Spektrum SPM7800 DX7S - Manual (Page 21)

21 SPEKTRUM DX7s • RADIO INSTRUCTION MANUAL
EN
RECEIVER AND SERVO INFORMATION
Receiver Installation
Where supplied with the transmitter, install the primary receiver
in your model. Put the primary receiver in protective foam and
install the receiver in the model using rubber bands or hook-
and-loop straps. Use thick double-sided foam tape to install the
primary receiver in electric airplanes or helicopters.
Install the remote receiver apart from the primary receiver to
improve RF path diversity (a receiver’s ability to detect a signal in
all conditions). Each receiver needs a different RF environment,
especially in aircraft containing conductive materials (such as
large gas engines, carbon fiber, pipes, etc.) that block a radio
signal.
Install the remote receiver in the model using servo tape. Keep
primary and remote receiver antennas at least 2 inches (51mm)
apart. Install the receivers so the antenna wires are perpendicu-
lar to each other.
In airplanes, install the main receiver in the servo tray in the
center of the fuselage. Install the remote receiver in the servo
tray by the side of the fuselage or in the turtle deck (space
behind the canopy and in front of the vertical stabilizer).
In helicopters, install receivers in the radio tray, where there is
usually sufficient room for receiver separation. Where there is
not sufficient room, install a receiver on an external receiver
mount made of clear plastic.
NOTICE: The DSMX DX7s is compatible with all current Spe-
ktrum DSM2 and DSMX aircraft receivers, but NOT compatible
with the original DSM AR6000 receiver.
CAUTION: When using the DSMX DX7s with parkflyer
receivers (the AR6100, AR6110, and AR6115), it’s imperative
that these receivers only be flown in parkflyer-type aircraft (small
electric airplanes or mini and micro helicopters). Flying receivers
designed for park flyers in larger aircraft could cause loss of
connection.
Servo Installation
Do not over-tighten mounting screws. See model instructions for
installing servo(s) in your model.
Servo Precautions
Do NOT lubricate servo gears or motors.
Do NOT overload retract servos during retracted or extended
conditions.
Always make sure servo arms and linkages can move freely over
the whole path of their intended travel. A blocked servo linkage
or servo arm can cause a servo to draw too much current so a
battery charge is quickly drained.
Always correct control surface vibration, such as “buzz” or “flut-
ter.” Vibration can destroy feedback potentiometers in servos.
Always install servos using rubber grommets and brass eyelets.
Do NOT over-tighten servo mounting screws. Doing so inhibits
the screws from dampening vibration.
Always make sure a servo arm is fully attached to the servo. Use
only supplied servo arm screws. Use of other sizes of screws or
screws from other manufacturers can result in damage to the
servo.
Always remove and discard “yellowed” or otherwise discolored
servo arms. Discoloration shows material may be brittle and can
break at any time, possibly causing an aircraft crash.
Always make sure model screws and linkages are tight. Vibra-
tion loosens screws and linkages so that damage can result.
Power System Requirements
Set up and operate a model so power to the receiver is NEVER
interrupted while flying. This is especially critical on giant-scale
models that use several high-torque or high-current servos.
Power systems unable to provide minimum receiver voltage
in flight are the number-one cause of in-flight failures. Some
components that cause a receiver to have too little power supply
include:
• Receiver battery
(number of cells, capacity, cell type, state of charge)
• Switch harness
• Battery leads
• Regulator (where used),
• Power bus (where used)
A Spektrum receiver’s minimum operational voltage is 3.5 volts.
This battery charge capacity compensates for discharge during
flight or for flight loads larger than ground test loads.
CAUTION: We recommend that you DO NOT fly a model
with battery charges at less than 5.3-volts.
Recommended Power System Guidelines
1. When setting up large or complex aircraft with multiple high-
torque servos, use a current and voltmeter (HAN172). Plug
the voltmeter in an open channel port in the receiver, and
with the system on, load the control surfaces on your aircraft
by applying pressure with your hand. Monitor the current as
you load control surfaces. The voltage should remain above
4.8 volts even when all servos are heavily loaded.
2. With the current meter inline with the receiver battery lead,
load control surfaces while monitoring the current. The
maximum continuous recommended current for a single
heavy-duty servo/battery lead is 3 amps. Short-duration cur-
rent spikes of up to 5 amps are acceptable. If your system
draws more than these currents, you need to use multiple
packs of the same capacity with multiple switches and
multiple leads plugged into the receiver.
3. If using a regulator, perform tests for a 5-minute period. A
regulator may provide adequate short-term power, but this
tests its ability to maintain voltage at significant power levels
over time.
4. For really large aircraft or complex models, multiple battery
packs with multiple switch harnesses are necessary. No
matter what power systems you choose, always carry out
test #1. Make sure the receiver is constantly provided with
4.8 volts or more under all conditions.
CAUTION: When charging any brand of NiMH battery pack,
make sure the battery is fully charged. Due to the nature of peak
charges and variations in charging rates, heat development, and
cell types–the capacity reading of a battery charged on a fast
peak charger may only reach 80% of its nominal value. Use a
charger that displays total charge capacity. Note the number of
mAh put into a discharged pack to verify the charge is at full
capacity.