Varactor controlled push-pull oscillator

Claim 2

An oscillator arrangement which is controllable in frequency, comprising: a frequency control input; a frequency-determining circuit including two varactor diodes connected in opposing fashion, the capacitance of said varactor diodes largely representing the oscillating circuit capacitance, and an inductance having first and second terminals connected to respective varactor diodes and a tap connected to said frequency control input; an output transformer including first and second terminals and a tap connected to a reference potential; and a pair of feedback oscillator circuits each including a first terminal connected to a respective varactor diode, a second terminal connected to a respective transformer terminal to provide push-pull operation, and an emitter terminal connected to the emitter terminal of the other.

Claim 3

The oscillator arrangement of claim 1, wherein each of said feedback oscillator circuits comprises: a transistor having a base, a collector and an emitter, said base connected to the respective varactor diode, first and second capacitors connected in series between said base and the reference potential to a.c. couple said emitter to said base; and a voltage divider including a tap connected to said base for establishing the operating point voltage.

Claim 4

The oscillator arrangement of claim 2, wherein said voltage divider comprises: an adjustable resistor for controlling the operating point voltage to limit the generated oscillation.

Claim 5

The oscillator arrangement of claim 1, comprising: a resistor connecting said tap of said transformer to the reference potential.

Claim 6

The oscillator arrangement of claim 1, and further comprising: a control voltage source connected to said frequency control input and having an internal resistance; an absorption wave trap comprising a capacitor, an inductor and a first resistor connected in series between said frequency control input and the reference potential, the resonant frequency of said absorption wave trap being more than twice the middle frequency of the frequency variation range; and a second resistor connected in parallel to said absorption wave trap and having a resistance equal to said internal resistance and at least five times smaller than the surge impedance of said absorption wave trap.

Claim 7

The oscillator arrangement of claim 5 wherein: said inductor is a variable inductor.

Claim 8

The oscillator arrangement of claim 5 wherein: said first resistor is a variable resistor.

Claim 9

An oscillator arrangement having controlled frequency, comprising: a frequency control input; a control voltage source connected to said frequency control input and having an internal resistance; an absorption wave trap connected to said frequency control input and to a reference potential, said absorption wave trap having a resonant frequency greater than twice the middle frequency of the frequency range; a first resistor connected in parallel to said absorption wave trap and having a resistance equal to said internal resistance and at least five times smaller than the surge impedance of said absorption wave trap; an inductor including a pair of terminals, and a tap connected to said frequency control input; an output transformer including a pair of terminals, and a tap; a second resistor connecting said transformer tap to the reference potential; a pair of transistors each including a base, an emitter and a collector, said collectors connected to respective terminals of said output transformer; third and fourth resistors connecting respective emitters to an operating potential; first and second capacitors connected in series between said base of one of said transistors and the reference potential, said emitter of said transistor connected to the junction of said series-connected capacitors to a. c. couple to said base to its respective emitter, and third and fourth capacitors connected in series between said base of the other of said transistors and the reference potential, said emitter of said transistor connected to the junction of said series-connected capacitors, to a.c. couple said base to its respective emitter; a pair of voltage dividers connected to respective ones of said bases for establishing the operating points; and a pair of varactor diodes connected in opposing fashion between respective ones of said bases and respective ones of said inductor terminals to form oscillating circuits.

Claim 10

An oscillator arrangement having controlled frequency, comprising: a frequency control input; a control voltage source connected to said frequency control input and having an internal resistance; an absorption wave trap connected to said frequency control input and to a reference potential, said absorption wave trap having a resonant frequency greater than twice the middle frequency of the frequency range; a first resistor connected in parallel to said absorption wave trap and having a resistance equal to said internal resistance and at least five times smaller than the surge impedance of said absorption wave trap; an inductor including a pair of terminals, and a tap connected to said frequency control input; an output transformer including a pair of terminals, and a tap; a second resistor connecting said transformer tap to the reference potential; a pair of transistors each including a base, an emitter and a collector, said collectors connected to respective terminals of said output transformer; third and fourth resistors connecting respective emitters to an operating potential; first and second capacitors connected in series between said base of one of said transistors and the reference potential, said emitter of said transistor connected to the junction of said series-connected capacitors to a. c. couple to said base to its respective emitter, and third and fourth capacitors connected in series between said base of the other of said transistors and the reference potential, said emitter of said transistor connected to the junction of said series-connected capacitors, to a.c. couple said base to its respective emitter; a pair of voltage dividers connected to respective ones of said bases for establishing the operating points; and a pair of varactor diodes connected in opposing fashion between respective ones of said bases and respective ones of said inductor terminals to form oscillating circuits.

Claim 11

The oscillator arrangement of claim 8, wherein said absorption wave trap comprises: a capacitor, a second inductor and a fifth resistor connected in series.

Claim 12

The oscillator arrangement of claim 9, wherein: said second inductor is a variable inductor.

Claim 13

The oscillator arrangement of claim 9, wherein: said fifth resistor is a variable resistor.

Claim 14

The oscillator arrangement of claim 9, wherein: said second inductor is a variable inductor and said fifth resistor is a variable resistor.

Claim 15

The oscillator arrangement of claim 8, wherein each of said voltage dividers comprises: a variable resistor.

Claim 16

The oscillator arrangement of claim 8, wherein: said absorption wave trap comprises a capacitor, a variable inductor and a variable resistor connected in series; and each of said voltage dividers comprises a fixed resistor and a variable resistor.