Originally Posted by 2Doggs
I noticed that someone wrote about that 280Hz limit on all the HK product pages, referencing some discussion on HeliFreak. Unless I've missed something with recent ZYX firmware, however, that 280Hz restriction is pretty onerous, since setting the tail to 250Hz will set your cyclic servos to analog.
"analog mode" just means a 50hz control signal to the servo. A digital servo operates as a digital servo no matter what speed the signal piloting it is. You can test this by hooking up an analog and a digital servo directly to an RX and then trying to push the arm off it's position. Even on a 50hz signal a digital servo holds it's position as if glued to the spot. Compare that an analog servo where you can feel the 50hz refresh rate on the motor when you push on the arm. The difference between an analog servo and a digital servo is basically that an analog servo only refreshes it's position in time with the control signal while with a digital servo the control signal and position refresh rate are independent and the position is refreshed at a higher rate than 50hz, usually somewhere between 120-333hz. 250hz, 280hz and 333hz seem to be the most common refresh rates used by digital servos.
I have never heard of an analog servo that could run at 250hz, 50hz-60hz is the maximum (you can push them faster, and it may even increase performance but it will damage them over time if it doesn't immediately smoke them)