I observe strong camera-servo oscilation, only when the throttle stick is in the middle position and the motors are armed (instead of ESC i plugged 4 servos and they are undisturbed).  Annoing!  I tested on BEC 5.1 and 4x NiCd 4.8V and discovered that the controlling signal for servos are distorted (not an ideal rectangle), especially while moving the throttle stick.. After connecting the External BEC 5.8V(6A) to the AC board I noticed, that there are no response to the Transmiter! Why ?  What is the correct supply voltage?     I can't belive that voltage a bit higher than 5V could block the processor. 

Its not servo fault, I tested other and look the same.