It is illegal. If you want to make sure, just call your local FCC office and tell them where to come and issue the citation and confiscate the illegal equipment at. Just because you can sometimes get away with something does not make it correct or smart. Sort of like jumping into a lake without knowing what is below the surface. They sell crystal sets so that you can take the new equipment to a proper facility and have it properly tuned and not expect the facility to stock every possible crystal. Yes, odds are in your favor but it's still not right. Synthesizer modules deal with a whole different type of freq generation and the modules have been proved and certified by the FCC to comply with all appropriate regulations. It is not illegal to jump bands in Futaba receivers but you may sacrifice range and therein lose a plane. [:'(]