[HomeBrew] Options For FM RX & TX Crystal Replacement?

[Robin Midgett]

Greetings,.
I'm interested in options for substituting a frequency synthesized RF souce 
for a crystal in FM TX & RX strips. Why? The synthesized approach allows 
easy frequency agility without purchasing new crystals. My questions are:
Would a frequency synthesized source be stable enough to substitute for a 
crystal oscillator?
Is there an inexpensive synthesizer or PLL kit available for experimentation ?
Does the base oscillator in a FM RX or TX chain have to be a sinusoidal 
waveform, or is a square wave or distorted sine waveform acceptable?
What about the inexpensive clock oscillators modules? Some of them are 
variable via a control voltage; stable enough? Square wave output acceptable?



Thanks & 73,
Robin Midgett KB4IDC
VHF+ Glutton, /Rover & fixed station EM66se