Just putting a crystal in the radio seems to crash the game completely for me.
Sometimes I manage to get it in, but then the music will play for about 3 seconds and then stop. If I turn the radio off (via a lever) and then back on, I crash. Then if I try to take the crystal out, I crash again.
I tried testing on a single player world, but the crystals don't appear in creative.
EDIT: I also kinda wished it worked like Computercraft. If HTTP is enabled, it would allow you to craft your own crystals.