Must have expressed myself badly. Let's try again:

There are 6 channel sets of 3 pins, AND there is a set for BATT, which also have 3 pins.
I just need to know which 2 of these 3 pins I must connect power to. The connector to this receiver has 2 pins, so it is important to connect it correctly. I suppose that ground is towards the edge of the unit (???)