GRAUPNER mx-20 Hott Owner's manual

Programming Manual
33124.mx-20 HoTT.1.en
HOPPING.TELEMETRY.TRANSMISSION
mx-20

2Table of contents
Transmitter initialization ............................................... 38
Firmware update ................................................... 39
Receiver initialization................................................... 42
Firmware update ................................................... 43
Installation notices....................................................... 46
Receiver system power supply.............................. 47
Term definitions ........................................................... 50
Switch and control assignments.................................. 52
Digital trimming............................................................ 54
Winged models............................................................ 56
Receiver layout...................................................... 57
Helicopter models........................................................ 58
Receiver layout...................................................... 59
Program descriptions
Loading a new memory location.................................. 60
"Model select" ............................................................ 63
"Copy / Erase" ............................................................ 64
Erase model .......................................................... 64
Copy model model........................................... 64
Export to SD card.................................................. 65
Import from SD card.............................................. 66
Copy flight phase................................................... 66
"Suppress menus" ..................................................... 67
"Suppress models" .................................................... 67
"Base setup model"
Winged model ....................................................... 68
Model name .................................................... 68
Stick mode ...................................................... 68
Bound receiver................................................ 68
Binding receivers ............................................ 69
Receiver output ............................................... 70
RF transmit...................................................... 71
Range test....................................................... 71
DSC output...................................................... 72
General notices
Table of contents ...........................................................2
Environmental protection notices ..................................3
Safety notices ................................................................ 4
Safety notices and handling regulations
for nickel-metal-hydride rechargeable batteries.............8
Foreword...................................................................... 10
Remote control set description.................................... 11
Recommended chargers ............................................. 13
Transmitter power supply............................................. 14
Receiver power supply .......................................... 16
Joystick length adjustment........................................... 17
Opening the transmitter housing .................................17
Changing joystick behavior.......................................... 18
Transmitter description ................................................ 20
Operating elements ............................................... 20
Backside of the transmitter.................................... 21
Headset connector ................................................ 21
Mini-USB connector .............................................. 21
Data jack ............................................................... 21
DSC (Direct Servo Control)................................... 22
Data storage / card slot ......................................... 22
Display and keypad ............................................... 24
Operating the "data terminal" ................................ 25
Shortcuts............................................................... 26
Hidden menu columns........................................... 27
Hidden mode......................................................... 28
Language selection and display contrast .............. 28
Joystick calibration ................................................ 29
Telemetry data display...........................................32
Displayed warnings ............................................... 36
Function field displays........................................... 37
Position display for rotary controls, CTRL 7 & 8.... 37
Entry lockout.......................................................... 37
Table of contents
Cut-off ............................................................. 72
Helicopter model ................................................... 74
Model name .................................................... 74
Stick mode ...................................................... 74
Bound receiver................................................ 74
Binding receivers ............................................ 75
Receiver output ............................................... 76
RF transmit...................................................... 77
Range test....................................................... 77
DSC output...................................................... 78
Autorotation..................................................... 78
Auto.C1 Pos..................................................... 79
Cut-off ............................................................. 79
"Model type" ............................................................... 82
"Helicopter type" ........................................................ 86
"Servo adjustment".................................................... 90
"Stick mode"
Winged model ....................................................... 92
Helicopter model ................................................... 94
"Control adjust"
Winged model ....................................................... 96
Helicopter model ................................................. 100
Throttle limit function ...................................... 104
Idle setting ...................................................... 105
Throttle limit in combination with AR in the
"Stick mode" menu ...................................... 107
"Dual Rate / Expo"
Winged model ..................................................... 108
Helicopter model ................................................. 112
"Channel 1 curve"
Winged model ..................................................... 116
Helicopter model ................................................. 119
"Switch display" ....................................................... 122
"Control switch" ....................................................... 123
How do I program a flight phase?.............................. 126

3
Table of contents
"Phase settings"
Winged model ..................................................... 128
Helicopter model ................................................. 132
"Phase assignment" ................................................ 134
"Phase trim" (winged model).................................... 136
"Non-delayed channels".......................................... 137
"Timers (general)" .................................................... 138
"Flight phase timers" ............................................... 142
What is a mixer?........................................................ 145
"Wing mixers"........................................................... 146
"Helicopter mixer".................................................... 164
Adjusting the throttle and pitch curve .................. 175
Autorotation setting ............................................. 178
General remarks about freely progr. Mixers ..............180
"Free mixers"............................................................ 181
Linear mixers...................................... beginning 185
Curve mixer........................................ beginning 187
Examples............................................................. 190
"MIX active/phase" ................................................... 192
"Mix Only Channel".................................................. 193
"Dual mixer".............................................................. 194
"Swashplate mixer".................................................. 196
"Fail-safe" ................................................................. 196
"Teacher / pupil"....................................................... 198
Connection schematic......................................... 201
Wireless HoTT system ........................................ 202
"Tx. output swap"..................................................... 206
"Telemetry" ...............................................................208
Setting& Data View.............................................. 209
Satellite operation of two receivers ..............218
Sensor Select...................................................... 220
RF Status View.................................................... 221
Voice Trigger........................................................ 222
"Basic Settings" ....................................................... 224
"Servo display"......................................................... 230
"Servo test"............................................................... 231
"Code lock"............................................................... 232
"Info display" ........................................................... 234
Programming examples
Introduction................................................................ 236
Winged model
First steps............................................................ 238
Incorporating an electric drive............................. 244
C1 joystick switchover between
electric motor and butterfly............................ 247
electric motor and airbrake............................ 250
Timer activation by control or switch ................... 252
Parallel operating servos..................................... 254
Using flight phases
Example 1 ..................................................... 256
Example 2 ..................................................... 260
Control of temporal processes ............................ 266
Eight-flap wing..................................................... 268
Delta and flying wing models............................... 272
F3A model........................................................... 276
Helicopter model........................................................ 280
Appendix
Appendix.................................................................... 290
FCC Information ........................................................ 293
Declaration of Conformity .......................................... 294
Warranty Certificate................................................... 295
Environmentalprotection notices
The symbol on this product, its operating instructions
or packaging gives notice that this product may not
be discarded as common household waste at the end
of its service life. It must be turned over to a recycling
collection point for electric and electronic apparatus.
The materials can be recycled according to their
markings.You make an important contribution to
protection of the environment by utilizing facilities for
reuse, material recycling or other means of exploiting
obsolete equipment.
Batteries must be removed from the unit and disposed
of separately at an appropriate
collection point.
Please inquire with local authorities
about the responsible waste collection
locations.
This manual serves only as a source of information and
can be changed without prior notification. Graupner
accepts no responsibility or liability for errors or
inaccuracies which may be contained in the information
section of this manual.

4Safety notices
In order to enjoy your modeling hobby for a long time,
please read these instructions thoroughly and give
particular attention to the safety notices.You should
also register yourself at https://www.graupner.de/de/
service/produktregistrierung.aspx right away in order
to automatically receive current information per email
about your product.
If you are a beginner with remote controlled model
aircraft, ships or cars, you should really ask an
experienced model pilot for assistance.
If this remote control system changes ownership, these
instructions should surely be included with remote
control system.
Intended usage
This remote control system may only be used for the
purpose intended by the manufacturer - specifically - for
the operation of unmanned remote controlled models.
Any other usage is not permissible.
Safety notices
SAFETY IS NO ACCIDENT
and
REMOTE CONTROLLED MODELS ARE NOT
TOYS
… because even small models can cause substantial
property damage and/or personal injuries if they are not
handled properly - even if caused by third parties.
Technical defects of an electrical or mechanical nature
can lead to unexpected startup of a motor and/or parts
being hurled through the air to pose a danger of injury to
you and to others.
Short circuit conditions are to be avoided absolutely!
A short circuit condition may not only destroy parts
of the remote control system but, depending on
the circumstances and the battery energy involved,
may also pose acute danger of incineration or even
explosion.
All motor-driven parts, such as aircraft or ship
propellers, helicopter rotors, open gearboxes etc.
represent a constant danger. Contact with these parts
must be avoided. A rapidly turning aircraft propeller
can, for example, sever a finger. Also pay attention that
other objects do not come into contact with driven parts.
When a drive battery is connected or a motor is running:
never get into the danger zone of driving mechanisms.
Be sure to pay attention that motors do not start
up unintentionally while performing programming
operations. Disconnect the fuel supply or battery
terminals to motors before programming.
Protect all units from dust, dirt, moisture and other
foreign parts. Never expose these units to vibrations
or excessive hot or cold temperatures. Remote control
operation may only be performed under "normal"
outdoor temperatures, i.e. within a range of -15 ° C to
+55 ° C.
Avoid mechanical jarring and pressure stresses. Always
check units for damage to housings and cables. Do not
use units which have been damaged or become wet,
even after they are dry again.
Only those components and accessories which we
recommend may be used. Always use original Graupner
plug and jack connectors which are made for one
another out of the same materials.
When routing cables, pay attention that they are not
stressed, unduly kinked or broken. The sharp edges
of adjacent parts also represent a hazard for insulated
conductors.
Be sure that all plug and jack connections are firmly
seated. Do not pull on the cable to disconnect a plugged
connector.
No modifications whatsoever may be made to units.
Modifications will void the operating permit and all
insurance protection.
Receiver installation
The receiver is to be installed with a cushion of foam
rubber to afford protection against jarring; in aircraft
models behind a strong rib, for a car or ship model the
location must be protected against dust and spray water.
The receiver may not be mounted in direct contact with
the hull or chassis as this would allow motor vibrations
and/or roadway jarring to be transferred directly to the
receiver. When a receiver system is installed in a model
with a combustion motor, all receiver parts should
always be protected against the intrusion of exhaust
gasses and oil residue. Above all, this applies to the
model's ON/OFF switch, which is typically built into the
model's outer surface.
Position the receiver such that connecting cables to
the servos and the power supply are routed with a bit
of slack and that the receiver's antenna is at least 5 cm
away from any large metal parts or wiring except for
other receiver wires/cables. In addition to steel, this also
includes carbon fiber parts, servos, electric motors, fuel
pumps and all sorts of cables, etc.
Preferably, the receiver should be mounted in a readily
accessible location in the model that is well apart from
all electrically operated units. Under no circumstances
may a servo cable be wrapped around the antenna or
routed close to it.
Make sure that cables near the antenna cannot move
about during flight.
Safety notices
Be sure to pay attention!

5
Safety notices
transmitter's antenna directly toward the model will not
produce good reception but rather degrade reception.
When multiple remote controls are operating
simultaneously, pilots should position themselves in a
loose group. Pilots standing off to themselves not only
endanger their own models but those of others as well.
However, when 2 or more pilots using 2.4 GHz remote
control systems are closer than 5 m to one another this
can lead to return channel overdrive which, in turn, will
trigger a range warning much too early. Increase your
distance between one another until the range warning
ceases.
Pre-start checks
Before switching the receiver on, ensure that the gas
control is at its Stop/Idle position.
Always switch the transmitter on first and then the
receiver.
Always switch the receiver off first and then the
transmitter.
If this sequence is not maintained, such that the receiver
is still switched on when the corresponding transmitter
is switched to "OFF", then the receiver may respond to
other transmitters or general radio frequency noise. This
can cause the model to execute uncontrolled operations
that may cause personal injuries and/or property
damage.
In particular, for models equipped with a mechanical
gyro:
before switching off the receiver, disconnect the model's
power supply to prevent the motor from revving up
unintentionally.
The residual spin of a gyro often produces so much
voltage that the receiver may falsely interpret a
throttle signal! This will then cause the motor to
start up unexpectedly.
Range test
Perform checks for proper operation and range before
every session. Secure the model adequately in place
and ensure that no one is in front of the model.
Perform a complete functional test on the ground and
execute a complete simulated flight to exclude the
possibility of system faults or problems with the model's
programming. When doing this, be sure to follow the
notices provided on pages 71 and77.
Never operate the transmitter in Model mode, i.e.
for flying or driving, without an antenna. Be sure the
antenna is firmly seated in its socket.
Operating a winged aircraft, helicopter, ship or car
Never fly over spectators or other pilots. Never endanger
humans or animals. Never fly in the vicinity of high-
voltage wires. Do not operate the model in the vicinity of
sluice locks or where real boats or ships are operating.
Do not operate a model on public streets or highways,
paths or plazas, etc.
Monitoring transmitter and receiver batteries
You must stop running the model to recharge the
transmitter's battery no later than when low transmitter
battery voltage triggers the "Batt must be recharged!!"
display and acoustic signal.
Check the charge in batteries routinely, particularly the
receiver's battery. Do not wait until the movements of
controlled mechanisms are noticeably slower. Replace
expended batteries before they cause problems.
The battery manufacturer's charging instructions
Routing the receiver's antenna
The receiver and its antennas must be positioned as far
away as possible from drives of any kind. If the model's
hull is made of carbon fiber material, the ends of the
antennas must extend outside of the hull.
The orientation of antennas is not critical. Nevertheless,
a vertical (upright) installation of receiver antennas is
advantageous. In the case of diversity antennas (two
antennas), the second antenna should be oriented at a
90° angle to the first antenna.
Servo installation
Always mount servos with the provided rubber vibration-
damper parts. Only in this manner can these parts be
protected against excessively hard vibrations.
Installing control rods
Control rods must be installed such that they operate
freely and smoothly. It is particularly important that all
rudder levers are able to move to their full limits, i.e. not
otherwise mechanically blocked.
In order to be able to stop a running motor at any time,
control rods must be adjusted such that the carburetor
tap is completely closed when the joystick and trim lever
are brought into their end idle position.
Pay attention that no metal parts, e.g. as a result of
rudder actuation, vibration, rotating parts, etc., rub
against one another. Metal-to-metal contact causes
electrical "noise" which can interfere with the correct
operation of the receiver.
Transmitter antenna orientation
Transmission field strength is minimal in an imaginary
line extending straight out from the end of the
transmitter's antenna. This means that "pointing" the

6Safety notices
are always to be followed, this includes mandatory
adherence to the length of charging time. Never leave
batteries being charged unattended.
Never attempt to charge primary batteries (non-
rechargeable batteries) because they can explode.
All secondary batteries (rechargeable batteries) must
be charged before every session. To avoid short circuit
conditions, first connect the charger cable's banana
plugs, polarity correct, into the charger and thereafter
connect the charger cable's plugs to the transmitter and
receiver batteries.
Disconnect all power sources from the model when it is
not to be used for an extended period of time.
Never attempt to use defective batteries, damaged
batteries or mixed-type battery combinations as a single
group. Do not use mixed combinations of old and new
batteries or batteries of different manufacture.
Capacity and operating time
The rule: "capacity is reduced with every successive
recharging", applies to all batteries. Internal resistance
increases at low temperatures to further reduce capacity.
As a consequence, the battery's ability to provide
current and hold its voltage is reduced.
Frequent charging or the use of battery maintenance
programs can also result in gradual loss of battery
capacity. Therefore the capacity of batteries should be
checked at regular intervals, not in excess of every six
months, and replaced if performance is found to be
significantly deficient.
Purchase only genuine Graupner batteries!
Interference suppression for electric motors
All conventional electric motors produce sparks between
their collector and brushes. Depending on the type of
motor involved, this may cause more or less interference
with the functionality of the remote control system.
The electric motors of a properly built system should
therefore have interference suppression features.
For electric drive models it is particularly important
that every one of its motors is provided with proper
interference suppression. Interference filters extensively
suppress such disturbances and should always be
included.
Follow the respective recommendations included in the
motor's operating and installation notices.
For further details about interference filters, refer to the
Graupner RC main catalog or in Internet at
www.graupner.de.
Servo interference filters for extension cables
Order No. 1040
The servo interference filter is necessary when an
extended-length servo cable is used. This filter is
attached directly to the receiver output. In critical cases
a second filter can be attached to the servo.
Using electronic speed controllers
Choosing the right electronic controller is largely a
matter of matching controller performance to the motor
to be controlled.
In order to prevent an overload or damage to the speed
controller, its current rating should be at least half of
the maximum locked-rotor current draw of the motor to
which it is connected.
Particular attention is appropriate for so-called "tuning
motors". Because of their low-turns coils these motors
can draw a multiple of their rated current in a locked-
rotor condition and this can lead to the destruction of the
speed controller.
Electric ignition systems
Combustion motor ignition systems also produce
interference that can negatively influence remote control
functionality.
Always supply power to an electric ignition system from
a separate, dedicated battery.
Use only interference-suppressed spark plugs, spark
caps and shielded ignition leads.
Mount the receiver sufficiently far away from ignition
system components.
Static charges
A remote control system will be destroyed by the
magnetic shock waves produced by a lightning strike -
even if the storm is miles away. Therefore …
… stop flying right away if a storm is approaching.
Static charging via the antenna also represents a
lethal hazard.
Attention
In order to fulfill FCC HF emission requirements for•
mobile transmitters, a distance of at least 20 cm
must be maintained between this system's antenna
and other persons when this system is operating.
Operation of this system at a lesser distance is
therefore not recommended.
To avoid disturbance caused by the electrical•
characteristics and emissions of other transmitters,
keep at least a 20 cm distance from other
transmitters.
Operation of the remote control system requires a•
correct program setting for the given country in the
transmitter unit. This is necessary for compliance with
diverse regulations like FCC, ETSI, CE etc. Follow
the respective instructions provided for this with the
Safety notices

7
Safety notices
transmitter and receiver.
Prior to every flight, perform a complete functional•
test, range test and execute a complete simulated
flight in order to exclude the possibility of system
faults or problems with the model's programming.
Never program the transmitter or receiver while the•
model is being operated.
Care and maintenance
Never clean the housing, antenna, etc. with cleaning
agents, gasoline, water or similar means. Use only a dry,
soft cloth.
Components and accessories
As manufacturer of this equipment Graupner GmbH
& Co. KG recommends only components and
accessories which have been tested and approved by
Graupner for their suitability, functionality and safety.
If this recommendation is followed, Graupner accepts
responsibility for the product.
Graupner cannot accept any responsibility for the
parts or accessories of other manufacturers which
have not been approved and Graupner cannot
evaluate every individual product made by other
companies to assess if they are safe to use.
Liability exclusion / damage compensation
This manual serves only as a source of information and
can be changed without prior notification. Graupner
accepts no responsibility or liability for errors or
inaccuracies which may be contained in this manual.
Graupner cannot monitor compliance with the assembly
instructions, the operating instructions or the conditions
and methods under which remote control components
are installed, operated, utilized or maintained. Therefore
Graupner accepts no form of liability for loss, damage or
costs consequential to incorrect usage or operation or
which can be attributed to same.
Unless otherwise prescribed by law, the obligation of
Graupner to provide damage compensation, regardless
of legal grounds, is limited to the invoice value of the
quantity of Graupner. goods contributing directly to the
damage-inducing event. This does not apply if Graupner
is found to be subject to unlimited liability pursuant to
binding legal stipulations with respect to intent or gross
negligence.

8Safety notices
Safety notices and handling instructions for nickel-metal-hydride rechargeable batteries
As applicable for all highly technical products,
observance of the following safety notices, along with
the handling instructions, is essential for a long service
life, fault-free operation, and harmless utilization.
Safety notices
Individual battery cells and batteries are not toys and•
must therefore not get into the hands of children.
Batteries/cells must be kept out of the reach of
children.
Batteries are to be checked for flawless condition•
prior to every use. Defective or damaged cells/
batteries may no longer be used.
Cells/batteries may only be utilized within the limits•
specified by the technical data for the given battery
type.
Batteries/cells may not be heated, burned, short-•
circuited or subjected to overload current or
reverse polarity.
Battery configurations formed by parallel•
connected cells, combinations of old and new
cells, or cells of different production, size,
capacity, manufacturer, brand or cell type may
not be used.
Remove batteries from the unit prior to long-term•
storage periods (weeks or months). Always switch
off units whenever they are no longer in use (short-
term). Always charge batteries before it is too late.
The battery to be charged must be placed on a non-•
combustible, heat resistant, non-conducting surface
during the charging process. Combustible or readily
ignited objects are to be kept away from the charging
configuration.
Batteries may only be charged under supervision.•
The quick charge current rating for the given type of
battery must never be exceeded.
If the battery heats up during charging above 60 °C•
charging must be stopped immediately. Allow the
battery to cool off to about 30 °C before resuming the
charging process.
Never charge batteries which are already charged,•
batteries which are hot or batteries which have not
been discharged to their end-point voltage.
No modifications may be made to the batteries.•
Never solder or weld directly on battery terminals.
The mistreatment of batteries presents a danger of•
ignition, explosion, chemical burns and combustion
burns. Use of an extinguishing blanket, CO2-fire
extinguisher or sand are suitable methods of
extinguishing such a fire.
Leaking electrolyte is caustic; do not allow it•
to contact the skin or eyes. In the event of an
emergency, immediately rinse with a generous
amount of water and get the care of a doctor.
Battery vent openings may never be blocked or•
sealed, e.g. by solder. Soldering temperature may
not exceed 220 °C and not be applied for longer than
20 seconds.
To avoid deformation, do not exert excessive•
mechanical force.
If a battery should become overcharged, proceed as•
follows:
Simply disconnect the battery and place it on a non-
combustible surface (e.g. masonry floor) until it has
cooled off. To avoid the hazards associated with an
explosion, never hold the battery in your hands.
Pay attention that the charging and discharging rules•
are followed.
General notices
Battery capacity is reduced by every charge/discharge
cycle. Storage can also be cause for a gradual reduction
of battery capacity.
Storage
Batteries should only be stored when they are not in a
completely discharged condition. They should be stored
in a dry room having an ambient temperature between
+5 °C to +25 °C. When stored for longer than 4 weeks,
cell voltage should not be more than 1.2 V.
Matching up individual batteries
To match new batteries with older ones, put a full•
charge on all of the batteries using a standard
charging process. As a rule of thumb, an empty
battery must be charged for 12 hours at a current
rate equal to one tenth of its specified capacity
("1/10 C" method). The batteries are then all charged
equally. Such a matching procedure should be
repeated about every 10th charge cycle so that
batteries are matched again, which contributes to
longer battery life.
If it is possible to discharge individual batteries, this•
should be done prior to every charging process.
Otherwise the battery pack should be discharged
to a voltage of 0.9 V per cell. For example, this
corresponds to a charge voltage of 3.6 V for the
4-cell pack used in the transmitter.
Charging
Charging is only permissible at specified current rates,
charging durations, temperature ranges and continuous

9
Safety notices
supervision. If a suitable quick charger is not available
on which the exact charging current can be set, the
battery can be charged by standard charging according
to the 1/10 C-method, see example above.
Whenever possible, transmitter batteries should
charged with the 1/10 C method because of the
differing charge states of the cells. However,
charging current may never be allowed to exceed
the maximum permissible rate specified in the given
transmitter's instructions.
Quick charging
If your charger offers this option then set the delta•
peak charge cutoff voltage to 5 mV per cell. However,
most chargers are set to a fixed value of 15 …
20 mV per cell so they can be used for both NiCd
batteries as well as NiMH batteries If in doubt, find
out if your charger is also suitable for NiMH batteries
by referring to the charger's operating instructions
or consulting a dealership. If you are unsure, charge
your batteries at half of the specified maximum
current rate.
Discharge
All batteries sold under the Graupner and GM-Racing
trade names are, depending on battery type, suitable for
a continuous maximum current load of 6 … 13 C (check
the manufacturer's data). In general, the higher the
continuous current load, the lower the battery's service
life will be.
Use your battery until its performance degrades or•
the under-voltage warning sounds.
Attention:
A cell voltage of 1.2 V should not be underrun during
a long storage period. If necessary, charge the
battery before putting it into storage.
Reflex charging and charge/discharge programs•
unnecessarily shorten a battery's service life and are
only useful in checking battery quality or to "revive"
old cells. It is also meaningless to charge/discharge a
battery before using it. The exception to this is if your
intention is to check the battery's quality.
Disposal of used batteries
Some countries have laws requiring that all used
batteries be turned over to an authorized collection
center.
Disposing of batteries along with common household
garbage is forbidden. Old batteries can be turned into
communal collection centers for disposal at no charge
or they can be returned to one of our dealerships or
anywhere else where batteries of that given type are
sold. Used batteries we have delivered can also be sent
back to us, at your cost, through the mail. Use the return
address below:
Graupner GmbH & Co. KG
Service: Used batteries
Henriettenstr. 94 - 96
D-73230 Kirchheim unter Teck
This represents an essential contribution to
environmental protection.
Caution:
Damaged batteries require among other things, special
packaging, because they are very toxic!

10 Introduction
mx-20 the newest generation of remote control technology
HoTT (Hopping Telemetry Transmission) is a synthesis
of know-how, engineering and testing done around the
world by experienced model pilots. HoTT technology
combines 2.4 GHz band transmission/reception with
bi-directional communications via a "return channel"
integrated into the receiver unit.
Based on the Graupner/JR computerized remote
control system mc-24 that was introduced in 1997,
the mx-20 HoTT remote control system has been
especially developed for experienced RC pilots All
conventional model types can be readily operated
with the mx-20 HoTT system, regardless of whether
the model is a winged aircraft, helicopter, ship or land
vehicle.
Complex mixed-control functions of guiding surfaces are
often necessary for winged aircraft (rudder, elevators)
and helicopter models (swashplate). Thanks to this
computer technology it is possible to activate these
diverse functional requirements with a single "press
of a button". Simply select the given model type from
the mx-20 HoTT program and its software will
automatically assemble significant mixed-control and
coupled functions. This eliminates the need for separate
modules in the transmitter to implement complex
coupled functions and also makes sophisticated
mechanical mixer mechanisms in the model
unnecessary. The mx-20 HoTT remote control system
offers the highest level of safety and reliability.
Its software is clearly structured. Functionally-related
options are clearly arranged by content in a simple
organization.
The mx-20 HoTT remote control system has 24
model memory locations. Additional flight-phase-specific
settings can be stored in every model memory location.
For example, such settings can be made for various
parameters that can be called up to implement particular
flight maneuvers at the "press of a button".
The large graphic display is well organized and simple
to operate. The mixer's graphic representation is
exceptionally helpful.
Familiarization with the various functions in this remote
control system is quick, even for a beginner, because
of its clear, straightforward program structure. The user
makes his settings with the four-way, touch sensitive
buttons located to the left and right of the high-contrast
display. Thus, with only little practice, the pilot learns to
implement all of the remote controlled model options
with which he/she has experience.
This Graupner HoTT technique theoretically allows over
200 models to be operated simultaneously However,
because of the interspersed radio-frequency utilization
permitted by certification for the 2.4 GHz ISM band, this
number is significantly lower in practical application.
Nevertheless, in general more models can be operated
simultaneously in the 2.4 GHz band than would be the
case in conventional 35 or 40 MHz frequency bands.
The real limiting factor is –as often before – is still likely
to be the size of available operating space (i.e. airspace
for aircraft). Alone the fact that it is no longer necessary
to coordinate transmitting frequencies with other pilots in
the vicinity (which is sometimes quite difficult in broken
landscapes, such as on hillside slopes) represents an
enormous boost for remote control operating security.
The integrated telemetry menu affords simple access
to data and HoTT receiver programming. For example,
this can be used to map receiver outputs, assign control
functions to multiple servos, and to coordinate the
magnitude and direction of multiple servo movements
with one another.
This handbook describes every menu in detail. There
are tips, many notices and programming examples to
supplement the descriptions and also explanations for
model specific technical terms, like transducer, dual
rate, butterfly, etc.
An appendix is provided which contains additional
information about the HoTT system. This manual is
rounded out with the conformity declaration and the
guarantee certificate for the transmitter.
Please observe the safety notices and technical notices.
Read the instructions carefully then test all functions by
simply attaching servos to the receiver included in the kit
for order no. 33124. When doing this, please observe the
corresponding notice provided on page 20. This will help
you learn the essential operating steps and functions of
the mx-20 HoTT in the least amount of time.
Always handle your remote controlled model with a
sense of responsibility so that you do not endanger
yourself or others.
The Graupner team wishes you much fun and success
with your mx-20 HoTT remote control system of the
newest generation
Kirchheim-Teck, September 2011

11
Introduction - Remote control set
Computer System mx-20
12 channel remote control set in 2.4 GHz Graupner HoTT technology (Hopping Telemetry Transmission)
The superior functional security of Graupner
HoTT technology accomplished with bidirectional
communications between transmitter and receiver
with integrated telemetry, freely programmable
voice output via headset connector, and ultra-fast
response times.
Programming is simplified by a programming
technique implemented with capacitive touch
buttons.
High contrast, 8 line, blue illuminated graphic
display for perfect presentation of all parameter
settings and telemetry data. Storage of telemetry
data on a micro SD memory card.
Integrated real time clock
4096 steps of 12-bit resolution on the channel signal
assures extreme control sensitivity.
USB connection to read and write the model's
memories as well as for making firmware updates.
Microcomputer remote control system in modern•
2.4 GHz Graupner HoTT technology
Bidirectional communications between transmitter•
and receiver
Five different languages:•
German, English, French, coming soon per software
update Italian and Spanish.
Ultra fast response times due to reliable, direct•
transmission of data from the main processor to the
2.4 GHz HF module. No additional delays due to
routing over a module processor.
Telemetry menu for display of telemetry data and•
for programming optional attachment sensors and
receiver outputs
The telemetry screen provides many programming•
and evaluation functions to be presented directly in
the transmitters display
Voice output can be called up via freely•
programmable switches
Digital servo cycle times of 10 ms selectable•
Short antenna, collapsible•
Operating and programming techniques are similar•
to the proven concepts implemented in mc-19 to
mc-24
High contrast, blue illuminated graphic display•
assures perfect control of parameter settings like
model type, model memory, clocks and operating
voltage.
Function encoder with two touch-sensitive, four-way•
buttons permit simplified programming and precise
settings
Key-lock function to prevent unintentional operation.•
7 flight phases can be programmed•

12 Introduction - Remote control set
24 model memories with storage for all model-•
specific programs and parameter settings
7 switches (2 three stage switches, 3 two stage•
switches and 2 touch switches) and 3 digital
actuators are already built-in and can be used as
desired
Free assignment of switches to switched functions by•
simply switching the desired switch
Simple programming of motor and brake switchover•
for electric gliders on the K1 joystick.
Internal realtime clock for time-stamping log files•
User-replaceable CR2032 buffer battery for the•
internal realtime clock
Model memory storage in a modern, non-volatile•
backup system
12 control functions with simplified arrangement•
of operating elements for supplementary functions
like switches and proportional transducers make
operating convenient
Convenience mode selector for simplified switchover•
between MODES 1 … 4 (Gas left/right, etc.)
All affected settings are also automatically switched
over.
Graphic servo position display for fast, simple•
overview and for checking servo movements
Transmitter output swapping•
Extensive programs for winged aircraft and helicopter•
models:
Winged aircraft menu for: 1 QR, 2 QR, 2 QR + 1, 2
and 4 WK as well as 4 QR + 2 and 4 WK, V tail unit,
delta/all-wing, 2 elevator servos
Surface mix: QR-diff, WK-diff, QR SR, QR 
WK, brake HR, brake WK, brake QR, HR
WK, HR QR, WK HR, WK QR and diff.
reduction
Heli menu for: 1-, 2-, 3- and 4-point linkage (1 Sv,
2 Sv, 3 Sv (2 roll), 3 Sv (140°), 3 Sv (2 nick), 4 Sv
(90°))
16 free mixers,• 8 linear mixers, 4 curve mixers and 4
cross mixers
Swashplate limiter•
±150 % servo adjustment for all servo outputs,•
independently adjustable per side (Single Side Servo
Throw)
Sub-trim in the ±125 % range for setting all neutral•
servo positions
Servo reverse can be programmed for all servos•
Two stage DUAL RATE/EXPO system, individually•
adjustable for specific flight phase and switchable
during flight
Stop watches/countdown timers with alarm function•
Copy function for model memory•
Built-in DSC jack for connecting flight simulators or a•
teacher/pupil system
Envisioned for a later update:•
Voith-Schneider limiter, works similar to a swashplate
limiter
Door sequencer, e.g. for putting down landing gear
automatically or retractable powerplant with runout
controller
Nautical program
General HoTT features
Maximum noise immunity due to optimized frequency•
hopping and wider channel spread
Intelligent data transfer with correction function•
Computer System mx-20
12 channel remote control set with 2.4 GHz Graupner HoTT technology (Hopping Telemetry Transmission)
Realtime telemetry evaluation•
Over 200 systems can be used simultaneously•
Update capability via USB interface guarantees•
future viability
Simple, very fast transmitter to receiver binding•
Binding with multiple receivers per model• in parallel
operation is possible
Extremely fast rebinding, even at maximum distance•
Range test and warning function•
Receiver under-voltage warning in the transmitter's•
display
Extremely wide receiver operating voltage range of•
3.6 V to 8.4 V (fully functional to 2.5 V)
Failsafe•
Arbitrary channel assignment (channel mapping), mix•
functions and all servo settings can be programmed
in the telemetry menu
Up to 4 servos can be controlled simultaneously as•
a block at a servo cycle time of 10 ms (digital servos
only)

13
Introduction - Remote control set
mx-20 HoTT technical data
Frequency band 2.4 … 2.4835 GHz
Modulation FHSS
Transmit power see country setting, page 227
Control functions 12 functions, 4 of these can
be trimmed
Temperature range -10 … +55 °C
Antennae collapsible
Operating voltage 3.4 … 6 V
Current draw about 180 mA
Dimensions about 190 x 195 x 90 mm
Weight about 770 g with transmitter
battery
Accessories
Order No. Description
1121 Neck strap, 20 mm wide
70 Neck strap, 30 mm wide
3097 Hand transmitter wind protection
Teacher/pupil cable for mx-20 HoTT
see page 201
Replacement parts
Order No. Description
2498.4FBEC
4NH-2000 RX RTU flat
33800 HoTT transmitter antenna
Technical data, receiver GR-24 HoTT
Order No. 33512
Operating voltage 3.6 … 8.4 V*
Current draw about 70 mA
Frequency band 2.4 … 2.4835 GHz
Modulation FHSS
Antenna Diversity antennas,
2 x about 145 mm long,
about 115 mm encapsulated
and about 30 mm active
Plug-in servos 12
Plug-in sensors 1
Temperature range about -10 … +55 °C
Dimensions about 46 x 31 x 14 mm
Weight about 16 g
* The specification for permissible operating voltage range applies
only to the receiver. Please note in this context that receiver input
voltage is applied without regulation to connected servos but the
voltage range for most connectible servos (speed controls, gyros,
etc.) is only 4.8 to 6 V.
The Order No. 33124 set includes
Microcomputer transmitter mx-20 HoTT with built-
in NiMH transmitter battery 4NH-2000 RX RTU flat
(change reserved), plug-in charger and Graupner
bidirectional receiver GR-24 HoTT.
Recommended charger units (accessories)
Order
No. Designation
Input voltage 220 V Input voltage 12 V
appropriate for
the following
batteries
integr. balancer NiCd NiMH LiPo lead battery
6411 Ultramat 8 x x x x x
6463 Ultramat 12 plus x x x x x x
6424 Ultramat 14 plus x x x x x x x
6466 Ultra Trio plus 14 x x x x x x x
6468 Ultramat 16S x x x x x x x
6469 Ultra Trio Plus 16 x x x x x x
6470 Ultramat 18 x x x x x x x
6475 Ultra Duo Plus 45 x x x x x x x
6478 Ultra Duo Plus 60 x x x x x x x
6480 Ultra Duo Plus 80 x x x x x x x
Transmitter charger cable, order no. 3022 and receiver charger cable,
order no. 3021 are also needed to charge batteries.
Other charger units and details about the listed chargers can be found
in the Graupner RC main catalog or in Internet at www.graupner.de.
Other accessories are listed in the appendix or can
be found in Internet at www.graupner.de. Feel free
to contact your dealer too. He will be glad to provide
advice.

14 Operating notices
Operating notices
Transmitter power supply
The mx-20 HoTT transmitter has a highly capacitive,
rechargeable NiMH battery, 4NH-2000 RX RTU (Order
no. 2498.4FBEC), as standard equipment. (changes
reserved) However, the standard built-in battery is
not charged upon delivery of the transmitter.
When the transmitter is used, its battery voltage
should be monitored by way of the indicators provided
in the LCD display. If battery voltage drops below
the adjustable voltage setting (set via item "Batterie
warning" in the "Basic Settings" menu, page 226,),
default value 4.7 V, an audible warning signal will sound
and the message window shown below will appear in
the screen
GRAUBELE
#01
0:22h
Stop
Flug
«normal »
K78
0:00
0:00
0.0V
10%
4.6V
Mx
x
HoTT
battery
needs
charging
No later than now, operation must be terminated so the
battery can be charged again.
Notice:
Be sure that the correct battery type is set in the "Basic
Settings" menu, page 224! NiMH must be set as
standard.
Charging the transmitter's battery
The transmitter's rechargeable NiMH battery can be
recharged by connecting the charging jack located,
on the right side of the transmitter, with the included
charger (order no. 33116.2).
As a rule of thumb for charging time, an completely
discharged battery will require 12 hours to recharge at a
current rate equal to one tenth of its specified capacity.
For the standard transmitter battery and included
charger, this is a current rate of 200 mA. However,
you must yourself ensure that the charging process is
terminated when it should be …
The transmitter must be switched "OFF" during
the entire charging procedure. Never switch on the
transmitter when it is connected to the charger. Even
a brief interruption to charging can cause charging
voltage to rise to a level that will immediately damage
the transmitter with over-voltage. Also for this reason, be
sure all connectors are always plugged in securely and
have good contact.
mx-20 HoTT charging jack polarity
The charger cables on the market from other
manufacturers often have different polarities. Therefore use
only an original Graupner charger cable, order no. 3022.
Charging with automatic chargers
The transmitter's charger jack does come standard
with reverse polarity protection but nevertheless it can
be used with suitable chargers for quick charging the
transmitter's battery.
Set the quick charger unit, according to its manual, for
a delta peak voltage difference of 5 mV … 20 mV or
equivalent such that it is adapted for quick charging
NiMH cells
First connect the charger cable's banana plugs to
the charger and only then connect the cable's other
end into the charging jack on the transmitter. Never
allow the bare ends of the banana plugs to come
into contact with one another when the other end of
the cable is plugged into the transmitter. In order to
prevent damage to the transmitter, charging current
should never exceed 1 A. If necessary, limit the
current at the charger.
Removing the transmitter's battery
To remove the transmitter's battery, first unlatch the
cover of the battery compartment on the rear side of the
transmitter housing then remove the cover.
Take out the transmitter's battery then disconnect the
transmitter battery's connector by carefully pulling on the
supply line cable.
Inserting the transmitter's battery
Hold the transmitter battery connector
such that the black or brown cable is
oriented toward the antenna side and
the empty jack of the battery connector
is oriented toward the floor side then push the battery
connector in the direction of the board onto the three pins
sticking out out of the board inside the transmitter. (The
battery connector is protected against a reverse polarity
connection by two slanted edges, see illustration.)
Place the battery into its compartment and close the
cover.
Transmitter
connector polarity

15
Operating notices
Battery operation timer at the bottom left of the
screen
This timer shows the transmitter's cumulative operating
time since the transmitter's battery was last charged.
This timer is automatically reset to "0:00" when the
transmitter is switched on and its battery voltage is
significantly higher than when the transmitter was last
used, e.g. because the battery was charged.
GRAUBELE
#01
0:00h
Stop
Flt
«normal »
K78
0:00
0:00
0.0V
5.9V
Mx
HoTT
Lithium battery, CR 2032
At the left side of the transmitter board there is a fixture
for a lithium battery. The user can replace this battery
when necessary with another lithium battery of type
CR 2032:
This battery maintains the date and time settings during
a transmitter power supply outage, for example when
the transmitter's main battery is being replaced.

16 Operating notices
Receiver power supply
A selection of 4 and 5 cell NiMH battery packs having
different capacities are available to power the receiver. If
digital servos are in use, we recommend a 5 cell battery
pack (6 V) to afford adequate battery capacity. If analog
and digital servos are used in mixed operation, be sure
to pay attention to the given maximum permissible
operating voltage. A stabilized, adjustable power
supply for the receiver with 1 or 2 receiver batteries
can be provided, e.g. the PRX-unit, order no. 4136, see
appendix.
For reasons of safety, do not use battery boxes or dry
cell batteries.
The voltage of the on-board power supply will be
displayed at the bottom right of the transmitter's screen
while the model is in operation.
GRAUBELE
#01
2:22h
Stop
Flt
«normal »
K78
0:00
0:00
5.5V
5.2V
M
HoTT
If the adjustable warning threshold (default value 3.8 V)
set in the Telemetry menu, see page 217, is underrun,
an optical and acoustic under-voltage warning will be
issued.
Despite this feature, be sure to check the condition
of the battery at regular intervals. Do not wait for the
warning to be issued before recharging the battery.
Notice:
An overview of available batteries, chargers and current
source test instruments can be found in the Graupner
RC main catalog or in Internet at www.graupner.de.
Charging the receiver battery
Charger cable, order no. 3021, can be plugged directly
onto the receiver's battery for charging. If the battery in
the model is connected by way of an order no. 3046,
3934, 3934.1 or 3934.3 power supply cable, then
charging can be accomplished via the charging jack or
special charging connector integrated into the switch.
The switch in the power supply cable must be in its
"OFF" position for charging.
Receiver battery connection polarity
General charging notices
The charging instructions for the charger as well as•
for the battery from its manufacturer to be observed.
Pay attention to the maximum permissible charging•
current specified by the battery's manufacturer. In
order to prevent damage to the transmitter, charging
current should never exceed 1 A. If necessary, limit
the current at the charger.
If the transmitter battery is nevertheless to be•
charged at a current rate in excess of 1 A, then
it is imperative that this is done outside the
transmitter. Otherwise there is a risk of damage to
the transmitter's board due to overloading its printed
circuit paths and/or overheating of the battery.
If an automatic charger is to be used for charging,•
perform several test charging procedures to ensure
the flawless functionality of its automatic shut-off.
This applies particularly if you want to charge the
standard installed NiMH battery with an automatic
charger unit intended for NiCd batteries Monitor the
charger's shut-off behavior if it has that option.
Do not execute a battery discharge or battery•
maintenance program through the charger jack.The
charger jack is not suitable for this purpose.
Alway connect the charger cable to the charger first•
and then to the receiver or transmitter battery. This
avoids the possibility of shorting the bare banana
plug ends together.
If the battery heats up significantly, check the•
battery's condition, replace the battery or reduce the
charging current.
Never leave a charging battery unattended.•
Follow the safety notices and handling•
instructions provided on page 8.
Operating notices

17
Operating notices
Joystick length adjustment
The length of both joysticks can be continuously
adjusted to adapt these transmitter controls to the pilot's
preference.
Hold the lower half of the knurled grip in place then turn
the upper section to release its counter-locked threads.
Now pull up or push down on the joystick's end to the
desired length. When the length is suitable, tighten the
counter-locked threads of the upper and lower sections
again.
Opening the transmitter housing
Carefully read the notices below before opening the
transmitter housing. It may be better if unexperienced
users ask a Graupner Service location to take care of
the procedures described below.
The transmitter should only be opened in the following
situations:
to convert a neutralized joystick to a non-neutralized•
joystick or a non-neutralized joystick to a neutralized
joystick.
to adjust joystick return tension.•
Switch off the transmitter before opening its cover
(power switch to "OFF").
Open the battery compartment as described on the
previous double-page, remove the battery and if a micro
SD card is inserted be sure to remove it too.
Once the battery and any micro SD card have been
removed, loosen the six countersunk screws on the rear
of the transmitter with a Phillips, size PH1, screwdriver,
see illustration.
Housing screw locations
Hold the two housing sections together by hand then
turn the transmitter upright over a suitable surface so
these 6 screws can fall out without getting lost. Now lift
up on the backplate carefully and turn it open to the right
like you would open a book.
A T T E N T I O N:
Two multi-conductor cables connect the backplate
with the transmitter electronics in the upper section.
These connections must not be damaged.
Important notices:
Make no modifications of any kind to the circuitry•
as this will void the guarantee as well as the
unit's official permit.
Be sure not to touch the circuit boards with any•
metallic objects. Do not touch contacts with your
fingers.
Never switch the transmitter on when its housing•
is open.
When you close the transmitter again, be sure
that …
… no cables are caught between housing edges•
when the backplate is put into position.
… both housing parts are properly seated with one•
another before screwing them together. Never force
the housing sections together.
Turn the screws down into the existing housing•
threads without stripping them out.
… reconnect the battery.•

18 Operating notices
Operating notices
Converting joysticks
Neutralization
Both the left and the right joystick can be configured
for neutralized or non-neutralized operation as desired.
Open the transmitter housing as previously described.
To change the joystick's factory setting, locate the screw
shown in the figure below enclosed in a white circle.
Notice:
The aggregate for the right joystick is a mirror image of
the left joystick so the corresponding screw for the right
joystick is on the right side just below the middle.
Now turn this screw down until the respective joystick
is free to move from limit to limit - or turn the screw out
until the joystick again completely self-restoring.
Do not touch the
Do not touch the
circuit board!
circuit board!
Do not touch t
Do not touch t
he circuit board!
he circuit board!
user-replaceable
CR2032 lithium battery to buffer the
integrated realtime clock
Slot for
memory cards
Charger jack
left
left
joystick aggregate
joystick aggregate
brake springs
adjustment screws
brake springs
adjustment screws
collapsible antenna
neutralization screw
right
right
joystick aggregate
joystick aggregate
neutralization screw
adjustment screw for joystick restoration force

19
Operating notices
Joystick restoring force
The joystick's restoring force can also be adjusted to the
pilot's preference. The adjustment is located next to the
return springs, see markings in the figure below.
Spring force for the given direction of motion can be
adjusted by turning the respective screw with a Phillips
screwdriver.
Right turn (clockwise) = return harder,•
Left turn (counter clockwise) = return softer.•
horizontal
horizontal
vertical
vertical
Notice:
The aggregate for the right joystick is a mirror image of
the left joystick so corresponding screws for the right
joystick are located to the right of the middle.
Brake spring and ratchet
The outboard screw of the two marked in the next figure
adjusts the braking force and the inboard screw adjusts
the strength of the ratchet for the respective joystick.
Notice:
The aggregate for the right joystick is a mirror image of
the left joystick so corresponding screws for the right
joystick are located at the top left.

20 Transmitter description
Transmitter description
Transmitter operating elements
Attaching the transmitter's neck strap
There is an eyelet on the top side of the mx-20 HoTT
transmitter (see figure at the right) to which a neck strap
can be attached. This anchor point has been chosen
because the transmitter is optimally balanced here when
it hangs from the strap.
Order No. 1121 Neck strap, 20 mm wide
Order No. 70 Neck strap, 30 mm wide
Important notice:
In its delivered configuration, the transmitter can only
operate any servos attached to the receiver by way
of the two joysticks. For reasons of flexibility, all other
operating elements (CTRL 6 … 8, SW 1 … 9) are
designated as "free" by the software. These other
operating elements can be freely assigned to actuators
as described in the text for the "Control adjust" menu
on page 96 (winged aircraft models) or page 100
(helicopter models).
antenna with kink and twist joint
proportional speed control CTRL 7
3 position switch
SW 4/5 or CTRL 9
2 position momentary
contact switch SW 1
proportional speed
control CTRL 6
left joystick
trimmer
ON/OFF switch
left touch pad
LC display
right touch pad
trimmer
right joystick
2 position switch SW 3
carrying handle
eyelet for neck strap
3 position switch
SW 6/7 or CTRL 10
proportional speed control CTRL 8
2 position switch SW 2
2 position switch SW 8
2 position momentary
contact switch SW 9
main status LED