What's with radio gear compatibility/
Lets make it easy for you. If you have a new airtronics reciever, you may use futaba,jr,hitec,or airtronics "z" connector servos. There is no reverse polarity except on old style airtronics servos and recievers.However recievers are a different story. Hitec makes recievers compatibile for airtronics,futaba,hitec and jr. All chargers will work with all radios as they are EXCEPT JR. JR is a reverse polarity charged radio. You can buy a plug to convert standard to reverse polarity for $8.00. Just plug in end to your charger that says futaba end and plug end that says radio to your radio. Then your charger will charge JR in reverse polarity. I have many different servo and reciever configurations in alot of my airplanes and helis. But I only fly with JR radios. If you have any particular questions feel free to email me. I do work in a hobby shop and dont know all the answers but I can find out almost anything you would like to know. I hope this helps.
Best Regards
Duane
PS trainer cords: futaba fits hitec /futaba,airtronics fits airtronics.and jr fits jr. The expert company makes cords to fit all and are nearly 50% less in cost then name brand.