which is the oscillator part!

[aj_silverthunder]

i this schematic which is the oscillator section." https://www.flickr.com/photos/aj_silverthunder/4160942540/sizes/o/ "
i think from R4 till C9 is the VCO! the VHF comes out of C9!
And assume if the value of the inductor is 170nH ,so if i have to calculate the resonance frequency then i have to add the value of capacitors which are (the two varicaps,C6.C7,C8 ) AND THEN CALCULATE THE FREQUENCY, and is there any other cap in the circuit which takes part in producing the RF frequency!please tell me!

 

[Audioguru]

You cannot calculate the frequency because the frequency is so high that stray capacitance of the wiring is up to as high as the capacitor values.

 

[aj_silverthunder]

so then how to reduce the stray capacitance of the wires!

 

[Audioguru]

so then how to reduce the stray capacitance of the wires!

If you build a VHF circuit on a breadboard then the stray capacitance is so high that the circuit will not work.
Use a compact pcb layout for low stray capacitance. But you still cannot calculate the amount of capacitance and its effect on the circuit.

 

[aj_silverthunder]

what if i use printed circuit board! the leads line made up of thinnest metal sheets! will there be any stray capacitance then!

 

[Audioguru]

There is always some stray capacitance.

 

[aj_silverthunder]

but with the help of frequency counter i can know the frequency of the oscillator ,right!

 

[Audioguru]

The capacitance of the cable to the frequency counter will kill the oscillator unless the frequency counter has an antenna that is a couple of metres away from the antenna of the transmitter. Then the frequency counter will need an RF amplifier to amplify the small signal picked up by the antenna.

The antenna will also pickup and the RF amplifier might be overloaded by every FM radio station and TV station in town. Good luck.