Had a JR radio about 10 years ago. All others were Futaba. Not thinking, I plugged the JR into the Futaba charger. Herd a pop sound and nothing worked. JR's are reverse polarity to other radios. Took it in to Pete Waters for repair. It blew a diod because of the reverse polarity. Safety feature to protect the radio for this reason. Cost about $25 for the repair.