Re: 100Mhz oscillator
I assume you mean for reception on an FM radio. You need to vary the frequency of the 100 MHz oscillator in proportion to the audio signal. If there is a voltage control for frequency tuning, you can tune the oscillator with that. It is possible to also tune the oscillator (in a much more crude fashion) by AC coupling the audio signal onto the oscillator power supply pin. For instance, put a 47 ohm resistor between the oscillator Vcc pin and the supply, then put a 1 uF series cap between the oscillator Vcc and your audio source.
You may have to vary the audio level to keep it from distorting in the radio. And, I assume that you are not using a crystal 100 MHz oscillator, which will not tune enough no matter what you do to it.