I am with John on this one . I think you would be further ahead to purchase a new radio system . They are loaded with features like end point adjustments , servo reversing and on and on . And they are not that expensive . You can often pick up a good used one from a club member that is upgrading .Try for at least 6 channels . Something newer will be 2.4 GHz and that is much easier to use than the old er radios . The older radios interfere with each other so you can only have one on the same frequency at a time . The new 2.4 GHz don't interfere with each other so you can turn your radio on when ever you want to with no worries about shooting somebody down .