I have a dumb question but i will appreciate any help.I have a JR 8103H FM that is on ch.54 72mhz and need another rx, my friend has a JR R700 72mhz that is on ch.38, can i buy a ch.54 rx crystal and use that rx or do i need a different rx. I know some rx's will only operate correctly on certain channels, but anyway thanks.

You wont have any problems that will work. Its futaba that has channel ranges and even then its only certain models of receivers, you'll be fine.

thank you very much for the help.