Hi I'm new here i just purchased a Futaba R304SB 3 channel controller/receiver but nothing as far as a on/off switch or a battery pack for the receiver? This seems kinda strange what powers the servos?
For electric, the esc goes into channel 2 which will output voltage to the receiver and to anything plugged into it. Since you plug the battery in the ESC.
If nitro, no clue as I'm not a nitro guy, but you would probably need a receiver pack with a futaba servo plug on it. As for a on/off switch, no clue.
I'm guessing you got the 3PV system as it's 3 channels?