Here's a link to the manul that you can dnload and view as a pdf -

http://www.modelflight.com.au/manual...30ManualHR.pdf


Usually the neg lead is to the outside of the rcvr, but dbl check in the manual. The extra wire is prob a charge lead that let you charge the rcvr batt (nitro setup) without removing it from the rcvr box - it would connect ot the charger and with switch off, would charge the rcvr batt. Doesn't sound like you'll be using it though...