The port on the back of your radio transmitter of which you speak is the trainer jack. This jack doubles as the simulator interface cable port which in turn plugs into your computer. The Great Planes g-2, or even the older GP simulators give you the option of either the model that comes with the control box or the model that requires the use of your transmitter utilizing an "interface cable" that plugs into the port on the back of your transmitter.



Good luck
Sincerely, S. Helland