Spektrum SPMAR7100 - Manual (Page 9)

Spektrum AR7100 15 Spektrum AR7100 16
RevLimit Instructions (AR7100R only)
Servo Requirements
Connections Modes of Operation
The Spektrum AR7100R features an integrated RevLimit limiter.
The RevLimit functions as a digital rpm limiter preventing the main
rotor from over-speeding. When the rotor speed is at or below
the programmed rpm, throttle position is controlled via the radio
(i.e. throttle curves). The RevLimit only engages when the rotor
rpm exceeds the programmed rpm reducing the throttle position
preventing over-speed.
The RevLimit limiter is designed to limit engine speed between 9,500
and 20,500 rpm. Engine rpm = Rotor rpm * Main gear ratio
All common three-wire servos (analog and digital) are compatible
and can be used for the throttle servo. Note that two throttle channel
outputs are available: unregulated and regulated. The unregulated
throttle operates at the battery voltage. The regulated throttle
is regulated to 5.2 volts and is to be used when a high-voltage
compatible servo is not being used for throttle control.
The RevLimit is totally integrated and the target rpm is adjusted via
the Gear channel (channel 5). The only external connection needed
is to mount the backplate rpm sensor to the backplate of your engine
using two backplate screws. Note that the rpm sensor mount has two
positions: extended for .90-size engines and retracted for .50-size
engines. When installed correctly, the rpm sensor should just contact
the backplate. On some engines and specifically the YS .50 and
.90, the sensors must be spaced .5 to 1mm from the backplate. No
additional magnets or brackets are needed. The rpm sensor picks up
the magnetic effect of the crankpin as it passes the rpm sensor.
If your system is not limiting RPM in flight, re-position the sensor .5
to 1mm away from the backplate. This can be easily accomplished
by loosening the 2-56 button head screw on the sensor mount,
re-adjusting the position, and then tightening. This should resolve
the issue.
Install the servos in their appropriately labeled ports. Note: The
throttle and gear channels have two outputs. Output 1 is unregulated
and the pack voltage is provided at this port. Throttle and Gear
outputs 2 are regulated to 5.2 volts when a throttle servo and gyro
are used that are not compatible with high voltage. (Most gyros
require less than 6 volts.)
DX7
If using the DX7, the following is recommended.
In system setup mode program AUX2 to GYRO and GEAR to AUX2,
the RevLimit will be controlled and adjusted via the AUX2 switch,
and all the target rpm’s will be adjusted using the GEAR channel
travel adjust.
Note: The Gyro Gain channel will plug into the AUX2 channel and the
gyro screen will be used to adjust the gyro gain (see the DX7 manual
for more detail on gyro gain settings).
In the travel adjust screen two values can be selected that will
correspond with the desired rpm. Note that two different rpms can be
selected, or if one value is programmed to zero, the RevLimit will be
turned off when the AUX2 switch is in that position.
Important: When calibrating the system the AUX2 channel must
remain at 100% in both directions.
The RevLimit target rpm is adjusted thru the Gear channel (channel
5) output.