Crystal is an electro mechanical
resonator used to set the transmitter on a
particular frequency. The crystal, along with
a circuit called an oscillator, generates a
carrier frequency. The signal output of the
oscillator is much too low to use on the air
by itself, so the small signal is first
passed through an amplifier circuit to boost
the power.
That amplifier feeds its power to the last
stage of the transmitter before the antenna,
the final amplifier. The signal going
to the antenna is about 1,000 times stronger
than what the oscillator circuit puts out..
