RE: Dumb Radio Question
ATV is the lazy man's way of setting the control rates. It should be done mechanically as best you can, and then use ATV for fine tuning (if you must).
That said, once you set the ATV, that is now 100% of your throw. So if you set the ATV to 50%, that becomes 100% of your throw as far as your radio is concerned - So when you set your High Rates to 100%, you still get 50% of your servo's throw. If you set the Low Rate to 50%, you're getting only 25% of your servo's throw.