You use the special trainer cord in this situation: When the Futaba 8FG or 12FG is used with another Futaba transmitter with a micro port and standard 9.6V battery are used together. Micro connectors on both ends. Fixed directional hookup is labeled "T" for teacher side and "S" for student side to insure proper connection.

You use the regular micro-to-micro cord between two 8FG's or between an 8FG and 12FG.