Forum Diagram

The most difficult to build an oscillator VFO (in Portuguese OFV variable frequency oscillator) is to get him to have a good frequency stability, for it must feed the VFO with a source of good quality, make the short connections and shielding in a box metal. 

This schema operates up to 10 MHz frequency and can be used for testing since it is quite simple. In this project VFO is used 1N4001 rectifier diode common that can work as a varicap when polarized in reverse. The coil L1 is formed by 80 turns of 28 AWG wire on a ferrite rod 1 centimeter in diameter. For the RF transistor may be a transistor used BF494.

 VFO schema Diagram with Varicap