RE: Buddy box
Regular Futaba and Hitec transmitters can be used interchangebly with each other as buddy boxes.
The Connector for the buddy box cord is different on a JR.
The non computer four channel transmitters make better buddy boxes.
As noted below... Airtronics and JR are Positive shift whereas Futaba and Hitec are negative shift. The two systems cannot be interchanged.
Enjoy,
Jim