Charger
If it's an old Orbit, that charger is original equipment. I had a couple, and, if I remember right, that's the way it worked. Lots of collectors out there who might have original manuals and such.
In the summer of '71, I went through about 6 crystals in my Orbit. Receiver had a metal case and a second half size circuit board in it. That was the year I was experimenting with cardboard covered foam fuselages and wings. Lots of people back then liked the single stick with rudder knob type radios. Has died off since except for those few who have kept the old systems.
PS: I knew there was a 72.40 but couldn't remember the color code for the life of me.