Forget about using the cord that comes from your Real Flight. It is ONLY for using with the simulator and will not work in a real world solution. However, here are the cords you need to connect your other radios to your 7C.

Futaba 6da FM to Futaba 7C 2.4
Futaba Micro plug to round plug - http://www3.towerhobbies.com/cgi-bin...LXBEK8&P=7

Connecting the Spektrum as a slave radio to the Futaba 7C won't work. There is a cable made that will connect the 7C to your Spektrum but it only works with the Futaba as the slave and the Spektrum as the master. It won't work the other way around.

Ken