JWLaRue wrote:That definitely helps. So two of those wires is where one would need to splice in the two wires that would go to the antenna.
Not quite - the signal that comes off this line is what gets fet into
the transmitter module, and from the module it is sent to the antenna. You can basically break down an RC transmitter into a box of pots and switches which are all read by an encoder block, the encoder feeds a transmitter module, and the transmitter module drives the antenna. The PPM signal in question is almost certainly the output of the encoder to the transmitter module. This is the same signal that's used in a trainer-mode setup with RC aircraft, or fed to a computer to operate a simulator.
Typically when the encoded signal is routed from to the trainer port the transmitter module is disabled. (At least that's how it works with aircraft transmitters.)