Reference Drawing
Receiver Mounting
The receiver mounts in the center of the unit. 3M dual-lock mounting
tape has been supplied to mount the receiver. This tape’s holding
power is extremely strong. It is recommended that the whole 1”x2”
piece not be used, instead cut some 1”x ½” strips and use these on
either end of the receiver.
We also have available an “L” shaped receiver mount that will mount
the receiver at a sixty degree angle and get the antenna(s) up, away
from the unit. While we have not found this to be necessary some
pilots like to get the short 2.4GHz antennas up off the unit towards the
canopy. In general, pilots use this receiver mount with 2.4GHz
receivers.
Receiver Connections
CAUTION: Do not plug any receiver pigtails into the battery input
of your receiver. On PCM it will put your receiver into DSC mode,
on 2.4GHz receivers it may cause your receiver to unbind. All
connections from the PowerExpander are meant to plug into servo
outputs ONLY.
The receiver servo outputs are connected to the pigtails coming out of
the PowerExpander Competition 12 in the area with the notations “Ch
A” through “Ch L” on the reference drawing. The two channels on the
end (“Chan A” and “Chan L”) have power connections to the receiver
in addition to the signal connection. If you have a receiver that has
less than twelve channels, you should still use both the end connections
as this will provide you with power redundancy to the receiver in the
event that a power or ground lead should fail.
The unit will accommodate both end-loading receivers and top-loading
receivers. All signals from the receiver into the PowerExpander
Competition 12 are RF filtered. This prevents noise from the servos
entering the receiver connections to the receiver. If all channels are not
going to be used, then the unused pigtail can be tucked away.
Connections Directly To Receiver
If you want to connect a device directly to the receiver instead of going
through the PowerExpander Competition 12, make sure the current
draw of the receiver and the device is less than one amp. We
recommend you do not connect servos directly to the receiver
There are several reasons that a device might be connected directly to
the receiver instead of going through the PowerSystem Competition 12.
The most likely would be if you had a fourteen channel receiver and
needed to use the extra channels. Items such as jet ECUs and smoke
pump control do not draw much current and could be used.
Servo Connections
Servos are connected to the PowerExpander Competition 12 along the
two rails on either side of the receiver. The servo connectors are
universal in that they will work with Futaba or JR connectors. When
using a JR connector, be careful to observe the polarity of the
connection. The ground lead (black on Futaba, brown on JR) is
indicated by the “minus” sign, the positive power lead (red on Futaba
and JR) is indicated by the “plus” sign and the signal line (white on
Futaba, orange on JR) is indicated by the “top hat” symbol.
All receiver channels have each servo signal output individually
buffered. If a servo were to short its signal wire, the other servos on
that channel would not be affected. Ten of the channels have three
servo outputs while two channels have four servo outputs.
The unit also RF filters each signal output and matches line impedance
resulting in a cleaner signal down long servo leads. The impedance
matching reduces the electrical “ringing” that can occur on long servo
leads. Ringing can generate RF interference and can reduce receiver
range.
Power Connections
5-cell NiCd/NiMH or 2-cell A123 batteries should be used with this
unit although the inputs will tolerate voltages up to 8.5V (lithium-ion or
lithium-polymer 2-cell packs). The power inputs are protected from
each other in case of a dead cell or short. There is about a half-volt
drop between the input and the servos. If lithium packs were used the
servos would see 8.0V for fully charged packs which is generally not
advisable. For A123 packs this means that after they flatten out at 6.6V
the servos will see about 6.1V.
CAUTION: Input voltage to the PowerExpander Competition 12
should be at least 5.8V. This is due to the 0.45V drop across the
“BatShare” and the 0.35V dropout voltage of the receiver regulator
to maintain a 5.0V output to the receiver.
It is highly recommended that you use two battery packs for
redundancy and to provide extra current to the unit. Power is supplied
to the unit through the two Deans Ultraplug connectors at the top of the
servo block.
Servo Power LEDs
The servo power LEDs are next to the Deans Ultraplug connectors and
indicate power is present on that connector. These do not indicate the
voltage input is above the minimum required.
Receiver Power LEDs
The receiver power LEDs show the receiver is getting voltage greater
than 4.75V. If the receiver regulator output voltage drops below 4.75
volts the LEDs will go out. There are two possible causes of the
receiver voltage going below 4.75 volts. First the load the receiver is
presenting to the regulator is greater than one amp causing the regulator
output to droop. This could be caused by directly plugging something
into the receiver that is overloading the circuit. The second cause of
