pinion for revo & problem signal

[REfuso]

do I give you excuse the bad English, do I give The hopes that she am the correct section where formulated to the question, gives The have to converted revo to electric with to novak hv for 4.5, that pinion advised to use with to 40 spur gear?

Other question: often to 50\60 meters I lose the signal radio and I don't understand because, I have used a multiplex 404 and now use a 3pk futaba always to 40mhz, but the problem persists.

thanks regards Al.