RE: JR R921 RX Bind
I Bind through a 3 wire DSC compatible switch Harness (JR or MPI), however, if you have a Voltage Regulator connected between the Switch Harness and the Rx, you cannot Bind through the Switch Harness. When I used 2cell LiPo Rx batteries, I used a Voltage Regulator and thus I had to connect a Y Harness to the Bat port on the Rx, connect the Switch Harness to one side and the Bind Plug to the other side.