltage-variable capacitance of said third voltage-tuned circuit being coupled to said tuning voltage input for control in common with said first tuned circuit and said oscillator tuned circuit;

said first solid-state voltage-variable capacitance, said oscillator solid state voltage-variable capacitance, and said third solid state voltage-variable capacitance, and each of them, are varicap diodes whose electrical characteristics are generally similar to one another; and

wherein said housing is conductive, at ground potential, and defines at least three longitudinal boxlike cavities and said first, said oscillator, and said third inductances are each longitudinal conductive line elements longitudinally disposed within different ones of the cavities, with one longitudinal end thereof grounded and the other longitudinal end connected to, respectively, said first, said oscillator, and said third varicap diodes; and

wherein a trimmer reactance (44 or

     156) is provided between the inductance element and ground in at least one of said first, oscillator and third voltage tuned circuits which trimmer reactance is formed by a planar conductive segment electrically connected to one of said housing and said element and extended adjacent to but spaced from the other of said housing and said element, which trimmer reactance affixed so as to be adjustable by physiCally displacing it from and to said other of said housing and said element.

2. The television tuner for tuning the American UHF television frequency band as defined in claim 1, wherein:

the inductance element in said at least one voltage tuned circuit is formed by a flat wire segment; and

said trimmer reactance is essentially a capacitive reactance and is formed unitarily with the inductance element of said at least one voltage tuned circuit and constitutes an extension of said flat wire segment, which extension proceeds from the junction of the inductance element and the varicap diode of said at least one voltage tuned circuit.

3. The television tuner for tuning the American UHF television frequency band as defined in claim 1, wherein:

said trimmer reactance formed by said generally planar segment (156) which segment is connected, physically and electrically, along one edge (157) to said housing to extend longitudinally along said inductance element of said at least one voltage tuned circuit.

4. The television tuner for tuning the American UHF television frequency band as defined in claim 1, wherein:

said oscillator includes;

a transistor having a base, collector and emitter as said amplifying device, with the base at effective oscillatory frequency ground potential; and

said solid-state voltage-variable capacitor is coupled across the emitter-collector circuit of said oscillator transistor.

5. In a television tuner for tuning the UHF television frequency band and for selecting therefrom one television frequency channel signal and converting that channel signal into a modulated IF signal of predetermined IF carrier frequencies of the type having a RF amplifier, an oscillator and a mixer, the improvement comprising:

having a solid-state voltage-variable capacitance tuned interstage double tuned circuit coupled between the RF amplifier and the mixer, said interstage double tuned circuit comprising;

a first tuned circuit (B1) coupled to the RF amplifier including;

a first inductance (861), and a first solid-state voltage-variable capacitance (881) coupled to said first inductance; and

a second tuned circuit (B2) coupled to the mixer and said first tuned circuit (B1) and including;

a second inductance (862), and a second solid state voltage-variable capacitance (882) coupled to said second inductance;

tuning voltage input; and

having means connecting said tuning voltage input to said first solid-state voltage-variable capacitance and to said second solid-state voltage-variable capacitance for selectively varying the capacitance thereof, said tuner includes a housing defining a first interstage cavity (301), a second interstage cavity (302) and an oscillator cavity (32) with said first interstage tuned circuit in said first interstage cavity and said second interstage tuned circuit in said second interstage cavity, said first and said second interstage cavities being separated by a conductive shielding wall (300) and said first and said second interstage tuned circuits being coupled together by inductive coupling through a cutout portion of said wall;

the oscillator of said tuner including an oscillatory frequency tuned circuit comprising an oscillator inductance and an oscillator solid-state voltage tuned capacitance;

each of said first, second and oscillator solid state voltage tuned capacitances being a varactor diode matched in electric characteristics to each other;

each of said first, second and oscillator inductances being longitudinal line elements extending within respectively said first interstage, said second interstage and said oscillator cavities and each of which have two longitudinal ends one of which is connected to said housing and the other of which is connected to the respective first, second and oscillator voltage-variable capacitance varactor diodes;

said oscillator varactor diode being connected to said tuning voltage input so that said oscillator tuned circuit may track along with said interstage double tuned circuit;

said tuner including a closed conductive loop which is physically adjustable in said housing attached to the wall dividing said first interstage cavity from said second interstage cavity in the cutout portion thereof to provide manually adjustable means for altering the coupling between said first interstage tuned circuit and said second interstage tuned circuit;

the mixer being a solid state diode having two leads one of which is in said second interstage cavity and is connected to said second inductance line element; and

the RF amplifier including a transistor whose output is coupled to the junction of said first inductance line element and said first capacitance varactor diode.

6. In a UHF television tuner of the type including at least one tuned circuit for selecting a television channel signal and an oscillator tuned circuit for generating an oscillator signal having conductive housing walls bounding a boxlike mounting cavity, the improvement of having at least one of the tuned circuits being a voltage tuned circuit mounted in the cavity and comprising:

a flat wire element having one end grounded to a conductive housing wall, said element providing an inductance segment extending in spaced relation to the remaining housing walls and terminating at the grounded end;

a capacitance segment at the other end and a generally transverse segment connecting said inductance and said capacitance segments in lengthwise offset parallel relation, said segments lying in planes transverse to the plane of the main housing wall;

a solid-state voltage-variable capacitor connected in tunable relationship with said inductance segment; and

a tuning voltage input line coupled to said capacitor.

7. In a UHF television tuner having conductive housing walls, one being an intermediate partition wall, bounding adjacent mounting cavities, the improvement comprising an interstage double tuned circuit having:

a flat wire input inductance segment in one cavity extending parallel to the intermediate partition wall and grounded to a conductive housing wall;

an input solid state voltage-variable capacitor connected in tunable relation with said input inductance segment;

a flat wire output inductance segment in the other cavity extending parallel to the intermediate partition wall and grounded to a conductive housing wall;

an output solid-state voltage-variable capacitor connected in tunable relation with said output inductance segment;

a tuning voltage input line coupled to each of said solid state voltage-variable capacitors; and

a closed conductive loop element mounted in a wall opening of said intermediate partition wall to inductively couple said segments.