but whats that about it being 6 channel when its realy 5 if you use a normal battery connection ?
I dont get what they mean, i can only see 6 places to put servo / battery connections.
so whats going on there ?
Each connector has three pins:
Power +
Power -
Signal
All the Power + pins are connected together, and all the Power - pins are connected together. (the signal pins are all separate...!) So, as well as providing output + and - power for each servo, those pins can also act as inputs. If you look at a battery connector, you will see that it is usually exactly the same as a servo connector, but without the signal pin. It just feeds power onto the + and - bus.
For a traditional receiver on, say, an i/c powered plane or a glider, you connected a battery pack to the receiver via a servo plug using a 'cut-down' servo connector. A separate 'power-in' socket was often provided. But nowadays, most receivers are used for electrically powered vehicles, and these have an ESC to control the motor. The ESC has a power input and a BEC already built in, so it makes sense to just plug it into one socket and let it power the receiver.
If you have a glider and want to use all six channels, you make up an airborne battery of +5v, and then connect it to a servo with a 'Y' lead, and plug both into the same socket....