In all radio and television applications, the voltage controlled oscillator (VCO) is a varactor tuned, LC type of circuit.
In this electronic project circuit you can see a very simple high efficiency Colpitts oscillator .
In the higher frequency ranges, above 50 MHz, Colpitts oscillators are used because stray circuit capacitance will be in parallel with desired feedback capacitance and not cause undesirable spurious resonances that might occur with the tapped coil Hartley design. The FM VCO shown is a grounded base design with feedback from collector to emitter.
A Colpitts oscillator is one of a number of designs for electronic oscillator circuits using the combination of an inductance with a capacitor for frequency determination. The distinguishing feature of the Colpitts oscillator circuit is that the feedback signal is taken from a voltage divider made by two capacitors in series. As you can see in the circuit diagram , this electronic project require few electronic parts an provide a 50 MHz-300MHz VCO with a tuning range of 2:1 .