100MHz RX VCO Frequency??

[sunville]

What is the limitation when changing a RX VCO operating frequency from 145 ~ 160MHz to 108 ~ 123 MHz? I tried to tune the tank circuitry but the frequency cannot go lower than 115MHz at lower frequency and there might be start up issue. Please advice.

 

[Sadegh.j]

What happens when you decrease the frequency?

 

[sunville]

Not to say what will happen if I decrease the frequency. I actually need and have to make sure the operating frequency starts from 108MHz. or in other word, I need the system to oscillate from 108MHz. But now the system starts to oscillate at 115MHz and not 108MHz. Based on calculation, I should be able to get lower frequency if I increase the tank capacitor but somehow the system has start up issue.