No, violates FCC regs. The user cannot change TX freq in the US on the 72MHz band. HOWEVER, you can probably put a CH26 RX XTAL in his receiver without a problem assuming his RX is compatible with your TX. That way you can use your TX and BB on CH26 with his plane. I'm assuming you are asking this becasue there is a compaitbility issue hooking your BB up to his TX? You didn't mention the make/model of your buddies radio. Anyway, whenever you change RX or XTAls in a RX, always be sure to range check.

Edit... Mr. Foamie beat me to it by 90 seconds... ditto... what he said.