One other thing with the JR when the trainer cord is plugged in both transmitters light up. The instructors still needs to be turned on the switch on the student box stays off as said in an earlier post. after the flight when you turn off the instructors transmitter the lights will still be on both transmitters. The trainer cord needs to be disconnected from both transmitters to turn the lights off. I have always used a regular transmitter battery in the student box. never tried a dry cell before. Don't see why it would'nt work if you did'nt have a stock transmitter battery.
Dennis