Hi Friends!
There is a nice idea to exclude varicap from circuit.
There is another method of changing frequency by yttrium iron garnet sphere - it is tuned by changing constant magnetic field. As a rule there are two coils for rough and fine tuning by DC. This method allows to make resonators with very high Q up to 4000. They are working to 26 GHz. Changing of a frequency in a wide band up to one octave. Level of phase noice remains constant on all this band. Another advantage is high linearity of tuning in all band (plus minus of 0.2 %). Also they allow to obtain big power of generator up to +7 dBm on 18 GHz.
This information is from nice book of V. Manassewitsch "Frequency Synthesizers, Theory and Design".
Price for this YIG resonators is high near 200 $, so it is too expencive for home, but idea is interesting.
73! klug.