Switched reactances in VCO
 

In the book "Introduction to Radio Frequency Design" of W7ZOI and in
the section 7.9 "Voltage Controlled Oscillators" I read about how to
switch in and out a capacitor or an inductor in a VCO, using a diode
switch in order to alter the frequency of the oscillator.

Unfortunately this information is theoritical to me and I couldn't
make my oscillator change its frequency.

Does any one have a practical example of a Switched reactance VCO ?

Thanks
Thanasis Lazos