12 13
• Move the throttle stick to full
throttle. Does the barrel of the
engine’s carburetor open
completely? Does it open
completely before the servo has
moved its full distance, so the
servo is pushing against the barrel
at full throttle causing the servo to
“buzz” or the pushrod to flex?
Always correct the throw as
closely as possible by adjusting
the linkage. Then use the Throttle
High EPA pot to fine-tune the full
throttle setting.
• Now close the throttle
completely, including pulling the
throttle trim closed. Does the
barrel just close completely on
your engine as the trim hits
bottom? If not, adjust the Throttle
Low EPA pot until it does, so the
engine can be shut off safely
from the radio.
Servo
Buzzing
Pushrod
Bowing
When adjusted
correctly, there is no
servo buzz or bowing
of the pushrod
Turning the Throttle High
EPA pot counterclockwise
decreases the throttle
servo travel.
THROTTLE END POINT ADJUSTMENTS (EPA)
BEFORE
AFTER
• Read your model’s instructions to
determine the proper distance
each control surface should move.
This is called “throw.” If the model's
instructions specify a “High” and
“Low” rate, use the High rate here.
With the dual rate switches in the
“off” positions, move each control
its full distance and measure the
throw. Note that it is very common
for your initial installation/set up to
provide you more or less
movement of the control surface
than is desirable to fly the aircraft.
• Always adjust the throw as closely
as possible first by moving the
clevises in or out on the model's
control horns and servo arms.
(Using AST settings below 80%
will significantly affect the precision
of the servos’ response to your
commands.) If needed, adjust the
AST pots for each surface until the
proper throw is set.
Too Much Throw Correct Throw
ADJUSTABLE SERVO TRAVEL (AST)
BEFORE
AFTER
Turning the AST pot
counterclockwise
decreases the servo’s travel
at full stick deflection.
1. Move the throttle stick
to full up.
1. Move the stick to
full deflection.
3. Adjust the proper
AST pot.
4. Confirm
the throw is
correct.
2. Measure the
throw.
2. Adjust the servo's
end point.
