APPROXIMATELY 18 months ago a new company—Spektrum—
came onto the radio control market with the first production 2.4 GHz
system using spread spectrum technology. It was for surface use.
Roughly six months later Spektrum introduced the first
production system for aircraft using the 2.4 GHz band and spread
spectrum technology. This unit was designed for park-size models
only. In a short amount of time the DX6 became popular with those
flying electric-powered models. The system has a nice range of
features but was lacking the ability to fly larger models.
In October 2006 Spektrum introduced the new “full range” DX7
system at the iHobby Expo in Chicago, Illinois, and many have
hailed it as evolutionary. The DX7 is capable of flying any size
model whether it is fixed or rotary wing.
To understand why the introduction of this full-range system is
so evolutionary, you need to understand more about the 2.4 GHz
band and spread spectrum. Model Aviation has published two
articles about the technology, the most recent of which was in the
December 2006 issue. I encourage you to read both articles, but for
now I’ll review a bit so you can understand why the technology
employed by the DX7 works so well.
The 2.4 GHz band has a fairly short wavelength; as such the
antennas are short. The shorter wavelengths are more easily blocked
by objects such as big battery packs, mufflers, engines, and other
components that could be found in large models. When you put a
receiver (that has a short antenna) in a model with these larger
components, they could easily block the signal from the transmitter.
I will cover how the DX7 and its AR7000 receiver get around
this problem in a bit.
DX7 Advantages: So what are the advantages of using a spread
spectrum system in the 2.4
GHz band? To begin with,
you never have to worry
about frequency control
again. You simply turn on
the system and go fly.
Additionally, 2.4 GHz is
well above the frequency
range at which most
interference (noise) is
generated.
Most of the noise
models and their
various parts (including such items as speed controls and motors)
generate is below 300 MHz. This means 2.4 GHz is virtually
immune to this type of interference. When you couple this with the
added security of spread spectrum, you end up with a system that,
for all practical purposes, is immune to outside interference!
The DX7 is sold as a complete system. It includes the
transmitter, AR7000 receiver, 1100 mAh, 4.8-volt Ni-Cd receiver
battery pack, 1500 mAh NiMH transmitter battery, four DS821
digital servos, switch harness, servo mounting hardware and output
arms, dual wall charger, bind plug, and hex wrench for adjusting the
transmitter stick height.
The system uses Spektrum’s trademarked DSM2 (Digital
Spectrum Modulation second generation) DuaLink technology. The
original DX6 uses the first generation (DSM) of this technology.
The DX7 transmits on two frequencies at the same time, and the
AR7000 receiver is actually two discrete receivers connected by a
cable that receives those frequencies at the same time.
The transmitter antenna
is shown fully extended. It
is hinged roughly halfway
down, where it can fold
down 90° and rotate 180°.
The Spektrum DX7 is up to
date with high-capacity batteries and the
same type of sport digital servos most
people pay extra money to get.
The Academy recommends that clubs
provide a flightline control system with
the use of spread spectrum radios. This
system should be similar to the
frequency-control plan that is currently
in use at flying sites. Multiple pins or
identification spaces should be provided
for spread spectrum.
The preceding is recommended for
two reasons, the first of which is that it
keeps members in the practice of taking
a pin. This is important if they ever
return to 72 MHz use. Second, it
provides clubs with a method of
flightline (not frequency) control. MA
—AMA Headquarters
Feature Packed: The DX7 features a 20-
model memory with ModelMatch that
prevents the operation of an airplane if the
wrong memory is selected. When the
receiver is bound to the transmitter (the
process whereby the receiver recognizes that
the transmitter’s GUID [Globally Unique
Identifier]), it actually remembers the
specific model memory the transmitter is
operating.
If you ever attempt to operate a receiver
that was bound to a model memory other
than the correct one, the model will not
function. This makes flight operations even
safer. As far as I know, this feature is unique
to spread spectrum systems.
The DX7 is also the first transmitter to
feature pure digital processing. The
transmitter does not convert a PPM or PCM
data stream to the DSM2 digital stream; in
the DX7 the data starts out digital and
remains digital. That means the system’s
latency (the time from stick movement to
servo movement) is extremely low.
Because of this low latency, the feeling
you get when flying this system is hard to
describe. It is perhaps the most connected
feeling I’ve ever had when flying a model.
The system also has a feature called
“ServoSync.” It is not covered in the
owner’s manual for some reason, but all the
promotional literature mentions it.
ServoSync resequences the transmitted
data depending on what type of mixing the
model being flown has programmed. That
means any servos that have to work together
receive the information at the same time. It
happens in applications such as dual
elevators, Cyclic Collective Pitch Mixing
(CCPM) in a helicopter, etc. This is no
doubt part of the connected feeling I have
when flying with this transmitter.
Fortunately the DX7 is backward
compatible with the AR6000 Park Flyer
receiver, which comes with the DX6 system.
When using the AR6000 it is important to
remember that the combination can be used
only in park-size models. When being used
with the AR6000 the DX7 automatically
switches to DSM (not DSM2) modulation.
The 1500 mAh NiMH battery in the
transmitter will give you approximately six
hours of transmitter run time when operating
the AR7000 receiver. If the transmitter is
turned on but not connected to a receiver,
the current draw goes up and run time is
reduced.
That may seem odd at first, but it begins
to make sense if you think about it in terms
of a cell phone that is searching for a signal.
The system uses more power as it seeks for
a receiver with which to connect.
It is odd that the charger supplied with
this system is set for only 50 mAh. The
owner’s manual clearly indicates that the
supplied charger should be set for 110 mAh.
I’m not sure why there is this discrepancy.
I’d certainly prefer to have a higher-rate
charger. When Horizon personnel were
questioned about the issue, they mentioned
that future versions will come with a 120
mAh battery charger.
The large LCD screen has great
resolution—much higher than most
transmitters in this class range. Data input or
value changes are made via two large rocker
switches, one of which is on either side of
the display. There are also two buttons on
either side of the display; they are used to
move the cursor around the screen or
Each DX7 system includes
everything shown and an
extremely well-written
instruction manual.
The AR7000 receiver system includes two
units linked by a short three-wire lead. The
short antennas stay inside the model once
mounted.
The voltage of the transmitter is displayed numerically at the top
right and at the top left with a bar scale.
The LCD screen’s fine resolution lets the operator see the
smallest adjustments made. That is especially appreciated with
control-throw curves.
confirm data entry.
Along the top front of the transmitter are
four toggle switches: elevator dual rate,
three-position flap mix (stunt mode for
helicopter), AUX 2, and aileron dual rate.
Two rocker-type momentary switches are
also along the top. The one on the left is
used for trainer/flap (hover pitch) and the
one on the right is for AUX 2 (hover
throttle).
On the top of the transmitter are two
more two-position toggle switches. On the
left is the gear switch (gyro) and on the right
is the mix-rudder dual rate (throttle hold)
switch.
Many of these switches may be
reconfigured for other uses by the
transmitter’s programming. The trim levers
are digital—what Spektrum calls ADT
(Advanced Digital Trim). Each of the trim
positions is automatically stored with all the
programming details for each model. The
trim levers only rock in one direction or the
other; they do not actually move.
When in the helicopter mode the trim
will change with each flight mode if desired.
This is a great feature if your trims are
different for hovering maneuvers in the
normal mode than they are in one of your
stunt (idle-up) modes.
Another unique trim feature is called
Throttle Recovery. When flying a model
with a glow or gas engine, Throttle
Recovery allows you to kill the engine with
full down throttle trim but then return to
your original throttle trim position with a
single up “click” of the throttle trim lever.
Trim positions are shown on the LCD, as
are the hover pitch and hover throttle
positions in the helicopter mode. During
normal operation the LCD screen shows an
analog bar graph of battery condition and a
digital voltmeter.
It also shows the model number and
model name. A graphic of either a fixed
wing or a helicopter is displayed to quickly
show you which mode you are in. Trim
positions are indicated, and a countup/
count-down timer can be displayed when
that feature is activated.
Stick tension is adjustable; however, you
must remove the back of the transmitter case
to make the adjustments. This requires you
to remove the battery and the six screws that
hold the back of the transmitter case. This is
a simple operation, but it could make some
users nervous.
A single screw adjusts the tension for
each of the functions. For helicopter or
airplane pilots who do not like a ratchet on
throttle, a non-ratchet strap for the throttle
stick is supplied and easy to install. Stick
length can also be adjusted; that is done with
the supplied hex wrench.
The AR7000 receiver is unique and
could be somewhat considered the heart of
this system. It is actually two discrete
receivers in one. The main receiver is fairly
standard in size (on the small side) and is
the unit that links the servos and battery.
The remote receiver is connected to the
main receiver via a 6-inch, three-wire lead.
Each receiver has two 1.5-inch wires
coming out of it. These are the dipole
antennas for each receiver. The remote
receiver is small, at just 0.625 x 0.875 inch.
The concept with these two receivers is
that by placing them at least 2 inches apart,
each is in a different radio frequency
environment. The antennas would ideally be
oriented perpendicular to each other,
although that is noncritical. With the
receivers located in different areas of the
aircraft and each receiving on a different
frequency, the AR7000 really provides a
bulletproof link from the transmitter to the
receiver.
Binding is an operation that is unique to
spread spectrum systems. The process of
binding teaches the receiver the unique code
of the transmitter. Once bound, the receiver
will “listen” only for that specific
transmitter. In the case of the DX7,
ModelMatch (described previously) causes
the receiver to recognize the specific
transmitter and the specific model memory.
The DX7 also features a switch harness
that allows you to place the receiver in the
bind mode without directly accessing the
receiver. To place the receiver in the bind
mode you simply insert the special bind
plug into the charge jack of the switch
harness and turn on the receiver.
To actually bind, press and hold the bind
button on the back of the transmitter while
Torque: 72 ounce-inch at 4.8 volts,
88 ounce-inch at 6.0 volts
Speed: .19 seconds/60° at 4.8 volts,
.15 seconds/60° at 6.0 volts
Size: 1.50 x 0.94 x 1.47 inches
Weight: 1.5 ounces
Ball bearing: Single
Motor: Cored
DS821 Sport Digital Servo Specifications
Number of channels: Seven
Modulation: DSM2
Band: 2.4 GHz
Servos: DS821 Sport Digital
(four included)
Receiver: AR7000
Programming features: Aircraft
and helicopter
Model memory: 20 models
Transmitter battery type: 1500 mAh
NiMH
Receiver battery type: 1100 mAh
Ni-Cd
Trim lever type: Fully digital
Price: $349.99
System Specifications
• Seven channels DSM2
• Features external and internal receiver
• DuaLink
• Model match
• Servo synchronization
AR7000 Receiver Specifications
“Auto D/R EXP” screen (available in “heli” mode) permits dual
rate and expo values to change, depending on single (flight mode)
switch position (“Norm,” “ST-1,” “ST-2”).
Flap system screen (available in “Acro” mode) controls threeposition
switch that may be used to engage the system or
programmed to be automatic with throttle position (5% here).
turning it on. The two LEDs on the AR7000
receivers that began blinking when you
turned on the receivers will stop blinking
and stay on, indicating that the binding
process has been completed.
Another important part of the binding
process is that it sets the fail-safe
positions. The stick and switch positions
the transmitter is in during binding are
established as the fail-safe positions.
Anytime you make a programming change
to the system, it’s a good idea to rebind it.
I found that to be the only way to assure
that the fail-safe settings are correct.
The DX7 has a nice variety of features
for fixed-wing aircraft and helicopters.
There are no sailplane-specific
preprogrammed mixes; however, there are
more than enough programmable mixes to
handle almost any sailplane function.
The menu structure in the DX7 is easy
to understand. You can view the menu as a
list in one mode or you can scroll through
each of the functions individually. I tend
to use the scroll method more than the list
method.
Two programming levels exist. The top
level is the System Setup Mode, which
you access by holding down the SCROLL
rocker and SELECT button while turning
on the transmitter. In the System Setup
Mode you can:
• Choose the model you want to fly.
• Name the model you want to fly.
• Pick the model type (ACRO or HELI).
• Reset the model to factory default
settings.
• Reset the integral timer.
• Turn the trainer function on or off and
select its mode of operation.
• Select dual rate switches.
• Choose the wing type (FLAPERON, VTAIL,
DELTA) or helicopter swashplate
type (standard, 180° CCPM, 120° CCPM,
90° CCPM).
• Access Input Select (which determines
how Aux 2 will be used or select the
switch input that gyro gain will use).
• Enable or disable throttle recovery.
The Function mode is accessed by
holding down the SCROLL and SELECT
buttons when the transmitter is already
powered up. The aircraft’s main
programming functions are accessed from
this menu.
The SCROLL rocker switch will move
you backward or forward through each
menu. The SELECT button moves the
cursor around, the ADJUST button
changes values, and the CLEAR button is
typically used to lock in a value.
Programming features available in the
ACRO mode are dual and exponential
rates, servo reversing, subtrims, travel
adjust, elevator-to-flap mixing, aileron-torudder
mixing, servo monitor screen,
count-up/count-down timer, six
programmable mixes, and the differential
and flap system.
The HELI mode’s available
programming includes dual and
exponential rates, servo reversing,
subtrims, travel adjust, swashplate mixing,
throttle hold, throttle curve (Normal, Stunt
1, Stunt 2), pitch curve (Normal, Stunt 1,
Stunt 2, Hold), servo monitor screen,
count-up/count-down timer, three
programmable mixes, gyro sensing, and
revo mix.
Dual and exponential (expo) rates are
programmed from the same screen. Expo
is shown on the display, which is a great
aid in seeing how the expo rate you set
will affect the sticks’ sensitivity.
As I mentioned, this system has
numerous features. Let’s take a closer look
at a few of the more unique ones. In the
helicopter mode you have five-point pitch
and throttle curves available.
In the airplane mode, preprogrammed
mixes make the popular forms of mixing
easy to accomplish. In addition, the system
has a flap program that allows you to set
3° of flaps and couple the elevator to those
positions to control pitch changes. You
can also set an automatic landing system
that will activate the flaps with elevator
compensation at any point you wish to
select based on the position of the throttle
stick.
Helicopter mode gives you the ability
to set up automatic dual or exponential
rates based on flight mode. With this
feature the flip of a switch changes dual
and expo rates (as well as other
parameters).
One item I really like in the helicopter
mode is that if you power up with throttle
hold on or with the flight mode switch in
any mode other than normal, the main
display will warn you. The display will
not return to normal until the switches are
returned to the normal (and safe)
positions. This feature is a great safety
reminder to help prevent hot starts.
The DX7 is a super system I’ve really
enjoyed flying. I’ve gotten used to not
having to wait on a channel at large
events. I also find it to be one of the safest
systems I have ever used. In almost five
months I haven’t experienced a single
problem—not a bump, not an issue.
The instruction manual is extremely
well laid out. I wished for additional
programming examples from time to time,
but they are not really needed. In fact, you
could easily program this transmitter
without the manual; it is that easy.
The DX7 system is available for a
street price of $349.99, which is not bad
considering what all it includes. I plan to
fly with the DX7 for many years to come.
It is worth your serious consideration. MA
Steve Kaluf
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 352-1913
www.horizonhobby.com
Other Published Resources:
Model Airplane News
February 2007
Fly R/C
February 2007
Model Aviation
December 2006
Edition: Model Aviation - 2007/03
Page Numbers: 53,54,55,56,58
Edition: Model Aviation - 2007/03
Page Numbers: 53,54,55,56,58
APPROXIMATELY 18 months ago a new company—Spektrum—
came onto the radio control market with the first production 2.4 GHz
system using spread spectrum technology. It was for surface use.
Roughly six months later Spektrum introduced the first
production system for aircraft using the 2.4 GHz band and spread
spectrum technology. This unit was designed for park-size models
only. In a short amount of time the DX6 became popular with those
flying electric-powered models. The system has a nice range of
features but was lacking the ability to fly larger models.
In October 2006 Spektrum introduced the new “full range” DX7
system at the iHobby Expo in Chicago, Illinois, and many have
hailed it as evolutionary. The DX7 is capable of flying any size
model whether it is fixed or rotary wing.
To understand why the introduction of this full-range system is
so evolutionary, you need to understand more about the 2.4 GHz
band and spread spectrum. Model Aviation has published two
articles about the technology, the most recent of which was in the
December 2006 issue. I encourage you to read both articles, but for
now I’ll review a bit so you can understand why the technology
employed by the DX7 works so well.
The 2.4 GHz band has a fairly short wavelength; as such the
antennas are short. The shorter wavelengths are more easily blocked
by objects such as big battery packs, mufflers, engines, and other
components that could be found in large models. When you put a
receiver (that has a short antenna) in a model with these larger
components, they could easily block the signal from the transmitter.
I will cover how the DX7 and its AR7000 receiver get around
this problem in a bit.
DX7 Advantages: So what are the advantages of using a spread
spectrum system in the 2.4
GHz band? To begin with,
you never have to worry
about frequency control
again. You simply turn on
the system and go fly.
Additionally, 2.4 GHz is
well above the frequency
range at which most
interference (noise) is
generated.
Most of the noise
models and their
various parts (including such items as speed controls and motors)
generate is below 300 MHz. This means 2.4 GHz is virtually
immune to this type of interference. When you couple this with the
added security of spread spectrum, you end up with a system that,
for all practical purposes, is immune to outside interference!
The DX7 is sold as a complete system. It includes the
transmitter, AR7000 receiver, 1100 mAh, 4.8-volt Ni-Cd receiver
battery pack, 1500 mAh NiMH transmitter battery, four DS821
digital servos, switch harness, servo mounting hardware and output
arms, dual wall charger, bind plug, and hex wrench for adjusting the
transmitter stick height.
The system uses Spektrum’s trademarked DSM2 (Digital
Spectrum Modulation second generation) DuaLink technology. The
original DX6 uses the first generation (DSM) of this technology.
The DX7 transmits on two frequencies at the same time, and the
AR7000 receiver is actually two discrete receivers connected by a
cable that receives those frequencies at the same time.
The transmitter antenna
is shown fully extended. It
is hinged roughly halfway
down, where it can fold
down 90° and rotate 180°.
The Spektrum DX7 is up to
date with high-capacity batteries and the
same type of sport digital servos most
people pay extra money to get.
The Academy recommends that clubs
provide a flightline control system with
the use of spread spectrum radios. This
system should be similar to the
frequency-control plan that is currently
in use at flying sites. Multiple pins or
identification spaces should be provided
for spread spectrum.
The preceding is recommended for
two reasons, the first of which is that it
keeps members in the practice of taking
a pin. This is important if they ever
return to 72 MHz use. Second, it
provides clubs with a method of
flightline (not frequency) control. MA
—AMA Headquarters
Feature Packed: The DX7 features a 20-
model memory with ModelMatch that
prevents the operation of an airplane if the
wrong memory is selected. When the
receiver is bound to the transmitter (the
process whereby the receiver recognizes that
the transmitter’s GUID [Globally Unique
Identifier]), it actually remembers the
specific model memory the transmitter is
operating.
If you ever attempt to operate a receiver
that was bound to a model memory other
than the correct one, the model will not
function. This makes flight operations even
safer. As far as I know, this feature is unique
to spread spectrum systems.
The DX7 is also the first transmitter to
feature pure digital processing. The
transmitter does not convert a PPM or PCM
data stream to the DSM2 digital stream; in
the DX7 the data starts out digital and
remains digital. That means the system’s
latency (the time from stick movement to
servo movement) is extremely low.
Because of this low latency, the feeling
you get when flying this system is hard to
describe. It is perhaps the most connected
feeling I’ve ever had when flying a model.
The system also has a feature called
“ServoSync.” It is not covered in the
owner’s manual for some reason, but all the
promotional literature mentions it.
ServoSync resequences the transmitted
data depending on what type of mixing the
model being flown has programmed. That
means any servos that have to work together
receive the information at the same time. It
happens in applications such as dual
elevators, Cyclic Collective Pitch Mixing
(CCPM) in a helicopter, etc. This is no
doubt part of the connected feeling I have
when flying with this transmitter.
Fortunately the DX7 is backward
compatible with the AR6000 Park Flyer
receiver, which comes with the DX6 system.
When using the AR6000 it is important to
remember that the combination can be used
only in park-size models. When being used
with the AR6000 the DX7 automatically
switches to DSM (not DSM2) modulation.
The 1500 mAh NiMH battery in the
transmitter will give you approximately six
hours of transmitter run time when operating
the AR7000 receiver. If the transmitter is
turned on but not connected to a receiver,
the current draw goes up and run time is
reduced.
That may seem odd at first, but it begins
to make sense if you think about it in terms
of a cell phone that is searching for a signal.
The system uses more power as it seeks for
a receiver with which to connect.
It is odd that the charger supplied with
this system is set for only 50 mAh. The
owner’s manual clearly indicates that the
supplied charger should be set for 110 mAh.
I’m not sure why there is this discrepancy.
I’d certainly prefer to have a higher-rate
charger. When Horizon personnel were
questioned about the issue, they mentioned
that future versions will come with a 120
mAh battery charger.
The large LCD screen has great
resolution—much higher than most
transmitters in this class range. Data input or
value changes are made via two large rocker
switches, one of which is on either side of
the display. There are also two buttons on
either side of the display; they are used to
move the cursor around the screen or
Each DX7 system includes
everything shown and an
extremely well-written
instruction manual.
The AR7000 receiver system includes two
units linked by a short three-wire lead. The
short antennas stay inside the model once
mounted.
The voltage of the transmitter is displayed numerically at the top
right and at the top left with a bar scale.
The LCD screen’s fine resolution lets the operator see the
smallest adjustments made. That is especially appreciated with
control-throw curves.
confirm data entry.
Along the top front of the transmitter are
four toggle switches: elevator dual rate,
three-position flap mix (stunt mode for
helicopter), AUX 2, and aileron dual rate.
Two rocker-type momentary switches are
also along the top. The one on the left is
used for trainer/flap (hover pitch) and the
one on the right is for AUX 2 (hover
throttle).
On the top of the transmitter are two
more two-position toggle switches. On the
left is the gear switch (gyro) and on the right
is the mix-rudder dual rate (throttle hold)
switch.
Many of these switches may be
reconfigured for other uses by the
transmitter’s programming. The trim levers
are digital—what Spektrum calls ADT
(Advanced Digital Trim). Each of the trim
positions is automatically stored with all the
programming details for each model. The
trim levers only rock in one direction or the
other; they do not actually move.
When in the helicopter mode the trim
will change with each flight mode if desired.
This is a great feature if your trims are
different for hovering maneuvers in the
normal mode than they are in one of your
stunt (idle-up) modes.
Another unique trim feature is called
Throttle Recovery. When flying a model
with a glow or gas engine, Throttle
Recovery allows you to kill the engine with
full down throttle trim but then return to
your original throttle trim position with a
single up “click” of the throttle trim lever.
Trim positions are shown on the LCD, as
are the hover pitch and hover throttle
positions in the helicopter mode. During
normal operation the LCD screen shows an
analog bar graph of battery condition and a
digital voltmeter.
It also shows the model number and
model name. A graphic of either a fixed
wing or a helicopter is displayed to quickly
show you which mode you are in. Trim
positions are indicated, and a countup/
count-down timer can be displayed when
that feature is activated.
Stick tension is adjustable; however, you
must remove the back of the transmitter case
to make the adjustments. This requires you
to remove the battery and the six screws that
hold the back of the transmitter case. This is
a simple operation, but it could make some
users nervous.
A single screw adjusts the tension for
each of the functions. For helicopter or
airplane pilots who do not like a ratchet on
throttle, a non-ratchet strap for the throttle
stick is supplied and easy to install. Stick
length can also be adjusted; that is done with
the supplied hex wrench.
The AR7000 receiver is unique and
could be somewhat considered the heart of
this system. It is actually two discrete
receivers in one. The main receiver is fairly
standard in size (on the small side) and is
the unit that links the servos and battery.
The remote receiver is connected to the
main receiver via a 6-inch, three-wire lead.
Each receiver has two 1.5-inch wires
coming out of it. These are the dipole
antennas for each receiver. The remote
receiver is small, at just 0.625 x 0.875 inch.
The concept with these two receivers is
that by placing them at least 2 inches apart,
each is in a different radio frequency
environment. The antennas would ideally be
oriented perpendicular to each other,
although that is noncritical. With the
receivers located in different areas of the
aircraft and each receiving on a different
frequency, the AR7000 really provides a
bulletproof link from the transmitter to the
receiver.
Binding is an operation that is unique to
spread spectrum systems. The process of
binding teaches the receiver the unique code
of the transmitter. Once bound, the receiver
will “listen” only for that specific
transmitter. In the case of the DX7,
ModelMatch (described previously) causes
the receiver to recognize the specific
transmitter and the specific model memory.
The DX7 also features a switch harness
that allows you to place the receiver in the
bind mode without directly accessing the
receiver. To place the receiver in the bind
mode you simply insert the special bind
plug into the charge jack of the switch
harness and turn on the receiver.
To actually bind, press and hold the bind
button on the back of the transmitter while
Torque: 72 ounce-inch at 4.8 volts,
88 ounce-inch at 6.0 volts
Speed: .19 seconds/60° at 4.8 volts,
.15 seconds/60° at 6.0 volts
Size: 1.50 x 0.94 x 1.47 inches
Weight: 1.5 ounces
Ball bearing: Single
Motor: Cored
DS821 Sport Digital Servo Specifications
Number of channels: Seven
Modulation: DSM2
Band: 2.4 GHz
Servos: DS821 Sport Digital
(four included)
Receiver: AR7000
Programming features: Aircraft
and helicopter
Model memory: 20 models
Transmitter battery type: 1500 mAh
NiMH
Receiver battery type: 1100 mAh
Ni-Cd
Trim lever type: Fully digital
Price: $349.99
System Specifications
• Seven channels DSM2
• Features external and internal receiver
• DuaLink
• Model match
• Servo synchronization
AR7000 Receiver Specifications
“Auto D/R EXP” screen (available in “heli” mode) permits dual
rate and expo values to change, depending on single (flight mode)
switch position (“Norm,” “ST-1,” “ST-2”).
Flap system screen (available in “Acro” mode) controls threeposition
switch that may be used to engage the system or
programmed to be automatic with throttle position (5% here).
turning it on. The two LEDs on the AR7000
receivers that began blinking when you
turned on the receivers will stop blinking
and stay on, indicating that the binding
process has been completed.
Another important part of the binding
process is that it sets the fail-safe
positions. The stick and switch positions
the transmitter is in during binding are
established as the fail-safe positions.
Anytime you make a programming change
to the system, it’s a good idea to rebind it.
I found that to be the only way to assure
that the fail-safe settings are correct.
The DX7 has a nice variety of features
for fixed-wing aircraft and helicopters.
There are no sailplane-specific
preprogrammed mixes; however, there are
more than enough programmable mixes to
handle almost any sailplane function.
The menu structure in the DX7 is easy
to understand. You can view the menu as a
list in one mode or you can scroll through
each of the functions individually. I tend
to use the scroll method more than the list
method.
Two programming levels exist. The top
level is the System Setup Mode, which
you access by holding down the SCROLL
rocker and SELECT button while turning
on the transmitter. In the System Setup
Mode you can:
• Choose the model you want to fly.
• Name the model you want to fly.
• Pick the model type (ACRO or HELI).
• Reset the model to factory default
settings.
• Reset the integral timer.
• Turn the trainer function on or off and
select its mode of operation.
• Select dual rate switches.
• Choose the wing type (FLAPERON, VTAIL,
DELTA) or helicopter swashplate
type (standard, 180° CCPM, 120° CCPM,
90° CCPM).
• Access Input Select (which determines
how Aux 2 will be used or select the
switch input that gyro gain will use).
• Enable or disable throttle recovery.
The Function mode is accessed by
holding down the SCROLL and SELECT
buttons when the transmitter is already
powered up. The aircraft’s main
programming functions are accessed from
this menu.
The SCROLL rocker switch will move
you backward or forward through each
menu. The SELECT button moves the
cursor around, the ADJUST button
changes values, and the CLEAR button is
typically used to lock in a value.
Programming features available in the
ACRO mode are dual and exponential
rates, servo reversing, subtrims, travel
adjust, elevator-to-flap mixing, aileron-torudder
mixing, servo monitor screen,
count-up/count-down timer, six
programmable mixes, and the differential
and flap system.
The HELI mode’s available
programming includes dual and
exponential rates, servo reversing,
subtrims, travel adjust, swashplate mixing,
throttle hold, throttle curve (Normal, Stunt
1, Stunt 2), pitch curve (Normal, Stunt 1,
Stunt 2, Hold), servo monitor screen,
count-up/count-down timer, three
programmable mixes, gyro sensing, and
revo mix.
Dual and exponential (expo) rates are
programmed from the same screen. Expo
is shown on the display, which is a great
aid in seeing how the expo rate you set
will affect the sticks’ sensitivity.
As I mentioned, this system has
numerous features. Let’s take a closer look
at a few of the more unique ones. In the
helicopter mode you have five-point pitch
and throttle curves available.
In the airplane mode, preprogrammed
mixes make the popular forms of mixing
easy to accomplish. In addition, the system
has a flap program that allows you to set
3° of flaps and couple the elevator to those
positions to control pitch changes. You
can also set an automatic landing system
that will activate the flaps with elevator
compensation at any point you wish to
select based on the position of the throttle
stick.
Helicopter mode gives you the ability
to set up automatic dual or exponential
rates based on flight mode. With this
feature the flip of a switch changes dual
and expo rates (as well as other
parameters).
One item I really like in the helicopter
mode is that if you power up with throttle
hold on or with the flight mode switch in
any mode other than normal, the main
display will warn you. The display will
not return to normal until the switches are
returned to the normal (and safe)
positions. This feature is a great safety
reminder to help prevent hot starts.
The DX7 is a super system I’ve really
enjoyed flying. I’ve gotten used to not
having to wait on a channel at large
events. I also find it to be one of the safest
systems I have ever used. In almost five
months I haven’t experienced a single
problem—not a bump, not an issue.
The instruction manual is extremely
well laid out. I wished for additional
programming examples from time to time,
but they are not really needed. In fact, you
could easily program this transmitter
without the manual; it is that easy.
The DX7 system is available for a
street price of $349.99, which is not bad
considering what all it includes. I plan to
fly with the DX7 for many years to come.
It is worth your serious consideration. MA
Steve Kaluf
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 352-1913
www.horizonhobby.com
Other Published Resources:
Model Airplane News
February 2007
Fly R/C
February 2007
Model Aviation
December 2006
Edition: Model Aviation - 2007/03
Page Numbers: 53,54,55,56,58
APPROXIMATELY 18 months ago a new company—Spektrum—
came onto the radio control market with the first production 2.4 GHz
system using spread spectrum technology. It was for surface use.
Roughly six months later Spektrum introduced the first
production system for aircraft using the 2.4 GHz band and spread
spectrum technology. This unit was designed for park-size models
only. In a short amount of time the DX6 became popular with those
flying electric-powered models. The system has a nice range of
features but was lacking the ability to fly larger models.
In October 2006 Spektrum introduced the new “full range” DX7
system at the iHobby Expo in Chicago, Illinois, and many have
hailed it as evolutionary. The DX7 is capable of flying any size
model whether it is fixed or rotary wing.
To understand why the introduction of this full-range system is
so evolutionary, you need to understand more about the 2.4 GHz
band and spread spectrum. Model Aviation has published two
articles about the technology, the most recent of which was in the
December 2006 issue. I encourage you to read both articles, but for
now I’ll review a bit so you can understand why the technology
employed by the DX7 works so well.
The 2.4 GHz band has a fairly short wavelength; as such the
antennas are short. The shorter wavelengths are more easily blocked
by objects such as big battery packs, mufflers, engines, and other
components that could be found in large models. When you put a
receiver (that has a short antenna) in a model with these larger
components, they could easily block the signal from the transmitter.
I will cover how the DX7 and its AR7000 receiver get around
this problem in a bit.
DX7 Advantages: So what are the advantages of using a spread
spectrum system in the 2.4
GHz band? To begin with,
you never have to worry
about frequency control
again. You simply turn on
the system and go fly.
Additionally, 2.4 GHz is
well above the frequency
range at which most
interference (noise) is
generated.
Most of the noise
models and their
various parts (including such items as speed controls and motors)
generate is below 300 MHz. This means 2.4 GHz is virtually
immune to this type of interference. When you couple this with the
added security of spread spectrum, you end up with a system that,
for all practical purposes, is immune to outside interference!
The DX7 is sold as a complete system. It includes the
transmitter, AR7000 receiver, 1100 mAh, 4.8-volt Ni-Cd receiver
battery pack, 1500 mAh NiMH transmitter battery, four DS821
digital servos, switch harness, servo mounting hardware and output
arms, dual wall charger, bind plug, and hex wrench for adjusting the
transmitter stick height.
The system uses Spektrum’s trademarked DSM2 (Digital
Spectrum Modulation second generation) DuaLink technology. The
original DX6 uses the first generation (DSM) of this technology.
The DX7 transmits on two frequencies at the same time, and the
AR7000 receiver is actually two discrete receivers connected by a
cable that receives those frequencies at the same time.
The transmitter antenna
is shown fully extended. It
is hinged roughly halfway
down, where it can fold
down 90° and rotate 180°.
The Spektrum DX7 is up to
date with high-capacity batteries and the
same type of sport digital servos most
people pay extra money to get.
The Academy recommends that clubs
provide a flightline control system with
the use of spread spectrum radios. This
system should be similar to the
frequency-control plan that is currently
in use at flying sites. Multiple pins or
identification spaces should be provided
for spread spectrum.
The preceding is recommended for
two reasons, the first of which is that it
keeps members in the practice of taking
a pin. This is important if they ever
return to 72 MHz use. Second, it
provides clubs with a method of
flightline (not frequency) control. MA
—AMA Headquarters
Feature Packed: The DX7 features a 20-
model memory with ModelMatch that
prevents the operation of an airplane if the
wrong memory is selected. When the
receiver is bound to the transmitter (the
process whereby the receiver recognizes that
the transmitter’s GUID [Globally Unique
Identifier]), it actually remembers the
specific model memory the transmitter is
operating.
If you ever attempt to operate a receiver
that was bound to a model memory other
than the correct one, the model will not
function. This makes flight operations even
safer. As far as I know, this feature is unique
to spread spectrum systems.
The DX7 is also the first transmitter to
feature pure digital processing. The
transmitter does not convert a PPM or PCM
data stream to the DSM2 digital stream; in
the DX7 the data starts out digital and
remains digital. That means the system’s
latency (the time from stick movement to
servo movement) is extremely low.
Because of this low latency, the feeling
you get when flying this system is hard to
describe. It is perhaps the most connected
feeling I’ve ever had when flying a model.
The system also has a feature called
“ServoSync.” It is not covered in the
owner’s manual for some reason, but all the
promotional literature mentions it.
ServoSync resequences the transmitted
data depending on what type of mixing the
model being flown has programmed. That
means any servos that have to work together
receive the information at the same time. It
happens in applications such as dual
elevators, Cyclic Collective Pitch Mixing
(CCPM) in a helicopter, etc. This is no
doubt part of the connected feeling I have
when flying with this transmitter.
Fortunately the DX7 is backward
compatible with the AR6000 Park Flyer
receiver, which comes with the DX6 system.
When using the AR6000 it is important to
remember that the combination can be used
only in park-size models. When being used
with the AR6000 the DX7 automatically
switches to DSM (not DSM2) modulation.
The 1500 mAh NiMH battery in the
transmitter will give you approximately six
hours of transmitter run time when operating
the AR7000 receiver. If the transmitter is
turned on but not connected to a receiver,
the current draw goes up and run time is
reduced.
That may seem odd at first, but it begins
to make sense if you think about it in terms
of a cell phone that is searching for a signal.
The system uses more power as it seeks for
a receiver with which to connect.
It is odd that the charger supplied with
this system is set for only 50 mAh. The
owner’s manual clearly indicates that the
supplied charger should be set for 110 mAh.
I’m not sure why there is this discrepancy.
I’d certainly prefer to have a higher-rate
charger. When Horizon personnel were
questioned about the issue, they mentioned
that future versions will come with a 120
mAh battery charger.
The large LCD screen has great
resolution—much higher than most
transmitters in this class range. Data input or
value changes are made via two large rocker
switches, one of which is on either side of
the display. There are also two buttons on
either side of the display; they are used to
move the cursor around the screen or
Each DX7 system includes
everything shown and an
extremely well-written
instruction manual.
The AR7000 receiver system includes two
units linked by a short three-wire lead. The
short antennas stay inside the model once
mounted.
The voltage of the transmitter is displayed numerically at the top
right and at the top left with a bar scale.
The LCD screen’s fine resolution lets the operator see the
smallest adjustments made. That is especially appreciated with
control-throw curves.
confirm data entry.
Along the top front of the transmitter are
four toggle switches: elevator dual rate,
three-position flap mix (stunt mode for
helicopter), AUX 2, and aileron dual rate.
Two rocker-type momentary switches are
also along the top. The one on the left is
used for trainer/flap (hover pitch) and the
one on the right is for AUX 2 (hover
throttle).
On the top of the transmitter are two
more two-position toggle switches. On the
left is the gear switch (gyro) and on the right
is the mix-rudder dual rate (throttle hold)
switch.
Many of these switches may be
reconfigured for other uses by the
transmitter’s programming. The trim levers
are digital—what Spektrum calls ADT
(Advanced Digital Trim). Each of the trim
positions is automatically stored with all the
programming details for each model. The
trim levers only rock in one direction or the
other; they do not actually move.
When in the helicopter mode the trim
will change with each flight mode if desired.
This is a great feature if your trims are
different for hovering maneuvers in the
normal mode than they are in one of your
stunt (idle-up) modes.
Another unique trim feature is called
Throttle Recovery. When flying a model
with a glow or gas engine, Throttle
Recovery allows you to kill the engine with
full down throttle trim but then return to
your original throttle trim position with a
single up “click” of the throttle trim lever.
Trim positions are shown on the LCD, as
are the hover pitch and hover throttle
positions in the helicopter mode. During
normal operation the LCD screen shows an
analog bar graph of battery condition and a
digital voltmeter.
It also shows the model number and
model name. A graphic of either a fixed
wing or a helicopter is displayed to quickly
show you which mode you are in. Trim
positions are indicated, and a countup/
count-down timer can be displayed when
that feature is activated.
Stick tension is adjustable; however, you
must remove the back of the transmitter case
to make the adjustments. This requires you
to remove the battery and the six screws that
hold the back of the transmitter case. This is
a simple operation, but it could make some
users nervous.
A single screw adjusts the tension for
each of the functions. For helicopter or
airplane pilots who do not like a ratchet on
throttle, a non-ratchet strap for the throttle
stick is supplied and easy to install. Stick
length can also be adjusted; that is done with
the supplied hex wrench.
The AR7000 receiver is unique and
could be somewhat considered the heart of
this system. It is actually two discrete
receivers in one. The main receiver is fairly
standard in size (on the small side) and is
the unit that links the servos and battery.
The remote receiver is connected to the
main receiver via a 6-inch, three-wire lead.
Each receiver has two 1.5-inch wires
coming out of it. These are the dipole
antennas for each receiver. The remote
receiver is small, at just 0.625 x 0.875 inch.
The concept with these two receivers is
that by placing them at least 2 inches apart,
each is in a different radio frequency
environment. The antennas would ideally be
oriented perpendicular to each other,
although that is noncritical. With the
receivers located in different areas of the
aircraft and each receiving on a different
frequency, the AR7000 really provides a
bulletproof link from the transmitter to the
receiver.
Binding is an operation that is unique to
spread spectrum systems. The process of
binding teaches the receiver the unique code
of the transmitter. Once bound, the receiver
will “listen” only for that specific
transmitter. In the case of the DX7,
ModelMatch (described previously) causes
the receiver to recognize the specific
transmitter and the specific model memory.
The DX7 also features a switch harness
that allows you to place the receiver in the
bind mode without directly accessing the
receiver. To place the receiver in the bind
mode you simply insert the special bind
plug into the charge jack of the switch
harness and turn on the receiver.
To actually bind, press and hold the bind
button on the back of the transmitter while
Torque: 72 ounce-inch at 4.8 volts,
88 ounce-inch at 6.0 volts
Speed: .19 seconds/60° at 4.8 volts,
.15 seconds/60° at 6.0 volts
Size: 1.50 x 0.94 x 1.47 inches
Weight: 1.5 ounces
Ball bearing: Single
Motor: Cored
DS821 Sport Digital Servo Specifications
Number of channels: Seven
Modulation: DSM2
Band: 2.4 GHz
Servos: DS821 Sport Digital
(four included)
Receiver: AR7000
Programming features: Aircraft
and helicopter
Model memory: 20 models
Transmitter battery type: 1500 mAh
NiMH
Receiver battery type: 1100 mAh
Ni-Cd
Trim lever type: Fully digital
Price: $349.99
System Specifications
• Seven channels DSM2
• Features external and internal receiver
• DuaLink
• Model match
• Servo synchronization
AR7000 Receiver Specifications
“Auto D/R EXP” screen (available in “heli” mode) permits dual
rate and expo values to change, depending on single (flight mode)
switch position (“Norm,” “ST-1,” “ST-2”).
Flap system screen (available in “Acro” mode) controls threeposition
switch that may be used to engage the system or
programmed to be automatic with throttle position (5% here).
turning it on. The two LEDs on the AR7000
receivers that began blinking when you
turned on the receivers will stop blinking
and stay on, indicating that the binding
process has been completed.
Another important part of the binding
process is that it sets the fail-safe
positions. The stick and switch positions
the transmitter is in during binding are
established as the fail-safe positions.
Anytime you make a programming change
to the system, it’s a good idea to rebind it.
I found that to be the only way to assure
that the fail-safe settings are correct.
The DX7 has a nice variety of features
for fixed-wing aircraft and helicopters.
There are no sailplane-specific
preprogrammed mixes; however, there are
more than enough programmable mixes to
handle almost any sailplane function.
The menu structure in the DX7 is easy
to understand. You can view the menu as a
list in one mode or you can scroll through
each of the functions individually. I tend
to use the scroll method more than the list
method.
Two programming levels exist. The top
level is the System Setup Mode, which
you access by holding down the SCROLL
rocker and SELECT button while turning
on the transmitter. In the System Setup
Mode you can:
• Choose the model you want to fly.
• Name the model you want to fly.
• Pick the model type (ACRO or HELI).
• Reset the model to factory default
settings.
• Reset the integral timer.
• Turn the trainer function on or off and
select its mode of operation.
• Select dual rate switches.
• Choose the wing type (FLAPERON, VTAIL,
DELTA) or helicopter swashplate
type (standard, 180° CCPM, 120° CCPM,
90° CCPM).
• Access Input Select (which determines
how Aux 2 will be used or select the
switch input that gyro gain will use).
• Enable or disable throttle recovery.
The Function mode is accessed by
holding down the SCROLL and SELECT
buttons when the transmitter is already
powered up. The aircraft’s main
programming functions are accessed from
this menu.
The SCROLL rocker switch will move
you backward or forward through each
menu. The SELECT button moves the
cursor around, the ADJUST button
changes values, and the CLEAR button is
typically used to lock in a value.
Programming features available in the
ACRO mode are dual and exponential
rates, servo reversing, subtrims, travel
adjust, elevator-to-flap mixing, aileron-torudder
mixing, servo monitor screen,
count-up/count-down timer, six
programmable mixes, and the differential
and flap system.
The HELI mode’s available
programming includes dual and
exponential rates, servo reversing,
subtrims, travel adjust, swashplate mixing,
throttle hold, throttle curve (Normal, Stunt
1, Stunt 2), pitch curve (Normal, Stunt 1,
Stunt 2, Hold), servo monitor screen,
count-up/count-down timer, three
programmable mixes, gyro sensing, and
revo mix.
Dual and exponential (expo) rates are
programmed from the same screen. Expo
is shown on the display, which is a great
aid in seeing how the expo rate you set
will affect the sticks’ sensitivity.
As I mentioned, this system has
numerous features. Let’s take a closer look
at a few of the more unique ones. In the
helicopter mode you have five-point pitch
and throttle curves available.
In the airplane mode, preprogrammed
mixes make the popular forms of mixing
easy to accomplish. In addition, the system
has a flap program that allows you to set
3° of flaps and couple the elevator to those
positions to control pitch changes. You
can also set an automatic landing system
that will activate the flaps with elevator
compensation at any point you wish to
select based on the position of the throttle
stick.
Helicopter mode gives you the ability
to set up automatic dual or exponential
rates based on flight mode. With this
feature the flip of a switch changes dual
and expo rates (as well as other
parameters).
One item I really like in the helicopter
mode is that if you power up with throttle
hold on or with the flight mode switch in
any mode other than normal, the main
display will warn you. The display will
not return to normal until the switches are
returned to the normal (and safe)
positions. This feature is a great safety
reminder to help prevent hot starts.
The DX7 is a super system I’ve really
enjoyed flying. I’ve gotten used to not
having to wait on a channel at large
events. I also find it to be one of the safest
systems I have ever used. In almost five
months I haven’t experienced a single
problem—not a bump, not an issue.
The instruction manual is extremely
well laid out. I wished for additional
programming examples from time to time,
but they are not really needed. In fact, you
could easily program this transmitter
without the manual; it is that easy.
The DX7 system is available for a
street price of $349.99, which is not bad
considering what all it includes. I plan to
fly with the DX7 for many years to come.
It is worth your serious consideration. MA
Steve Kaluf
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 352-1913
www.horizonhobby.com
Other Published Resources:
Model Airplane News
February 2007
Fly R/C
February 2007
Model Aviation
December 2006
Edition: Model Aviation - 2007/03
Page Numbers: 53,54,55,56,58
APPROXIMATELY 18 months ago a new company—Spektrum—
came onto the radio control market with the first production 2.4 GHz
system using spread spectrum technology. It was for surface use.
Roughly six months later Spektrum introduced the first
production system for aircraft using the 2.4 GHz band and spread
spectrum technology. This unit was designed for park-size models
only. In a short amount of time the DX6 became popular with those
flying electric-powered models. The system has a nice range of
features but was lacking the ability to fly larger models.
In October 2006 Spektrum introduced the new “full range” DX7
system at the iHobby Expo in Chicago, Illinois, and many have
hailed it as evolutionary. The DX7 is capable of flying any size
model whether it is fixed or rotary wing.
To understand why the introduction of this full-range system is
so evolutionary, you need to understand more about the 2.4 GHz
band and spread spectrum. Model Aviation has published two
articles about the technology, the most recent of which was in the
December 2006 issue. I encourage you to read both articles, but for
now I’ll review a bit so you can understand why the technology
employed by the DX7 works so well.
The 2.4 GHz band has a fairly short wavelength; as such the
antennas are short. The shorter wavelengths are more easily blocked
by objects such as big battery packs, mufflers, engines, and other
components that could be found in large models. When you put a
receiver (that has a short antenna) in a model with these larger
components, they could easily block the signal from the transmitter.
I will cover how the DX7 and its AR7000 receiver get around
this problem in a bit.
DX7 Advantages: So what are the advantages of using a spread
spectrum system in the 2.4
GHz band? To begin with,
you never have to worry
about frequency control
again. You simply turn on
the system and go fly.
Additionally, 2.4 GHz is
well above the frequency
range at which most
interference (noise) is
generated.
Most of the noise
models and their
various parts (including such items as speed controls and motors)
generate is below 300 MHz. This means 2.4 GHz is virtually
immune to this type of interference. When you couple this with the
added security of spread spectrum, you end up with a system that,
for all practical purposes, is immune to outside interference!
The DX7 is sold as a complete system. It includes the
transmitter, AR7000 receiver, 1100 mAh, 4.8-volt Ni-Cd receiver
battery pack, 1500 mAh NiMH transmitter battery, four DS821
digital servos, switch harness, servo mounting hardware and output
arms, dual wall charger, bind plug, and hex wrench for adjusting the
transmitter stick height.
The system uses Spektrum’s trademarked DSM2 (Digital
Spectrum Modulation second generation) DuaLink technology. The
original DX6 uses the first generation (DSM) of this technology.
The DX7 transmits on two frequencies at the same time, and the
AR7000 receiver is actually two discrete receivers connected by a
cable that receives those frequencies at the same time.
The transmitter antenna
is shown fully extended. It
is hinged roughly halfway
down, where it can fold
down 90° and rotate 180°.
The Spektrum DX7 is up to
date with high-capacity batteries and the
same type of sport digital servos most
people pay extra money to get.
The Academy recommends that clubs
provide a flightline control system with
the use of spread spectrum radios. This
system should be similar to the
frequency-control plan that is currently
in use at flying sites. Multiple pins or
identification spaces should be provided
for spread spectrum.
The preceding is recommended for
two reasons, the first of which is that it
keeps members in the practice of taking
a pin. This is important if they ever
return to 72 MHz use. Second, it
provides clubs with a method of
flightline (not frequency) control. MA
—AMA Headquarters
Feature Packed: The DX7 features a 20-
model memory with ModelMatch that
prevents the operation of an airplane if the
wrong memory is selected. When the
receiver is bound to the transmitter (the
process whereby the receiver recognizes that
the transmitter’s GUID [Globally Unique
Identifier]), it actually remembers the
specific model memory the transmitter is
operating.
If you ever attempt to operate a receiver
that was bound to a model memory other
than the correct one, the model will not
function. This makes flight operations even
safer. As far as I know, this feature is unique
to spread spectrum systems.
The DX7 is also the first transmitter to
feature pure digital processing. The
transmitter does not convert a PPM or PCM
data stream to the DSM2 digital stream; in
the DX7 the data starts out digital and
remains digital. That means the system’s
latency (the time from stick movement to
servo movement) is extremely low.
Because of this low latency, the feeling
you get when flying this system is hard to
describe. It is perhaps the most connected
feeling I’ve ever had when flying a model.
The system also has a feature called
“ServoSync.” It is not covered in the
owner’s manual for some reason, but all the
promotional literature mentions it.
ServoSync resequences the transmitted
data depending on what type of mixing the
model being flown has programmed. That
means any servos that have to work together
receive the information at the same time. It
happens in applications such as dual
elevators, Cyclic Collective Pitch Mixing
(CCPM) in a helicopter, etc. This is no
doubt part of the connected feeling I have
when flying with this transmitter.
Fortunately the DX7 is backward
compatible with the AR6000 Park Flyer
receiver, which comes with the DX6 system.
When using the AR6000 it is important to
remember that the combination can be used
only in park-size models. When being used
with the AR6000 the DX7 automatically
switches to DSM (not DSM2) modulation.
The 1500 mAh NiMH battery in the
transmitter will give you approximately six
hours of transmitter run time when operating
the AR7000 receiver. If the transmitter is
turned on but not connected to a receiver,
the current draw goes up and run time is
reduced.
That may seem odd at first, but it begins
to make sense if you think about it in terms
of a cell phone that is searching for a signal.
The system uses more power as it seeks for
a receiver with which to connect.
It is odd that the charger supplied with
this system is set for only 50 mAh. The
owner’s manual clearly indicates that the
supplied charger should be set for 110 mAh.
I’m not sure why there is this discrepancy.
I’d certainly prefer to have a higher-rate
charger. When Horizon personnel were
questioned about the issue, they mentioned
that future versions will come with a 120
mAh battery charger.
The large LCD screen has great
resolution—much higher than most
transmitters in this class range. Data input or
value changes are made via two large rocker
switches, one of which is on either side of
the display. There are also two buttons on
either side of the display; they are used to
move the cursor around the screen or
Each DX7 system includes
everything shown and an
extremely well-written
instruction manual.
The AR7000 receiver system includes two
units linked by a short three-wire lead. The
short antennas stay inside the model once
mounted.
The voltage of the transmitter is displayed numerically at the top
right and at the top left with a bar scale.
The LCD screen’s fine resolution lets the operator see the
smallest adjustments made. That is especially appreciated with
control-throw curves.
confirm data entry.
Along the top front of the transmitter are
four toggle switches: elevator dual rate,
three-position flap mix (stunt mode for
helicopter), AUX 2, and aileron dual rate.
Two rocker-type momentary switches are
also along the top. The one on the left is
used for trainer/flap (hover pitch) and the
one on the right is for AUX 2 (hover
throttle).
On the top of the transmitter are two
more two-position toggle switches. On the
left is the gear switch (gyro) and on the right
is the mix-rudder dual rate (throttle hold)
switch.
Many of these switches may be
reconfigured for other uses by the
transmitter’s programming. The trim levers
are digital—what Spektrum calls ADT
(Advanced Digital Trim). Each of the trim
positions is automatically stored with all the
programming details for each model. The
trim levers only rock in one direction or the
other; they do not actually move.
When in the helicopter mode the trim
will change with each flight mode if desired.
This is a great feature if your trims are
different for hovering maneuvers in the
normal mode than they are in one of your
stunt (idle-up) modes.
Another unique trim feature is called
Throttle Recovery. When flying a model
with a glow or gas engine, Throttle
Recovery allows you to kill the engine with
full down throttle trim but then return to
your original throttle trim position with a
single up “click” of the throttle trim lever.
Trim positions are shown on the LCD, as
are the hover pitch and hover throttle
positions in the helicopter mode. During
normal operation the LCD screen shows an
analog bar graph of battery condition and a
digital voltmeter.
It also shows the model number and
model name. A graphic of either a fixed
wing or a helicopter is displayed to quickly
show you which mode you are in. Trim
positions are indicated, and a countup/
count-down timer can be displayed when
that feature is activated.
Stick tension is adjustable; however, you
must remove the back of the transmitter case
to make the adjustments. This requires you
to remove the battery and the six screws that
hold the back of the transmitter case. This is
a simple operation, but it could make some
users nervous.
A single screw adjusts the tension for
each of the functions. For helicopter or
airplane pilots who do not like a ratchet on
throttle, a non-ratchet strap for the throttle
stick is supplied and easy to install. Stick
length can also be adjusted; that is done with
the supplied hex wrench.
The AR7000 receiver is unique and
could be somewhat considered the heart of
this system. It is actually two discrete
receivers in one. The main receiver is fairly
standard in size (on the small side) and is
the unit that links the servos and battery.
The remote receiver is connected to the
main receiver via a 6-inch, three-wire lead.
Each receiver has two 1.5-inch wires
coming out of it. These are the dipole
antennas for each receiver. The remote
receiver is small, at just 0.625 x 0.875 inch.
The concept with these two receivers is
that by placing them at least 2 inches apart,
each is in a different radio frequency
environment. The antennas would ideally be
oriented perpendicular to each other,
although that is noncritical. With the
receivers located in different areas of the
aircraft and each receiving on a different
frequency, the AR7000 really provides a
bulletproof link from the transmitter to the
receiver.
Binding is an operation that is unique to
spread spectrum systems. The process of
binding teaches the receiver the unique code
of the transmitter. Once bound, the receiver
will “listen” only for that specific
transmitter. In the case of the DX7,
ModelMatch (described previously) causes
the receiver to recognize the specific
transmitter and the specific model memory.
The DX7 also features a switch harness
that allows you to place the receiver in the
bind mode without directly accessing the
receiver. To place the receiver in the bind
mode you simply insert the special bind
plug into the charge jack of the switch
harness and turn on the receiver.
To actually bind, press and hold the bind
button on the back of the transmitter while
Torque: 72 ounce-inch at 4.8 volts,
88 ounce-inch at 6.0 volts
Speed: .19 seconds/60° at 4.8 volts,
.15 seconds/60° at 6.0 volts
Size: 1.50 x 0.94 x 1.47 inches
Weight: 1.5 ounces
Ball bearing: Single
Motor: Cored
DS821 Sport Digital Servo Specifications
Number of channels: Seven
Modulation: DSM2
Band: 2.4 GHz
Servos: DS821 Sport Digital
(four included)
Receiver: AR7000
Programming features: Aircraft
and helicopter
Model memory: 20 models
Transmitter battery type: 1500 mAh
NiMH
Receiver battery type: 1100 mAh
Ni-Cd
Trim lever type: Fully digital
Price: $349.99
System Specifications
• Seven channels DSM2
• Features external and internal receiver
• DuaLink
• Model match
• Servo synchronization
AR7000 Receiver Specifications
“Auto D/R EXP” screen (available in “heli” mode) permits dual
rate and expo values to change, depending on single (flight mode)
switch position (“Norm,” “ST-1,” “ST-2”).
Flap system screen (available in “Acro” mode) controls threeposition
switch that may be used to engage the system or
programmed to be automatic with throttle position (5% here).
turning it on. The two LEDs on the AR7000
receivers that began blinking when you
turned on the receivers will stop blinking
and stay on, indicating that the binding
process has been completed.
Another important part of the binding
process is that it sets the fail-safe
positions. The stick and switch positions
the transmitter is in during binding are
established as the fail-safe positions.
Anytime you make a programming change
to the system, it’s a good idea to rebind it.
I found that to be the only way to assure
that the fail-safe settings are correct.
The DX7 has a nice variety of features
for fixed-wing aircraft and helicopters.
There are no sailplane-specific
preprogrammed mixes; however, there are
more than enough programmable mixes to
handle almost any sailplane function.
The menu structure in the DX7 is easy
to understand. You can view the menu as a
list in one mode or you can scroll through
each of the functions individually. I tend
to use the scroll method more than the list
method.
Two programming levels exist. The top
level is the System Setup Mode, which
you access by holding down the SCROLL
rocker and SELECT button while turning
on the transmitter. In the System Setup
Mode you can:
• Choose the model you want to fly.
• Name the model you want to fly.
• Pick the model type (ACRO or HELI).
• Reset the model to factory default
settings.
• Reset the integral timer.
• Turn the trainer function on or off and
select its mode of operation.
• Select dual rate switches.
• Choose the wing type (FLAPERON, VTAIL,
DELTA) or helicopter swashplate
type (standard, 180° CCPM, 120° CCPM,
90° CCPM).
• Access Input Select (which determines
how Aux 2 will be used or select the
switch input that gyro gain will use).
• Enable or disable throttle recovery.
The Function mode is accessed by
holding down the SCROLL and SELECT
buttons when the transmitter is already
powered up. The aircraft’s main
programming functions are accessed from
this menu.
The SCROLL rocker switch will move
you backward or forward through each
menu. The SELECT button moves the
cursor around, the ADJUST button
changes values, and the CLEAR button is
typically used to lock in a value.
Programming features available in the
ACRO mode are dual and exponential
rates, servo reversing, subtrims, travel
adjust, elevator-to-flap mixing, aileron-torudder
mixing, servo monitor screen,
count-up/count-down timer, six
programmable mixes, and the differential
and flap system.
The HELI mode’s available
programming includes dual and
exponential rates, servo reversing,
subtrims, travel adjust, swashplate mixing,
throttle hold, throttle curve (Normal, Stunt
1, Stunt 2), pitch curve (Normal, Stunt 1,
Stunt 2, Hold), servo monitor screen,
count-up/count-down timer, three
programmable mixes, gyro sensing, and
revo mix.
Dual and exponential (expo) rates are
programmed from the same screen. Expo
is shown on the display, which is a great
aid in seeing how the expo rate you set
will affect the sticks’ sensitivity.
As I mentioned, this system has
numerous features. Let’s take a closer look
at a few of the more unique ones. In the
helicopter mode you have five-point pitch
and throttle curves available.
In the airplane mode, preprogrammed
mixes make the popular forms of mixing
easy to accomplish. In addition, the system
has a flap program that allows you to set
3° of flaps and couple the elevator to those
positions to control pitch changes. You
can also set an automatic landing system
that will activate the flaps with elevator
compensation at any point you wish to
select based on the position of the throttle
stick.
Helicopter mode gives you the ability
to set up automatic dual or exponential
rates based on flight mode. With this
feature the flip of a switch changes dual
and expo rates (as well as other
parameters).
One item I really like in the helicopter
mode is that if you power up with throttle
hold on or with the flight mode switch in
any mode other than normal, the main
display will warn you. The display will
not return to normal until the switches are
returned to the normal (and safe)
positions. This feature is a great safety
reminder to help prevent hot starts.
The DX7 is a super system I’ve really
enjoyed flying. I’ve gotten used to not
having to wait on a channel at large
events. I also find it to be one of the safest
systems I have ever used. In almost five
months I haven’t experienced a single
problem—not a bump, not an issue.
The instruction manual is extremely
well laid out. I wished for additional
programming examples from time to time,
but they are not really needed. In fact, you
could easily program this transmitter
without the manual; it is that easy.
The DX7 system is available for a
street price of $349.99, which is not bad
considering what all it includes. I plan to
fly with the DX7 for many years to come.
It is worth your serious consideration. MA
Steve Kaluf
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 352-1913
www.horizonhobby.com
Other Published Resources:
Model Airplane News
February 2007
Fly R/C
February 2007
Model Aviation
December 2006
Edition: Model Aviation - 2007/03
Page Numbers: 53,54,55,56,58
APPROXIMATELY 18 months ago a new company—Spektrum—
came onto the radio control market with the first production 2.4 GHz
system using spread spectrum technology. It was for surface use.
Roughly six months later Spektrum introduced the first
production system for aircraft using the 2.4 GHz band and spread
spectrum technology. This unit was designed for park-size models
only. In a short amount of time the DX6 became popular with those
flying electric-powered models. The system has a nice range of
features but was lacking the ability to fly larger models.
In October 2006 Spektrum introduced the new “full range” DX7
system at the iHobby Expo in Chicago, Illinois, and many have
hailed it as evolutionary. The DX7 is capable of flying any size
model whether it is fixed or rotary wing.
To understand why the introduction of this full-range system is
so evolutionary, you need to understand more about the 2.4 GHz
band and spread spectrum. Model Aviation has published two
articles about the technology, the most recent of which was in the
December 2006 issue. I encourage you to read both articles, but for
now I’ll review a bit so you can understand why the technology
employed by the DX7 works so well.
The 2.4 GHz band has a fairly short wavelength; as such the
antennas are short. The shorter wavelengths are more easily blocked
by objects such as big battery packs, mufflers, engines, and other
components that could be found in large models. When you put a
receiver (that has a short antenna) in a model with these larger
components, they could easily block the signal from the transmitter.
I will cover how the DX7 and its AR7000 receiver get around
this problem in a bit.
DX7 Advantages: So what are the advantages of using a spread
spectrum system in the 2.4
GHz band? To begin with,
you never have to worry
about frequency control
again. You simply turn on
the system and go fly.
Additionally, 2.4 GHz is
well above the frequency
range at which most
interference (noise) is
generated.
Most of the noise
models and their
various parts (including such items as speed controls and motors)
generate is below 300 MHz. This means 2.4 GHz is virtually
immune to this type of interference. When you couple this with the
added security of spread spectrum, you end up with a system that,
for all practical purposes, is immune to outside interference!
The DX7 is sold as a complete system. It includes the
transmitter, AR7000 receiver, 1100 mAh, 4.8-volt Ni-Cd receiver
battery pack, 1500 mAh NiMH transmitter battery, four DS821
digital servos, switch harness, servo mounting hardware and output
arms, dual wall charger, bind plug, and hex wrench for adjusting the
transmitter stick height.
The system uses Spektrum’s trademarked DSM2 (Digital
Spectrum Modulation second generation) DuaLink technology. The
original DX6 uses the first generation (DSM) of this technology.
The DX7 transmits on two frequencies at the same time, and the
AR7000 receiver is actually two discrete receivers connected by a
cable that receives those frequencies at the same time.
The transmitter antenna
is shown fully extended. It
is hinged roughly halfway
down, where it can fold
down 90° and rotate 180°.
The Spektrum DX7 is up to
date with high-capacity batteries and the
same type of sport digital servos most
people pay extra money to get.
The Academy recommends that clubs
provide a flightline control system with
the use of spread spectrum radios. This
system should be similar to the
frequency-control plan that is currently
in use at flying sites. Multiple pins or
identification spaces should be provided
for spread spectrum.
The preceding is recommended for
two reasons, the first of which is that it
keeps members in the practice of taking
a pin. This is important if they ever
return to 72 MHz use. Second, it
provides clubs with a method of
flightline (not frequency) control. MA
—AMA Headquarters
Feature Packed: The DX7 features a 20-
model memory with ModelMatch that
prevents the operation of an airplane if the
wrong memory is selected. When the
receiver is bound to the transmitter (the
process whereby the receiver recognizes that
the transmitter’s GUID [Globally Unique
Identifier]), it actually remembers the
specific model memory the transmitter is
operating.
If you ever attempt to operate a receiver
that was bound to a model memory other
than the correct one, the model will not
function. This makes flight operations even
safer. As far as I know, this feature is unique
to spread spectrum systems.
The DX7 is also the first transmitter to
feature pure digital processing. The
transmitter does not convert a PPM or PCM
data stream to the DSM2 digital stream; in
the DX7 the data starts out digital and
remains digital. That means the system’s
latency (the time from stick movement to
servo movement) is extremely low.
Because of this low latency, the feeling
you get when flying this system is hard to
describe. It is perhaps the most connected
feeling I’ve ever had when flying a model.
The system also has a feature called
“ServoSync.” It is not covered in the
owner’s manual for some reason, but all the
promotional literature mentions it.
ServoSync resequences the transmitted
data depending on what type of mixing the
model being flown has programmed. That
means any servos that have to work together
receive the information at the same time. It
happens in applications such as dual
elevators, Cyclic Collective Pitch Mixing
(CCPM) in a helicopter, etc. This is no
doubt part of the connected feeling I have
when flying with this transmitter.
Fortunately the DX7 is backward
compatible with the AR6000 Park Flyer
receiver, which comes with the DX6 system.
When using the AR6000 it is important to
remember that the combination can be used
only in park-size models. When being used
with the AR6000 the DX7 automatically
switches to DSM (not DSM2) modulation.
The 1500 mAh NiMH battery in the
transmitter will give you approximately six
hours of transmitter run time when operating
the AR7000 receiver. If the transmitter is
turned on but not connected to a receiver,
the current draw goes up and run time is
reduced.
That may seem odd at first, but it begins
to make sense if you think about it in terms
of a cell phone that is searching for a signal.
The system uses more power as it seeks for
a receiver with which to connect.
It is odd that the charger supplied with
this system is set for only 50 mAh. The
owner’s manual clearly indicates that the
supplied charger should be set for 110 mAh.
I’m not sure why there is this discrepancy.
I’d certainly prefer to have a higher-rate
charger. When Horizon personnel were
questioned about the issue, they mentioned
that future versions will come with a 120
mAh battery charger.
The large LCD screen has great
resolution—much higher than most
transmitters in this class range. Data input or
value changes are made via two large rocker
switches, one of which is on either side of
the display. There are also two buttons on
either side of the display; they are used to
move the cursor around the screen or
Each DX7 system includes
everything shown and an
extremely well-written
instruction manual.
The AR7000 receiver system includes two
units linked by a short three-wire lead. The
short antennas stay inside the model once
mounted.
The voltage of the transmitter is displayed numerically at the top
right and at the top left with a bar scale.
The LCD screen’s fine resolution lets the operator see the
smallest adjustments made. That is especially appreciated with
control-throw curves.
confirm data entry.
Along the top front of the transmitter are
four toggle switches: elevator dual rate,
three-position flap mix (stunt mode for
helicopter), AUX 2, and aileron dual rate.
Two rocker-type momentary switches are
also along the top. The one on the left is
used for trainer/flap (hover pitch) and the
one on the right is for AUX 2 (hover
throttle).
On the top of the transmitter are two
more two-position toggle switches. On the
left is the gear switch (gyro) and on the right
is the mix-rudder dual rate (throttle hold)
switch.
Many of these switches may be
reconfigured for other uses by the
transmitter’s programming. The trim levers
are digital—what Spektrum calls ADT
(Advanced Digital Trim). Each of the trim
positions is automatically stored with all the
programming details for each model. The
trim levers only rock in one direction or the
other; they do not actually move.
When in the helicopter mode the trim
will change with each flight mode if desired.
This is a great feature if your trims are
different for hovering maneuvers in the
normal mode than they are in one of your
stunt (idle-up) modes.
Another unique trim feature is called
Throttle Recovery. When flying a model
with a glow or gas engine, Throttle
Recovery allows you to kill the engine with
full down throttle trim but then return to
your original throttle trim position with a
single up “click” of the throttle trim lever.
Trim positions are shown on the LCD, as
are the hover pitch and hover throttle
positions in the helicopter mode. During
normal operation the LCD screen shows an
analog bar graph of battery condition and a
digital voltmeter.
It also shows the model number and
model name. A graphic of either a fixed
wing or a helicopter is displayed to quickly
show you which mode you are in. Trim
positions are indicated, and a countup/
count-down timer can be displayed when
that feature is activated.
Stick tension is adjustable; however, you
must remove the back of the transmitter case
to make the adjustments. This requires you
to remove the battery and the six screws that
hold the back of the transmitter case. This is
a simple operation, but it could make some
users nervous.
A single screw adjusts the tension for
each of the functions. For helicopter or
airplane pilots who do not like a ratchet on
throttle, a non-ratchet strap for the throttle
stick is supplied and easy to install. Stick
length can also be adjusted; that is done with
the supplied hex wrench.
The AR7000 receiver is unique and
could be somewhat considered the heart of
this system. It is actually two discrete
receivers in one. The main receiver is fairly
standard in size (on the small side) and is
the unit that links the servos and battery.
The remote receiver is connected to the
main receiver via a 6-inch, three-wire lead.
Each receiver has two 1.5-inch wires
coming out of it. These are the dipole
antennas for each receiver. The remote
receiver is small, at just 0.625 x 0.875 inch.
The concept with these two receivers is
that by placing them at least 2 inches apart,
each is in a different radio frequency
environment. The antennas would ideally be
oriented perpendicular to each other,
although that is noncritical. With the
receivers located in different areas of the
aircraft and each receiving on a different
frequency, the AR7000 really provides a
bulletproof link from the transmitter to the
receiver.
Binding is an operation that is unique to
spread spectrum systems. The process of
binding teaches the receiver the unique code
of the transmitter. Once bound, the receiver
will “listen” only for that specific
transmitter. In the case of the DX7,
ModelMatch (described previously) causes
the receiver to recognize the specific
transmitter and the specific model memory.
The DX7 also features a switch harness
that allows you to place the receiver in the
bind mode without directly accessing the
receiver. To place the receiver in the bind
mode you simply insert the special bind
plug into the charge jack of the switch
harness and turn on the receiver.
To actually bind, press and hold the bind
button on the back of the transmitter while
Torque: 72 ounce-inch at 4.8 volts,
88 ounce-inch at 6.0 volts
Speed: .19 seconds/60° at 4.8 volts,
.15 seconds/60° at 6.0 volts
Size: 1.50 x 0.94 x 1.47 inches
Weight: 1.5 ounces
Ball bearing: Single
Motor: Cored
DS821 Sport Digital Servo Specifications
Number of channels: Seven
Modulation: DSM2
Band: 2.4 GHz
Servos: DS821 Sport Digital
(four included)
Receiver: AR7000
Programming features: Aircraft
and helicopter
Model memory: 20 models
Transmitter battery type: 1500 mAh
NiMH
Receiver battery type: 1100 mAh
Ni-Cd
Trim lever type: Fully digital
Price: $349.99
System Specifications
• Seven channels DSM2
• Features external and internal receiver
• DuaLink
• Model match
• Servo synchronization
AR7000 Receiver Specifications
“Auto D/R EXP” screen (available in “heli” mode) permits dual
rate and expo values to change, depending on single (flight mode)
switch position (“Norm,” “ST-1,” “ST-2”).
Flap system screen (available in “Acro” mode) controls threeposition
switch that may be used to engage the system or
programmed to be automatic with throttle position (5% here).
turning it on. The two LEDs on the AR7000
receivers that began blinking when you
turned on the receivers will stop blinking
and stay on, indicating that the binding
process has been completed.
Another important part of the binding
process is that it sets the fail-safe
positions. The stick and switch positions
the transmitter is in during binding are
established as the fail-safe positions.
Anytime you make a programming change
to the system, it’s a good idea to rebind it.
I found that to be the only way to assure
that the fail-safe settings are correct.
The DX7 has a nice variety of features
for fixed-wing aircraft and helicopters.
There are no sailplane-specific
preprogrammed mixes; however, there are
more than enough programmable mixes to
handle almost any sailplane function.
The menu structure in the DX7 is easy
to understand. You can view the menu as a
list in one mode or you can scroll through
each of the functions individually. I tend
to use the scroll method more than the list
method.
Two programming levels exist. The top
level is the System Setup Mode, which
you access by holding down the SCROLL
rocker and SELECT button while turning
on the transmitter. In the System Setup
Mode you can:
• Choose the model you want to fly.
• Name the model you want to fly.
• Pick the model type (ACRO or HELI).
• Reset the model to factory default
settings.
• Reset the integral timer.
• Turn the trainer function on or off and
select its mode of operation.
• Select dual rate switches.
• Choose the wing type (FLAPERON, VTAIL,
DELTA) or helicopter swashplate
type (standard, 180° CCPM, 120° CCPM,
90° CCPM).
• Access Input Select (which determines
how Aux 2 will be used or select the
switch input that gyro gain will use).
• Enable or disable throttle recovery.
The Function mode is accessed by
holding down the SCROLL and SELECT
buttons when the transmitter is already
powered up. The aircraft’s main
programming functions are accessed from
this menu.
The SCROLL rocker switch will move
you backward or forward through each
menu. The SELECT button moves the
cursor around, the ADJUST button
changes values, and the CLEAR button is
typically used to lock in a value.
Programming features available in the
ACRO mode are dual and exponential
rates, servo reversing, subtrims, travel
adjust, elevator-to-flap mixing, aileron-torudder
mixing, servo monitor screen,
count-up/count-down timer, six
programmable mixes, and the differential
and flap system.
The HELI mode’s available
programming includes dual and
exponential rates, servo reversing,
subtrims, travel adjust, swashplate mixing,
throttle hold, throttle curve (Normal, Stunt
1, Stunt 2), pitch curve (Normal, Stunt 1,
Stunt 2, Hold), servo monitor screen,
count-up/count-down timer, three
programmable mixes, gyro sensing, and
revo mix.
Dual and exponential (expo) rates are
programmed from the same screen. Expo
is shown on the display, which is a great
aid in seeing how the expo rate you set
will affect the sticks’ sensitivity.
As I mentioned, this system has
numerous features. Let’s take a closer look
at a few of the more unique ones. In the
helicopter mode you have five-point pitch
and throttle curves available.
In the airplane mode, preprogrammed
mixes make the popular forms of mixing
easy to accomplish. In addition, the system
has a flap program that allows you to set
3° of flaps and couple the elevator to those
positions to control pitch changes. You
can also set an automatic landing system
that will activate the flaps with elevator
compensation at any point you wish to
select based on the position of the throttle
stick.
Helicopter mode gives you the ability
to set up automatic dual or exponential
rates based on flight mode. With this
feature the flip of a switch changes dual
and expo rates (as well as other
parameters).
One item I really like in the helicopter
mode is that if you power up with throttle
hold on or with the flight mode switch in
any mode other than normal, the main
display will warn you. The display will
not return to normal until the switches are
returned to the normal (and safe)
positions. This feature is a great safety
reminder to help prevent hot starts.
The DX7 is a super system I’ve really
enjoyed flying. I’ve gotten used to not
having to wait on a channel at large
events. I also find it to be one of the safest
systems I have ever used. In almost five
months I haven’t experienced a single
problem—not a bump, not an issue.
The instruction manual is extremely
well laid out. I wished for additional
programming examples from time to time,
but they are not really needed. In fact, you
could easily program this transmitter
without the manual; it is that easy.
The DX7 system is available for a
street price of $349.99, which is not bad
considering what all it includes. I plan to
fly with the DX7 for many years to come.
It is worth your serious consideration. MA
Steve Kaluf
[email protected]
Distributor:
Horizon Hobby, Inc.
4105 Fieldstone Rd.
Champaign IL 61822
(217) 352-1913
www.horizonhobby.com
Other Published Resources:
Model Airplane News
February 2007
Fly R/C
February 2007
Model Aviation
December 2006