Receiver and servo information. Spektrum SPM7800C, DX7s 7-Ch, DX7s 7-Ch DSMX Radio System, SPM55101, DX7s Transmitter Only MD2, SPMR7800

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 hookand-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 perpendicular 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 Spektrum 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 “flutter.” 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. Vibration 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 hightorque 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 current 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.

SPEKTRUM DX7s • RADIO INSTRUCTION MANUAL 21

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