regarding the removal crystals for transmitters ,it is a good thing to be able to remove the crystal from transmitters if you are going to be using them as a buddy box oras controls for flight simulators. with a buddy box it keeps the student who is learning from turning on the radio and causing damage to others flying on the frequency of the buddy box. For a simulator it keeps the power usuage low so the batteries last longer and you are not overheating the output transistors in the transmitter