hi do range check- an aircraft that has not been used for a period of time or just builtyou should go out 80-90 paces-have the first section of the antenna up- hold tx in front of your body- best to do this home -so you have no other radio interferenceyou can then judge if your radio equipments range is good or has been reduced over a period of timedo not fly the plane if you do not have control at 80 paces-people near the plane could effect the radios control distance-try to range check in the same controlled environment-so changes can be easily noted