The 8103 has a Module thats screwed on the back. You can purchase a new module if you so desire. IMO--not really any reason to--unless it's broke.

You buy a radio and then you buy reciever (RX) crystals to match the frequency of the TX.

Thats how it's done.

I got 2 radios. A JR652 which uses a crystal on ch 31. And an 8103 which uses a Module on ch 39.

I got 14 airplanes.

I buy Hitec RXs with positive shift for JR radios. Therefore, I buy lots of Hitec RX crystals on ch 31 and ch 39 to match my TXs.

You can yank and swap crystals in your RX anytime ya want. Tape them in with electrical tape.