Richard, as with everything else in life, this is a compromise. In general, moving the linkage towards the servo's output shaft trades speed and travel for increased torque and positioning accuracy. The opposite is also true, moving out on the servo arm trades torque for increased speed. Here's some real quick theory -
With a "1024" PCM system, you have 1024 positions or "steps" from one end of the servo's maximum travel to the other (this is with the radio's ATV set at 140%). When you change the servo's travel limits you don't lose or gain any resolution, just travel. In other words it does not compress or expand the steps, it just truncates them. With both limits set at 140% for instance, it will travel through all 1024 positions (steps). With both limits set at 100% however, it will only travel from position 146 through position 878. I have never really understood why the radio manufacturers use 0-140% instead of 0-100% (it may have something to do with mixing, or maybe they just like to complicate things!), anyway 140% actually equals 100% or maximum servo travel.
A good rule of thumb is to set-up the radio/servo at 100% then select the radius on the servo's arm that comes closest to the travel you need. After the linkage is installed, you can then fine-tune it so you get maximum travel but with no binding by using the ATV function and slightly increasing or decreasing travel.
Steve |
