ORIGINAL: Campgems
I hate to be argumentive, but all radios have a fequency. ALL. I have a Futaba 9CAP supper with a synthizer module on the RF module and a synthizer receiver. The still have a frequency. No crystals though. They can't talk to each other unless they are on the same frequency.
In all honesty, the synthesized radios DO have a crystal - the synthesizer has to have a reference oscillator. You just don't have to CHANGE crystals to change channels..