Garmin 01594 AIRBORNE COMMUNICATIONS TRANSCEIVER User Manual 190 01007 02 0A
Garmin International Inc AIRBORNE COMMUNICATIONS TRANSCEIVER 190 01007 02 0A
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Users Manual
190-01007-02 TBD 2010 Rev. A
GTN 725/750
TSO Installation Manual
GTN 725 and GTN 750
GTN 725/750 TSO Installation Manual Page A
190-01007-02 Rev. A
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RECORD OF REVISIONS
Revision Revision Date Description
A
Initial Release
Page B GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
DOCUMENT PAGINATION
Section Pagination
Table of Contents i - viii
Section 1 1-1 through 1-14
Section 2 2-1 through 2-12
Section 3 3-1 through 3-10
Section 4 4-1 through 4-28
Section 5 5-1 through 5-38
Section 6 6-1 through 6-2
Section 7 7-1 through 7-2
Appendix A A-1 through A-2
Appendix B B-1 through B-10
Appendix C C-1 through C-6
Appendix D D-1 through D-40
GTN 725/750 TSO Installation Manual Page i
190-01007-02 Rev. A
This manual is applicable for units with main software version 2.00 or later.
INFORMATION SUBJECT TO EXPORT CONTROL LAWS
This document may contain information which is subject to the Export Administration Regulations
("EAR") issued by the United States Department of Commerce (15 CFR, Chapter VII, Subchapter C) and
which may not be exported, released, or disclosed to foreign nationals inside or outside of the United
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Act of 1979. Include this notice with any reproduced portion of this document.
WARNING
This product, its packaging, and its components contain chemicals known to the State of
California to cause cancer, birth defects, or reproductive harm. This notice is being
provided in accordance with California's Proposition 65. If you have any questions or
would like additional information, please refer to our web site at
www.garmin.com/prop65.
Perchlorate Material – special handling may apply, See
www.dtsc.ca.gov./hazardouswaste/perchlorate.
WARNING
This product contains a Lithium battery that must be recycled or disposed of properly.
Battery replacement and removal must be performed by professional services.
Page ii GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
1. GENERAL DESCRIPTION ............................................................................................................1-1
1.1 Introduction ..............................................................................................................................1-1
1.2 Equipment Description.............................................................................................................1-1
1.3 Technical Specifications...........................................................................................................1-2
1.3.1 Physical Characteristics........................................................................................................1-2
1.3.2 General Specifications..........................................................................................................1-2
1.3.3 GPS Specifications...............................................................................................................1-3
1.3.4 COM Specifications (GTN 750 Only) .................................................................................1-4
1.3.5 VOR Specifications (GTN 750 Only)..................................................................................1-5
1.3.6 LOC Specifications (GTN 750 Only) ..................................................................................1-5
1.3.7 Glideslope Specifications (GTN 750 Only) .........................................................................1-6
1.3.8 GPS Antenna Requirements.................................................................................................1-7
1.4 License Requirements...............................................................................................................1-8
1.5 Regulatory Compliance ............................................................................................................1-9
1.5.1 TSO Authorization and Advisory Circular References........................................................1-9
1.5.2 TSO Deviations..................................................................................................................1-11
1.5.3 FCC Grant of Equipment Authorization ............................................................................1-11
1.6 Database Options and Updates ...............................................................................................1-12
1.6.1 Navigation Database ..........................................................................................................1-12
1.6.2 TAWS/Terrain Database ....................................................................................................1-12
1.7 Fault Detection and Exclusion (FDE) ....................................................................................1-12
1.8 Limited Warranty ...................................................................................................................1-13
2. INSTALLATION OVERVIEW ......................................................................................................2-1
2.1 Introduction ..............................................................................................................................2-1
2.2 Minimum System Configuration ..............................................................................................2-1
2.2.1 VFR Installation ...................................................................................................................2-1
2.2.2 IFR GPS Installation ............................................................................................................2-1
2.2.3 IFR VOR/LOC/GLIDESLOPE Installation.........................................................................2-2
2.3 External Sensors .......................................................................................................................2-2
2.3.1 Multiple Uncorrected Pressure Altitude Sources .................................................................2-2
2.3.2 Multiple Baro-Corrected Altitude Sources...........................................................................2-3
2.3.3 Multiple Heading Sources....................................................................................................2-3
2.3.4 Multiple Indicated Airspeed Sources ...................................................................................2-4
2.3.5 Multiple True Airspeed Sources ..........................................................................................2-4
2.3.6 Multiple VLOC Course Select Sources ...............................................................................2-4
2.3.7 GPS Course Select Sources..................................................................................................2-5
2.3.8 Total Air Temperature Sources ............................................................................................2-5
2.3.9 Static Air Temperature Sources ...........................................................................................2-5
2.3.10 Joystick Waypoint Data .......................................................................................................2-6
2.4 Antenna Considerations............................................................................................................2-7
2.4.1 GPS Antenna Location.........................................................................................................2-7
2.4.2 COM Antenna Location.......................................................................................................2-8
2.4.3 VOR/LOC Antenna Location.............................................................................................2-10
2.4.4 Glideslope Antenna Location.............................................................................................2-10
2.4.5 Electrical Bonding..............................................................................................................2-10
2.4.6 Interference of GPS............................................................................................................2-10
2.5 Mounting Considerations .......................................................................................................2-11
2.6 Cabling and Wiring Considerations .......................................................................................2-11
GTN 725/750 TSO Installation Manual Page iii
190-01007-02 Rev. A
2.7 Air Circulation and Cooling ...................................................................................................2-11
2.8 Compass Safe Distance ..........................................................................................................2-11
3. INSTALLATION PROCEDURES..................................................................................................3-1
3.1 Unit and Accessories ................................................................................................................3-1
3.2 Optional Accessories ................................................................................................................3-2
3.2.1 GPS Antenna Options ..........................................................................................................3-2
3.3 Database Options......................................................................................................................3-3
3.4 Miscellaneous Options .............................................................................................................3-3
3.5 Optional Reference Material ....................................................................................................3-3
3.6 Installation Materials Required but Not Provided....................................................................3-4
3.6.1 Optional Accessories Not Supplied......................................................................................3-4
3.6.2 Materials Required But Not Supplied (New Installations Only)..........................................3-4
3.7 Special Tools Required.............................................................................................................3-4
3.8 Cable Installation......................................................................................................................3-5
3.9 Equipment Mounting................................................................................................................3-7
3.9.1 Rack Installation...................................................................................................................3-7
3.9.2 GTN Unit Insertion and Removal ........................................................................................3-7
3.9.3 Unit Replacement.................................................................................................................3-7
3.10 Antenna Installation and Connections......................................................................................3-8
3.10.1 GPS Antenna........................................................................................................................3-8
3.10.2 COM Antenna ......................................................................................................................3-9
3.10.3 NAV Antenna.......................................................................................................................3-9
4. SYSTEM INTERCONNECTS ........................................................................................................4-1
4.1 Pin Function List ......................................................................................................................4-1
4.1.1 P1001 Main Connector – Main Board .................................................................................4-1
4.1.2 P1002 Connector..................................................................................................................4-3
4.1.3 P1003 COM Connector........................................................................................................4-4
4.1.4 P1004 NAV Connector ........................................................................................................4-5
4.2 I/O Board..................................................................................................................................4-7
4.2.1 P1005 Connector..................................................................................................................4-7
4.3 Power, Lighting, And Antennas ...............................................................................................4-9
4.3.1 Power....................................................................................................................................4-9
4.3.2 Lighting Bus.........................................................................................................................4-9
4.3.3 Antennas...............................................................................................................................4-9
4.3.4 Serial Data..........................................................................................................................4-10
4.3.5 Ethernet (HSDB)................................................................................................................4-15
4.3.6 Main Audio Output ............................................................................................................4-15
4.3.7 Main Indicator....................................................................................................................4-16
4.3.8 OBS....................................................................................................................................4-17
4.3.9 Discrete Inputs ...................................................................................................................4-17
4.3.10 Discrete Outputs.................................................................................................................4-19
4.3.11 Heading Synchro................................................................................................................4-21
4.3.12 Composite Video (function not currently implemented) ...................................................4-22
4.3.13 COM Audio (GTN 750 only).............................................................................................4-23
4.3.14 COM Discrete Inputs .........................................................................................................4-24
4.3.15 VOR/ILS Indicator (GTN 750 only)..................................................................................4-25
4.3.16 RMI/OBI (GTN 750 only) .................................................................................................4-27
4.3.17 DME Tuning (GTN 750 only) ...........................................................................................4-28
Page iv GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5. POST INSTALLATION CONFIGURATION AND CHECKOUT PROCEDURES.....................5-1
5.1 System Configuration Overview ..............................................................................................5-1
5.2 Mounting, Wiring, and Power Checks .....................................................................................5-1
5.3 Connector Engagement Check .................................................................................................5-2
5.4 Configuration Mode Operations...............................................................................................5-2
5.4.1 Main ARINC 429 Config Page ............................................................................................5-3
5.4.2 Main RS-232 Config Page ...................................................................................................5-6
5.4.3 HSDB (Ethernet) Configuration Page..................................................................................5-8
5.4.4 Interface Equipment Page ....................................................................................................5-8
5.4.5 Main CDI Indicator (Analog) Configuration Page...............................................................5-9
5.4.6 Lighting Configuration Page..............................................................................................5-10
5.4.7 Audio Configuration Page..................................................................................................5-12
5.4.8 Traffic Configuration Page.................................................................................................5-13
5.4.9 Main System Configuration Page ......................................................................................5-13
5.4.10 COM Configuration Page (GTN 750 Only)......................................................................5-14
5.4.11 VOR/LOC/GS Configuration Page....................................................................................5-15
5.5 Ground Checks (Configuration Mode)...................................................................................5-17
5.5.1 Main Indicator Check (Analog Only) ................................................................................5-17
5.5.2 VOR/ILS Indicator (Analog) .............................................................................................5-17
5.5.3 Discrete Inputs Checkout ...................................................................................................5-17
5.5.4 Discrete Outputs Checkout.................................................................................................5-18
5.5.5 HSDB Provisional Wiring Checkout .................................................................................5-18
5.5.6 TAWS Audio Check (For Units with TAWS Only) ..........................................................5-19
5.5.7 GAD 42 Interface Check....................................................................................................5-20
5.5.8 Lighting Bus Interface Check ............................................................................................5-20
5.6 Ground Checks (Normal Mode) .............................................................................................5-21
5.6.1 Display of Self-Test Data...................................................................................................5-21
5.6.2 Signal Acquisition Check...................................................................................................5-22
5.6.3 VHF COM Interference Check ..........................................................................................5-22
5.6.4 VHF NAV Checkout (GTN 750 Only) ..............................................................................5-24
5.6.5 VHF COM Checkout (GTN 750 Only)..............................................................................5-24
5.6.6 TAWS System Check (For Units with TAWS Only) ........................................................5-24
5.6.7 Altitude Encoder or Air Data Computer Check .................................................................5-25
5.6.8 AHRS/IRU Interface Check...............................................................................................5-25
5.6.9 Interface Checkout .............................................................................................................5-26
5.6.10 Magnetic Compass Check..................................................................................................5-31
5.7 Flight Checks..........................................................................................................................5-32
5.7.1 GPS Flight Check...............................................................................................................5-32
5.7.2 VHF COM Flight Check (GTN 750) .................................................................................5-32
5.7.3 VOR Flight Check (GTN 750)...........................................................................................5-32
5.7.4 ILS Flight Check (GTN 750) .............................................................................................5-33
5.7.5 Autopilot Flight Check.......................................................................................................5-33
5.7.6 TAWS Audio Flight Check (TAWS-equipped Units Only) ..............................................5-33
5.8 Database Check ......................................................................................................................5-33
5.9 Data Card Replacement ..........................................................................................................5-34
5.10 Software Loading ...................................................................................................................5-34
5.11 System Setup ..........................................................................................................................5-34
5.12 Documentation Checks...........................................................................................................5-34
GTN 725/750 TSO Installation Manual Page v
190-01007-02 Rev. A
5.12.1 Airplane Flight Manual Supplement..................................................................................5-34
5.12.2 Instructions for Continued Airworthiness (ICAW)............................................................5-34
5.13 Configuration and Checkout Log ...........................................................................................5-35
6. LIMITATIONS................................................................................................................................6-1
6.1 Operations.................................................................................................................................6-1
6.2 Installation ................................................................................................................................6-1
6.2.1 GPS Antenna........................................................................................................................6-1
6.3 Aircraft Radio Station License .................................................................................................6-1
7. PERIODIC MAINTENANCE .........................................................................................................7-1
7.1 Equipment Calibration..............................................................................................................7-1
7.2 VOR Checks.............................................................................................................................7-1
7.3 Cleaning....................................................................................................................................7-1
7.4 Battery Replacement.................................................................................................................7-1
Appendix A ENVIRONMENTAL QUALIFICATION FORM..........................................................A-1
Appendix B GTN DATA FORMAT .................................................................................................. B-1
B.1 RS-232 Aviation Data Format................................................................................................. B-1
B.1.1 Electrical Interface .............................................................................................................. B-1
B.1.2 General Output Format ....................................................................................................... B-1
B.1.3 Output Sentence Type 1 ...................................................................................................... B-1
B.1.4 Output Sentence Type 2 ...................................................................................................... B-3
B.2 GTN RS-232 Fuel/Air Data Input Format............................................................................... B-5
B.2.1 Electrical Interface .............................................................................................................. B-5
B.2.2 Shadin Altitude Sentence .................................................................................................... B-5
B.2.3 Icarus Altitude Sentence...................................................................................................... B-5
B.2.4 Shadin Fuel Flow Sentence................................................................................................. B-6
B.2.5 ARNAV/EI Fuel Flow Sentence ......................................................................................... B-6
B.2.6 Shadin Fuel/Air Data Computer Sentence .......................................................................... B-7
Appendix C MECHANICAL DRAWINGS ....................................................................................... C-1
C.1 Drawing List............................................................................................................................ C-1
Appendix D INTERCONNECT DIAGRAMS....................................................................................D-1
D.1 Drawing List............................................................................................................................D-1
Page vi GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
LIST OF FIGURES
Figure 2-1. GPS Antenna Installation Considerations ..............................................................................2-9
Figure 3-1. Coaxial Cable Installation ......................................................................................................3-5
Figure 5-1. Configuration Mode Home Page............................................................................................5-2
Figure 5-2. Main ARINC 429 Configuration Page...................................................................................5-3
Figure 5-3. Main GTN Setup Page ...........................................................................................................5-3
Figure 5-4. Main RS-232 Configuration Page ..........................................................................................5-6
Figure 5-5. HSDB Ethernet Port Configuration Page...............................................................................5-8
Figure 5-6. Main CDI Configuration Page ...............................................................................................5-9
Figure 5-7. Main Lighting Configuration Page ......................................................................................5-10
Figure 5-8. Photocell Configuration Page...............................................................................................5-11
Figure 5-9. Lighting Bus Configuration Page..........................................................................................5-12
Figure 5-10. Audio Configuration Page..................................................................................................5-12
Figure 5-11. COM Configuration Page...................................................................................................5-14
Figure 5-12. Traffic Configuration Page.................................................................................................5-13
Figure 5-13. Miscellaneous Configuration Page.....................................................................................5-13
Figure 5-14. Measurement of GPS Antenna Vertical Offset ..................................................................5-14
Figure 5-15. VOR/LOC/GS Configuration Page....................................................................................5-15
Figure 5-16. GTN Diagnostics Page.......................................................................................................5-17
Figure 5-17. HSDB Diagnostics Page.....................................................................................................5-18
Figure 5-18. GTN Audio Configuration Page ........................................................................................5-19
Figure 5-19. GAD 42 Configuration Page..............................................................................................5-20
Figure 5-20. Lighting Bus Configuration Page.......................................................................................5-20
Figure 5-21. Map Menu Page .................................................................................................................5-25
Figure C-1. GTN Mounting Rack Dimensions........................................................................................ C-3
Figure C-2. GTN Mounting Rack Installation ......................................................................................... C-4
Figure C-3. GTN Mounting Rack Assembly ........................................................................................... C-5
Figure C-4. GTN Recommended Panel Cutout Dimensions ................................................................... C-6
Figure D-1. GTN System Interface Diagram...........................................................................................D-3
Figure D-2. GTN 750 Typical Installation...............................................................................................D-4
Figure D-3. GTN 725 Typical Installation...............................................................................................D-6
Figure D-4. GTN Power Lighting Configuration Interconnect ...............................................................D-8
Figure D-5. GTN – Antenna Interconnect .............................................................................................D-10
Figure D-6. GTN - Main Indicator Interconnect....................................................................................D-13
Figure D-7. GTN - Autopilot Interconnect ............................................................................................D-14
Figure D-8. GTN - Traffic Interconnect ................................................................................................D-15
Figure D-9. GTN - Transponder Interconnect .......................................................................................D-16
Figure D-10. Dual GTN to Single GDU Interconnect ...........................................................................D-17
Figure D-11. GTN - GDU/AHRS Interconnect .....................................................................................D-18
Figure D-12. GTN - ARINC 429 EFIS Interconnect.............................................................................D-19
Figure D-13. GTN - GDL 69/69A Interconnect .................................................................................... D-21
Figure D-14. Audio Panel Interconnect .................................................................................................D-22
Figure D-15. Air Data/IRU/AHRS RS-232 Interconnect ......................................................................D-24
Figure D-16. Air Data/IRU/AHRS ARINC 429 Interconnect ...............................................................D-26
Figure D-17. GAD 42 Interconnect .......................................................................................................D-27
Figure D-18. VOR/ILS Indicator Interconnect ......................................................................................D-28
Figure D-19. RMI OBI Interconnect......................................................................................................D-29
Figure D-20. GTN – WX-500 Interconnect...........................................................................................D-30
Figure D-21. GTN 750 - DME Interconnect..........................................................................................D-31
Figure D-22. GTN 750 – Remote DME Interconnect............................................................................D-32
Figure D-23. Parallel 2 of 5 DME Tuning.............................................................................................D-33
Figure D-24. Parallel Slip Code DME Tuning Interconnect..................................................................D-34
GTN 725/750 TSO Installation Manual Page vii
190-01007-02 Rev. A
Figure D-25. Heading Synchro Interconnect .........................................................................................D-35
Figure D-26. GPS Annunciator Interconnect.........................................................................................D-36
Figure D-27. NAV Source Select Annunciator Interconnect.................................................................D-37
Figure D-28. TAWS Interconnect..........................................................................................................D-38
Figure D-29. Switches Interconnect.......................................................................................................D-39
Table 1-1. GTN Units ...............................................................................................................................1-1
Table 1-2. GTN Current Specifications ....................................................................................................1-6
Table 1-3. Approved GPS Antennas.........................................................................................................1-7
Table 1-4. TSO Authorization ..................................................................................................................1-9
Table 1-5. Main Software Part Number and Version .............................................................................1-10
Table 1-6. GPS/WAAS Software Part Number and Version..................................................................1-10
Table 3-1. Catalog Part Numbers..............................................................................................................3-1
Table 3-2. Standard Kit Accessories.........................................................................................................3-1
Table 3-3. Recommended Crimp Tools (or Equivalent)...........................................................................3-4
Table 3-4. Socket Contact Part Numbers..................................................................................................3-6
Table 5-1. GTN Post-Installation Checkout Log ....................................................................................5-35
LIST OF TABLES
Table B-1. Type 1 Output Sentence Format ............................................................................................ B-2
Table B-2. Type 2 Output Sentence Format ............................................................................................ B-4
Page viii GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
GTN 725/750 HARDWARE MOD LEVEL HISTORY
The following table identifies hardware modification (Mod) Levels for the GTN 725 and GTN 750. Mod
Levels are listed with the associated service bulletin number, service bulletin date, and the purpose of the
modification. The table is current at the time of publication of this manual (see date on front cover) and is
subject to change without notice. Authorized Garmin Sales and Service Centers are encouraged to access
the most up-to-date bulletin and advisory information on the Garmin Dealer Resource web site at
www.garmin.com using their Garmin-provided user name and password.
MOD LEVEL
SERVICE
BULLETIN
NUMBER
SERVICE BULLETIN
DATE PURPOSE OF MODIFICATION
GTN 725/750 TSO Installation Manual Page 1-1
190-01007-02 Rev. A
1. GENERAL DESCRIPTION
1.1 Introduction
This manual describes the physical, mechanical, and electrical characteristics, as well as instructions and
other conditions and limitations for installation and approval of the GTN units. Refer to Section 6,
Limitations, for additional information and other considerations.
NOTE
Except where specifically noted, references made to GTN will equally apply to the
GTN 725 and GTN 750.
Table 1-1. GTN Units
MODEL PART NUMBER COLOR NOTES
GTN 725 011-02281-00 BLACK
011-02282-00 BLACK 10 WATT UNIT
GTN 750 011-02282-10 GRAY 10 WATT UNIT
1.2 Equipment Description
The GTN 725 is a GPS/WAAS unit that meets the requirements of TSO-C146a (specified in Table 1-4)
and may be approved for IFR en route, terminal, non-precision, and precision approach operations.
The GTN 750 includes all the features of the GTN 725 and includes an airborne VHF communications
transceiver and airborne VOR/LOC and glideslope receivers. The GTN 750 meets the requirements of the
TSOs specified in Table 1-4.
CAUTION
The GTN use lenses coated with a special anti-reflective coating that is very sensitive to
waxes and abrasive cleaners. CLEANERS CONTAINING AMMONIA WILL HARM
THE ANTI-REFLECTIVE COATING. It is very important to clean the lens using a
clean, lint-free cloth and an eyeglass lens cleaner that is specified as safe for anti-
reflective coatings.
CAUTION
The use of ground-based cellular telephones while aircraft are airborne is prohibited by
FCC rules. Due to potential interference with onboard systems, the use of ground-based
cell phones while the aircraft is on the ground is subject to FAA regulation 14
CFR §91.21.
FCC regulation 47 CFR §22.925 prohibits airborne operation of ground-based cellular
telephones installed in or carried aboard aircraft. Ground-based cellular telephones must
not be operated while aircraft are off the ground. When any aircraft leaves the ground, all
ground-based cellular telephones on board that aircraft must be turned off. Ground-based
cell phones that are on, even in a monitoring state, can disrupt GPS performance.
CAUTION
All screen shots used in this document are current at the time of publication. Screen shots
are intended to provide visual reference only. All information depicted in screen shots,
including software file names, versions, and part numbers, is subject to change and may
not be up to date.
Page 1-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
1.3 Technical Specifications
1.3.1 Physical Characteristics
Bezel Height 6.00 in. (152 mm)
Bezel Width 6.25 in. (159 mm)
Rack Height (Dimple-to-Dimple) 6.025 in. (153 mm)
Rack Width 6.300 in (160 mm)
Depth Behind Panel with Connectors (Measured from
face of aircraft panel to rear of connector backshells) 11.25 in. (286 mm)
GTN 725 Weight (Unit only) TBD
GTN 725 Weight (With rack and back plate) TBD
GTN 750 Weight (Unit only) 7.50 lbs (3.40 kg)
GTN 750 Weight (With rack and back plate) 9.16 lbs (4.15 kg)
1.3.2 General Specifications
Operating Temperature Range
-20°C to +55°C. For more details see
Environmental Qualification Form on the
Dealers Only page on www.garmin.com. See
Appendix A for part numbers.
Humidity 95% non-condensing
Altitude Range -1,500 ft to 50,000 ft
Input Power Requirements
Input Voltage Range - All Units (Main Connector) 9 to 33 VDC
Input Voltage Range (COM Connector on GTN 750) 9 to 33 VDC
Input Voltage Range (NAV Connector on GTN 750) 9 to 33 VDC
GTN Current Draw Refer to Table 1-2
Superflag Power Requirements 400 mA maximum per superflag output
Environmental Testing
See Environmental Qualification Form on the
Dealers Only page on www.garmin.com. See
Appendix A for part numbers.
The display on the GTN is a sunlight readable LCD display.
Display Size 6.9 inch diagonal
Active Area 4.46 inches (W) x 5.27 inches (H)
Resolution 600 x 708 pixels
Viewing Angle
Left/Right: 45°
Up: 10°
Down: 30°
GTN 725/750 TSO Installation Manual Page 1-3
190-01007-02 Rev. A
1.3.3 GPS Specifications
Number Of Channels 15 (12 GPS and 3 GPS/WAAS/SBAS)
Frequency 1575.42 MHz L1, C/A code
-134.5 dBm GPS
Sensitivity (Acquisition, No Interference) -135.5 dBm WAAS
Sensitivity (Drop Lock) -144 dBm
Dynamic Range > 20 dB
Lat/Lon Position Accuracy <1.25 meter RMS horizontal, <2 meter vertical, with WAAS
Velocity 1000 knots maximum (above 60,000 ft)
TTFF (Time To First Fix) 1:45 min. typical with current almanac, position, and time
Reacquisition 10 seconds typical
Position Update Interval 0.2 sec (5 Hz)
1 PPS (Pulse Per Second) ±275 Nsec of UTC second
Datum WGS-84
SATCOM Compatibility SATCOM compatibility is dependent upon antenna selection.
See Section TBD for additional information.
Antenna Power Supply 35 mA typical, 40 mA max at 4.7 VDC
Page 1-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
1.3.4 COM Specifications (GTN 750 Only)
1.3.4.1 COM Transmitter Specifications
Classes 3,4,5,6
Microphone Input Two inputs, standard carbon or dynamic mic with integrated
preamp providing minimum 70 mVRMS into 1000 load
Modulation Capability 85% with 100 to 1000 mVRMS microphone input at 1000 Hz
Modulation AM Double sided, Emission Designator 6K00A3E
Frequency Range 118.000 to 136.975 MHz, 25 kHz and 8.33 kHz channel spacing
Frequency Tolerance +/-2ppm from -40°C to +70°C
Output Power 10 Watt Mode: 10 watts minimum
16 Watt Mode: 16 watts minimum
Duty Cycle 10W: 100%
16W: Recommended 25% (15 seconds on/45 seconds off,
5 seconds on/15 seconds off, etc.)
Carrier Noise Level At least 35 dB (SNR).
Stuck Mic Time-Out 35 seconds time-out, reverts to receive
Demodulated Audio Distortion Less than 5% distortion when the transmitter is at 85%
modulation at 350 to 2500 Hz
Sidetone 1.4 Vrms into a 500 load
1.3.4.2 COM Receiver Specifications
Classes D and E
Frequency Range 118.000 to 136.975 MHz, 25 kHz and 8.33 kHz channel spacing
Headset Audio Output 110 mW minimum into a 500 load
Speaker Audio Output 12 watts minimum into a 4 load
Audio Response Less than 6 dB of variation between 350 and 2500 Hz.
Audio Distortion Less than 5% at rated output power
AGC Characteristics Less than 3 dB of variation in the audio output from -93 to -13
dBm (power absorbed by a 50Ω load)
Sensitivity
SINAD on all channels is greater than 6 dB when the RF level is
2 uV (hard) or -107 dBm (power absorbed by a 50Ω load)
modulated 30% at 1000 Hz at rated audio output power
Squelch Automatic squelch with manual override
Selectivity
6 dB BW is greater than + 7 kHz for 25 kHz channeling.
60 dB BW is less than ±22 kHz for 25 kHz channeling.
6 dB BW is greater than ±3.5 kHz for 8.33 kHz channeling.
60 dB BW is less than ±7.37 kHz for 8.33 kHz channeling.
GTN 725/750 TSO Installation Manual Page 1-5
190-01007-02 Rev. A
1.3.5 VOR Specifications (GTN 750 Only)
Receiver Audio Sensitivity At -103.5 dBm (S+N)/N is not less than 6 dB.
Course Deviation Sensitivity -103.5 dBm or less for 60% of standard deflection.
Flag
The VOR Course Deviation Flag must be flagged:
in the absence of an RF signal.
in the absence of the 9960 Hz modulation.
in the absence of either one of the two 30 Hz modulations.
When the level of a standard VOR deviation test signal produces
less than a 50% of standard deflection.
AGC Characteristics From -99 dBm to -13 dBm input of a Standard VOR Audio Test
Signal, audio output level does not vary more than 3 dB.
Spurious Response Greater than 80 dB.
VOR OBS Bearing Accuracy
The bearing information as presented to the pilot does not have an
error in excess of 2.7° as specified by RTCA DO-196 and
EuroCAE ED-22B.
Audio Output A minimum 100 mW into a 500Ω load.
Audio Response Less than 6 dB of variation between 350 and 2500 Hz. Except the
1020 Hz Ident Tone is at least 20 dB down in voice mode.
Audio Distortion The distortion in the receiver audio output does not exceed 10% at
all levels up to 100 mW.
1.3.6 LOC Specifications (GTN 750 Only)
Receiver Audio Sensitivity At -103.5 dBm (S+N)/N is not less than 6 dB.
Course Deviation Sensitivity -103.5 dBm or less for 60% of standard deflection.
Flag
The VLOC Course Deviation Flag must be flagged:
in the absence of an RF signal.
in the absence of the 9960 Hz modulation.
in the absence of either one of the two 30 Hz modulations.
When the level of a standard VOR deviation test signal produces
less than a 50% of standard deflection.
AGC Characteristics From -99 dBm to -13 dBm input of a Standard VOR Audio Test
Signal, audio output level does not vary more than 3 dB.
Spurious Response Greater than 80 dB.
VOR OBS Bearing Accuracy
The bearing information as presented to the pilot does not have an
error in excess of 2.7° as specified by RTCA DO-196 and
EuroCAE ED-22B.
Audio Output A minimum 100 mW into a 500Ω load.
Audio Response Less than 6 dB of variation between 350 and 2500 Hz. Except the
1020 Hz Ident Tone is at least 20 dB down in voice mode.
Audio Distortion The distortion in the receiver audio output does not exceed 10% at
all levels up to 100 mW.
Page 1-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
1.3.7 Glideslope Specifications (GTN 750 Only)
Sensitivity -87 dBm or less for 60% of standard deflection.
Centering Accuracy 0 ±.0091 ddm or 0 ±7.8 mV.
Selectivity
The course deviation is 0 ddm ± .0091 ddm when using the
Glideslope Centering Test Signal as the RF frequency is varied
±17 kHz from the assigned channel.
At frequencies displaced by ±132 kHz or greater, the input signal is
at least 60 dB down.
Standard Deflection
a) With a standard deflection ‘FLY DOWN’ condition (90 Hz
dominant), the output is -78 mV ±7.8 mV.
b) With a standard deflection ‘FLY UP’ condition (150 Hz
dominant), the output is +78 mV ±7.8 mV.
Flag
The unit Flags:
When the level of a standard deviation test signal produces 50% or
less of standard deflection of the deviation indicator.
In the absence of 150 Hz modulation.
In the absence of 90 Hz modulation.
In the absence of both 90 Hz and 150 Hz modulation.
In the absence of RF.
Table 1-2. GTN Current Specifications
14 Volt Current Draw 28 Volt Current Draw
LRU Typical Maximum Typical Maximum
GTN 725
Main Connector 1.123 A
GTN 750
Main Connector 1.123 A
COM Connector 470 mA (RX)
5.16 A (TX:10W)
6.93 A (TX:16W)
220 mA (RX)
2.04 A (TX:10W)
2.73 A (TX:16W)
NAV Connector 308 mA
GTN 725/750 TSO Installation Manual Page 1-7
190-01007-02 Rev. A
1.3.8 GPS Antenna Requirements
Antenna performance is critical to the GPS/WAAS operation. The antennas listed in Table 1-3 are
approved for installation with the GTNs.
Table 1-3. Approved GPS Antennas
Model/Description Conn Type Mfr Part Number
Garmin
Order
Number
Garmin 013-00235-( )
GA 35, GPS/WAAS
[1] TNC Aero Antenna AT575-93G( )-TNCF-000-RG-27-NM 013-00235-( )
Garmin 013-00244-( )
GA 36, GPS/WAAS TNC Aero Antenna AT575-126G( )-TNCF-000-RG-27-NM 013-00244-( )
Garmin 013-00245-( )
GA 37, GPS/WAAS/XM TNC Aero Antenna AT2300-126G( )-TNCF-000-RG-27-NM 013-00245-( )
Garmin 013-00261-( )
A33W, WAAS Antenna
[3] TNC Aero Antenna AT575-332G( )- TNCF-000-RG-27-NM 013-00261-( )
GPS/VHF Antenna TNC/BNC
[2] Comant [3] CI-2580-200 N/A
GPS/VHF Antenna TNC/BNC
[2] Comant [3] CI-2728-200 N/A
GPS/XM/VHF Antenna TNC/TNC/BNC
[4] Comant [3] CI-2580-410 N/A
GPS/XM/VHF Antenna TNC/TNC/BNC
[4] Comant [3] CI-2728-410 N/A
GPS Antenna TNC Comant [3] CI-428-200 N/A
GPS/XM Antenna TNC/TNC Comant [3] CI-428-410 N/A
[1] Same mounting hole pattern as GA 56, but GA 35 antenna has a physically larger footprint.
[2] The GPS/WAAS connector is a TNC type. The VHF connector is a BNC type.
[3] Installation of this antenna is not covered by the Garmin GA Antenna AML STC SA01695SE.
[4] The GPS/WAAS connector is a TNC type. The XM connector is a TNC type. The VHF connector is
a BNC type.
Page 1-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
1.4 License Requirements
The Telecommunications Act of 1996, effective February 8, 1996, provides the FCC discretion to
eliminate radio station license requirements for aircraft and ships. The GTN 725 and GTN 750
installations must comply with current transmitter licensing requirements. In the US, to find out the
specific details on whether a particular installation is exempt from licensing, please visit the FCC web site
http://wireless.fcc.gov/aviation. If an aircraft license is required, make application for a license on FCC
form 404, Application for Aircraft Radio Station License. The FCC also has a fax-on-demand service to
provide forms by fax. Outside the US, contact the responsible telecommunication authority. The GTN
725 and GTN 750 owner accepts all responsibility for obtaining the proper licensing before using the
transceiver. The maximum transmitting power, modulation identification, and frequency band
information may be required for licensing and are detailed in Section 1.4.4.
CAUTION
The VHF transmitter in this equipment is guaranteed to meet Federal Communications
Commission acceptance over the operating temperature range. Modifications not
expressly approved by Garmin could invalidate the license and make it unlawful to
operate the equipment.
GTN 725/750 TSO Installation Manual Page 1-9
190-01007-02 Rev. A
1.5 Regulatory Compliance
1.5.1 TSO Authorization and Advisory Circular References
The conditions and tests required for TSO approval of this article are minimum performance standards. It
is the responsibility of those installing this article either on or within a specific type or class of aircraft to
determine that the aircraft installation conditions are within the TSO standards. TSO articles must have
separate approval for installation in an aircraft. The article may be installed only in compliance with
14 CFR part 43 or the applicable airworthiness requirements.
Table 1-4. TSO Authorization
GTN 725
GTN 750
Function TSO
Environmental
Standard
Minimum
Operational
Performance
Standard
Class/Type Applicable SW
P/Ns
●
ILS Glideslope Receiving
Equipment TSO-C34e DO-160B DO-192 TBD
●
ILS Localizer Receiving
Equipment TSO-C36e DO-160B DO-195 TBD
●
VOR Receiving
Equipment TSO-C40c DO-160B DO-196 TBD
● ●
Airborne Weather and
Ground Mapping Pulsed
Radars
TSO-C63c DO-160A DO-173 TBD
● ●
Airborne ATC
Transponder Equipment TSO-C74d DO-160F DO-144A TBD
● ●
Optional Display
Equipment for Weather
and Ground Mapping
Radar Indicators
TSO-C105 DO-160A DO-174 TBD
● ●
Airborne Passive
Thunderstorm Detection
Equipment
TSO-C110a DO-160B DO-191 TBD
● ●
Air Traffic Control Radar
Beacon System/Mode
Select ATCRABS/Mode S
TSO-C112c DO-160F DO-181D TBD
● ●
Multipurpose Electronic
Displays TSO-C113 DO-160A AS 8034 TBD
● ●
TCAS Airborne
Equipment TSO-C118 DO-160B DO-197 TBD
●
Equipment that
Prevents Blocked
Channels in
2-way Radio
Communications due to
Unintentional
Transmissions
TSO-C128a DO-160E DO-207 TBD
● ●
Aircraft Audio Systems
and Equipment TSO-C139 DO-160E DO-214 TBD
● ●
Stand-Alone Airborne
Navigation Equipment
using the GPS
Augmented by the
Satellite Based
Augmentation System
TSO-C146c DO-160E DO-229D TBD
● ● TAS Airborne Equipment TSO-C147 DO-160D DO-197A TBD
● ● TAWS TSO-C151b DO-160E TSO-C151b TBD
Page 1-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
GTN 725
GTN 750
Function TSO
Environmental
Standard
Minimum
Operational
Performance
Standard
Class/Type Applicable SW
P/Ns
● ●
Aircraft Flight Information
Services – Broadcast
(FIS-B) Datalink Systems
and Equipment
TSO-C157 DO-160E DO-267A TBD
● ●
Electronic Map Display
Equipment for Graphical
Depiction of Aircraft
Position
TSO-C165 DO-160E DO-257A TBD
●
VHF Radio
Communications
Transceiver Equipment
Operating with Radio
Frequency Range
117.975 to 137.000 MHz
TSO-C169a DO-160E DO-186B TBD
Table 1-5. Main Software Part Number and Version
Software Part Number Software Version
TBD TBD
Table 1-6. GPS/WAAS Software Part Number and Version
Software Part Number Software Version
006-B0339-10 V4.0
NOTE
For main or GPS software versions previous to those listed Table 1-5 or Table 1-6,
contact Garmin for assistance.
System Function DO-178B Level
Operating System B
GPS Navigation Information B
VOR Information C
LOC/Glideslope Information C
VHF Communication C
TAWS (Class B) Functionality C
Display of altitude, heading, course, speed, and track C
Display of other information - moving map, terrain, flight plan overlay and flight
mode, TAS/TIS traffic information, XM Weather data, data from passive lightning
detection equipment, checklist and timer
D
Terrain (Fixed Wing) D
Terrain Prox (Helicopter) D
HTAWS (Helicopter) C
NOTE
Unauthorized changes or modifications to any GTN unit product may void the
compliance to required regulations and authorization for continued equipment usage. All
GTN unit functions are design approved under the TSO.
GTN 725/750 TSO Installation Manual Page 1-11
190-01007-02 Rev. A
1.5.2 TSO Deviations
TSO Deviation
1. Garmin was granted a deviation from TSO-C110 not to mark the computer software level(s) on the unit.
TSO-C110
2. Garmin was granted a deviation from the TSO-C110 to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from TSO-C113 not to mark the computer software level(s) on the unit.
TSO-C113
2. Garmin was granted a deviation from TSO-C113 to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from TSO-C118 not to mark the computer software level(s) on the unit.
2. Garmin was granted a deviation from TSO-C118 to use RTCA/DO-197A instead of RTCA/DO-197 as the
Minimum Operational Performance Standards.
TSO-C118 3. Garmin was granted a deviation from TSO-C118 to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from TSO-C139 not to furnish each person receiving a GTN 725/750 copies of
the data in Paragraph 5.l of the TSO.
2. Garmin was granted a deviation from TSO-C139 not to furnish each person receiving a GTN 725/750 copies of
the data in Paragraph 5.l, 5.m, 5.n of the TSO, if the equipment performs functions beyond those in paragraph 3
and paragraph 3.a.
TSO-C139
3. Garmin was granted a deviation from TSO-C139 to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from RTCA/DO-229D to use a 10 degree vertical viewing angle below the
lower display edge.
2. Garmin was granted a deviation from RTCA/DO-229D to use GPS antennas that meet Garmin minimum
performance specifications.
TSO-C146c 3. Garmin was granted a deviation from TSO-C146c to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from TSO-C147 not to furnish each person receiving a GTN 725/750 copies of
the data in paragraphs 3(a)(10) through (12) of the TSO.
TSO-C147 2. Garmin was granted a deviation from TSO-C147 to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from TSO-C151b Section 5.c(2) not to furnish each person receiving a GTN
725/750 copies of the data in paragraphs 5.a(11) through (13) of the TSO.
TSO-C151b 2. Garmin was granted a deviation from TSO-C151b to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1. Garmin was granted a deviation from TSO-C165 Section 5.c(2) not to furnish each person receiving a GTN
725/750 copies of the data in paragraphs 5.a(11) through (13) of the TSO.
TSO-C165 2. Garmin was granted a deviation from TSO-C165 to mark product name, part number, serial number and a
statement on the unit’s nameplate label “TSO-C146c Class 3, See IM for Add’l Appliance Approvals ”, instead of
Product Type, TSO Numbers, Equipment Class, “Dev” (deviation), Environmental Categories, Date of
Manufacture, weight and Software Part Number.
1.5.3 FCC Grant of Equipment Authorization
Model FCC ID
GTN 750 IPH-01594
Page 1-12 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
1.6 Database Options and Updates
1.6.1 Navigation Database
The navigation database resides on a database card that is inserted in the card slot on the unit front panel.
The database is generated on periodic cycles from current Jeppesen data and converted to the format used
by the GTN products. The data conversion process is performed using software that is developed and
maintained under Garmin document control processes according to RTCA/DO-200A, Standards for
Processing Aeronautical Data.
The database can be updated by purchasing a database subscription from Jeppesen. The database updates
include either replacing or re-programming the database card and inserting the updated card in the left
card slot on the unit front panel. Contact Jeppesen at 800-621-5377 or www.jeppesen.com for more
information and instructions.
Contact Garmin for more information on databases available for the GTN.
1.6.2 TAWS/Terrain Database
The TAWS/Terrain database resides on a database card that is inserted in the card slot on the unit front
panel.
The TAWS/Terrain database which serves both functions of Terrain Awareness and Warning System
(TAWS) and the standard configured GTN providing terrain functionality is available for updating on
periodic cycles and is available from Garmin. TAWS/Terrain database updates can be accomplished by
replacing or reprogramming the database card and inserting the updated card in the card slot on the unit
front panel. The TAWS/Terrain database can be downloaded via the internet and the card programmed
using a USB programmer available from Garmin. Contact Garmin at 800-800-1020 or www.garmin.com
for more information or instructions.
1.7 Fault Detection and Exclusion (FDE)
The GTN unit, when installed as defined in this manual, complies with the requirements for GPS primary
means navigation in oceanic and remote airspace when used in conjunction with the FDE Prediction
program.
The GTN unit includes fault detection and exclusion (FDE), which is active for all flight phases including
oceanic and remote operations, en route and terminal, and precision and non-precision approaches, and
does not require any pilot interaction. The FDE consists of two parts:
1. The fault detection function detects a satellite failure that can affect navigation; and
2. The exclusion function is the capability to exclude one or more failed satellites and prevent them
from affecting navigation.
The FDE Prediction program is used to predict FDE availability. The FDE Prediction program must be
used prior to oceanic or remote area flights for all operators using the GTN unit as primary means
navigation under FAR parts 91, 121, 125, and 135.
GTN 725/750 TSO Installation Manual Page 1-13
190-01007-02 Rev. A
1.8 Limited Warranty
All Garmin avionics products are warranted to be free from defects in materials or workmanship for: two
years from the date of purchase for new Remote-Mount and Panel-Mount products; one year from the
date of purchase for new portable products and any purchased newly-overhauled products; six months for
newly-overhauled products exchanged through a Garmin Authorized Service Center; and 90 days for
factory repaired or newly-overhauled products exchanged at Garmin in lieu of repair. Within the
applicable period, Garmin will, at its sole option, repair or replace any components that fail in normal use.
Such repairs or replacement will be made at no charge to the customer for parts or labor, provided that the
customer shall be responsible for any transportation cost. This warranty does not apply to: (i) cosmetic
damage, such as scratches, nicks and dents; (ii) consumable parts, such as batteries, unless product
damage has occurred due to a defect in materials or workmanship; (iii) damage caused by accident, abuse,
misuse, water, flood, fire, or other acts of nature or external causes; (iv) damage caused by service
performed by anyone who is not an authorized service provider of Garmin; or (v) damage to a product
that has been modified or altered without the written permission of Garmin. In addition, Garmin reserves
the right to refuse warranty claims against products or services that are obtained and/or used in
contravention of the laws of any country.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN LIEU OF
ALL OTHER WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING
ANY LIABILITY ARISING UNDER ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE, STATUTORY OR OTHERWISE. THIS WARRANTY GIVES
YOU SPECIFIC LEGAL RIGHTS, WHICH MAY VARY FROM STATE TO STATE.
IN NO EVENT SHALL GARMIN BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT OR
CONSEQUENTIAL DAMAGES, WHETHER RESULTING FROM THE USE, MISUSE OR
INABILITY TO USE THE PRODUCT OR FROM DEFECTS IN THE PRODUCT. SOME STATES DO
NOT ALLOW THE EXCLUSION OF INCIDENTAL OR CONSEQUENTIAL DAMAGES, SO THE
ABOVE LIMITATIONS MAY NOT APPLY TO YOU.
Garmin retains the exclusive right to repair or replace (with a new or newly-overhauled replacement
product) the product or software or offer a full refund of the purchase price at its sole discretion. SUCH
REMEDY SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY BREACH OF
WARRANTY.
Online Auction Purchases: Products purchased through online auctions are not eligible for warranty
coverage. Online auction confirmations are not accepted for warranty verification. To obtain warranty
service, an original or copy of the sales receipt from the original retailer is required. Garmin will not
replace missing components from any package purchased through an online auction.
International Purchases: A separate warranty may be provided by international distributors for devices
purchased outside the United States depending on the country. If applicable, this warranty is provided by
the local in-country distributor and this distributor provides local service for your device. Distributor
warranties are only valid in the area of intended distribution. Devices purchased in the United States or
Canada must be returned to the Garmin service center in the United Kingdom, the United States, Canada,
or Taiwan for service.
Page 1-14 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
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GTN 725/750 TSO Installation Manual Page 2-1
190-01007-02 Rev. A
2. INSTALLATION OVERVIEW
2.1 Introduction
Always follow acceptable avionics installation practices per AC 43.13-1B, AC 43.13-2B, or later FAA
approved revisions of these documents. The GPS/WAAS installation instructions have been prepared to
meet the guidance material contained in AC 20-138A “Airworthiness Approval of Global Navigation
Satellite System (GNSS) Equipment”. The communications installation instructions have been prepared
to meet the guidance material defined by AC 20-67B, “Airborne VHF Communications Equipment
Installations”.
2.2 Minimum System Configuration
2.2.1 VFR Installation
The minimum GTN installation requires the following items for a VFR Installation:
• GTN (installed in the aircraft manufacturer approved location for 6.25” wide avionics equipment)
• GPS antenna is required for GPS navigation functions.
• An external CDI is required for installations using the VOR navigation and glideslope
information.
• A NAV antenna is required for VHF NAV functions.
• A COM antenna is required for COM functions.
VFR installations must be placarded “GPS LIMITED TO VFR USE ONLY” in clear view of the pilot.
2.2.2 IFR GPS Installation
In order for the GTN to be utilized for IFR GPS Navigation, the criteria in Section 2.2.1 must be met in
addition to the following:
• An External CDI/HSI indicator must be installed in the pilot’s primary field-of-view (or in the
aircraft manufacturer approved mounting location). The indicator must have a vertical deviation
indicator (glideslope) in order to perform VNAV operations/approaches.
• Any annunciation required for Source Selection or IFR GPS Navigation must meet the acceptable
field-of-view requirements.
NOTE
To take full advantage of the GTN capabilities, an optional barometric altitude source is
recommended for automatic sequencing of fix-to-altitude (FA) and hold-to-altitude (HA)
leg types. If no barometric altitude data is provided to the GTN, FA and HA legs must be
manually sequenced.
Page 2-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
2.2.3 IFR VOR/LOC/GLIDESLOPE Installation
The minimum GTN unit installation requires the following items for an IFR VOR/LOC/GLIDESLOPE
installation:
• GTN (installed in the aircraft manufacturer approved location)
• GPS antenna, NAV antenna, and COM antenna.
• An External CDI/HSI indicator must be installed in the pilot’s primary field-of-view (or in the
aircraft manufacturer approved mounting location). The indicator must have a vertical deviation
indicator for glideslope and VNAV operations/approaches.
• Any annunciation required for Source Selection or IFR GPS Navigation must meet the acceptable
field-of-view requirements.
• A second GPS navigator, COM radio, or NAV radio must be installed.
2.3 External Sensors
When GTN is installed with external sensors, these sensors must be installed in accordance with the
manufacturer's data. This manual does not provide information for the installation of specific external
sensors.
The GTN can accept data from multiple altitude, heading, and baro correction sources. If multiple sources
are used, the GTN will accept data as described below.
NOTE
Barometric altitude is not required by the GTN to meet the requirements of TSO C146a.
2.3.1 Multiple Uncorrected Pressure Altitude Sources
The GTN can accept altitude from a RS-232 altitude encoder, fuel/air data computer (FADC),
ARINC 429 air data computer (ADC), ARINC 429 EFIS, and ARINC 429 traffic advisory system. If
multiple sources of altitude data are supplied to the GTN, only valid data from the highest priority source
is used (input priority cannot be configured). If the highest priority source becomes unavailable, data is
taken from the next-highest priority source. The priorities of the altitude sources are as follows (from
highest to lowest):
1. ARINC 429 ADC
2. ARINC 429 ADC/AHRS
3. ARINC 429 GDU
4. ARINC 429 EFIS/ADC
5. ARINC 429 Data Concentrator
6. ARINC 429 Traffic Advisory System
7. RS-232 Shadin Fuel and ADC
8. RS-232 Shadin Altitude or Icarus Altitude
GTN 725/750 TSO Installation Manual Page 2-3
190-01007-02 Rev. A
2.3.2 Multiple Baro-Corrected Altitude Sources
The GTN unit can accept baro-corrected altitude from multiple ARINC 429 and RS-232 sources.
If multiple sources of baro-corrected altitude data are supplied to the GTN, only valid data from the
highest priority source is used. If the highest priority source becomes unavailable, data is taken from the
next-highest priority source. The priorities of the baro-corrected altitude sources are as follows from
highest to lowest:
1. ARINC 429 label 204 from Airdata
2. ARINC 429 label 204 from Garmin GDU
3. ARINC 429 label 204 from EFIS/Airdata
4. ARINC 429 label 204 from Data Concentrator
5. RS-232 bus from Shadin Fuel and Air Data Computer
2.3.3 Multiple Heading Sources
The GTN unit can accept heading data from multiple ARINC 429, RS-232, and Synchro sources. If
multiple sources of heading data are supplied to the GTN, only valid data from the highest priority source
is used. If the highest priority source becomes unavailable, data is taken from the next-highest priority
source. The priorities of the heading sources are as follows from highest to lowest:
1. ARINC 429 label 314 from EFIS or Honeywell EFIS
2. ARINC 429 label 320 from EFIS or Honeywell EFIS, corrected for local magnetic variation
3. ARINC 429 label 320 from EFIS/Airdata, corrected for local magnetic variation
4. ARINC 429 label 320 from Garmin GDU, corrected for local magnetic variation
5. ARINC 429 label 314 from INS/IRU
6. ARINC 429 label 314 from Data Concentrator
7. ARINC 429 label 320 from INS/IRU, corrected for local magnetic variation
8. ARINC 429 label 320 from Airdata/AHRS, corrected for local magnetic variation
9. ARINC 429 label 320 from Garmin GAD 42, corrected for local magnetic variation
10. ARINC 429 label 320 from Sandel EHSI, corrected for local magnetic variation
11. ARINC 429 label 314 from GAD 42
12. XYZ Synchro
13. ARINC 429 label 320 from Data Concentrator
14. ARINC 429 label 320 from Traffic Advisory, corrected for local magnetic variation
15. RS-232 bus from Shadin Fuel and Air Data Computer
16. RS-232 bus from WX-500
Page 2-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
2.3.4 Multiple Indicated Airspeed Sources
The GTN unit can accept indicated airspeed data from multiple ARINC 429 and RS-232 sources. If
multiple sources of indicated airspeed data are supplied to the GTN, only valid data from the highest
priority source is used. If the highest priority source becomes unavailable, data is taken from the next-
highest priority source. The priorities of the indicated airspeed sources are as follows from highest to
lowest:
1. ARINC 429 label 206 from Garmin GDU
2. ARINC 429 label 206 from Airdata/AHRS
3. ARINC 429 label 206 from Data Concentrator
4. RS-232 bus from Shadin Fuel and Air Data Computer
2.3.5 Multiple True Airspeed Sources
The GTN unit can accept heading data from multiple ARINC 429 and RS-232 sources. If multiple
sources of true airspeed data are supplied to the GTN, only valid data from the highest priority source is
used. If the highest priority source becomes unavailable, data is taken from the next-highest priority
source. The priorities of the true airspeed sources are as follows from highest to lowest:
1. ARINC 429 label 210 from Airdata
2. ARINC 429 label 210 from Airdata/AHRS
3. ARINC 429 label 210 from Garmin GDU
4. ARINC 429 label 210 from EFIS/Airdata
5. ARINC 429 label 210 from Garmin GAD 42
6. ARINC 429 label 210 from Data Concentrator
7. RS-232 bus from Shadin Fuel and Air Data Computer
2.3.6 Multiple VLOC Course Select Sources
The GTN unit can accept VLOC course select data from the sources list below. If multiple sources of
VLOC course select data are supplied to the GTN, only valid data from the highest priority source is used.
If the highest priority source becomes unavailable, data is taken from the next-highest priority source. The
priorities of the VLOC course select sources are as follows from highest to lowest:
1. ARINC 429 label 100 from Sandel EHSI
2. ARINC 429 label 110 from Garmin GAD 42
3. TO/FROM course from the appliance’s Omni-Bearing Selector (OBS) control
GTN 725/750 TSO Installation Manual Page 2-5
190-01007-02 Rev. A
2.3.7 GPS Course Select Sources
The GTN unit can accept GPS course select data from multiple ARINC 429 sources. If multiple sources
of GPS course select data are supplied to the GTN, only valid data from the highest priority source is
used. If the highest priority source becomes unavailable, data is taken from the next-highest priority
source. The priorities of the GPS course select sources are as follows from highest to lowest:
1. ARINC 429 label 100 from EFIS or Honeywell EFIS
2. ARINC 429 label 100 from Garmin GDU
3. ARINC 429 label 100 from EFIS/Airdata
4. ARINC 429 label 100 from Sandel EHSI
5. ARINC 429 label 100 from Garmin GAD 42
6. ARINC 429 label 100 from Data Concentrator
7. TO/FROM course from the appliance's Omni-Bearing Selector (OBS) control
2.3.8 Total Air Temperature Sources
The GTN unit can accept total air temperature data from multiple ARINC 429 and RS-232 sources. If
multiple sources of total air temperature data are supplied to the GTN, only valid data from the highest
priority source is used. If the highest priority source becomes unavailable, data is taken from the next-
highest priority source. The priorities of the total air temperature sources are as follows from highest to
lowest:
1. ARINC 429 label 211 from Airdata
2. ARINC 429 label 211 from Garmin GDU
3. ARINC 429 label 211 from EFIS/Airdata
4. ARINC 429 label 211 from Data Concentrator
5. RS-232 bus from Shadin Fuel and Air Data Computer
2.3.9 Static Air Temperature Sources
The GTN unit can accept static air temperature data from multiple ARINC 429 sources. If multiple
sources of static air temperature data are supplied to the GTN, only valid data from the highest priority
source is used. If the highest priority source becomes unavailable, data is taken from the next-highest
priority source. The priorities of the static air temperature sources are as follows from highest to lowest:
1. ARINC 429 label 213 from Airdata
2. ARINC 429 label 213 from Garmin GDU
3. ARINC 429 label 213 from EFIS/Airdata
4. ARINC 429 label 213 from Data Concentrator
Page 2-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
2.3.10 Joystick Waypoint Data
The GTN unit can accept joystick waypoint data from multiple ARINC 429 sources. If multiple sources
of joystick waypoint data are supplied to the GTN, only valid data from the highest priority source is
used. If the highest priority source becomes unavailable, data is taken from the next-highest priority
source. The priorities of the joystick waypoint data sources are as follows from highest to lowest:
1. ARINC 429 labels 306 and 307 from EFIS or Honeywell EFIS
2. ARINC 429 labels 306 and 307 from Garmin GDU
3. ARINC 429 labels 306 and 307 from EFIS/Airdata
4. ARINC 429 labels 306 and 307 from Radar Graphics
5. ARINC 429 labels 306 and 307 from Garmin GAD 42
6. ARINC 429 labels 306 and 307 from Data Concentrator
GTN 725/750 TSO Installation Manual Page 2-7
190-01007-02 Rev. A
2.4 Antenna Considerations
This section contains mounting location considerations for the antennas required for the GTN units.
Structural substantiation for mounting of antennas is beyond the scope of the GTN AML STC. For
mounting the GA GPS/WAAS antenna, refer to Garmin GA Antenna AML STC SA01695SE or other
FAA approved data. For mounting the COM and NAV antennas, refer to the aircraft manufacturer’s data.
2.4.1 GPS Antenna Location
The GPS antenna is a key element in the overall system performance and integrity for a GPS/WAAS
navigation system. The mounting location, geometry, and surroundings of the antenna can affect the
system performance and/or availability. The following guidance provides information to aid the installer
in ensuring that the most optimum location is selected for the installation of the GPS antenna. The
installation guidelines presented here meet the intent of AC 20-138A section 16. The greater the variance
from these guidelines, the greater the chance of decreased availability. Approach procedures with vertical
guidance are the most sensitive to these effects. LNAV only approaches, terminal operations, and enroute
operations may also be affected. Because meeting all of these installations guidelines may not be possible
on all aircraft, these guidelines are listed in order of importance to achieve optimum performance. Items 3
below are of equal importance and their significance may depend on the aircraft installation. The installer
should use their best judgment to balance the installation guidelines.
1. Mount the antenna as close to level as possible with respect to the normal cruise flight
attitude of the aircraft. If the normal flight attitude is not known, substitute the waterline,
which is typically referenced as level while performing a weight and balance check.
2. The GPS antenna should be mounted in a location to minimize the effects of airframe
shadowing during typical maneuvers. Typically mounting farther away from the tail section
reduces signal blockage seen by the GPS antenna.
3a. The GPS antenna should be mounted no closer than two feet from any VHF COM antenna or
any other antenna which may emit harmonic interference at the L1 frequency of
1575.42 MHz. An aircraft EMC check (reference VHF COM interference check in Post
Installation Checkout procedures) can verify the degradation of GPS in the presence of
interference signals. If an EMC check reveals unacceptable interference, insert a GPS notch
filter in line with the offending VHF COM or the (re-radiating) ELT transmitter.
Note: When mounting a combination antenna (ex. GPS and COM, GPS and XM), the
recommended distance of two feet or more is not applicable to the distance between
the antenna elements provided the combination antenna is TSO authorized and has
been tested to meet Garmin’s minimum performance standards.
3b. The GPS antenna should be mounted no closer than two feet from any antennas emitting
more than 25 watts of power. An aircraft EMC check can verify the degradation of GPS in
the presence of interference signals.
3c. To minimize the effects of shadowing at 5° elevation angles, the GPS antenna should be
mounted no closer than 6” (edge to edge) from other antennas, including passive antennas
such as another GPS antenna or XM antenna.
4. To maintain a constant gain pattern and limit degradation by the windscreen, avoid mounting
the antenna closer than 3 inches from the windscreen.
5. For multiple GPS installations, the antennas should not be mounted in a straight line from the
front to the rear of the fuselage. Also varying the mounting location will help minimize any
aircraft shading by the wings or tail section (in a particular azimuth, when one antenna is
blocked the other antenna may have a clear view).
Figure 2-1 shows the recommended placement of antennas.
Page 2-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
2.4.2 COM Antenna Location
The GTN COM antenna should be well removed from all projections, engines and propellers. The ground
plane surface directly below the antenna should be a flat plane over as large an area as possible (18”
square, minimum). The antenna should be mounted a minimum of six feet from any DME or other COM
antennas, four feet from any ADF sense antennas, and two feet from the GTN and its GPS antenna. The
COM antenna should also be mounted as far apart as practical from the ELT antenna. Some ELTs have
exhibited re-radiation problems generating harmonics that may interfere with GPS signals. This can
happen when the COM (GTN or any other COM) is transmitting on certain frequencies such as 121.15 or
121.175 MHz, which may cause the ELT output circuit to oscillate from the signal coming in on the ELT
antenna coax.
If simultaneous use of two COM transceivers is desired (split-COM or simul-comm), use of the TX
interlock function is mandatory. In addition, the COM antennas should be spaced for maximum isolation.
A configuration of one topside antenna and one bottom side antenna is recommended.
GTN 725/750 TSO Installation Manual Page 2-9
190-01007-02 Rev. A
Figure 2-1. GPS Antenna Installation Considerations
Page 2-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
2.4.3 VOR/LOC Antenna Location
The GTN VOR/LOC antenna should be well removed from all projections, engines and propellers. It
should have a clear line of sight if possible. The antenna must be mounted along the centerline of the
aircraft, minimizing the lateral offset.
2.4.4 Glideslope Antenna Location
The GTN Glideslope antenna should be well removed from all projections, engines and propellers. It
should have a clear line of sight if possible.
2.4.5 Electrical Bonding
No special precautions need to be taken to provide a bonding path between the GPS antenna and the
aircraft structure. Follow the manufacturers’ instructions for the COM, VOR/LOC and Glideslope
antennas.
2.4.6 Interference of GPS
On some installations, VHF COM transceivers, Emergency Locator Transmitter (ELT) antennas, and
Direction Finder (DF) receiver antennas can re-radiate through the GPS antenna. The GTN COM does
not interfere with its own GPS section. However, placement of the GPS antenna relative to a COM
transceiver and COM antenna (including the GTN COM antenna), ELT antenna, and
DF receiver antenna is critical.
Use the following guidelines, in addition to others in this document, when locating the GTN and its
antennas.
• GPS Antenna—Locate as far as possible from all COM antennas and all COM transceivers
(including the GTN COM), ELT antennas, and DF receiver antennas. The GPS antenna is less
susceptible to harmonic interference if a 1.57542 GHz notch filter is installed on the COM
transceiver antenna output.
• Locate the GTN as far as possible from all COM antennas.
If a COM antenna is found to be the problem, a 1.57542 GHz notch filter (Garmin P/N 330-00067-00)
may be installed in the VHF COM coax, as close to the COM as possible. This filter is not required for
the GTN transmitter.
If a COM is found to be radiating, the following can be done:
1. Replace or clean VHF COM rack connector to ensure good coax ground.
2. Place a grounding brace between the GTN, VHF COM and ground.
3. Shield the VHF COM wiring harness.
COM, VOR/LOC, and Glideslope Antenna Installation Instructions
Install the COM, VOR/LOC, and Glideslope antennas according to the manufacturer’s recommendations.
Avoid running other wires and coaxial cables near the VOR/LOC antenna cable.
GTN 725/750 TSO Installation Manual Page 2-11
190-01007-02 Rev. A
2.5 Mounting Considerations
The GTN is designed to mount in the avionics stack in the aircraft instrument panel within view and reach
of the pilot. The primary unit location should minimize pilot head movement when transitioning between
looking outside of the cockpit and viewing/operating the GTN. The location should be such that the GTN
unit is not blocked by the glare shield on top, or by the throttles, control yoke, etc. on the bottom. If
aircraft has a throw-over yoke, be sure the yoke does not interfere with the GTN.
2.6 Cabling and Wiring Considerations
Wiring should be installed in accordance with AC 43.13-1B Chapter 11. For dual GTN unit installations,
care should be taken to ensure separation between wires of redundant systems to reduce the possibility of
loss of navigation due to a single event. When wire separation cannot be achieved, the following issues
should be addressed:
• It should not be possible for a cable harness to be exposed to wire chafing in a manner that both
GPS units fail simultaneously;
• The cable harness should not be located near flight control cables and controls, high electrical
capacity lines or fuel lines;
• The cable harness should be located in a protected area of the aircraft (e.g., isolated from engine
rotor burst); and
• Do not route cable near high-energy sources.
NOTE
Wiring which is required to be shielded must be shielded per Section 2.6. Pigtail lengths
must be less than 3.0 inches.
Refer to Section 3.7 and Section 3.8 for connector and tooling information.
Refer to Section 3.10 for recommended coax cable.
Refer to Appendix D for the appropriate wiring connections to assemble the wiring connector.
Once the cable assemblies have been made, attach the cable connectors to the rear connector plate. After
installing the mounting tube, attach the assembled connector plate. Route the wiring bundle as
appropriate. Use 22 to 24 AWG wire for all connections except for power. Use 20 AWG for power and
ground. Avoid sharp bends.
2.7 Air Circulation and Cooling
The GTN unit meets all TSO requirements without external cooling. However, as with all electronic
equipment, lower operating temperatures extend equipment life. On the average, reducing the operating
temperature by 15° to 20°C (27° to 36°F) reduces the mean time between failures (MTBF).
Units tightly packed in the avionics stack heat each other through radiation, convection, and sometimes
by direct conduction. Even a single unit operates at a much higher temperature in still air than in moving
air. Fans or some other means of moving the air around electronic equipment are usually a worthwhile
investment.
The GTN has a cooling fan integrated into the backplate to draw forced-air cooling through the unit.
There are inlets along the left, right, and bottom sides of the GTN bezel that allow air to flow through the
unit. Ensure that there are no obstructions to the air inlets. Air should be able to freely flow from the bezel
inlets to the backplate fan outlet on the rear of the unit.
2.8 Compass Safe Distance
After reconfiguring the avionics in the cockpit panel, if the GTN unit is mounted less than 12 inches from
the compass, recalibrate the compass and make the necessary changes for noting correction data.
Page 2-12 GTN 725/750 TSO Installation Manual
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GTN 725/750 TSO Installation Manual Page 3-1
190-01007-02 Rev. A
3. INSTALLATION PROCEDURES
3.1 Unit and Accessories
For description of units see Table 1-1.
Table 3-1. Catalog Part Numbers
Model Unit Only Kit Standard Kit Unit P/N Color COM
GTN 725 010-00819-00 010-00819-50 011-02281-00 BLK
010-00820-00 010-00820-50 011-02282-00 BLK 10W [1]
GTN 750 010-00890-00 010-00890-50 011-02282-50 GRY
[1] Unit is available with COM and is calibrated for both 10W and 16W COM; 16W COM is a
software enablement feature using an enablement card.
Table 3-2. Standard Kit Accessories
Model Item Part Number
Mounting Rack 115-01294-00
Connector Kit 011-02326-00
Back Plate Assembly 011-02246-00
GTN 725
Product Information Kit K00-00488-00
Mounting Rack 115-01294-00
Connector Kit 011-02326-02
Back Plate Assembly 011-02246-02
GTN 750
Product Information Kit K00-00488-00
Page 3-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
3.2 Optional Accessories
3.2.1 GPS Antenna Options
For details regarding antenna selection, refer to Section 1.3.8. Once the antenna type is decided upon,
refer to the information below for detailed parts information for antennas available directly from Garmin.
Contact manufacturer directly for information on other antennas.
GA 35 Antenna:
GA 35 Antenna Garmin P/N 013-00235-00 contains the following items:
ITEM PART NUMBER QTY
013-00235-00 (Garmin)
GA 35 GPS/WAAS Antenna [1] AT575-93G (Aero Antenna) 1
[1] Antenna includes 8-32 UNC-2A x 1.00” SS 303 mounting screws (qty 4) and O-ring (qty 1).
An antenna doubler may also be required. Refer to the appropriate antenna installation data.
To secure the antenna #8 washers (qty 4) and #8 (qty 4) self-locking nuts are required in addition to
the antenna, or suitable nutplates may be installed on the doubler.
To connect the GPS antenna coaxial cable to the antenna a TNC plug is required.
GA 36 Antenna:
GA 36 Antenna Garmin P/N 013-00244-00 contains the following items:
ITEM PART NUMBER QTY
013-00244-00 (Garmin)
GA 36 GPS/WAAS Antenna [1] AT575-126G (Aero Antenna) 1
[1] Antenna includes 8-32 UNC-2A x 1.00” SS 303 mounting screws (qty 4) and O-ring (qty 1).
An antenna doubler may also be required. Refer to the appropriate antenna installation data.
To secure the antenna #8 washers (qty 4) and #8 (qty 4) self-locking nuts are required in addition to
the antenna, or suitable nutplates may be installed on the doubler.
To connect the GPS antenna coaxial cable to the antenna a TNC plug is required.
GA 37 Antenna:
GA 37 Antenna Garmin P/N 013-00245-00 contains the following items:
ITEM PART NUMBER QTY
013-00245-00 (Garmin)
GA 37 GPS/WAAS + XM Antenna [1] AT2300-126G (Aero Antenna) 1
[1] Antenna includes 8-32 UNC-2A x 1.00” SS 303 mounting screws (qty 4) and O-ring (qty 1).
An antenna doubler may also be required. Refer to the appropriate antenna installation data.
To secure the antenna #8 washers (qty 4) and #8 (qty 4) self-locking nuts are required in addition to
the antenna, or suitable nutplates may be installed on the doubler.
To connect the GPS antenna coaxial cable to the antenna a TNC plug is required.
A33W Antenna:
ITEM PART NUMBER QTY
A33W, WAAS [1] 013-00261-00 (Garmin) 1
[1] Antenna includes 6-32 UNC-2A x 1.00” SS 303 mounting screws (qty 4) and O-ring (qty 1).
An antenna doubler may also be required. To secure the antenna, #6 washers (qty 4) and #6 (qty 4)
self-locking nuts are required in addition to the antenna, or suitable nutplates may be installed on the
doubler that is used.
To connect the GPS antenna coaxial cable to the antenna a TNC plug is required.
GTN 725/750 TSO Installation Manual Page 3-3
190-01007-02 Rev. A
3.3 Database Options
ITEM GARMIN P/N
Data Card, World Wide (Aviation Database) 010-10546-00
Data Card, Americas (Aviation Database) 010-10546-01
Data Card, International (Aviation Database) 010-10546-02
Data Card, TAWS/Terrain (128 MB) (Note 1) 010-xxxxx-xx
Data Card, TAWS/Terrain (256 MB) (Note 1) 010-xxxxx-xx
Note 1: Data cards 010-xxxxx-xx and 010-xxxxx-xx are functionally equivalent.
3.4 Miscellaneous Options
ITEM GARMIN P/N
Connector, BNC, Male, Clamp 330-00087-00
GPS 1.57542 GHz Notch Filter 330-00067-00
3.5 Optional Reference Material
ITEM GARMIN P/N
GTN 725/750 Pilot’s Guide 190-01007-03
GTN 725/750 Cockpit Reference Guide 190-01007-04
GTN 725/750 Training CD TBD
Page 3-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
3.6 Installation Materials Required but Not Provided
3.6.1 Optional Accessories Not Supplied
The following installation accessories are required but not provided.
ITEM REQUIREMENTS
COM Antenna Shall meet TSO C37( ) and C38( ). Broad band, 50Ω, vertically polarized
with coaxial cable
VOR/LOC Antenna Shall meet TSO C40( ) and C36( ). Broad band, 50Ω, horizontally
polarized with coaxial cable
Glideslope Antenna Shall meet TSO C34( ). Broad band, 50Ω, horizontally polarized with
coaxial cable or low-loss splitter used with the VOR/LOC antenna
Headphones 500Ω nominal impedance
Microphone Low impedance, carbon or dynamic, with transistorized pre-amp
3.6.2 Materials Required But Not Supplied (New Installations Only)
The GTN is intended for use with the standard aviation accessories. The following items are required for
installation, but not supplied:
• Wire (MIL-W-22759/16 or equivalent)
• Shielded Wire (MIL-C-27500 or equivalent)
• Mounting Screws (8 minimum – AN577 6-32 screw with 100° countersink)
• Circuit Breakers
• Tie Wraps or Lacing Cord
• Ring Terminals (for grounding)
• Coaxial Cable (RG-400, RG-142B or equivalent – Refer to Section 3.10 for additional
information).
3.7 Special Tools Required
Some of the connectors use crimp contacts. The table below identifies crimp tools required to ensure
consistent, reliable crimp contact connections for the rear D-sub connectors.
Table 3-3. Recommended Crimp Tools (or Equivalent)
22 – 28 AWG (P1001 – P1005)
Manufacturer Hand Crimping
Tool Positioner Insertion/
Extraction Tool
Military P/N M22520/2-01 M22520/2-09 M81969/14-01
M81969/1-04
Positronic 9507 9502-3 M81969/1-04
ITT Cannon 995-0001-584 995-0001-739 N/A
AMP 601966-1 601966-6 91067-1
Daniels AFM8 K42 N/A
Astro 615717 615725 N/A
NOTE
Insertion/extraction tools from ITT Cannon are all plastic; others are plastic with metal tip.
GTN 725/750 TSO Installation Manual Page 3-5
190-01007-02 Rev. A
3.8 Cable Installation
Follow the steps below for installation of the coax cables:
1. Route the coaxial cable to the rack location keeping in mind the recommendations of Section 2.6.
Secure the cable in accordance with good aviation practice.
2. Trim the coaxial cable to the desired length and install the BNC connector (330-00087-00)
per the cabling instructions on Figure 3-1.. If the connector is provided by the installer, follow
the connector manufacturer’s instructions for cable preparation.
Figure 3-1. Coaxial Cable Installation
The card-edge connector may be used to terminate shield grounds to the GTN unit back plate.
Feed wires through the connector backshells before insertion into the 25-, 44-, and 78-pin connectors.
Contacts for the 25-, 44-, and 78-pin connectors must be crimped onto the individual wires of the aircraft
wiring harness. The following table lists contact part numbers (for reference). See Table 3-3 for
recommended crimp tools.
Page 3-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Table 3-4. Socket Contact Part Numbers
Configuration Module
78-pin Connector (P1001) P1001-P1005
Wire Gauge
28 AWG [1] 22-28 AWG [2]
Garmin P/N 336-00021-00 336-00021-00
Military P/N N/A M39029/58-360
AMP N/A 204370-2
Positronic N/A MC8522D
ITT Cannon N/A 010-2042-000
Notes:
[1] For configuration module pins, ensure that the crimp tool is set to crimp 28 AWG wire
(indenter setting of ‘4’).
[2] Contacts listed are not to be used for configuration module wiring. Use the contacts
supplied with the configuration module when installing configuration module wires in
P1001.
GTN 725/750 TSO Installation Manual Page 3-7
190-01007-02 Rev. A
3.9 Equipment Mounting
3.9.1 Rack Installation
Use the dimensions shown in TBD to prepare the mounting holes for the GTN unit. You may also use the
GTN unit mounting rack itself as a template for drilling the mounting holes.
1. The back plate of the rack may optionally be removed for ease of mounting in the aircraft panel.
To do so, remove the two #4-40 screws, tilt the back plate away from the tray, and then slide the
back plate to the side.
2. TBD shows outline dimensions for the aviation rack for the various GTN units. Install the rack in
a rectangular 6.320” x 4.600” hole (or gap between units) in the instrument panel (see TBD). The
lower-front lip of the rack should be flush with, or extend slightly beyond, the finished aircraft
panel.
NOTE
If the front lip of the mounting rack is behind the surface of the aircraft panel, the
GTN unit connectors may not fully engage.
Make sure that no screw heads or other obstructions prevent the unit from fully engaging
in the rack (see the “Connector Engagement Test,” Section 5.3). Exercise caution when
installing the rack into the instrument panel. The rack is designed to facilitate removal of
the GTN unit for use in Demo Mode outside the aircraft. Deformation of the rack may
make it difficult to install and remove the GTN unit.
3. Install the rack in the aircraft panel using six #6-32 flat head screws and six self-locking nuts.
The screws are inserted from the inside through the holes in the sides of the rack.
4. If the back plate was previously removed (see Step 1), replace the back plate by positioning the
tabs on the back plate in the slots of the left side of the rack (viewing it from the cockpit) and
attaching it by replacing the two #4-40 screws.
3.9.2 GTN Unit Insertion and Removal
It may be necessary to insert the hex drive tool into the access hole and rotate the mechanism 90°
counterclockwise to insure correct position prior to placing the unit in the rack. The GTN unit is installed
in the rack by sliding it straight in until it stops, about 1 inch short of the final position. A 3/32-inch hex
drive tool is then inserted into the access hole at the bottom of the unit face. Rotate the hex tool clockwise
while pressing on the left side of the bezel until the unit is firmly seated in the rack.
To remove the unit from the rack, insert the hex drive tool into the access hole on the unit face and rotate
counterclockwise until the unit is forced out about 3/8 inches and can be freely pulled from the rack.
Be sure not to over tighten the unit into the rack. The application of hex drive tool torque exceeding
15 in-lbs can damage the locking mechanism.
3.9.3 Unit Replacement
Whenever the GTN unit is removed or reinstalled, verify that the unit power-up self-test sequence is
successfully completed and no failure messages are annunciated. Section TBD outlines the power-up self-
test sequence.
Page 3-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
3.10 Antenna Installation and Connections
3.10.1 GPS Antenna
This section provides information on the antenna cable installation. Refer to 0 herein for installation
location considerations.
NOTE
The internal GTN unit COM does not interfere with its own GPS receiver. However,
placement of the GTN unit antenna relative to other COM transceivers and antennas
(including the GTN unit COM antenna) is critical.
SUGGESTION: Temporarily locate the GPS antenna with coax connected to the GTN unit and check
the GPS performance as described in Section TBD and Section TBD. Once a suitable location has been
verified, then permanently mount the antenna.
Once the antenna mounting position has been prepared, route the coax cable from the antenna to the GTN
unit. Proper selection of coax cable and assembly of connectors is critical to GPS signal performance.
The cable loss from the GPS antenna shall be between 1.5 dB and 6.5 dB in order to maintain
proper rejection to interference signals.
The coaxial connectors and adapters, such as TNC to BNC, add additional loss to the cable and should be
considered when computing the cable loss. A typical loss of 0.2 dB can be used for each connection. To
maintain integrity of the WAAS signal, the GPS antenna coaxial cable must have a minimum of two
shields (e.g. RG-400 or RG-142B).
NOTE
If RG-142B or RG-400 is used, 1.5 dB equates to a length of approximately 6.5 feet of
cable with a connector on each end. RG-142B or RG-400 cable can be used as long as
the length is less than 35 feet. For longer lengths, use low-loss double or triple shielded
50Ω coax.
For very short runs, where the loss is less than 1.5 dB, additional cable should be used to increase the loss
to within 1.5 dB to 6.5 dB. This additional cable may be coiled, taking into account the minimum bend
radius of the cable.
During the post-installation checkout, susceptibility to harmonics of VHF COM transmitters will be
evaluated. If problems arise, then better isolation, or distance, may be required between the GPS and
COM antennas, or a 1575.42 MHz notch filter may be installed in series with the antenna coax of the
VHF COM transceiver to reduce or eliminate the harmonic interference. A notch filter for this use
(P/N 330-00067-00) is available from Garmin.
If a VHF COM transmitter causes problems with the GPS on the selected frequencies as listed in the post-
installation checkout, the problem may be due to the ELT. This can be verified by disconnecting the ELT
antenna coax at the ELT unit. If the ELT is found to cause the problem, then contact the ELT
manufacturer or replace the ELT.
GTN 725/750 TSO Installation Manual Page 3-9
190-01007-02 Rev. A
3.10.2 COM Antenna
The GTN unit requires a standard 50Ω vertically polarized antenna. Follow the antenna manufacturer’s
installation instructions for mounting the antenna.
The antenna should be mounted on a metal surface or a ground plane with a minimum area of
18 inches x 18 inches. Refer to Section 2.4.2 for installation location considerations.
The antenna coax cable should be made of RG-142B, RG-400 or a comparable quality 50Ω coax.
Check for insertion loss and VSWR (voltage standing wave ratio). VSWR should be checked with an in-
line type VSWR/wattmeter inserted in the coaxial transmission line between the transceiver and the
antenna. The VSWR should be inserted as close to the transceiver as possible. When rack and harness
buildup is performed in the shop, the coax termination may be provisioned by using a 6-inch inline BNC
connection. This would be an acceptable place to insert the VSWR. Any problem with the antenna
installation is most likely seen as high reflected power. A VSWR of 3:1 may result in up to a 50% loss in
transmit power.
3.10.3 NAV Antenna
The NAV antenna is a standard 50Ω horizontally polarized NAV/VOR/Localizer/Glideslope antenna (the
glideslope may be a separate antenna in some aircraft) that receives VOR frequencies between 108 and
117.95 MHz, and localizer frequencies between 108 and 112 MHz, and glideslope information between
328.6 and 335.4 MHz. Follow the antenna manufacturer’s installation instructions for mounting antennas.
It is recommended that the installer use RG-142B, RG-400 or equivalent 50Ω coax for the NAV
antenna(s).
The GTN has a single VOR/LOC/Glideslope input requiring some installations to use a standard external
diplexer or triplexer. See Section TBD.
Page 3-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
This page intentionally left blank
GTN 725/750 TSO Installation Manual Page 4-1
190-01007-02 Rev. A
4. SYSTEM INTERCONNECTS
4.1 Pin Function List
4.1.1 P1001 Main Connector – Main Board
(View looking at rear of unit, Pin 1 is top right)
1
2
345678910111314151617181920
2223242526
27
282930313233343536373839
4041
21
42434445
46
47484950515253545556575859
606162
636465
66
676869707172737475767778
Pin Pin Name I/O
1 MAIN OBS ROTOR H (GND) --
2 MAIN OBS ROTOR C Out
3 TIME MARK OUT A Out
4 AUDIO OUT HI Out
5 RS-232 OUT 4 Out
6 RS-232 OUT 3 Out
7 RS-232 OUT 2 Out
8 RS-232 OUT 1 Out
9 ARINC 429 OUT 2A Out
10 ARINC 429 OUT 1A Out
11 MAIN +TO OUT Out
12 MAIN VERTICAL +UP OUT Out
13 MAIN LATERAL SUPERFLAG OUT Out
14 OBS ANNUNCIATE* Out
15 GPS ANNUNCIATE* Out
16 OBS MODE SELECT* In
17 LIGHTING BUS 1 LO In
18 LIGHTING BUS 1 HI In
19 AIRCRAFT POWER In
20 AIRCRAFT POWER In
21 MAIN OBS STATOR D In
22 TIME MARK OUT B Out
23 AUDIO OUT LO Out
24 RS-232 IN 4 In
25 RS-232 IN 3 In
26 RS-232 IN 2 In
27 RS-232 IN 1 In
28 ARINC 429 OUT 2B Out
29 ARINC 429 OUT 1B Out
30 MAIN +FROM OUT Out
31 MAIN VERTICAL +DOWN OUT Out
32 MAIN VERTICAL SUPERFLAG OUT Out
33 WAYPOINT ANNUNCIATE* Out
34 TERMINAL ANNUNCIATE* Out
35 TAWS AUDIO ACTIVE OUT* Out
36 AUDIO INHIBIT IN* In
37 TAWS INHIBIT IN* In
38 AIR/GROUND* --
39 CDI SOURCE SELECT* In
40 MAIN OBS STATOR E (GND) --
41 MAIN OBS STATOR F In
Page 4-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
P1001 Connector Cont’d
Pin Pin Name I/O
42 LIGHTING BUS 2 LO In
43 FAN GROUND --
44 RS-232 GND 3/4 --
45 RS-232 GND 2 --
46 RS-232 GND 1 --
47 ARINC 429 IN 2A In
48 ARINC 429 IN 1A In
49 MAIN LATERAL +LEFT OUT Out
50 MAIN LATERAL +FLAG OUT Out
51 MAIN VERTICAL +FLAG OUT Out
52 VLOC ANNUNCIATE* Out
53 LOI ANNUNCIATE* Out
54 MESSAGE ANNUNCIATE* Out
55 APPROACH ANNUNCIATE* Out
56 ILS/GPS APPROACH Out
57 TAWS INHIBIT ANNUNCIATE* Out
58 FAN TACH IN In
59 FAN POWER OUT (12 VDC) Out
60 MAIN OBS STATOR G (GND) --
61 LIGHTING BUS 2 HI In
62 CONFIG MODULE DATA I/O
63 CONFIG MODULE CLOCK Out
64 CONFIG MODULE GND Out
65 CONFIG MODULE POWER Out
66 ARINC 429 IN 2B In
67 ARINC 429 IN 1B In
68 MAIN LATERAL +RIGHT OUT Out
69 MAIN LATERAL -FLAG OUT Out
70 MAIN VERTICAL -FLAG OUT Out
71 TERRAIN WARNING ANNUNCIATE* Out
72 TERRAIN NOT AVAILABLE ANNUNCIATE* Out
73 TERRAIN CAUTION ANNUNCIATE* Out
74 GPS SELECT* Out
75 TRAFFIC TEST* Out
76 TRAFFIC STANDBY* Out
77 AIRCRAFT GND --
78 AIRCRAFT GND --
GTN 725/750 TSO Installation Manual Page 4-3
190-01007-02 Rev. A
4.1.2 P1002 Connector
(View looking at rear of unit, Pin 1 is top right)
123456789
1011
131415161718
1920
2223242526 21
Pin Pin Name I/O
1 DEMO MODE SELECT* In
2 RESERVED In
3 SPARE DISC OUT A* Out
4 ETHERNET OUT 4A Out
5 ETHERNET OUT 4B Out
6 ETHERNET IN 1A In
7 ETHERNET IN 1B In
8 ETHERNET OUT 1A Out
9 ETHERNET OUT 1B Out
10 SYSTEM ID PROGRAM* In
11 SPARE DISC IN D* In
12 SPARE DISC OUT B* Out
13 ETHERNET IN 4A In
14 ETHERNET IN 4B In
15 ETHERNET IN 2A In
16 ETHERNET IN 2B In
17 ETHERNET OUT 2A Out
18 ETHERNET OUT 2B Out
19 RS-422 IN A In
20 RS-422 IN B In
21 RS-422 OUT A Out
22 RS-422 OUT B Out
23 ETHERNET IN 3A In
24 ETHERNET IN 3B In
25 ETHERNET OUT 3A Out
26 ETHERNET OUT 3B Out
Page 4-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.1.3 P1003 COM Connector
(View looking at rear of unit, Pin 1 is top right)
1234567891011131415
1617181920
2223242526
27
282930 21
313233343536373839
4041
424344
Pin Pin Name I/O
1 RESERVED Out
2 RESERVED In
3 AUX AUDIO LINE LEVEL HI (function not currently implemented) In
4 AUX AUDIO SIGNAL LEVEL HI (function not currently implemented) In
5 COM MIC 1 AUDIO IN HI In
6 COM MIC 2 AUDIO IN HI (function not currently implemented) In
7 500 Ω COM AUDIO HI Out
8 RESERVED In
9 RESERVED In
10 RESERVED In
11 COM MIC 1 KEY* In
12 INTERCOM ENABLE* (function not currently implemented) In
13 SPEAKER OUT (function not currently implemented) Out
14 RESERVED In
15 RESERVED Out
16 RESERVED In
17 RESERVED In
18 500 Ω COM AUDIO LO --
19 AUX AUDIO LINE LEVEL GND (function not currently implemented) --
20 MIC AUDIO IN LO In
21 AUX AUDIO SIGNAL LEVEL GND (function not currently implemented) --
22 RESERVED In
23 RESERVED Out
24 RESERVED Out
25 RESERVED Out
26 COM MIC 2 KEY* (function not currently implemented) In
27 COM REMOTE TRANSFER* In
28 COM REMOTE TUNE UP* In
29 COM REMOTE TUNE DOWN* In
30 AIRCRAFT POWER In
31 RESERVED --
32 RESERVED In
33 RESERVED Out
34 RESERVED --
35 RESERVED Out
36 RESERVED --
37 AIRCRAFT GND --
38 AIRCRAFT GND --
39 SPEAKER GND (function not currently implemented) --
40 AIRCRAFT GND --
41 RESERVED In
42 RESERVED In
43 AIRCRAFT POWER In
44 AIRCRAFT POWER In
GTN 725/750 TSO Installation Manual Page 4-5
190-01007-02 Rev. A
4.1.4 P1004 NAV Connector
(View looking at rear of unit, Pin 1 is on bottom left)
1234567891011 13 14 15 16 17 18 19 20 21
4241403938
37
363534333231302928272625
2423
22
626160
59
58575655545352515049484746
454443
Pin Pin Name I/O
1 VOR/LOC +TO Out
2 VOR/LOC +FROM Out
3 VOR/LOC +FLAG Out
4 VOR/LOC -FLAG Out
5 VOR/LOC +LEFT Out
6 VOR/LOC +RIGHT Out
7 RESERVED Out
8 VOR/LOC COMPOSITE OUT Out
9 VOR OBS ROTOR C Out
10 VOR OBS ROTOR H (GND) Out
11 VOR OBS STATOR E (GND) Out
12 VOR OBS STATOR F In
13 VOR OBS STATOR D In
14 VOR OBS STATOR G (GND) Out
15 VOR/LOC SUPERFLAG Out
16 500 Ω VOR/LOC AUDIO OUT HI Out
17 500 Ω VOR/LOC AUDIO OUT LO Out
18 SERIAL DME - CLOCK In/Out
19 SERIAL DME - DATA In/Out
20 SERIAL DME- RNAV/CH REQ In
21 SERIAL DME - RNAV MODE In
22 AIRCRAFT GND --
23 VOR/ILS ARINC 429 OUT B Out
24 VOR/ILS ARINC 429 OUT A Out
25 VOR OBI CLOCK In
26 VOR OBI SYNC In
27 VOR OBI DATA In
28 VLOC REMOTE TRANSFER In
29 ILS ENERGIZE Out
30 RESERVED --
31 RESERVED --
32 GLIDESLOPE +FLAG Out
33 PAR DME 1MHZ-D/SERIAL DME ON Out
34 GLIDESLOPE +UP Out
35 VOR/ILS ARINC 429 IN B In
36 VOR/ILS ARINC 429 IN A In
37 PAR DME 100KHZ-A/SERIAL DME HOLD Out
38 GLIDESLOPE SUPERFLAG Out
39 PAR DME 100KHZ-B Out
40 PAR DME 100KHZ-C Out
41 DME COMMON In
42 PAR DME 100KHZ-D Out
43 PAR DME 50KHZ Out
44 SERIAL DME - DME REQUEST In/Out
45 PAR DME 1MHZ-A Out
46 PAR DME 1MHZ-B Out
Page 4-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
P1004 Connector Cont’d
Pin Pin Name I/O
47 PAR DME 1MHZ-C Out
48 RESERVED --
49 AIRCRAFT GND --
50 RESERVED --
51 AIRCRAFT POWER In
52 AIRCRAFT POWER In
53 GLIDESLOPE -FLAG Out
54 PAR DME 100KHZ-E Out
55 GLIDESLOPE +DOWN Out
56 PAR DME 1MHZ-E Out
57 RESERVED --
58 GLIDESLOPE COMPOSITE OUT Out
59 VOR/LOC DIGITAL AUDIO OUT Out
60 AIRCRAFT GND --
61 AIRCRAFT GND --
62 AIRCRAFT GND --
GTN 725/750 TSO Installation Manual Page 4-7
190-01007-02 Rev. A
4.2 I/O Board
4.2.1 P1005 Connector
(View looking at rear of unit, Pin 1 is on bottom left)
1234567891011 13 14 15 16 17 18 19 20 21
4241403938
37
363534333231302928272625
2423
22
626160
59
58575655545352515049484746
454443
Pin Pin Name I/O
1 VIDEO INPUT 2 (function not currently implemented) In
2 VIDEO INPUT 1 (function not currently implemented) In
3 RESERVED --
4 RESERVED --
5 RESERVED --
6 RESERVED --
7 ARINC 429 OUT 3B Out
8 RS-232 OUT 5 Out
9 RS-232 OUT 6 Out
10 RS-485 2A/422 OUT 1 (function not currently implemented) Out
11 RS-485 2B/422 OUT 2 (function not currently implemented) Out
12 RESERVED --
13 WX RADAR ON* (function not currently implemented) Out
14 SYNCHRO Y In
15 SYNCHRO REF LO In
16 ARINC 429 IN 3B In
17 ARINC 429 IN 4B In
18 ARINC 453/708 IN 1A (function not currently implemented) In
19 ARINC 453/708 TERM 1B (function not currently implemented) In
20 ARINC 453/708 IN 2A (function not currently implemented) In
21 ARINC 453/708 TERM 2B (function not currently implemented) In
22 VIDEO INPUT 2 GND (function not currently implemented) In
23 VIDEO INPUT 1 GND (function not currently implemented) In
24 RESERVED --
25 RESERVED --
26 RESERVED --
27 RESERVED --
28 ARINC 429 OUT 3A Out
29 RS-232 IN 5 In
30 RS-232 IN 6 In
31 RS-485 1A/422 IN 1 (function not currently implemented) In
32 RS-485 1B/422 IN 2 (function not currently implemented) In
33 SYNCHRO VALID INPUT (ACTIVE LO) In
34 SPARE OUTPUT C Out
35 SYNCHRO X In
36 SYNCHRO REF HIGH In
37 ARINC 429 IN 3A In
38 ARINC 429 IN 4A In
39 RESERVED --
40 ARINC 453/708 TERM 1A (function not currently implemented) In
41 RESERVED --
42 ARINC 453/708 TERM 2A (function not currently implemented) In
43 RESERVED --
44 RESERVED --
Page 4-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
P1005 Connector Cont’d
Pin Pin Name I/O
45 RESERVED --
46 RESERVED --
47 RESERVED --
48 RESERVED --
49 RS-232 GND 5 --
50 RS-232 GND 6 --
51 RESERVED --
52 RESERVED --
53 SPARE INPUT 1 In
54 SYNCHRO VALID INPUT (ACTIVE HI) --
55 RESERVED --
56 SYNCHRO Z In
57 RESERVED --
58 RESERVED --
59 RESERVED --
60 ARINC 453/708 IN 1B (function not currently implemented) In
61 RESERVED --
62 ARINC 453/708 IN 2B (function not currently implemented) In
GTN 725/750 TSO Installation Manual Page 4-9
190-01007-02 Rev. A
4.3 Power, Lighting, And Antennas
This section covers the power input requirements, lighting bus input, and antenna connections.
See Figure TBD for interconnect information.
4.3.1 Power
Pin Name Connector Pin I/O
AIRCRAFT POWER (MAIN) P1001 19 In
AIRCRAFT POWER (MAIN) P1001 20 In
AIRCRAFT POWER (COM) P1003 30 In
AIRCRAFT POWER (COM) P1003 43 In
AIRCRAFT POWER (COM) P1003 44 In
AIRCRAFT POWER (NAV) P1004 51 In
AIRCRAFT POWER (NAV) P1004 52 In
AIRCRAFT GROUND (MAIN) P1001 77 --
AIRCRAFT GROUND (MAIN) P1001 78 --
AIRCRAFT GROUND (COM) P1003 37 --
AIRCRAFT GROUND (COM) P1003 38 --
AIRCRAFT GROUND (COM) P1003 40 --
AIRCRAFT GROUND (NAV) P1004 61 --
AIRCRAFT GROUND (NAV) P1004 62 --
The power inputs P1001-19 and P1001-20 provide power for everything except for the COM radio and
NAV radio. Both pins must be connected.
The power inputs P1003-30, P1003-43, and P1003-44 provide power for the COM radio. All three pins
must be connected.
The power inputs P1004-51 and P1004-52 provide power for the NAV radio. Both pins must be
connected.
4.3.2 Lighting Bus
Pin Name Connector Pin I/O
LIGHTING BUS 1 HI P1001 18 In
LIGHTING BUS 1 LO P1001 17 In
LIGHTING BUS 2 HI P1001 42 In
LIGHTING BUS 2 LO P1001 61 In
The GTN can be configured to track 28 VDC, 14 VDC, 5 VDC or 5 VAC lighting buses using these
inputs. Two lighting buses allow for independent control of display and bezel lighting. Alternatively, the
GTN can automatically adjust for ambient lighting conditions based on the photocell. Refer to Section
TBD for instructions on configuring the lighting inputs.
4.3.3 Antennas
Pin Name Connector I/O
GPS/WAAS ANTENNA P1006 In
COM ANTENNA P1007 I/O
NAV ANTENNA P1008 In
The GPS/WAAS, COM, and NAV antennas use BNC coaxial connectors on the connector backplate.
Reference Figure TBD for splitter/diplexer block diagrams.
Page 4-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.4 Serial Data
4.3.4.1 Serial Data Function
4.3.4.1.1 RS-232
The GTN is capable of interfacing with other aviation instruments by transmitting RS-232 Type 1 (often
known as ARNAV format) and Type 2 (often known as Northstar format) data on any RS-232 OUT port.
The data consists of the following (refer to Section B.1 for a detailed data format description):
• Current latitude, longitude, and GPS altitude in feet (see Note below)
• Current velocity vector (ground speed and direction of velocity vector over the ground)
• Distance to waypoint
• Cross track error
• Desired track
• Destination waypoint identifier
• Bearing to destination waypoint
• Magnetic variation
• Navigation and warning status
• Waypoint sequence in route
• Waypoint position (latitude and longitude) and magnetic variation
NOTE
Aviation RS-232 data may be transmitted with or without the current GPS altitude in feet.
Refer to Appendix B.
The GTN can receive pressure altitude, air data, and fuel data from certain systems on any RS-232 IN port.
If a GTN is installed with a 400W or 500W Series in an aircraft, any of the RS-232 ports on the GTN may
be cross-connected to RS-232 Port 3 on the GTN to manually transfer user-defined waypoints between
the two units.
GTN 725/750 TSO Installation Manual Page 4-11
190-01007-02 Rev. A
4.3.4.1.2 ARINC 429
The data output on the ARINC 429 OUT ports depends on the configuration (see Section TBD). Below is
a list of the configurations and the labels output for each one:
• ARINC 429
• GAMA 429
• GAMA 429 Graphics
• GAMA 429 Graphics w/Int
• GAMA 429 Pro Line 21
• GAMA 429 Sextant
• GAMA 429 Bendix King
Label # Parameter Name 1 2 3 4 5 6 7
001 Distance to Go (BCD) ● ● ● ● ● ● ●
002 Time to Go (BCD) ● ● ● ● ● ● ●
012 Ground Speed (BCD) ● ● ● ● ● ● ●
074G Data Record Header ● ● ● ● ● ●
075G Active Wpt From/To Data ● ● ● ● ● ●
100 Selected Course 1 ●
100P Selected Course 1 ● ● ● ● ● ●
113G Message Checksum ● ● ● ● ● ●
114 Desired Track (True) ● ● ● ● ● ● ●
115 Waypoint Bearing (True) ● ● ● ● ● ● ●
116 Cross Track Distance ●
116G [1] Cross Track Distance ● ● ● ● ● ●
117G Vertical Deviation ● ● ● ● ●
117P Vertical Deviation ●
121 Horizontal Command (to Autopilot) ● ● ● ● ● ● ●
125 Greenwich Mean Time (BCD) ● ● ● ● ● ● ●
147G Magnetic Variation ● ● ● ● ● ●
251 Distance to Go ●
251G Distance to Go ● ● ● ● ● ●
252 Time to Go ● ● ● ● ● ● ●
260G Date (BCD) ● ● ● ● ● ●
261G GPS Discrete Word 1 ● ● ● ● ● ●
275G LRN Status Word ● ● ● ● ● ●
300G Station Declination, Type, and Class ● ● ● ● ● ●
303 Message Length/Type/Number ● ● ● ● ● ●
304G Message Characters 1-3 ● ● ● ● ● ●
305G Message Characters 4-6 ● ● ● ● ● ●
306G NAV/Waypoint/Airport Latitude ● ● ● ● ● ●
307G NAV/Waypoint/Airport Longitude ● ● ● ● ● ●
310 Present Position Latitude ● ● ● ● ● ● ●
311 Present Position Longitude ● ● ● ● ● ● ●
312 Ground Speed ● ● ● ● ● ● ●
313 Track Angle (True) ● ● ● ● ● ● ●
314 True Heading ● ● ● ● ● ● ●
315 Wind Speed ● ● ● ● ● ● ●
316 Wind Angle (True) ● ● ● ● ● ● ●
320 Magnetic Heading ● ● ● ● ● ● ●
Page 4-12 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Label # Parameter Name 1 2 3 4 5 6 7
321 Drift Angle ● ● ● ● ● ● ●
326G [1] Lateral Scale Factor ● ● ● ● ● ●
327G Vertical Scale Factor ● ● ● ● ●
330 Conic Arc Inbound Course ● ●
331 Conic Arc Radius ● ●
332 Conic Arc Course Change Angle ● ●
333 Airport Runway Azimuth ● ●
334 Airport Runway Length in Feet ● ●
335 Left/Right Hand Holding Pattern Azimuth ● ●
340 Left/Right Hand Procedure Turn Azimuth ● ●
351G Distance to Destination (Via Flight Plan) ● ● ● ● ● ●
352G Estimated Time to Destination (Via Flight Plan) ● ● ● ● ● ●
371G Specific Equipment ID ● ● ● ● ● ●
377 Equipment Hex ID Code ● ● ● ● ● ● ●
[1] Label 116G and 326G utilize the optional resolution extension bits (bits 11-13).
The following labels are output on the VOR/ILS ARINC 429 OUT port:
Label # Parameter Name
034G VOR/ILS Frequency (BCD)
035G DME Frequency (BCD)
100G Selected Course #1
173 Localizer Deviation
174 Glideslope Deviation
222 VOR Omnibearing
371G Specific Equipment ID
377 Equipment Hex ID Code
The labels recognized on the ARINC 429 IN ports depend on the configuration (see Section TBD).
4.3.4.1.3 ARINC 453/708
The GTN can receive ARINC 453/708 weather radar data from specific weather radars. For more
information, refer to Section TBD.
GTN 725/750 TSO Installation Manual Page 4-13
190-01007-02 Rev. A
4.3.4.2 Serial Data Electrical Characteristics
4.3.4.2.1 RS-232
Pin Name Connector Pin I/O
RS-232 OUT 1 P1001 8 Out
RS-232 IN 1 P1001 27 In
RS-232 GND 1 P1001 46 --
RS-232 OUT 2 P1001 7 Out
RS-232 IN 2 P1001 26 In
RS-232 GND 2 P1001 45 --
RS-232 OUT 3 P1001 6 Out
RS-232 IN 3 P1001 25 In
RS-232 GND 3 P1001 44 --
RS-232 OUT 4 P1001 5 Out
RS-232 IN 4 P1001 24 In
RS-232 GND 4 P1001 43 --
RS-232 OUT 5 P1005 8 Out
RS-232 IN 5 P1005 29 In
RS-232 GND 5 P1005 49 --
RS-232 OUT 6 P1005 9 Out
RS-232 IN 6 P1005 30 In
RS-232 GND 6 P1005 50 --
The RS-232 outputs are compatible with EIA Standard RS-232C with an output voltage swing of at least
±5 V when driving a standard RS-232 load.
4.3.4.2.2 ARINC 429
Pin Name Connector Pin I/O
ARINC 429 OUT 1A P1001 10 Out
ARINC 429 OUT 1B P1001 29 Out
ARINC 429 OUT 2A P1001 9 Out
ARINC 429 OUT 2B P1001 28 Out
ARINC 429 IN 1A P1001 48 In
ARINC 429 IN 1B P1001 67 In
ARINC 429 IN 2A P1001 47 In
ARINC 429 IN 2B P1001 66 In
VOR/ILS ARINC 429 OUT A P1004 24 Out
VOR/ILS ARINC 429 OUT B P1004 23 Out
VOR/ILS ARINC 429 IN A P1004 36 In
VOR/ILS ARINC 429 IN B P1004 35 In
ARINC 429 OUT 3A P1005 28 Out
ARINC 429 OUT 3B P1005 7 Out
ARINC 429 IN 3A P1005 37 In
ARINC 429 IN 3B P1005 16 In
ARINC 429 IN 4A P1005 38 In
ARINC 429 IN 4B P1005 17 In
The ARINC 429 outputs conform to ARINC 429 electrical specifications when loaded with up to five
standard ARINC 429 receivers.
Page 4-14 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.4.2.3 RS-422
The RS-422 port is provisional; no RS-422 interfaces are currently supported.
Pin Name Connector Pin I/O
RS-422 IN A P1002 19 In
RS-422 IN B P1002 20 In
RS-422 OUT A P1002 21 Out
RS-422 OUT B P1002 22 Out
The RS-422 ports are compatible with EIA Standard RS-422 with a differential output voltage swing of at
least ±1.5V when driving a standard RS-422 load.
4.3.4.2.4 RS-422/RS-485
The RS-422/RS-485 ports are provisional; no RS-422 or RS-485 interfaces are currently supported.
Pin Name Connector Pin I/O
RS-485 1A/422 IN 1 P1005 31 I/O
RS-485 1B/422 IN 2 P1005 32 I/O
RS-485 2A/422 OUT 1 P1005 10 I/O
RS-485 2B/422 OUT 2 P1005 11 I/O
The RS-422/485 ports are compatible with EIA Standard RS-485 (RS-422 when configured as RS-422)
with a differential output voltage swing of at least ±1.5V when driving a standard RS-422/485 load.
4.3.4.2.5 ARINC 453/708
Pin Name Connector Pin I/O
ARINC 453/708 IN 1A P1005 18 In
ARINC 453/708 IN 1B P1005 60 In
ARINC 453/708 TERM 1A P1005 40 --
ARINC 453/708 TERM 1B P1005 19 --
ARINC 453/708 IN 2A P1005 20 In
ARINC 453/708 IN 2B P1005 62 In
ARINC 453/708 TERM 2A P1005 42 --
ARINC 453/708 TERM 2B P1005 21 --
The ARINC 453/708 port 1 is compatible with specific weather radar units. If the GTN is the only
receiver or if it is the last receiver in a chain of receivers, a jumper should be installed between P1005-40
and P1005-19 for port 1. This jumper adds resistance of approximately 75Ω between P1005-18 and
P1005-60.
GTN 725/750 TSO Installation Manual Page 4-15
190-01007-02 Rev. A
4.3.5 Ethernet (HSDB)
Pin Name Connector Pin I/O
ETHERNET OUT 1 A P1002 8 Out
ETHERNET OUT 1 B P1002 9 Out
ETHERNET IN 1 A P1002 6 In
ETHERNET IN 1 B P1002 7 In
ETHERNET OUT 2 A P1002 17 Out
ETHERNET OUT 2 B P1002 18 Out
ETHERNET IN 2 A P1002 15 In
ETHERNET IN 2 B P1002 16 In
ETHERNET OUT 3 A P1002 25 Out
ETHERNET OUT 3 B P1002 26 Out
ETHERNET IN 3 A P1002 23 In
ETHERNET IN 3 B P1002 24 In
ETHERNET OUT 4 A P1002 4 Out
ETHERNET OUT 4 B P1002 5 Out
ETHERNET IN 4 A P1002 13 In
ETHERNET IN 4 B P1002 14 In
The Ethernet-based HSDB (High Speed Data Bus) meets the hardware aspects of IEEE standard 802.3 for
10 base T Ethernet communications.
4.3.6 Main Audio Output
The main audio output is used to play the ‘clicks’ associated with the touch screen, as well as TAWS
alerts on GTN units that are equipped with TAWS.
Pin Name Connector Pin I/O
AUDIO OUT HI P1001 4 Out
AUDIO OUT LO P1001 23 Out
The audio output will be 80 mW across a 500Ω load.
Page 4-16 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.7 Main Indicator
4.3.7.1 Main Indicator Function
The Main Indicator displays both lateral and vertical deviation from selected course, To/From indications,
lateral and vertical flags and superflags.
The “CDI” button on the screen of the GTN takes the place of remote “NAV/GPS” switches, and is used
to toggle between display of GPS and VOR/ILS navigation on a remote indicator. The navigation source
is annunciated on the display below the ‘CDI’ button. The navigation method is optionally annunciated
externally by connecting to the VLOC ANNUNCIATE output (P1001-52) and GPS ANNUNCIATE
output (P1001-15). GPS and VOR/ILS navigation may be toggled externally when the CDI SOURCE
SELECT input (P1001-39) is momentarily grounded. See Section TBD and TBD for more information
on the discrete inputs and outputs.
An OBS resolver connection to the GPS is preferred, but not required. For the GTN 650 and GTN 750,
an OBS resolver typically is connected to the MAIN OBS inputs for use with the VOR receiver.
4.3.7.2 Main Indicator Electrical Characteristics
4.3.7.2.1 Deviation
Pin Name Connector Pin I/O
MAIN LATERAL +LEFT OUT P1001 49 Out
MAIN LATERAL +RIGHT OUT P1001 68 Out
MAIN VERTICAL +UP OUT P1001 12 Out
MAIN VERTICAL +DOWN OUT P1001 31 Out
The deviation output is capable of driving up to three 1000Ω meter loads with ±150 mVDC ±10% for
full-scale deflection. The drive circuit provides for more than full-scale deflection with a maximum
course deviation output voltage of ±300 mVDC ±10%.
4.3.7.2.2 TO/FROM
Pin Name Connector Pin I/O
MAIN +TO OUT P1001 11 Out
MAIN +FROM OUT P1001 30 Out
The output is capable of driving up to three 200Ω meter loads. When indicating TO, MAIN +TO OUT is
+225 ±75 mV DC with respect to MAIN +FROM OUT. When indicating FROM, MAIN +TO OUT is -
225 ±75 mV DC with respect to MAIN +FROM OUT. When invalid information is present (Flag IN
VIEW) the TO/FROM output is 0 ±20 mV DC.
4.3.7.2.3 Flags
Pin Name Connector Pin I/O
MAIN LATERAL +FLAG OUT P1001 50 Out
MAIN LATERAL -FLAG OUT P1001 69 Out
MAIN VERTICAL +FLAG OUT P1001 51 Out
MAIN VERTICAL -FLAG OUT P1001 70 Out
The Flag outputs are capable of driving up to three 1000Ω meter loads. When valid information is present
(Flag OUT OF VIEW) the Flag output is 375 ±80 mV DC. When invalid information is present (Flag IN
VIEW) the Flag output is 0 ±25 mV DC.
GTN 725/750 TSO Installation Manual Page 4-17
190-01007-02 Rev. A
4.3.7.2.4 Superflags
Pin Name Connector Pin I/O
LATERAL SUPERFLAG OUT P1001 13 Out
MAIN VERTICAL SUPERFLAG OUT P1001 32 Out
The output supplies not less than 400 mA with the output voltage not less than (AIRCRAFT POWER –
2.0 VDC) when the flag is to be OUT OF VIEW. The output is electrically open when the flag is to be
IN VIEW.
4.3.8 OBS
Pin Name Connector Pin I/O
MAIN OBS ROTOR C P1001 2 Out
MAIN OBS ROTOR H (GND) P1001 1 --
MAIN OBS STATOR D P1001 21 In
MAIN OBS STATOR E (GND) P1001 40 --
MAIN OBS STATOR F P1001 41 In
MAIN OBS STATOR G (GND) P1001 60 --
MAIN OBS ROTOR C and H (GND) are a buffered output that is intended to drive the OBS rotors.
MAIN OBS STATOR D and MAIN OBS STATOR F are each phase and amplitude shifted version of the
MAIN ROTOR C output. Each pair is intended to read one of the two windings of the indicator’s OBS
stator.
4.3.9 Discrete Inputs
Pin Name Connector Pin I/O
OBS MODE SELECT* P1001 16 In
AUDIO INHIBIT IN* P1001 36 In
TAWS INHIBIT IN* P1001 37 In
AIR/GROUND* P1001 38 In
CDI SOURCE SELECT* P1001 39 In
DEMO MODE SELECT* P1002 1 In
SYSTEM ID PROGRAM* P1002 10 In
SPARE DISC IN D* P1002 11 In
RESERVED P1005 12 In
SYNCHRO VALID INPUT (ACTIVE LO) P1005 33 In
An asterisk (*) following a signal name denotes that the signal is Active-Low, requiring a ground to
activate. If there is no asterisk, the signal is Active-High.
Active-low discrete inputs are considered active if either the voltage to ground is ≤3.5 VDC or the
resistance to ground is ≤375Ω. These inputs are considered inactive if the voltage to ground is
6.5-33 VDC or the resistance to ground is >100 kΩ.
Active-high discrete inputs are considered active if either the voltage to ground is >6.5 VDC. These
inputs are considered inactive if the voltage to ground is ≤3.5 VDC or the resistance to ground is
≤375Ω.
4.3.9.1 OBS MODE SELECT*
The OBS MODE SELECT discrete input may be used to toggle between GPS OBS and GPS AUTO
modes of operation. A momentary low on this pin performs the same function as pressing the ‘OBS’
button on the GTN display.
Page 4-18 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.9.2 AUDIO INHIBIT IN*
The AUDIO INHIBIT IN discrete input may be used to suppress TAWS and touch screen feedback audio
from the GTN.
4.3.9.3 TAWS INHIBIT IN*
The TAWS INHIBIT IN discrete input, when toggled momentarily low, may be used to inhibit TAWS
alerts from the GTN.
4.3.9.4 AIR/GROUND*
The AIR/GROUND discrete input may be used to control the air/ground status of the GTN.
4.3.9.5 CDI SOURCE SELECT* (GTN 750 only)
The CDI SOURCE SELECT discrete input may be used to toggle between display of GPS and
VOR/LOC/Glideslope information on the MAIN external CDI/HSI. A momentary low on this pin
performs the same function as pressing the ‘CDI’ button on the GTN display.
4.3.9.6 DEMO MODE SELECT*
The DEMO MODE SELECT discrete input may be used to select Demo Mode on the GTN. When this
pin is connected to ground during power up, the GTN starts up in Demo Mode. Demo Mode allows the
GTN to simulate reception of GPS satellite signals.
CAUTION
Do not connect DEMO MODE SELECT in an aircraft installation.
NOTE
Demo Mode can also be accessed by holding down the D button during power-up.
4.3.9.7 SYSTEM ID PROGRAM*
The System ID PROGRAM discrete input is used to identify the #2 unit in an installation with more than
one GTN. This input must be strapped to ground on the second GTN.
SYSTEM ID PROGRAM* GTN Installation
Open GTN #1 or single-GTN installation
Ground GTN #2
4.3.9.8 SYNCHRO VALID INPUT
There are two SYNCHRO VALID INPUTs; one is active-high and the other is active-low. Unless one of
the two input is active, the GTN considers the synchro heading input to be invalid.
GTN 725/750 TSO Installation Manual Page 4-19
190-01007-02 Rev. A
4.3.10 Discrete Outputs
Pin Name Connector Pin I/O
OBS ANNUNCIATE* P1001 14 Out
GPS ANNUNCIATE* P1001 15 Out
WAYPOINT ANNUNCIATE* P1001 33 Out
TERMINAL ANNUNCIATE* P1001 34 Out
TAWS AUDIO ACTIVE OUT P1001 35 Out
VLOC ANNUNCIATE* P1001 52 Out
LOI ANNUNCIATE* P1001 53 Out
MESSAGE ANNUNCIATE* P1001 54 Out
APPROACH ANNUNCIATE* P1001 55 Out
ILS/GPS APPROACH* P1001 56 Out
TAWS INHIBIT ANNUNCIATE* P1001 57 Out
TERRAIN WARNING ANNUNCIATE* P1001 71 Out
TERRAIN NOT AVAILABLE ANNUNCIATE* P1001 72 Out
TERRAIN CAUTION ANNUNCIATE* P1001 73 Out
GPS SELECT* [1] P1001 74 Out
TRAFFIC TEST* P1001 75 Out
TRAFFIC STANDBY* P1001 76 Out
SPARE DISC OUT A* P1002 3 Out
SPARE DISC OUT B* P1002 12 Out
WX RADAR ON* (function not currently implemented) P1005 13 Out
SPARE OUTPUT C* P1005 34 Out
[1] The operation of the GPS SELECT can be configured.
An asterisk (*) following a signal name denotes that the signal is Active-Low, producing a low (ground)
on the output when active.
All discrete outputs from the GTN are Active-Low. Each is an “open drain” output capable of sinking 500
mA when active.
4.3.10.1 OBS ANNUNCIATE*
The OBS ANNUNCIATE output is driven to indicate GPS OBS mode of operation. This output is active
when the OBS or SUSP annunciation is on the display.
4.3.10.2 GPS ANNUNCIATE* (GTN 750 Only)
The GPS ANNUNCIATE output is driven when the unit is configured with a single CDI/HSI and the
GPS data is being displayed on the CDI/HSI. This output parallels the GPS annunciation on the display.
4.3.10.3 WAYPOINT ANNUNCIATE*
The WAYPOINT ANNUNCIATE output is driven in the following manner:
1. When the aircraft is within 10 seconds of reaching the turning point for a course change, the
waypoint annunciator flashes.
2. When the aircraft is in a turn, the waypoint annunciator illuminates and remains illuminated until
the turn is completed.
3. When a user arrival alarm is set and the aircraft is within the circle defined by the arrival alarm
radius at the arrival waypoint, the waypoint annunciator flashes for 10 seconds.
4. When a user arrival alarm is not set and the aircraft is within 10 seconds of reaching the arrival
waypoint, the waypoint annunciator flashes.
Page 4-20 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.10.4 TERMINAL ANNUNCIATE*
When performing approach navigation, the TERMINAL ANNUNCIATE output is active when operating
within 30 nautical miles of the departure or arrival airport and the CDI scale is the equivalent or 1.0 nm or
less.
4.3.10.5 TAWS AUDIO ACTIVE OUT*
The TAWS AUDIO ACTIVE OUT is active when the GTN is playing a TAWS alert. This output can be
connected to the Audio Inhibit input of other units with audio that is lower priority than TAWS.
4.3.10.6 VLOC ANNUNCIATE* (GTN 750 Only)
The VLOC ANNUNCIATE output is driven when the unit is configured with a single CDI/HSI and the
VOR/ILS data is being displayed on the CDI/HSI. This output parallels the VLOC annunciator on the
display.
4.3.10.7 LOI ANNUNCIATE*
The LOI ANNUNCIATE output is active when the GPS receiver detects a position error, or is unable to
calculate the integrity of the position. On the 400W/500W Series navigators, this output was called
‘Integrity Annunciate’.
4.3.10.8 MESSAGE ANNUNCIATE*
When a new status message is available, the MESSAGE ANNUNCIATE output is active and the
message annunciator flashes. When status messages remain effective, the message annunciator
illuminates continuously.
4.3.10.9 APPROACH ANNUNCIATE*
When performing approach navigation, the APPROACH ANNUNCIATE output is active while an
approach is active.
4.3.10.10 ILS/GPS APPROACH*
The ILS/GPS APPROACH output is active when:
• GPS navigation is selected and either a GPS approach mode is active or 0.3 nm is selected for the
CDI full scale deflection; or
• VLOC navigation is selected and an ILS channel has been selected.
This output may be connected to the ILS Engage input of an autopilot or flight director to provide higher
autopilot gain while the GTN is operating in the ILS or GPS Approach modes of operation.
4.3.10.11 TAWS INHIBIT ANNUNCIATE*
The TAWS INHIBIT ANNUNCIATE is active when TAWS is inhibited on the GTN.
4.3.10.12 TERRAIN WARNING ANNUNCIATE*
The TERRAIN WARNING ANNUNCIATE is active when a TAWS warning is active on the GTN.
4.3.10.13 TERRAIN NOT AVAILABLE ANNUNCIATE*
The TERRAIN NOT AVAILABLE ANNUNCIATE is active when TAWS on the GTN is enabled but
not available.
4.3.10.14 TERRAIN CAUTION ANNUNCIATE*
The TERRAIN CAUTION ANNUNCIATE is active when a TAWS caution is active on the GTN.
GTN 725/750 TSO Installation Manual Page 4-21
190-01007-02 Rev. A
4.3.10.15 GPS SELECT*
The GPS SELECT discrete output is active when GPS data is being displayed on the CDI/HSI and the
ILS/GPS Approach Output is not active. It is intended for use with autopilots having a GPS SELECT
input (such as the Bendix/King KAP 140 and KFC 225), so that the autopilot can capture vertical
guidance while GPS data is being displayed on the CDI/HSI.
4.3.10.16 TRAFFIC TEST*
The TRAFFIC TEST discrete output is used to command compatible traffic systems into test mode.
4.3.10.17 TRAFFIC STANDBY*
The TRAFFIC STANDBY discrete output is used to command compatible traffic systems into standby or
operate mode.
4.3.10.18 WX RADAR ON*
The WX RADAR ON discrete output is used to command an ARINC 453/708 weather radar into ON
mode.
4.3.10.19 TIME MARK OUT
Pin Name Connector Pin I/O
TIME MARK OUT A P1001 3 Out
TIME MARK OUT B P1001 22 Out
TIME MARK OUT outputs a differential 1 ms ± 1 μs wide pulse once every second. TIME MARK OUT
is a logic level output, capable of sourcing 1 mA at greater than 3.8 V and sinking 1 mA at less
than 0.4 V.
4.3.11 Heading Synchro
The GTN accepts heading information using either a synchro input or serially, using either RS-232 or
ARINC 429 inputs. If synchro heading is provided, refer to the paragraphs below.
4.3.11.1 Heading Synchro
Pin Name Connector Pin I/O
SYNCHRO X P1005 35 In
SYNCHRO Y P1005 14 In
SYNCHRO Z P1005 56 In
Connect these pins to an XYZ type directional gyro.
4.3.11.2 Heading Synchro Reference Voltage
Pin Name Connector Pin I/O
SYNCHRO REF HIGH P1005 36 In
SYNCHRO REF LO P1005 15 In
A reference voltage must be provided if the synchro heading input is used. This input should be 26 VAC
400 Hz (nominal) and provided by the same source that provides the excitation voltage to the synchro
heading source.
Page 4-22 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.11.3 Heading Synchro Valid Input
Pin Name Connector Pin I/O
SYNCHRO VALID INPUT (ACTIVE HI) P1005 12 In
SYNCHRO VALID INPUT* P1005 33 In
P1005-12 is considered active if the voltage on this input is 6.5-33 VDC. If the voltage is ≤3.5 VDC, the
input is considered inactive.
P1005-33 is considered active if either the voltage to ground is <1.9 V or the resistance to ground
is <375Ω. This input is considered inactive if the voltage to ground is 11-33 VDC.
Unless P1005-12 or P1005-33 is active, the GTN will consider the synchro heading input to be invalid.
4.3.12 Composite Video (function not currently implemented)
Pin Name Connector Pin I/O
VIDEO INPUT 1 P1005 2 In
VIDEO INPUT 1 GND P1005 23 In
VIDEO INPUT 2 P1005 1 In
VIDEO INPUT 2 GND P1005 22 In
The GTN supports the following composite video input formats:
• NTSC “National Television Standards Committee” (J,M,4.43)
• PAL “Phase Alternating Line” (B,D,G,H,I,M,N,Nc,60)
• SECAM “Sequential Color with Memory” (B,D,G,K,K1,L)
Composite video is a one-wire format with intensity, color, and timing information transferred together.
Video signals are transferred using a 75Ω coaxial cable. Reference TBD for approved types of coaxial
cable.
NOTE
Particular attention must be taken in routing the coaxial cable through the aircraft to
avoid potential radiated interference sources in addition to minimizing the cable bend
radii. Concerns about interference sources may necessitate the use of coaxial cable with
a higher noise rejection rating.
NTSC (M), also called RS-170A, is the most common video format supported by the GTN.
NTSC has the following characteristics:
• 59.94 Hz vertical interlaced refresh rate
• 15.75 kHz horizontal line frequency
• 525 scan lines
• 29.97 frame per second update rate
• Luminance or luma (black and white) also called “monochrome NTSC” or RS-170, is the
standard black and white format which contains both image and timing information.
• Chrominance or chroma (color) encoding system
GTN 725/750 TSO Installation Manual Page 4-23
190-01007-02 Rev. A
4.3.13 COM Audio (GTN 750 only)
4.3.13.1 COM Audio Function
Activation of MIC 1 TRANSMIT enables MIC 1 AUDIO IN HI and causes the transceiver to transmit.
500Ω COM AUDIO is a 100 mW audio output that is intended to drive a headset or an audio panel.
4.3.13.2 COM Audio Electrical Characteristics
4.3.13.2.1 COM Mic Audio
Pin Name Connector Pin I/O
COM MIC 1 AUDIO IN HI P1003 5 In
COM MIC 2 AUDIO IN HI (function not currently implemented) P1003 6 In
MIC AUDIO IN LO P1003 20 In
COM MIC 1 AUDIO IN HI and COM MIC 2 AUDIO IN HI are standard carbon or dynamic mic inputs
with integrated preamps providing minimum 70mVrms into a 1000Ω load.
COM MIC 1 AUDIO IN HI and MIC 2 AUDIO IN HI are set in the factory so that 100 mVrms
modulates the transmitter to 85% nominally at 1000 Hz. The microphone gain adjustment is made
through Configuration Mode
4.3.13.2.2 COM Audio
Pin Name Connector Pin I/O
500Ω COM AUDIO HI P1003 7 Out
500Ω COM AUDIO LO P1003 18 Out
500Ω COM AUDIO supplies 100 mW into a 500Ω load. This is a balanced output and the LO output
must be connected.
500Ω COM AUDIO is the summation of the COM receiver audio, COM sidetone audio, and intercom
audio.
4.3.13.2.3 Aux Audio (function not currently implemented)
Pin Name Connector Pin I/O
AUX AUDIO LINE LEVEL HI P1003 3 In
AUX AUDIO LINE LEVEL GND P1003 19 ---
AUX AUDIO SIGNAL LEVEL HI P1003 4 In
AUX AUDIO SIGNAL LEVEL GND P1003 21 ---
The AUX AUDIO inputs can be used to mix external audio into the COM Audio.
Page 4-24 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.14 COM Discrete Inputs
Pin Name Connector Pin I/O
COM MIC 1 KEY* P1003 11 In
INTERCOM ENABLE* (function not currently implemented) P1003 12 In
COM MIC 2 KEY* (function not currently implemented) P1003 26 In
COM REMOTE TRANSFER* P1003 27 In
COM REMOTE TUNE UP* P1003 28 In
COM REMOTE TUNE DOWN* P1003 29 In
An asterisk (*) following a signal name denotes that the signal is Active-Low, requiring a ground to
activate.
These inputs are considered active if either the voltage to ground is ≤3.5 VDC or the resistance to ground
is ≤375Ω. These inputs are considered inactive if the voltage to ground is 11-33 VDC or the resistance to
ground is >100kΩ.
4.3.14.1 COM MIC 1 KEY* (GTN 750 only)
The COM MIC 1 KEY discrete input, when pulled low, allows the audio that is present on the COM MIC
1 AUDIO IN HI (P1003-5) to be transmitted over the radio.
4.3.14.2 COM MIC 2 KEY* (GTN 750 only)
The COM MIC 2 KEY discrete input can be used in installations in which no audio panel is present.
When this input is pulled low, the audio that is present on the COM MIC 2 AUDIO IN HI (P1003-6) is
transmitted over the radio.
4.3.14.3 COM REMOTE TRANSFER* (GTN 750 only)
The COM REMOTE TRANSFER discrete input may be used to flip-flop between the active and standby
COM frequencies. A momentary low on this pin will load the standby COM frequency into the active
COM frequency field.
The COM REMOTE TRANSFER input may be used for emergency operation of the COM transmitter. If
the switch is depressed for two seconds, the active COM frequency changes to 121.500 MHz. Once the
emergency frequency is activated through COM REMOTE TRANSFER, the GTN transceiver ignores
inputs from the front panel controls for COM selections only. The pilot may exit this independent
mode—restoring COM selection control to the front panel knobs and buttons—by again depressing the
switch for two seconds.
4.3.14.4 COM REMOTE TUNE UP* (GTN 750 only)
The COM REMOTE TUNE UP discrete input may be used to scroll through a list of preset COM
frequencies. A momentary low on this pin will load the next preset frequency in the list into the standby
COM frequency field.
4.3.14.5 COM REMOTE TUNE DOWN* (GTN 750 only)
The COM REMOTE TUNE DOWN discrete input may be used to scroll through a list of preset COM
frequencies. A momentary low on this pin will load the previous preset frequency in the list into the
standby COM frequency field.
4.3.14.6 INTERCOM ENABLE* (GTN 750 only)
The INTERCOM ENABLE discrete input activates the intercom function in installations in which no
intercom is present.
GTN 725/750 TSO Installation Manual Page 4-25
190-01007-02 Rev. A
4.3.14.7 VOR/ILS Audio (GTN 750 only)
Pin Name Connector Pin I/O
500Ω VOR/LOC AUDIO OUT HI P1004 16 Out
500Ω VOR/LOC AUDIO OUT LO P1004 17 Out
500Ω VOR/LOC AUDIO OUT HI supplies 100 mW into a 500Ω load. It is a balanced output and the
500Ω VOR/LOC AUDIO OUT LO output must be connected.
4.3.14.8 VOR/ILS Discrete Inputs (GTN 750 only)
Pin Name Connector Pin I/O
VLOC REMOTE TRANSFER* P1004 28 In
An asterisk (*) following a signal name denotes that the signal is Active-Low, requiring a ground to
activate.
This input is considered active if either the voltage to ground is ≤3.5 VDC or the resistance to ground is
≤375Ω. This input is considered inactive if the voltage to ground is 11-33 VDC or the resistance to
ground is >100kΩ.
4.3.14.9 VLOC REMOTE TRANSFER
The VLOC REMOTE TRANSFER discrete input may be used to flip-flop between the active and standby
NAV frequencies. A momentary low on this pin will load the standby NAV frequency into the active
NAV frequency field.
4.3.15 VOR/ILS Indicator (GTN 750 only)
4.3.15.1 VOR/ILS Indicator Function
NOTE
Because the GTN 750 includes a “CDI” button that performs switching between GPS and
VOR/ILS on a remote indicator, it is seldom necessary to use these outputs to drive an
indicator. It is only necessary when it is desired for a separate indicator to display
VOR/ILS deviation full-time (regardless of the “CDI” button status).
The VOR/ILS indicator displays both lateral and vertical, To/From indications, lateral and vertical flags
and superflags. GTN 750 connector P1004 always outputs the VOR/Localizer/Glideslope navigation
information. The VOR/ILS pins on P1004 are used to drive an indicator that displays VOR/ILS
information at all times, regardless of the CDI selection on the GTN 750.
VOR/LOC COMPOSITE OUT is a standard VOR/localizer composite output signal which may be used
to drive the Left/Right, TO/FROM, and Flag indications of certain navigation indicators that contain an
internal converter.
The ILS ENERGIZE output goes low when the VLOC frequency is channeled to a localizer channel.
Page 4-26 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.15.2 VOR/ILS Indicator Electrical Characteristics
4.3.15.2.1 Superflags
Pin Name Connector Pin I/O
VOR/LOC SUPERFLAG P1004 15 Out
GLIDESLOPE SUPERFLAG P1004 38 Out
The output supplies not less than 400 mA the output voltage not less than (AIRCRAFT POWER -2 VDC)
when the flag is to be OUT OF VIEW. The output voltage with respect to ground is less than 3 VDC
when the flag is to be IN VIEW.
4.3.15.2.2 Deviation
Pin Name Connector Pin I/O
VOR/LOC +LEFT P1004 5 Out
VOR/LOC +RIGHT P1004 6 Out
GLIDESLOPE +UP P1004 34 Out
GLIDESLOPE +DOWN P1004 55 Out
The deviation outputs are each capable of driving up to three 1000Ω meter loads with ±150 mVDC ±10%
for full-scale deflection. The drive circuit provides for more than full-scale deflection with a maximum
course deviation output voltage of ±300 mVDC ±10%.
4.3.15.2.3 TO/FROM
Pin Name Connector Pin I/O
VOR/LOC +TO P1004 1 Out
VOR/LOC +FROM P1004 2 Out
The output is capable of driving up to three 200Ω meter loads. When indicating TO, the output is
+225 ±75 mVDC. When indicating FROM, output is -225 ±75 mVDC. When invalid information is
present (Flag IN VIEW) the TO/FROM output is 0 ±10 mVDC.
4.3.15.2.4 Flag
Pin Name Connector Pin I/O
VOR/LOC +FLAG P1004 3 Out
VOR/LOC -FLAG P1004 4 Out
GLIDESLOPE +FLAG P1004 32 Out
GLIDESLOPE -FLAG P1004 53 Out
The Flag output is capable of driving up to three 1000Ω meter loads. When valid information is present
(Flag OUT OF VIEW) the Flag output is 375 ±80 mV DC. When invalid information is present (Flag IN
VIEW) the Flag output is 0 ±25 mV DC.
4.3.15.2.5 OBS
Pin Name Connector Pin I/O
VOR OBS ROTOR C P1004 9 Out
VOR OBS ROTOR H (GND) P1004 10 --
VOR OBS STATOR D P1004 13 In
VOR OBS STATOR E (GND) P1004 11 --
VOR OBS STATOR F P1004 12 In
VOR OBS STATOR G (GND) P1004 14 --
VOR OBS ROTOR C and H are a buffered 500 Hz output that is intended to drive the OBS rotors. VOR
OBS STATOR D and VOR OBS STATOR F are each phase and amplitude shifted version of the VOR
ROTOR C output. Each pair is intended to read one of the two windings of the indicator’s OBS stator.
GTN 725/750 TSO Installation Manual Page 4-27
190-01007-02 Rev. A
4.3.15.2.6 VLOC COMPOSITE
Pin Name Connector Pin I/O
VOR/LOC COMPOSITE OUT P1004 8 Out
With a standard VOR test signal applied, VOR/LOC COMPOSITE OUT is 0.5 ± 0.1 Vrms into a 10 kΩ
load. With a standard Localizer centering test signal applied, VOR/LOC COMPOSITE OUT is 0.350
±0.05 Vrms into a 10 kΩ load.
4.3.15.2.7 GLIDESLOPE COMPOSITE
Pin Name Connector Pin I/O
GLIDESLOPE COMPOSITE OUT P1004 58 Out
With a standard glideslope test signal applied, GLIDESLOPE COMPOSITE OUT is 0.350 ±0.05 Vrms
into a 10 kΩ load.
4.3.15.2.8 NAV ILS ENERGIZE
Pin Name Connector Pin I/O
ILS ENERGIZE P1004 29 Out
The driver output voltage is not more than 1.0 V when sinking 20 mA. The maximum off state leakage
current with respect to GND is less than 10 μA.
4.3.16 RMI/OBI (GTN 750 only)
4.3.16.1 RMI/OBI Function
The VOR OBI output provides bearing information from the currently tuned VOR station for
Bendix/King Serial OBI devices based upon the GTN 750 VOR receiver. When a localizer channel is
tuned on the VLOC window, there is a bit in the data stream set to indicate that a localizer frequency is
tuned which stows the needle or drives it to the 3 o’clock position.
4.3.16.2 RMI/OBI Electrical Characteristics
Pin Name Connector Pin I/O
VOR OBI CLOCK P1004 25 Out
VOR OBI SYNC P1004 26 Out
VOR OBI DATA P1004 27 Out
The output driver is active low. The driver output voltage is not more than 1.0 V when sinking 20 mA.
The maximum off state leakage current with respect to ground is less than 10 μA.
Page 4-28 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
4.3.17 DME Tuning (GTN 750 only)
4.3.17.1 DME Tuning Function
The GTN 750 can channel a DME based on the tuned VLOC frequency. The GTN 750 outputs 2 of 5,
BCD, or Slip parallel DME and King Serial DME channeling format. When DME COMMON is held
low, the GTN 750 actively tunes the DME.
4.3.17.2 DME Tuning Electrical Characteristics
4.3.17.2.1 Parallel DME Tuning
Pin Name Connector Pin I/O
PAR DME 100KHZ-A/NAV SERIAL DME HOLD P1004 37 Out
PAR DME 100KHZ-B P1004 39 Out
PAR DME 100KHZ-C P1004 40 Out
PAR DME 100KHZ-D P1004 42 Out
PAR DME 100KHZ-E P1004 54 Out
PAR DME 50KHZ P1004 43 Out
PAR DME 1MHZ-A P1004 45 Out
PAR DME 1MHZ-B P1004 46 Out
PAR DME 1MHZ-C P1004 47 Out
PAR DME 1MHZ-D/NAV SERIAL DME ON P1004 33 Out
PAR DME 1 MHZ-E P1004 56 Out
DME COMMON P1004 41 In
For each of the parallel DME tuning discrete outputs, the driver output voltage is not more than 1.0 V
while sinking 20 mA. The maximum off state leakage current with respect to ground is less than 10 μA.
DME COMMON must be pulled low to indicate to the GTN 750 that it is the device channeling the DME.
DME COMMON is considered active if either the voltage to ground is <1.9 V or the resistance to ground
is <375Ω. These inputs are considered inactive if the voltage to ground is 11-33 VDC.
4.3.17.2.2 King Serial DME Tuning
Pin Name Connector Pin I/O
SERIAL DME – DATA P1004 19 Out
SERIAL DME – CLOCK P1004 18 Out
SERIAL DME- RNAV/CH REQ P1004 20 In
SERIAL DME - RNAV MODE P1004 21 In
DME COMMON P1004 41 In
SERIAL DME – DME REQUEST P1004 44 I/O
When SERIAL DME – DATA or SERIAL DME – CLOCK is asserted high and driving a 360Ω load, the
driver output voltage is not less than 8 V, and when asserted low is not greater than 10 mV.
SERIAL DME – RNAV/CH REQ, SER DME – RNAV MODE, and DME COMMON are considered
active if either the voltage to ground is <1.9 V or the resistance to ground is <375Ω. These inputs are
considered inactive if the voltage to ground is 11-33 VDC.
DME COMMON must be pulled low to indicate to the GTN 650/750 that it is the device channeling the
DME.
GTN 725/750 TSO Installation Manual Page 5-1
190-01007-02 Rev. A
5. POST INSTALLATION CONFIGURATION AND CHECKOUT
PROCEDURES
5.1 System Configuration Overview
This section contains instructions for configuring the GTN for each installation as well as checks to
ensure the system is properly installed and functioning correctly. The steps that are not applicable to a
particular installation may be skipped. A checkout log that is included in Table 5-1 at the end of this
section should be filled out during the checkout procedures. The completed checkout log sheet should be
maintained with the aircraft permanent records to document the configuration of this installation. A
summary of the steps required for configuration and checkout of the GTN is as follows:
• Perform the installation checks
• Load software into the GTN
• Configure the GTN for the specific installation
• Perform ground checks to verify the interfaces to external sensors
• Perform the specified flight checks
• Update the aircraft documentation
5.2 Mounting, Wiring, and Power Checks
Verify that all cables are properly secured and shields are connected to the shield block of the connectors.
Check the movement of the flight and engine controls to verify there is no interference between the
cabling and control systems. Ensure that all wiring is installed as described in Section 2.6
Prior to powering up the GTN, the wiring harness must be checked for proper connections to the aircraft
systems and other avionics equipment. Point to point continuity must be checked to expose any faults
such as shorting to ground. Any faults or discrepancies must be corrected before proceeding. If any TVSs
are installed as part of the installation, proper TVS installation should be verified prior to application of
power. Refer to TBD for guidance on checking each TVS.
After accomplishing a continuity check, perform power and ground checks to verify proper power
distribution to the GTN. Any faults or discrepancies should be corrected at this time. Remove power from
the aircraft upon completion of the harness checkout.
The GTN can be installed after completion of the continuity and power checks. The GTN should be
installed into the rack and secured appropriately, as described in Section TBD. The GTN must be
connected to the wiring harness and antennas.
NOTE
Throughout the next section of this document, many screenshots and examples are used
to illustrate the software and checkout loading process. Every effort has been made to
ensure the accuracy of these examples; however, changes may occur which results in the
examples being out of date. Always refer to the Master Drawing List (005-00533-C0) for
the correct software versions and part numbers.
Page 5-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5.3 Connector Engagement Check
Prior to configuration and checkout of the GTN, the connector engagement should be checked as
described below:
1. Turn on the GTN and turn on the avionics master switch (if installed).
2. Place the GTN in the rack and engage the cam mechanism.
3. Turn the Allen screw of the locking cam (located on the lower left side of the unit) slowly
clockwise until the GTN just powers on. A T-handle can be used for this, but ensure that the
screw is not over-tightened.
4. Count the number of complete revolutions the Allen screw can be turned until it cannot turn any
more. Take care not to over-tighten. TBD turns is the minimum for proper installation. If fewer
than TBD turns are possible, the mounting rack should be moved aft (toward the pilot) such that
the aircraft panel does not obstruct the unit from properly engaging in the rack.
5.4 Configuration Mode Operations
Configuration mode is used to configure the GTN settings for each specific installation. To access
configuration mode, apply power to the aviation rack. With the GTN turned off, press and hold the Home
key and turn the unit on. Release the Home key when the display activates and ‘Garmin’ appears fully lit
on the screen. The first page displayed is the configuration mode home page. See Figure 5-1. While in
configuration mode, pages can be selected by touching the desired button on the display.
NOTE
The configuration pages shown here reflect main software version 2.00. Some differences
in operation may be observed when comparing the information in this manual to later
software versions.
The following sections describe pages that are accessed from the main GTN Setup page, as shown in
Figure 5-3. To access the GTN Setup page, touch the ‘GTN Setup’ button from the Configuration Mode
home page as shown in Figure 5-1.
Figure 5-1. Configuration Mode Home Page
GTN 725/750 TSO Installation Manual Page 5-3
190-01007-02 Rev. A
5.4.1 Main ARINC 429 Config Page
Access the GTN Setup page from the Configuration home page by touching the ‘GTN Setup’ button.
Figure 5-2. Main GTN Setup Page
To access the ARINC 429 Configuration page, touch the ARINC 429 button. This page configures the
four ARINC 429 input ports and the three ARINC 429 output ports. Select the correct speed for each port
depending upon the installed interfaced equipment by touching the speed button and toggling the high or
low selection.
Select the correct Data In and Data Out settings for each port. Touch the UP or DOWN button to scroll
through the ARINC selections. The data selections are described below.
Figure 5-3. Main ARINC 420 Configuration Page
Page 5-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
SPEED SELECTIONS
Selection Description
Low Standard low-speed ARINC 429 (nominally 12.5 Kb per second)
High High-speed ARINC 429 (nominally 100 Kb per second)
DATA IN SELECTIONS
Selection Description
Off No unit connected to this ARINC 429 input
Airdata
Altitude, temperature, and speed information from the following Air Data
systems:
B & D 2600, 2601, 2800, 90004-003
Bendix/King KAD 280/480, Shadin ADC 2000
Airdata/AHRS Heading, altitude, temperature, and speed information from an Air Data/AHRS
system.
Data Concentrator
Garmin and Garmin w/TIS
This is a Garmin data concentration format. Only high speed ARINC 429
should be used.
Garmin GTX 330
EFIS
Selected course, heading, and joystick waypoint information from the following
EFIS systems:
Bendix/King EFS 40/50
Certain versions of Collins EFIS may also be compatible with this format.
EFIS/Airdata
Selected course, heading, joystick waypoint, altitude, temperature, and speed
information from the following systems:
Collins Pro Line 21
Bendix/King EFS 40/50 (with SW 1201 or later)
Garmin GAD 42 Selected course, heading, and true airspeed data from the Garmin GAD 42.
Garmin GDU
Selected course, heading, altitude, temperature and speed information from
the following systems:
Garmin GDU 620 (G500/G600)
GTS 800 Traffic Information from the GTS 800.
GTS 820 Traffic Information from the GTS 820.
GTS 850 Traffic Information from the GTS 850.
Honeywell EFIS
Selected course, heading, and joystick waypoint information from the following
EFIS systems:
Honeywell Primus 1000
INS/IRU
Heading information from the following Inertial systems:
Bendix/King KAH 460
Collins AHC 85
Honeywell Laseref
Litef LTR 81
Litton LTN 90-100, LTN 91, LTN 92
RADAR Graphics Joystick waypoint information from a RADAR graphics unit.
Sandel EHSI Selected Course and Magnetic Heading from a Sandel EHSI.
Skywatch Traffic Information from the SkyWatch system.
Skywatch HP Traffic Information from the SkyWatch system.
KTA 870 Traffic Information from the KTA 870.
KTA 970 Traffic Information from the KTA 970.
Avidyne TAS Traffic Information from the Avidyne TAS.
GTN 725/750 TSO Installation Manual Page 5-5
190-01007-02 Rev. A
DATA OUT SELECTIONS
Selection [1] Description
Off No unit(s) connected to ARINC 429 output
ARINC 429 Standard ARINC 429 output data (non-GAMA).
GAMA 429
Bendix King
ARINC 429 data as defined by the GAMA General Aviation Subset, 2nd
Edition. The output data includes navigation, flight plan and GPS vertical
guidance information to the following systems:
Bendix/King EFS 40/50 (GPS vertical guidance provided on EFIS)
GAMA 429
ARINC 429 data as defined by the General Aviation Manufacturers’
Association (GAMA) General Aviation Subset, 2nd Edition. The output data
includes navigation and flight plan information to the following systems:
Garmin GAD 42 Interface Adapter
Bendix/King EFS 40/50 (No GPS vertical guidance provided)
Collins EFIS 84
Certain other versions of Collins EFIS may also be compatible with this format.
GAMA 429
Graphics
ARINC 429 data as defined by the GAMA General Aviation Subset, 2nd
Edition including GAMA Graphics Protocol ‘A’. This format outputs intersection
symbols as generic waypoint symbols. The output data includes navigation
and flight plan information (including graphical representation of flight plan
procedures) to the following EFIS systems:
Honeywell Primus 1000
GAMA 429 Grph
w/Int
ARINC 429 data as defined by the GAMA General Aviation Subset, 2nd
Edition including GAMA Graphics Protocol ‘A’. The output data includes
navigation and flight plan information (including graphical representation of
flight plan procedures) to the following systems:
Sandel SN3308
Sandel SN3500/4500
GAMA 429
Pro Line 21
ARINC 429 data as defined by the GAMA General Aviation Subset, 2nd
Edition. The output data includes navigation and flight plan information to the
following EFIS systems:
Collins Pro Line 21
GAMA 429 Sextant
ARINC 429 data as defined by the GAMA General Aviation Subset, 2nd
Edition. The output data includes navigation and flight plan information to the
following EFIS systems:
Sextant SMD 45
[1] Garmin GTX 330 will work with any output setting
SDI
Selection Description
Common RX: Accepts all 429 inputs
TX: Generates all 429 outputs with SDI = 0.
LNAV 1
Number 1 (Pilot) long-range navigator
RX: Accepts 429 inputs with SDI = 0 or 1.
TX: Generates all 429 outputs with SDI = 1.
LNAV 2
Number 2 (Copilot) long-range navigator
RX: Accepts 429 inputs with SDI = 0 or 2.
TX: Generates all 429 outputs with SDI = 2.
Page 5-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5.4.2 Main RS-232 Config Page
Select the Main RS-232 Configuration page from the
Main GTN Setup page by touching the RS-232
button. See Figure 5-3. Change the inputs or outputs
to match the equipment that is installed in the
aircraft. Touch the button corresponding to the
RS-232 channel and select the applicable input or
output setting. The input/output settings are described
below. Touch the UP or DOWN button to scroll
through the RS-232 selections.
CHANNEL INPUT SELECTIONS
Selection Description
Off No unit(s) connected to input of this channel.
Arnav ei-fuel
Serial fuel flow information from the following units:
ARNAV FC-10, FT-10
Electronics International FP-5L
GMA 35 Audio panel status information.
GTX 32 # 1 Altitude data, flight ID, and GTX 32 status.
GTX 32 # 2 Altitude data, flight ID, and GTX 32 status.
GTX 33 # 1 GTX 33 status data, ICAO address, and Flight ID.
GTX 33 # 2 GTX 33 status data, ICAO address, and Flight ID.
GTX 33 # 1 with TIS GTX 33 status data, TIS data, ICAO address, and Flight ID.
GTX 33 # 2 with TIS GTX 33 status data, TIS data, ICAO address, and Flight ID.
Icarus ALT
Serial altitude data from the following units:
Icarus Instruments 3000
Sandia SAE5-35
Garmin GTX 327 Transponder
Trans-Cal Industries IA-RS232-X, SSD120
ACK Technologies A-30 (Mod 8 and above)
Shadin ADC Serial air data information from the following units:
Shadin ADC 200, 200+, 2000
Shadin ALT Serial altitude data from the following units:
Shadin 8800T, 9000T, 9200T
Shadin FADC
Serial air data and fuel flow information from the following units:
Shadin 9628XX-X Fuel/Air Data Computer
INSIGHT TAS 1000 Air Data Computer
Shadin Fuel
Serial fuel flow information from the following units:
Shadin 91053XM Digital Fuel Management System
Shadin 91204XM Digital Fuel Management System
JP Instruments EDM-700 or EDM-760 Engine Monitor
WX-500 Lightning strike information from an L3 Communications WX-500 Stormscope.
GPS
Figure 5-4. Main RS-232 Configuration Page
GTN 725/750 TSO Installation Manual Page 5-7
190-01007-02 Rev. A
CHANNEL OUTPUT SELECTIONS
Selection Description
Off No unit(s) connected to output of this channel.
ADS-B Serial communication to Garmin GTX 33/330 ES or 33D/330D ES
Transponders.
Aviation Output
Serial position, altitude, velocity, and navigation data to the following units:
Argus 3000, 5000, or 7000 Moving Map
Electronics International FP-5L Fuel Flow Computer (non-TSO’d)
Garmin MX20 (V5.6 or later), GMX 200 [1]
Garmin GPSMAP 195, GPSMAP 295 or GPS III Pilot
Garmin GPSMAP 196, GPSMAP 296, and GPSMAP 396
Garmin GTX 327 Transponder
JP Instruments EDM-700 or EDM-760 Engine Monitor
Shadin 91204XM Digital Fuel Management System
Shadin 91053XM Digital Fuel Management System
Shadin 9628XX-X Fuel/Air Data Computer
Stormscope Series II (with NAVAID) Moving Map
Aviation (no Altitude)
Serial position, velocity, and navigation data to the following units:
Garmin MX20 (V5.5 or earlier)
Horizon DDMP
INSIGHT TAS 1000 Air Data Computer
Honeywell EGPWS Serial communication to a Bendix/King (Honeywell) KGP 560 EGPWS.
GMA 35 Control of GMA 35 Audio Panel functions.
GTX 32 # 1 Control of GTX 32 transponder functions, pressure altitude data, and
groundspeed data.
GTX 32 # 2 Control of GTX 32 transponder functions, pressure altitude data, and
groundspeed data.
GTX 33 # 1 with TIS Control of GTX 33 transponder functions, pressure altitude data, and
groundspeed data.
GTX 33 # 2 with TIS Control of GTX 33 transponder functions, pressure altitude data, and
groundspeed data.
MapMX Serial position, altitude, velocity, and navigation data to the following units:
Garmin MX20 (V5.7 or later), GMX 200
WX-500 Serial communication to an L3 Communications WX-500 Stormscope.
GPS
Page 5-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5.4.3 HSDB (Ethernet) Configuration Page
The HSDB Ethernet page can be accessed from the GTN
Setup page. Touch the button next to the port to configure it
as ‘Connected’ or ‘Not Connected’. See Figure 5-5. If a
Garmin LRU is connected to a specific Ethernet port, then
configure the port as ‘Connected’. If no LRU is connected
to the port, configure it as ‘Not Connected’.
5.4.4 Interface Equipment Page
Touch the Interface Equipment button on the GTN Setup page.
This page allows the configuration of the presence of a cross-side
navigator, GDL 69/69A, Transponder #1 and Transponder #2.
Figure 5-5. HSDB Ethernet Port Configuration
Page
Figure 5-6. Interfaced Equipment Page
GTN 725/750 TSO Installation Manual Page 5-9
190-01007-02 Rev. A
5.4.5 Main CDI Indicator (Analog) Configuration Page
Touch the Main Indicator (Analog) button on the GTN
Setup page. See Figure 5-3. This page allows you to
calibrate the OBS resolver, enable the CDI key, selected
course for GPS and/or VLOC, and configure the V-Flag
state. The following fields can be configured, as shown in
Figure 5-7.
CALIBRATE OBS RESOLVER
To calibrate the OBS resolver, touch the ‘Calibrate’ button
on the Main CDI Configuration page. See Figure 5-7.
Next, select 150˚ on the OBS, then touch the OK button, as
prompted on the display. After the OBS resolver is
finished calibrating, the GTN will display ‘OBS Resolver
Calibration Complete’. Touch ‘OK’ after the calibration is
complete. Verify OBS operation by checking that the
course displayed on the GTN is within 2° of the selected
course. Do this at 30° intervals around the OBS card.
CDI KEY
If it is desired to disable the CDI key, touch the button to
the right of ‘CDI Key’ to toggle between enabling and
disabling the CDI key. Disabling the CDI key causes the CDI source to always be displayed as GPS
regardless of CDI button presses. This may be necessary for certain EFIS systems where navigation
sensor selection must be accomplished on the EFIS or its control panel.
SELECTED COURSE FOR GPS
If it is desired to ignore a selected course input for GPS operation in OBS mode, touch the button to the
right of ‘Selected Course for GPS’ until ‘Ignored’ is displayed on the button.
SELECTED COURSE FOR VLOC
If it is desired to ignore a selected course input such that the VOR valid flag is dependent only on a valid
VOR signal, with lateral deviation calculated by another display device, touch the button to the right of
‘Selected Course for VLOC’ until ‘Ignored’ is displayed on the button.
V-FLAG STATE
Select either Normal or Declutter for the V-Flag State by touching the button until the desired selection is
displayed on the button.
Selection Description
Declutter
Whenever vertical deviation is invalid, the vertical deviation bar is
parked in the maximum UP position and the vertical flag is removed
from view, except in the following cases: (i) the CDI is in VLOC mode
and an ILS frequency is tuned, or (ii) the CDI is in GPS mode and a
GPS approach with vertical guidance is active. In these cases,
whenever the vertical deviation is invalid, the vertical deviation bar
parks in the centered position and the vertical flag is shown.
Normal Whenever vertical deviation is invalid the vertical deviation bar parks in
the centered position and the vertical flag is shown.
Figure 5-7. Main Indicator (Analog) Configuration
Page
Page 5-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5.4.6 Lighting Configuration Page
Select the Lighting Page. See Figure 5-3. This page allows
you to set display parameters that affect the display
backlight and key lighting brightness. The Display and Key
lighting characteristics are adjusted separately, each with
the following fields:
SOURCE
Selection Description
Photocell Backlight or key lighting level is determined by the ambient light level
as measured by the photocell on the GTN.
Lighting Bus 1 Backlight or key levels track the Lighting Bus 1 levels.
Lighting Bus 2 Key lighting levels track the Lighting Bus 2 levels.
Note that the display source can only be configured to track the photocell or lighting bus 1.
MINIMUM LEVEL
This sets the minimum brightness of the keys or display, whichever is applicable. Touch the ‘Minimum
Level’ button corresponding to either the Keys or the Display to adjust the minimum brightness. The
minimum brightness level can be adjusted in a range from 0.05% to 100.00%, with 100.00% being the
highest brightness level. The minimum display and key brightness default level is set to 5.00% at the
factory. Enter the desired minimum value on the keypad and then touch ENTER to store the settings.
Figure 5-8. Main Lighting Configuration Page
GTN 725/750 TSO Installation Manual Page 5-11
190-01007-02 Rev. A
5.4.6.1 Configure Photocell Page
Touching ‘Configure Photocell’ (See Figure 5-8) from
the Lighting Configuration page allows the following
parameters to be configured by touching the
corresponding button. Each selection displays a
numeric keypad where the numeric values can be
entered.
RESPONSE TIME
Sets the speed with which the brightness responds to
the input level (bus voltage or ambient light) changes.
The higher the number the slower the display responds.
This field has a range of 2-7 seconds, and is set to 2
seconds as a default value.
SLOPE
Sets the sensitivity the brightness of the display has to
changes in the input level. The higher the number, the
brighter the display for a given increase in the input
level. This field has a range of 0-100, and is set to 50 as
the default setting.
OFFSET
Adjusts the lighting level up or down for any given input level. This field has a range of 0 (zero) to 99,
and is set to 50 as a default value. This may also be used to match lighting curves with other equipment
in the panel.
KEY BACKLIGHT CUTOFF
This parameter configures the point at which key backlighting is switched off in bright light. For example,
a value of 70% means that the key backlights will be off at photocell source input levels above 70%. This
field has a range of 0 (zero) to 100% and is set to 80% as the default setting.
PHOTOCELL TRANSITION
When a lighting bus is used to control the lighting of the display, this parameter sets the point on the
lighting bus control below which the display brightness tracks the GTN’s photocell. This field has a
range of 0 (zero) to 50, and is set to 25 as the default setting.
Figure 5-9. Photocell Configuration Page
Page 5-12 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5.4.6.2 Configure Lighting Bus Page
The Lighting Bus Configuration page offers the same
Response Time, Slope, and Offset adjustments as
described in Section 5.4.6.1.
LIGHTING BUS SOURCE
To configure the lighting bus source voltage, touch the
‘Lighting Bus 1’ or ‘Lighting Bus 2’ button. Select 14V
DC, 28V DC, 5V DC, or 5V AC depending on the
lighting bus voltage source.
5.4.7 Audio Configuration Page
The Audio Configuration page allows the adjustment of volume
alerts. See Figure 5-11. Touch the Audio button on the GTN
Setup page. To adjust the alert volume, press the ‘ – ‘ or the ‘ + ‘
sign to decrease or increase the volume accordingly. The
volume is displayed as a percentage of maximum volume, with
0% being muted and 100% being max volume. The selected
volume level can be checked by selecting ‘Test Sound’ and then
touching the green triangle to the right of the button.
Figure 5-10. Lighting Bus Configuration Page
Figure 5-11. Audio Configuration Page
GTN 725/750 TSO Installation Manual Page 5-13
190-01007-02 Rev. A
5.4.8 Traffic Configuration Page
Access the Traffic Configuration Page from the Main GTN
Configuration home page. See Figure 5-3. The Traffic
Configuration page allows the traffic intruder symbol color and
external control to be configured for each specific installation.
To adjust the traffic intruder symbol color, touch the button to
toggle between white or cyan, as shown in Figure 5-12. White
is the default symbol color.
Configure the GTN control of the traffic system. If the GTN is
used to control the traffic system, touch the button and select
‘Yes’. If a separate display device is used to control the traffic
system, select ‘No’.
5.4.9 Main System Configuration Page
Touch the Main System button from the GTN Setup page. See Figure 5-3. This page displays
miscellaneous configuration options.
AIR/GROUND THRESHOLD
The air/ground threshold is the speed at which the GTN transitions from a ground state to an airborne
state, and vice versa. To adjust the air/ground threshold, touch the button to the left and enter a value.
This field has a range of 0 (zero) to 99 knots and is set to 30 knots as a default value.
AIR/GROUND DISCRETE
The air/ground discrete is the ------. To adjust the air/ground
threshold, touch the button to the left and enter a value. This
field two options: Active for Airborne and Active for
Ground.
GPS ANTENNA HEIGHT ABOVE GROUND
This configures the height of the GPS antenna above ground
level while the aircraft is sitting on the ground. Before
proceeding, measure the GPS antenna vertical offset (to the
nearest tenth of a foot) as shown in Figure 5-13. Enter the
measured value by touching the button and entering the
measured value into the keypad on the display. This field has
a range of 0.0 to 99.9 feet.
FUEL TYPE
This configures the type of fuel the aircraft uses. Options
are AV Gas, Jet A, or Jet B.
GPS SELECT
????
Figure 5-12. Traffic Configuration Page
Figure 5-13. Main System Configuration Page
Page 5-14 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
GPS Antenna
Vertical Offset (ft)
Figure 5-14. Measurement of GPS Antenna Vertical Offset
5.4.10 COM Configuration Page (GTN 750 Only)
Select the COM configuration page from the main GTN Setup page as shown in Figure 5-3. These values
are set at the factory and rarely require calibration.
To enable or disable the COM radio, touch the button to toggle between ‘Enabled’ and ‘Disabled’. The
COM radio defaults to enabled state. See Figure 5-15.
COM RF SQUELCH
This setting configures the RF squelch threshold for
the COM radio. This field may be set to any value
between 0% and 100%.
MIC 1 GAIN
This can be adjusted to 12 dB, 18 dB, 24 dB, or 30
dB.
SIDETONE VOLUME
This parameter sets the audio sidetone output level.
This value may be set to values between 0.0 dB and
63.0 dB in 0.5 dB increments. The default is TBD
dB.
Figure 5-15. COM Configuration Page
GTN 725/750 TSO Installation Manual Page 5-15
190-01007-02 Rev. A
5.4.11 VOR/LOC/GS Configuration Page
Select the VOR/LOC/GS from the GTN Setup page
by touching the button on the display. See Figure 5-3.
This page allows you to verify and calibrate the CDI
outputs from the VOR/LOC/GS receiver as well as
the OBS resolver input to the VOR receiver. It also
allows you to select the format for the DME tuning
data.
ENABLE/DISABLE NAV RADIO
Touch the button to disable or enable the NAV Radio.
CALIBRATE OBS RESOLVER
To calibrate the OBS resolver, touch the ‘Calibrate’
button from the VOR/LOC/GS Configuration page.
See Figure 5-16. Next, select 150˚ on the OBS, then
touch the OK button, as prompted on the display.
After the OBS resolver is finished calibrating, the
GTN will display ‘OBS Resolver Calibration
Complete’. Touch ‘OK’ after the calibration is
complete. Verify OBS operation by checking that the
course displayed on the GTN is within 2° of the
selected course. Do this at 30° intervals around the
OBS card.
ARINC 429 CONFIGURATION SPEED (RX AND TX)
Selection Description
Low Standard low-speed ARINC 429 (nominally 12.5 kilobits per second)
High High-speed ARINC 429 (nominally 100 kilobits per second)
SDI
Selection Description
Common RX: Accepts all 429 inputs
TX: Generates all 429 outputs with SDI = 0.
VOR/ILS 1
Number 1 (Pilot) VOR/ILS Receiver
RX: Accepts 429 inputs with SDI = 0 or 1.
TX: Generates all 429 outputs with SDI = 1.
VOR/ILS 2
Number 2 (Copilot) VOR/ILS Receiver
RX: Accepts 429 inputs with SDI = 0 or 2.
TX: Generates all 429 outputs with SDI = 2.
DME MODE
Selection Description
Directed freq 1
If the GTN is connected to a multi-channel ARINC 429 DME, channel
1 of that DME is tuned. “Directed freq 1” should be selected if a
single-channel ARINC 429 DME is to be tuned.
Directed freq 2 If the GTN is connected to a multi-channel ARINC 429 DME, channel
2 of that DME is tuned.
Figure 5-16. VOR/LOC/GS Configuration Page
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Rev. A 190-01007-02
DME CHANNEL MODE
This configuration setting allows you to set the format for DME tuning data output.
Selection Description
King serial King Serial DME tuning data
Parallel 2x5 2 of 5 parallel DME tuning.
Parallel BCD Shifted BCD (Binary Coded Decimal) parallel DME tuning
Parallel slip Slip-code parallel DME tuning
Narco 890/891
2 of 5 parallel DME tuning, compatible with the following DME units:
Narco DME 890
Narco DME 891
ARC (Cessna) RTA-476A
GTN 725/750 TSO Installation Manual Page 5-17
190-01007-02 Rev. A
5.5 Ground Checks (Configuration Mode)
The following checks are done in Configuration Mode. For instructions concerning entering
Configuration Mode, see Section 5.4.
5.5.1 Main Indicator Check (Analog Only)
NOTE
If the GTN is interfaced to an electronic HSI and the main indicator analog output is not
used, this check is not required.
If the GTN is interfaced to an analog indicator on the main
CDI/OBS, perform the following steps:
1. Go to the GTN Diagnostics page. See Figure 5-17.
2. Go to the Main Indicator (Analog) page.
3. Verify correct operation of the lateral deviation, flag
and TO/FROM flag using the corresponding
selections.
4. Verify correct operation of the vertical deviation
and flag using the corresponding selections.
5. Verify correct operation of the OBS knob using the
SELECTED COURSE display. At 30° increments
around the OBS card, ensure that the indicated
value is within 2° of the value set on the indicator.
If the resolver is not within 2°, calibrate the resolver
as described in Section 5.4.4.
5.5.2 VOR/ILS Indicator (Analog)
If the GTN is interfaced to an analog indicator on the VOR/ILS Indicator output, perform the following
steps:
1. Go to the GTN Diagnostics page. See Figure 5-17.
2. Go to the NAV page.
3. Verify correct operation of the lateral deviation, flag and TO/FROM flag using the corresponding
selections.
4. Verify correct operation of the vertical deviation and flag using the corresponding selections.
5.5.3 Discrete Inputs Checkout
If the GTN is connected to external switches, perform the following steps:
1. Go to the GTN Diagnostics page. See Figure 5-17.
2. Go to the Discrete Inputs page.
3. For each external switch that is connected, exercise the switch and check the ‘active’ or ‘inactive’
indication on the screen correlating to the appropriate switch input, and ensure it is displayed
correctly.
Figure 5-17. GTN Diagnostics Page
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Rev. A 190-01007-02
5.5.4 Discrete Outputs Checkout
If the GTN is connected to external annunciators/systems, perform the following steps:
1. Go to the GTN Diagnostics page. See Figure 5-17.
2. Go to the Discrete Outputs page.
3. For each annunciator output that is connected to an external system or annunciator, toggle the
output ACTIVE (corresponding box is filled green and displays ‘ACTIVE’) and INACTIVE
(corresponding box is not filled green and displays ‘INACTIVE’) by touching the button
corresponding to the output. Verify that the appropriate external annunciator illuminates when the
output is set to ACTIVE and extinguishes when the output is set to INACTIVE. If the output is
not connected to an annunciator but provides an input to another system, verify that the other
system receives the signal.
5.5.5 HSDB Provisional Wiring Checkout
If provisional wiring has been installed for the
GTS 8XX, GDU 620, or other Garmin LRU to interface via
HSDB, follow the procedure below to ensure it has been
installed correctly.
1. Access the GTN Diagnostics page from the
Configuration Mode home page. See Figure 5-17.
2. Touch the HSDB (Ethernet) button.
3. For each Ethernet port that has provisional wiring
connected to it, ensure that the port status displays
‘Connected’.
Figure 5-18. HSDB Diagnostics Page
GTN 725/750 TSO Installation Manual Page 5-19
190-01007-02 Rev. A
5.5.6 TAWS Audio Check (For Units with TAWS Only)
NOTE
The audio panel should also be turned on for this test.
The TAWS audio volume has an initial default of 80% of the maximum volume value. The TAWS
volume needs to be set so as to ensure that aural alerts are audible under all anticipated noise
environmental conditions.
1. Touch the Audio configuration page from the GTN Setup
page. See Figure 5-19.
2. Next to ‘Alert Audio’, increase or decrease the volume by
touching the ‘+’ or ‘-‘ button.
3. Evaluate the TAWS audio messages for acceptable
volume and intelligibility during both low and high
cockpit noise levels (idle descent at low speed and high
power at Vmo).
4. Readjust the Volume as needed to ensure the TAWS
audio messages will be heard in all anticipated cockpit
noise conditions.
Figure 5-19. GTN Audio
Configuration Page
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Rev. A 190-01007-02
5.5.7 GAD 42 Interface Check
This check verifies that the GTN is interfaced with the GAD 42.
Go to the GAD 42 Configuration Page from the External
Systems page. Touch ‘External Systems’, then touch ‘GAD 42’.
1. Verify that Status is ACTIVE.
2. Change any of the options to a different number.
3. Verify that after changing one of the options the
STATUS field changes to SENDING then changes back
to ACTIVE. If the entry reverts to the previous number
when ACTIVE is displayed, then refer to the latest
revision of the GAD 42 Installation Manual
(P/N 190-00159-00).
5.5.8 Lighting Bus Interface Check
The display and key backlighting on the GTN can track an
external lighting/dimmer bus input and use it to vary the display
and key backlight levels accordingly. This check verifies that the
interface is connected correctly.
CAUTION
When 14 VDC or 28 VDC lighting buses are connected to the GTN, connection of the
aircraft lighting bus to the incorrect input pins can cause damage to the GTN. Always start
this test with the dimming bus at the lowest setting, and slowly increase the brightness. If it
is noticed that the LIGHTING level displayed on the GTN does not increase as the lighting
is increased in brightness, verify that the wiring is correct before proceeding.
1. Go to the Lighting Bus Configuration page from the
GTN Setup page. See Figure 5-21.
2. Ensure the lighting bus is set to its minimum setting.
3. Slowly vary the lighting bus level that is connected to
the GTN. Verify that the Source Input Level value
displayed on the configuration screen tracks the lighting
bus setting. Continue to maximum brightness and verify
proper operation.
Figure 5-20. GAD 42 Configuration
Page
Figure 5-21. Lighting Bus Configuration Page
GTN 725/750 TSO Installation Manual Page 5-21
190-01007-02 Rev. A
5.6 Ground Checks (Normal Mode)
For the following checks, cycle power on the GTN and power it up in normal mode.
5.6.1 Display of Self-Test Data
Following normal power-up, the Database pages are displayed, followed by the Instrument Panel Self-
Test page. Pressing ‘Continue’ displays the Instrument Panel Self-Test page. During this time, the
electrical outputs are activated and set to the values listed below. Touch ‘Continue’ to acknowledge the
self test page. This is not a required check, although this page can be useful for troubleshooting
installation problems.
Parameter Self-Test Value
Course Deviation Half-scale left deviation, TO indication, flag pulled
Glideslope/Vert. Deviation Half-scale up deviation, flag pulled
Annunciators All On
Bearing to Waypoint (RMI) 135°
Selected Course (OBS) The GTN displays the OBS value (149.5° if interfaced to an HSI
with driven course pointer).
Desired Track 149.5° (Displayed as 150°)
Items below are not displayed on the INSTRUMENT PANEL SELF-TEST page
Distance to Go 10.0 nautical miles
Time to Go 4 minutes
Active Waypoint “GARMN”
Groundspeed 150 knots
Present Position N 39°04.05’, W 94°53.86’
Waypoint Alert Active
Phase of Flight En Route
Message Alert Active
Leg/OBS Mode Leg Mode
GPS Integrity Invalid
Roll Steering (if applicable)
Flight Director commands 0° bank (level flight) for 5 seconds;
commands increasing right bank at 1°/second for 5 seconds;
commands 5° right bank for 5 seconds; commands decreasing
right bank at 1°/second for 5 seconds, until command is 0° bank
again. This cycle repeats continuously.
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Rev. A 190-01007-02
5.6.2 Signal Acquisition Check
NOTE
All other avionics should be turned off at the start of this test, with the GTN powered on.
Ensure the GTN is able to acquire sufficient satellites to compute a GPS position. From the Home page,
touch the AUX button and then touch the GPS Status button. Under ‘Status’, ensure that a 3D Fix, or 3D
Diff Fix is obtained. If the unit is unable to acquire satellites, move the aircraft away from obstructions
which might be shading GPS reception. If the situation does not improve, check the GPS antenna
installation.
NOTE
After installation, the initial acquisition of position can take up to 20 minutes.
Subsequent acquisitions will not take that long.
Once GPS position information is available, perform the following steps:
1. On the GPS Status Page, verify that the LAT/LON agree with a known reference position.
2. While monitoring the GPS Status Page, turn on other avionics one at a time and check the GPS
signal reception to make sure it is not affected (no significant signal degradation).
3. Before proceeding with the VHF COM interference check, ensure that any connected equipment
is transmitting and/or receiving data from the GTN and is functioning properly.
5.6.3 VHF COM Interference Check
NOTE
The interference check must be completed on all IFR installations.
NOTE
It is known that certain non-aviation radios, including marine transceivers, can interfere
with civil aviation navigation and surveillance equipment including the Garmin GTN.
When installing GTN equipment, it is the responsibility of the installer to ensure that the
GTN modification is compatible with all previous aircraft modifications. Garmin
recommends that whenever a GTN is installed in an aircraft that has been modified with
non-aviation radios, particular care should be exercised to verify that these do not
interfere with proper function of the GTN. Special care should also be taken to ensure
that there is no interference with the GTN if non-aviation radios are installed in an
aircraft after a GTN has been installed. If interference is found, it can be addressed by
relocating antennas, rerouting cables, using filters to attenuate unintentional harmonic
frequency transmissions, or using various other techniques for elimination of the
interference. It may be necessary to remove or replace the interfering radio with a model
that does not interfere with the proper functioning of the GTN.
If you are testing a transmitter from a non-aviation device, each frequency must be
verified by transmitting for at least 30 seconds on each channel.
GTN 725/750 TSO Installation Manual Page 5-23
190-01007-02 Rev. A
Once the Signal Acquisition Test has been completed successfully, perform the following steps:
1. View the Satellite Status Page and verify that at least 7 satellites have been acquired by the GTN.
2. Verify that the GPS “INTEG” flag is out of view.
3. Select 121.150 MHz on the COM transceiver to be tested.
4. Transmit for a period of 35 seconds.
5. Verify that the GPS “INTEG” flag does not come into view.
6. Repeat steps 4 and 5 for the following frequencies:
25 kHz COM CHANNEL SPACING
121.150 MHz 131.225 MHz
121.175 MHz 131.250 MHz
121.200 MHz 131.275 MHz
121.225 MHz 131.300 MHz
121.250 MHz 131.325 MHz
131.200 MHz 131.350 MHz
NOTE
For VHF radios with 8.33 kHz channel spacing, include the following frequencies in
addition to those listed above.
8.33 kHz COM CHANNEL SPACING
121.185 MHz 130.285 MHz
121.190 MHz 131.290 MHz
7. Repeat steps 3 through 6 for all remaining COM transceivers installed in the aircraft.
8. If aircraft is TCAS-equipped, turn on the TCAS system and verify that GPS position remains
valid (if position is lost, the status on the GPS Status page will change to “ACQUIRING”).
9. If aircraft is SATCOM-equipped, use the SATCOM system and verify that GPS position remains
valid (if position is lost, the status on the GPS Status page will change to “ACQUIRING”).
If the GPS “INTEG” flag comes into view, see TBD for options to improve performance.
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Rev. A 190-01007-02
5.6.4 VHF NAV Checkout (GTN 750 Only)
Touch the CDI key to select VLOC mode, which is indicated by a green ‘VLOC’ annunciation on the
bottom center of the display. Check the VOR reception with ground equipment, operating VOT or VOR,
and verify audio and Morse code ID functions (if possible). Tune a Localizer frequency and verify the
CDI needle and NAV flag, and VDI needle and GS flag operation.
5.6.5 VHF COM Checkout (GTN 750 Only)
5.6.5.1 Antenna Check
If desired, the antenna VSWR can be checked using an inline wattmeter in the antenna coax using
frequencies near both ends of the band. The VSWR should be < 2:1. A VSWR of 2:1 will cause a drop in
output power of approximately 12%.
5.6.5.2 Receiver/Transmitter Operation
Tune the unit to a local VHF frequency and verify the receiver output produces a clear and
understandable audio output. Verify the transmitter functions properly by contacting another station and
getting a report of reliable communications.
5.6.6 TAWS System Check (For Units with TAWS Only)
While on the ground, turn on the GTN following normal power-up procedures. Also turn on the audio
panel.
NOTE
A 3D GPS position fix is required to conduct this check.
1. Select the TAWS page.
2. Touch the MENU button.
3. Select the Test Terrain? field and press the ENT key.
4. Wait until the TAWS self-test completes (10-15 seconds) to hear the TAWS system status aural
message.
• The aural message “TAWS System Test OK” will be annunciated if the TAWS system is
functioning properly.
• The aural message “TAWS System Failure” will be annunciated if the TAWS system is
NOT functioning properly.
If no audio message is heard, then a fault exists within the audio system and the TAWS capability must
be considered non-functional.
GTN 725/750 TSO Installation Manual Page 5-25
190-01007-02 Rev. A
5.6.7 Altitude Encoder or Air Data Computer Check
The GTN can receive altitude data from an external source. This check verifies that the GTN is receiving
data from these sources. Ensure that the GTN is powered on and in normal mode. If the following steps
do not perform correctly, check the electrical connections and configuration setup.
1. Go to the map page from the home page in normal mode.
2. Touch the Menu button.
3. Under ‘Map Data Fields’ touch the Change Data Fields button. See Figure 5-22.
4. Touch one of the four data fields and configure it to display PRESS ALT—Pressure Altitude.
5. If there are multiple altitude sources providing data to the GTN, remove power from all but one
source.
6. Verify that PRESS—ALT is being displayed and agrees with the active altitude source.
NOTE
After applying power to an altitude source it may take several minutes to warm up.
During the warm-up period the altitude display on the GTN will be dashed out.
7. If there are multiple altitude sources, remove power from the currently active source and apply
power to another source that has not been checked.
8. Repeat steps 5-7 until all available sources have been checked.
5.6.8 AHRS/IRU Interface Check
The GTN can receive heading data from an external source. This check verifies that the GTN is receiving
data from these units. Ensure the GTN is turned on and in normal mode. If the following steps do not
perform correctly, check the electrical connections and configuration setup.
1. Go to the map page from the home page in normal
mode.
2. Touch the Menu button.
3. Under ‘Map Data Fields’ touch the Change Data
Fields button. See Figure 5-22.
4. Touch one of the four data fields and configure it
to display BRG — Bearing to Current Waypoint.
NOTE
If a Sandel EHSI or an ARINC 429 EFIS is also
installed, ensure that it is turned off so that it does
not supply heading to the GTN. Verify that the
HDG field displays valid heading data.
5. Remove power from the heading source and
verify that the heading in the BRG field is dashed
out.
Figure 5-22. Map Menu Page
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Rev. A 190-01007-02
5.6.9 Interface Checkout
This section describes the checks that must be carried out to verify that systems interfacing to the GTN
are communicating properly. Only those interfaces that are connected to the GTN must be verified.
5.6.9.1 Honeywell (Bendix/King) EFS40/50 Interface Check
If a Honeywell EFS40/50 has been connected to the GTN, the interface should be verified as described in
this section.
1. Cycle power to the first GTN and acknowledge the prompts until it gets to the self test page (see
Section 5.6.1).
2. Ensure that GPS1 data is displayed by pressing the “1-2” key on the EFS40/50 control panel.
3. While the GTN is displaying the self test page, verify that the EFS40/50 is displaying data from
the GPS source. Note that vertical deviation will not be displayed.
• Course Deviation: Half-scale left deviation, TO indication, flag pulled
• Active Waypoint: GARMN
• Vertical Deviation: Half-scale up deviation (only if installation is setup to display
GPS vertical deviation)
4. On the GTN verify that an OBS value is displayed (and not dashed out).
5. Using a VOR test set verify that the CDI deviation on the EFS40/50 is displayed correctly.
6. Cycle power to the second GTN and acknowledge the prompts until it gets to the self test page.
7. Switch to GPS2 data by pressing the “1-2” key on the EFS40/50 control panel and repeat steps 3
through 5 with the second GTN.
5.6.9.2 Sandel SN 3308 Interface Check
If a Sandel EHSI has been connected to the GTN, the interface should be verified as described in one of
the following sections, as appropriate for the installation.
5.6.9.2.1 One GTN/One SN 3308
1. Cycle power to the GTN and acknowledge the prompts until it gets to the self test page (see
Section 5.6.1).
2. Ensure that the SN3308 is receiving valid heading.
NOTE
The Vertical Deviation Indication will not be displayed unless the SN3308 is receiving
valid heading.
3. While the GTN is displaying the self test page, verify that the SN3308 is displaying the following
data from the GPS source.
• Course Deviation: Half-scale left deviation, TO indication, flag pulled
• Vertical Deviation: Half-scale up deviation, flag pulled
• Active Waypoint: GARMN
4. On the GTN verify that an OBS value is displayed (and not dashed out).
5. Acknowledge the self test on the GTN by touching the ‘Continue’ button.
6. Select VLOC on the GTN and verify that the SN3308 displays NAV 1 or NAV 2 (depending on
what navigation source the GTN is).
7. Using a VOR test set verify that the CDI deviation on the SN3308 is displayed correctly.
GTN 725/750 TSO Installation Manual Page 5-27
190-01007-02 Rev. A
5.6.9.2.2 Two GTNs/One SN3308
The checkout for two GTNs also applies to one GTN 6XX and one GTN 7XX.
1. Remove power from GTN #2.
2. Cycle power to the 1st GTN and acknowledge the prompts until it gets to the self test page (see
Section 5.6.1).
3. Select GPS1 as the navigation source by pressing the NAV key on the SN3308.
4. Ensure that the SN3308 is receiving valid heading.
NOTE
The Vertical Deviation Indication will not be displayed unless the SN3308 is receiving
valid heading.
5. While GTN #1 is displaying the self test page, verify that the SN3308 is displaying the following
data from GPS1.
• Course Deviation: Half-scale left deviation, TO indication, flag pulled
• Vertical Deviation: Half-scale up deviation, flag pulled
• Active Waypoint: GARMN
6. On GTN #1 verify that an OBS value is displayed (and not dashed out).
7. Acknowledge the self test on GTN #1 by touching the ‘Continue’ button.
8. Select VLOC on GTN #1 and verify that the SN3308 displays NAV 1 or NAV 2 (depending on
what navigation source the GTN is).
9. Using a VOR test set verify that the CDI deviation on the SN3308 is displayed correctly.
10. Remove power from GTN #1 and apply power to GTN #2 and acknowledge the prompts until it
gets to the self test page (see Section 5.6.1).
11. Select GPS2 by pressing the NAV key on the SN3308.
12. Repeat steps 4-9 with the second GTN.
5.6.9.3 Sandel SN3500/4500 Interface Check
If a Sandel SN3500/4500 EHSI has been connected to the GTN, the interface should be verified as
described in this section.
1. Cycle power to the GTN and acknowledge the prompts until it gets to the self test page (see
Section 5.6.1).
2. Ensure that the SN3500/4500 is receiving valid heading.
NOTE
The Vertical Deviation Indication will not be displayed unless the SN3500 is receiving
valid heading.
3. While the GTN is displaying the self test page, verify that the SN3500/4500 is displaying data
from the GPS source.
• Course Deviation: Half-scale left deviation, TO indication, flag pulled
• Vertical Deviation: Half-scale up deviation, flag pulled
• Active Waypoint: GARMN
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Rev. A 190-01007-02
NOTE
If the Vertical Deviation Indication is not displayed ensure that the Main ARINC 429
Config (See Section TBD) is set to Enable Labels for VNAV.
4. On the GTN verify that an OBS value is displayed (and not dashed out).
5. Acknowledge the self test on the GTN by touching the ‘Continue’ button.
6. Select VLOC on the GTN and verify that the SN3308 displays NAV 1 or
NAV 2 (depending on what navigation source the GTN is).
7. Ensure that the NAV1 (or NAV2) indication does not have a red line through it.
5.6.9.4 EHSI Deviation Scaling (If HSI/CDI Is Driven by the GTN Via Serial Data)
If the GTN has a serial connection to an EFIS display, proper scaling of the EFIS CDI and VDI must be
verified.
1. Cycle power to the GTN and acknowledge the prompts until it gets to the self test page (see
Section 5.6.1).
2. With the self test page displayed on the GTN, look on the EHSI/EFIS and verify that the lateral
deviation is not flagged and half-scale left.
3. With the self test page displayed on the GTN, look on the EHSI/EFIS and verify that the vertical
deviation is not flagged and half-scale up.
NOTE
If the deviations are not as described, the EHSI/EFIS does not scale the GTN deviations
properly and cannot be certified for GPS-based guidance. Contact Garmin for further
assistance.
5.6.9.5 ARINC 429 Traffic System Interface Check
If a Garmin GTS 8XX Traffic system, L3 Communications SKY497/SKY899 SkyWatch® sensor or a
Honeywell (Bendix/King) KTA 810 TAS/KMH 820 IHAS has been connected to the GTN via ARINC
429, the traffic interface should be verified as described in this section.
1. Go to the Traffic page on the GTN from the home page.
2. Verify that NO DATA is not displayed in yellow on the center of the traffic page.
3. Verify that the traffic system mode can be changed from STBY to OPER.
4. Switch the traffic system mode to STBY, and then run the traffic self test from the Menu.
5. Verify that the traffic system executes a self test and a self-test pattern is displayed on the GTN
traffic display.
5.6.9.6 Ryan TCAD Traffic System Interface Check
If a Ryan TCAD has been connected to the GTN, the traffic interface should be verified as described in
this section.
1. Go to the Traffic page on the GTN which can be accessed from the Home page.
2. Verify that NO DATA is not displayed in yellow on the center of the traffic page.
3. Using the SETUP selection under the Traffic Menu, verify that the shield mode can be changed.
GTN 725/750 TSO Installation Manual Page 5-29
190-01007-02 Rev. A
5.6.9.7 Stormscope Interface Check
If an L3 Communications WX-500W Stormscope has been connected to the GTN, the Stormscope
interface should be verified as described in this section.
1. Go to the Lightning page on the GTN.
2. Verify that LIGHTNING FAILED is not displayed in yellow on the center of the Lightning page.
Using the Self Test selection under the Lightning Menu, initiate a Stormscope self-test.
5.6.9.8 GMX 200/MX20 Interface Check
If a Garmin GMX 200 or MX20 has been connected to the GTN, the interface should be verified as
described in this section.
1. Ensure that the GTN has a 3-D fix.
2. Create and activate a flight plan on the GTN.
3. Verify that the RTE and POS data flags are not displayed on the GMX 200/MX20.
4. Verify that the flight plan is displayed on the GMX 200/MX20 using the flight plan (FPL)
function.
5.6.9.9 GDL 69/69A Interface Check
If a Garmin GDL 69 has been connected to the GTN, the interface should be verified as described in
Section 5.6.9.9.1. If a Garmin GDL 69A has been connected to the GTN, the interface should be verified
as described Sections 5.6.9.9.1 and 5.6.9.9.2. Each of these procedures involves verifying that the
satellite signal is acquired and tracked. Locate the aircraft where there is a clear view of the southeastern
or southwestern sky. XM Satellite Radio satellites are located above the equator over the eastern and
western coasts of the continental United States.
NOTE
The following sections only verify the correct interface of GDL 69/69A to the GTN. It
does not activate the GDL 69 XM data link radio. Complete instructions for activating
the XM data link radio can be found in document 190-00355-04, GDL 69/69A XM
Satellite Radio Activation Instructions.
5.6.9.9.1 XM Satellite Radio Weather Checkout Procedure
1. With the GTN running in the normal mode, go to the System Status page (in the AUX page
group) then touch the GDL69 button.
2. Verify that the Data Radio ID field has a valid ID. For a GDL 69A, the Audio Radio ID field
should also display a valid ID.
3. Go to the XM WX Timestamp page and verify that timestamp data is displayed. This may take
several minutes. (Time stamp data will not be available if the XM subscription has not been
activated.)
During XM activation, “Detecting Activation” will be displayed in the SERVICE CLASS field on the
XM Information page, and “Aviator” will be displayed once the XM signal is detected.
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Rev. A 190-01007-02
5.6.9.9.2 XM Satellite Radio Audio Checkout Procedure
1. Go to the Music page from the Home page.
NOTE
If the XM Satellite Radio audio subscription has not been activated, audio is available
only on Channel 1. If the audio subscription has been activated, audio should be
available on multiple channels.
2. Ensure that the GDL 69A audio is not muted.
3. Verify that audio can be heard over the headsets. Adjustment of the volume may be required.
5.6.9.10 Crossfill Check (If Dual GTNs Installed)
Turn on both GTN units in the aircraft. For each GTN unit:
1. Go to the HSDB Ethernet Diagnostics page from the GTN Diagnostics page. This can be reached
from the GTN Configuration home page.
2. For the port that the cross-side GTN is connected to, check the Ethernet Port Status and ensure
that ‘Connected’ is displayed under ‘Connection’ and ‘Receiving’ is displayed under ‘Data’.
3. If the previous steps do not perform correctly, check the electrical connections and configuration
setup.
5.6.9.11 External RMI/OBI Interface Check
The GTN RMI/OBI output can be used to drive an RMI (or OBI) navigation indicator. This check
verifies that the RMI/OBI is receiving data from the GTN. If the following steps do not perform
correctly, check the electrical connections and configuration setup.
NOTE
The aircraft heading system must be operating properly in order for the RMI needle to
point correctly.
5.6.9.11.1 Main OBI Output
If the Main OBI output from the GTN is connected to an RMI navigation indicator verify the interface as
described in this section.
1. Apply power to the equipment and wait for the GTN to acquire a position.
2. On the GTN, set a course to a destination waypoint and ensure GPS is selected for display on the
CDI.
3. If installed, set the RMI select switch to the GPS position.
4. Verify that the RMI needle swings and points toward the GPS waypoint selected.
5. If the Main OBI Output is configured to “Track CDI,” ensure that a valid VOR station is not
tuned. Select VLOC on the CDI and verify that the RMI needle is parked at the invalid position.
6. If the Main OBI Output is configured to output “Always GPS,” select VLOC on the CDI and
verify that the RMI needle still points towards the GPS waypoint selected.
GTN 725/750 TSO Installation Manual Page 5-31
190-01007-02 Rev. A
5.6.9.11.2 VOR OBI Output (GTN 750)
If the VOR OBI output from the GTN 650/750 is connected to an RMI navigation indicator verify the
interface as described in this section.
1. Apply power to the equipment.
2. If installed, set the RMI select switch to the VLOC position.
3. Tune a local VOR station, or use a simulated signal from an approved VOR Test System.
4. Verify that the RMI needle swings and points toward the VOR station.
5.6.9.12 DME Tuning Check (GTN 750 Only)
If the GTN is set up to remotely channel a DME, verify the interface as described in this section.
1. Select a VOR/ILS channel that corresponds to (1) a DME station within a 40 nautical mile range,
or (2) the frequency of a DME ground tester.
2. Verify that the DME locks on to the signal and a valid distance, ground speed and time are
displayed.
3. Tune an invalid VOR station. Verify that the DME changes to an invalid station.
5.6.9.13 GDU 620 (G500/G600) Interface Check
5.6.10 Magnetic Compass Check
A Compass swing should be carried out at completion of installation in accordance with AC 43.13-1B,
chapter 12, section 3, paragraph 12-37.
Page 5-32 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
5.7 Flight Checks
All GTN functions that cannot be adequately tested on the ground will require a flight check. Even if all
functions can be verified on the ground, a flight check is recommended as final installation verification.
Verify system operation as described in the following sections.
NOTE
The analog deviation (LEFT/RIGHT and UP/DOWN), TO/FROM, and FLAG (lateral
and vertical) outputs to a CDI or HSI should be verified in flight with potential sources of
electrical noise such as autopilot, flaps, gear, heater blowers, etc. operating. Lateral
deviation and flags may be checked with either GPS or VOR/ILS, and vertical deviation
and flags must be checked with Glideslope. Verify that the flags are hidden at the correct
times, and that the flag is in view at the correct times.
5.7.1 GPS Flight Check
1. Verify that GPS position is not lost during normal aircraft maneuvering (e.g. bank angles up to 30
degrees and pitch angles associated with take-off, departures, approaches, landing and missed
approaches as applicable). If GPS position is lost, a “Loss of GPS Navigation” message will be
displayed.
2. Enter and activate a flight plan on the GTN. Fly the flight plan and verify that the display of
flight plan data is consistent with the CDI indication (deviation, TO/FROM…) in the pilot’s
primary field of view.
5.7.2 VHF COM Flight Check (GTN 750)
After the installation is complete, a flight check is recommended to ensure satisfactory performance. To
check the communications transceiver, maintain an appropriate altitude and contact a ground station
facility at a range of at least 50 nautical miles. Contact a ground station in close proximity. Press the
COM volume knob to select manual squelch and listen for any unusual electrical noise, which would
increase the squelch threshold. If possible, verify the communications capability on both the high, low
and mid bands of the VHF COM band. It may be required by the governing regulatory agency to verify
operation of the COM transmitter and receiver at the extents of a ground facility’s service volume (e.g.,
FAA AC 23-8A).
5.7.3 VOR Flight Check (GTN 750)
1. Tune a local VOR station within 50 miles.
2. Verify the AUDIO IDENT and VOICE QUALITY have no objectionable electrical interference
such as magneto noise.
3. Verify the Morse code decoder IDs the station (95% probability).
4. Fly to and from the station.
5. Verify NAV flag, TO/FROM flag, and CDI are operational.
6. Record accuracy in System Log (see manual).
It may be required by the governing regulatory agency to verify operation of the VOR receiver at the
extents of a ground facility’s service volume (e.g., FAA AC 23-8A).
GTN 725/750 TSO Installation Manual Page 5-33
190-01007-02 Rev. A
5.7.4 ILS Flight Check (GTN 750)
1. Tune an ILS at the local airport.
2. Verify the AUDIO IDENT and AUDIO QUALITY have no objectionable electrical interference
such as magneto noise.
3. Verify the Morse code decoder IDs the station (95% probability).
4. Fly the approach.
5. Verify NAV flag, GS flag, and CDI and VDI are operational.
6. Verify BC annunciator.
5.7.5 Autopilot Flight Check
1. Enter and activate a flight plan on the GTN. For the GTN 650/750, ensure that GPS is selected on
the CDI. Engage the autopilot in the GPSS mode. Verify that the autopilot flies the course.
2. Disengage the autopilot and fly off course. Re-engage the autopilot (in GPSS mode) and verify
that it correctly intercepts the course and continues to fly it.
3. Turn off the autopilot GPSS but leave the autopilot engaged in NAV mode. Verify that it
maintains the current course.
4. (GTN 750 Only): Reselect the GPSS mode on the autopilot. Press the CDI key to select VLOC on
the GTN 750. Verify that the GPSS mode disengages.
5.7.6 TAWS Audio Flight Check (TAWS-equipped Units Only)
NOTE
The TAWS volume needs to be loud enough to ensure that aural alerts are audible under
all anticipated noise environmental conditions. This check verifies that TAWS aurals can
be heard during flight, but the ambient noise conditions under which it is verified are not
worst-case. Consequently, the “Five Hundred” callout should be louder than is required
for the conditions under which it is verified.
1. Set up for an approach to the airport.
2. During the approach, at approximately 500 ft AGL, the “Five Hundred” callout will occur.
Verify that “Five Hundred” can be easily heard and understood.
5.8 Database Check
Check the navigation database to ensure it is current. The database information is displayed during the
unit display start-up sequence. To check the database:
1. Turn off the GTN and then turn it on. The GTN will go through its normal start-up sequence.
2. Wait for the Navigation Database page to be displayed.
3. Verify that the expiration date displayed has not passed.
If the database has expired, then remove and replace the navigation database card as described in the
following section, and see Section 5.9.
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Rev. A 190-01007-02
5.9 Data Card Replacement
CAUTION
Handle the data cards carefully. Do not touch the connector edge of the data card.
To replace the data card do the following:
1. Ensure that the GTN is turned off.
2. Remove the data card by pressing the card until it disengages and then pull card to extract from
the unit.
3. With the label facing right, insert the new data card by pushing the card straight into the slot and
press until it is inserted fully.
5.10 Software Loading
5.11 System Setup
5.12 Documentation Checks
5.12.1 Airplane Flight Manual Supplement
Ensure that the Airplane Flight Manual Supplement (AFMS) is completed and inserted in the Airplane
Flight Manual (AFM) or Pilot’s Operating Handbook (POH).
1. Fill in the required airplane information in the AFMS.
2. Fill in the appropriate checkbox in the Limitations section of the AFMS corresponding to the
autopilot coupling limitations.
NOTE
The GPS SELECT setting will determine if the transition into approach mode is
automatic or requires pilot acknowledgement of a message prompt.
3. Fill in the appropriate checkbox in the Normal Procedures section of the AFMS corresponding to
the autopilot mode transitions.
4. Insert the completed AFMS into the AFM or POH.
5.12.2 Instructions for Continued Airworthiness (ICAW)
Ensure that the appropriate aircraft information is filled in on the Instructions for Continued
Airworthiness (ICAW) is completed and inserted in the aircraft permanent records. Fill in the Aircraft
Make, Model, Reg. No. and S/N information on the cover of the ICAW (Garmin document TBD)
Insert the completed ICAW in the aircraft permanent records.
GTN 725/750 TSO Installation Manual Page 5-35
190-01007-02 Rev. A
5.13 Configuration and Checkout Log
The completed checkout log sheet should be maintained with the aircraft permanent records. If a dual
GTN installation is being done, a checkout log for each system must be completed.
Table 5-1. GTN Post-Installation Checkout Log
GTN Post-Installation Checkout Log Date: ____ /____ /____
By: ________________
INSTALLATION
INFORMATION:
Aircraft Model: _________________________
Unit P/N: ______________________________
Unit Model: ____________________________
GPS Antenna P/N:_______________________
Aircraft S/N: ________________
Mod Level: _________________
S/N:_______________________
GPS Ant Model _____________
EXTERNAL ANNUNCIATION REQUIREMENT
CDI/HSI SOURCE SELECTION ANNUNCIATION: GPS NAVIGATION ANNUNCIATION:
Annunciation: Required Not Required Annunciation: Required Not Required
[ N/A] Annunciator Installed [ N/A] Annunciators Installed
CONNECTOR ENGAGEMENT CHECK
Connector engagement checked
CONFIGURATION ITEMS
MAIN ARINC 429 CONFIGURATION MAIN LIGHTING
In 1: High Low ____________________ Display Keys
In 2: High Low ____________________ Source: ___________ __________
In 3: High Low ____________________ Resp Time / Min: ____ / _____ ____ / _____
In 4: High Low ____________________ Slope / Offset: ____ / _____ ____ / _____
Out 1: High Low ____________________ Photo Transition: ___________ [ N/A]
Out 2: High Low ____________________ Photo Slp/Ofst: ____ / _____ [ N/A]
Out 3: High Low ____________________
SDI: Common LNAV 1 LNAV 2 MAIN CDI/OBS CONFIG
OBI Source: Always GPS Track CDI [ N/A]
MAIN RS-232 CONFIGURATION (RX/TX) V-Flag State: Normal Declutter
Chnl 1 _____________ / ________________ SEL CRS for GPS: Allow Ignore
Chnl 2 _____________ / _________________ SEL CRS for VLOC: Allow Ignore
Chnl 3 _____________ / _________________ CDI Key: Allow Ignore
Chnl 4 _____________ / _________________
Chnl 5 _____________ / _________________ GPS VERTICAL OFFSET
Chnl 6 _____________ / _________________ GPS Antenna Height Above Ground: _______ ft
MAIN SYSTEM CONFIGURATION GAD 42 CONFIGURATION [ N/A]
Fuel Type: ________________________ Main RMI/OBI: _____ Roll Steering: _____
Terrain Type: None TERRAIN TAWS NAV RMI/OBI: _____ Remote Crs Sel: _____
DISCRETES Sel Crs Drive: _____ TAS Input: _____
GPS SELECT: Auto Prompt Main RMI/OBI: _____ GPS/NAV 429 L/H: _____
COM PRESETS [ N/A]: Enabled Disabled Heading 429 L/H: _____
GAD SW Ver: _____________
Page 5-36 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
CONFIGURATION ITEMS (cont’d):
TAWS AUDIO CONFIG 1 [ N/A] TAWS AUDIO CONFIG 2 (CONT’D)
Voice: Female Male IOI – Caution: Caution, Obstacle (2x)
Volume: ___________% Obstacle Ahead (2x)
PDA – Caution: Too Low – Terrain IOI – Warning: Obstacle (2x); Pull Up (2x)
EDR – Caution: Sink Rate Obstacle Ahead; Pull Up (2x)
EDR – Warning: Pull Up VOR/LOC/GS CDI (GTN 750 only)
NCR – Caution: Don’t Sink NAV Radio: Enabled Disabled
VCO – Info Five Hundred
TAWS AUDIO CONFIG 2 [ N/A] VOR/LOC/GS ARINC 429 CONFIGURATION
RTC – Caution: Caution Terrain (2x) RX Speed: High Low
Terrain Ahead (2x) TX Speed: High Low
RTC – Warning: Terrain (2x); Pull Up (2x) SDI: Common VOR/ILS 1 VOR/ILS 2
Terrain Ahead, Pull Up (2x)
ROC – Caution: Caution, Obstacle (2x) DME Mode: Directed freq 1 Directed freq 2
Obstacle Ahead (2x) DME Channel Mode: ___________________
ROC – Warning: Obstacle (2x); Pull Up (2x)
Obstacle Ahead, Pull Up (2x) GDL Configuration [ N/A]
ITI – Caution: Caution, Terrain (2x) Attenuation: ______________
Terrain Ahead (2x) Model: GDL 69A GDL 69
ITI– Warning: Terrain (2x), Pull Up (2x)
Terrain Ahead, Pull Up (2x)
After completing configuration and prior to checkout, restart unit for changes to take effect
SYSTEM CHECKOUT
GROUND CHECKS (CONFIGURATION MODE)
MAIN ANALOG INDICATOR [ N/A] ANNUNCIATOR OUTPUTS
CDI (left, centered, right) [ N/A] Approach (APR)
VDI (down, centered, up) [ N/A] GPS Indicator (GPS)
TO/FROM flag (OFF, TO, FROM) [ N/A] Integrity (INTEG)
Valid flags [ N/A] Message (MSG)
OBS (Selected Course) [ N/A] OBS Mode (OBS)
[ N/A] Terminal Mode (TERM)
VOR/ILS INDICATOR [ N/A] [ N/A] VLOC Indicator (VLOC)
CDI (left, centered, right) [ N/A] Waypoint (WPT)
VDI (down, centered, up) [ N/A] ILS/GPS Approach (ILS/GPS APR)
TO/FROM flag (OFF, TO, FROM) [ N/A] GPS Select (GPS SELECT)
Valid flags [ N/A] Terrain Caution (TER CAUT)
[ N/A] Terrain Inhibit (TER INHB)
DISCRETE INPUTS [ N/A] Terrain Not Available (TER N/A)
[ N/A] Remote CDI Select [ N/A] Terrain Test (TER TEST)
[ N/A] Remote OBS Select [ N/A] Terrain Warning (TER WARN)
[ N/A] Terrain Inhibit
[ N/A] COM Remote Recall
GTN 725/750 TSO Installation Manual Page 5-37
190-01007-02 Rev. A
GROUND CHECKS (CONFIGURATION MODE) (CONT’D)
ADC/ENCODER/FUEL/F/ADC AHRS/IRU/ADC
[ N/A] Air Data Computer [ N/A] Air Data Computer
[ N/A] Altitude Encoder (serial) [ N/A] AHRS/IRU
[ N/A] Fuel Sensor
[ N/A] Fuel / Air Data Computer TAWS AUDIO [ N/A]
Audio checked
ALTITUDE ENCODER Audio level adjusted
[ N/A] Altitude Encoder (Gray code)
[ N/A] Altitude Encoder (serial) GAD 42
[ N/A]GAD 42 Interface Adapter
LIGHTING BUS
[ N/A] Aircraft Lighting Bus
GROUND CHECKS (NORMAL MODE)
SIGNAL ACQUISITION CHECK TAWS SYSTEM [ N/A]
Position checked TAWS System Test OK
Signal reception checked
Interference from other avionics checked INTERFACE CHECKS
[ N/A] Honeywell EFS 40/50
VHF COM INTERFERENCE [ N/A] Sandel SN3308
VHF COM interference checked [ N/A] Sandel SN3500/4500
[ N/A] ARINC 429 Traffic System
VHF NAV CHECKOUT (GTN 750 ONLY) [ N/A] Ryan TCAD
VOR reception checked [ N/A] L-3 Communications Stormscope
Localizer reception checked [ N/A] Garmin GMX 200 / MX20
Deviation needle and flag checked [ N/A] Garmin GDL 69/69A
[ N/A] Crossfill check
VHF COM CHECKOUT (GTN 750 ONLY) [ N/A] External RMI
Receiver / Transmitter operation checked [ N/A] DME Tuning
[ N/A] G600 System
Antenna checked VSWR __________
MAGNETIC COMPASS CHECK
[ N/A] Compass swing performed
FLIGHT CHECKS
GPS checked ILS checked (GTN 750 Only)
COM checked (GTN 750 Only) Autopilot checked
VOR checked (GTN 750 Only) TAWS aural level checked
DATABASE CHECKS
Database checked
AFMS CHECKS
Antenna type checked Autopilot coupling limitations checked
Autopilot Mode transitions checked Completed AFMS inserted in AFM/POH
COMMENTS:
Page 5-38 GTN 725/750 TSO Installation Manual
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GTN 725/750 TSO Installation Manual Page 6-1
190-01007-02 Rev. A
6. LIMITATIONS
6.1 Operations
All functions of the GTN meet the appropriate design assurance qualifications for a primary system for
aircraft in Class I, Class II, and Class III in accordance with AC 23.1309-1D, Figure 2.
6.2 Installation
The conditions and tests required for TSO approval of this article are minimum performance standards. It
is the responsibility of those installing this article either on or within a specific type or class of aircraft to
determine that the aircraft installation conditions are within the TSO standards. TSO articles must have
separate approval for installation in an aircraft. The article may be installed only if performed under 14
CFR part 43 or the applicable airworthiness requirements.
The GTN GPS/WAAS receiver, when installed with an appropriate antenna listed in Section 1.3.8, is
compatible with aircraft equipped with SATCOM when installed in accordance to this manual.
6.2.1 GPS Antenna
The GPS/WAAS receiver is compatible with the GPS antennas listed in Section 1.3.8.
6.3 Aircraft Radio Station License
An aircraft radio station license is not required when operating in U.S. airspace, but may be required
when operating internationally.
Page 6-2 GTN 725/750 TSO Installation Manual
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GTN 725/750 TSO Installation Manual Page 7-1
190-01007-02 Rev. A
7. PERIODIC MAINTENANCE
7.1 Equipment Calibration
No scheduled servicing tasks are required on the GTN 725 or GTN 750.
7.2 VOR Checks
Refer to CFR 14 paragraph 91.171. Every 30 days verify the limits of the permissible indicated bearing
error.
7.3 Cleaning
The front bezel, keypad, and display can be cleaned with a soft cotton cloth dampened with clean water.
DO NOT use any chemical cleaning agents. Care should be taken to avoid scratching the surface of the
display.
7.4 Battery Replacement
WARNING
This product contains a Lithium battery that must be recycled or disposed of properly.
Battery replacement and removal must be performed by professional services.
The GTN includes an internal battery that will last 5 to 8 years. The battery is used for internal time clock
and GPS system information. Regular planned replacement is not necessary. The GTN will display a
“Low Battery” and “Unit Needs Service” message when replacement is required. Once the low battery
message is displayed, the battery should be replaced within 1 to 2 months.
If the battery is not replaced and becomes totally discharged, the GTN will remain fully operational, but
the GPS signal acquisition time will be increased. There is no loss of function or accuracy of the GTN
with a dead battery.
The battery is not user replaceable. To replace the battery, contact the Garmin repair station or factory
authorized repair station.
Page 7-2 GTN 725/750 TSO Installation Manual
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GTN 725/750 TSO Installation Manual Page A-1
190-01007-02 Rev. A
Appendix A ENVIRONMENTAL QUALIFICATION FORM
For RTCA/DO-160F Environmental Qualification Forms (EQFs) visit the Dealers Only site on
http://www.garmin.com. The GTN 725 and GTN 750 use the same EQF, part number 005-00533-13.
Page A-2 GTN 725/750 TSO Installation Manual
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GTN 725/750 TSO Installation Manual Page B-1
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Appendix B GTN DATA FORMAT
B.1 RS-232 Aviation Data Format
B.1.1 Electrical Interface
The output signals are compatible with RS-232C. Data is generated at 9600 baud with a word length of 8
bits, one stop bit, and no parity.
B.1.2 General Output Format
The GTN RS-232 data has the following general format:
STX - ASCII start-of-text character (02 hex)
t1s - Type 1 output sentences (see following paragraphs for description)
t2s - One or more type 2 output sentences (see following paragraphs for description)
ETX - ASCII end-of-text character (03 hex)
B.1.3 Output Sentence Type 1
The Type 1 output sentences have the following general format:
id - item designator (single ASCII alphabetic character)
dddd - item data (1 to 10 printable ASCII characters)
CR - ASCII carriage return character (0D hex)
LF - ASCII line feed character (0A hex)*
Each Type 1 sentence is output by the GTN approximately once every second.
The track, desired track, and bearing to waypoint angles, and the magnetic variation are output according
to the current mode of the GTN (automatic magnetic heading, magnetic variation computed at last known
position; true heading, magnetic variation of E00.0°; or user-defined magnetic heading, magnetic
variation as entered by user).
Page B-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Table B-1 describes the Type 1 output sentence item designator (id) and item data (dddd) fields. If data
for these sentences is invalid or unavailable, dashes ("-") are used to fill in all non-blank character
positions.
Table B-1. Type 1 Output Sentence Format
Ident (1 byte) Data (10 bytes)
1 2 3 4 5 6 7 8 9 0 Description
z a a a a a Current GPS altitude in feet *
A s d d m m h h Current latitude, where:
s - N (north) or S (south)
dd - degrees
mm - minutes
hh - hundredths of minutes
B s d d d m m h h Current longitude, where:
s - E (east) or W (west)
ddd - degrees
mm - minutes
hh - hundredths of minutes
C d d d Track in whole degrees
D s s s Ground speed in knots
E d d d d d Distance to waypoint in tenths of nautical miles
G s n n n n Cross track error, where:
s - L (left) or R (right) of course
nnnn - error in hundredths of nautical miles
I d d d d Desired track in tenths of degrees
K c c c c c Destination waypoint identifier (will be blank filled
on right if less than 5 characters in identifier)
L d d d d Bearing to destination waypoint in tenths of
degrees
Q s d d d Magnetic variation, where:
s - E (east) or W (west)
ddd - tenths of degrees
S - - - - f NAV valid flag status, where:
f - N (NAV flagged) or - (NAV valid)
T - - - - - - - - - Warnings status, only data transmitted are dashes
(-). Used to indicate end of Type 1 sentences.
l (lower case
Lima)
d d d d d d Distance to destination waypoint in tenths of
nautical miles.
* The altitude is not output if the RS-232 port is configured as “Avtn no alt”.
* The line feed character is not output if the RS-232 port is configured as “Avtn no alt”.
GTN 725/750 TSO Installation Manual Page B-3
190-01007-02 Rev. A
B.1.4 Output Sentence Type 2
The GTN Type 2 output sentence has the following general format:
id - item designator (3 ASCII characters)
seq - sequence number (1 binary byte)
wpt - waypoint identifier (5 ASCII characters)
lat - waypoint latitude (3 binary bytes)
lon - waypoint longitude (4 binary bytes)
mvar - magnetic variation at waypoint (2 binary bytes)
CR - ASCII carriage return character (0D hex)
LF - ASCII line feed character (0A hex)
Each waypoint in the route being navigated by the GTN has a Type 2 sentence output by the GTN
approximately once every second.
If no route is being navigated by the GTN (i.e., the active route is empty), the following Type 2 sentence
is output approximately once every second:
id - item designator (3 ASCII characters; route sequence number is "01")
seq - sequence number (1 binary byte; last waypoint flag is set; route sequence number is 1)
CR - ASCII carriage return character (0D hex)
LF - ASCII line feed character (0A hex)
Page B-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Table B-2 describes the Type 2 output sentence item designator (id), sequence number (seq), waypoint
identifier (wpt), waypoint latitude (lat), waypoint longitude (lon), and magnetic variation at waypoint
(mvar) fields.
Table B-2. Type 2 Output Sentence Format
Field Byte Format
7 6 5 4 3 2 1 0 Description
id
1
2-3
ASCII character 'w' (77 hex)
Two ASCII numeric characters representing
route sequence number of waypoint (01 to 31)
seq
1 x l a n n n n n x - undefined
l - 1 if last waypoint in route
a - 1 if active to waypoint
nnnnn - route sequence number of waypoint
(unsigned binary)
wpt
1-5 Destination waypoint identifier (will be blank
filled on right if less than 5 characters in
identifier)
lat
1
2
3
s d d d d d d d
x x m m m m m m
x h h h h h h h
s - 0 (north) or 1 (south)
ddddddd - latitude degrees (unsigned
binary)
xx - undefined
mmmmmm - latitude minutes (unsigned
binary)
x - undefined
hhhhhhh - hundredths of latitude minutes
(unsigned binary)
lon
1
2
3
4
s x x x x x x x
d d d d d d d d
x x m m m m m m
x h h h h h h h
s - 0 (east) or 1 (west)
xxxxxxx - undefined
dddddddd - longitude degrees (unsigned
binary)
xx - undefined
mmmmmm - latitude minutes (unsigned
binary)
x - undefined
hhhhhhh - hundredths of latitude minutes
(unsigned binary)
mvar 1-2 Two's complement binary in 16ths of degrees.
Easterly variation is positive. MSB output first.
GTN 725/750 TSO Installation Manual Page B-5
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B.2 GTN RS-232 Fuel/Air Data Input Format
B.2.1 Electrical Interface
The input signals are compatible with RS-232C. Data is input at 9600 baud with a word length of 8 bits,
one stop bit, and no parity. One message is received per second.
B.2.2 Shadin Altitude Sentence
The Garmin GTN is capable of receiving the following 17-byte message from Shadin Altitude Encoders,
Altitude Serializers, and Altitude Converters:
RMS<sp><+/->12345T<+/->12ul<CR>
Where:
RMS ASCII characters
<sp> space (0x20)
<+/-> sign indicator (0x2b["+"] or 0x2d["-"])
12345 altitude in feet
T ASCII character
<+/-> sign indicator
12 sensor temperature
ul checksum of bytes 1 through 14 in hex ASCII (i.e., "FA")
<CR> carriage return (0x0d)
Note: Checksum is calculated by adding each byte in the message (1 through 14).
B.2.3 Icarus Altitude Sentence
The Garmin GTN is capable of receiving the following 10-byte message from the Icarus Altitude
Serializer:
ALT<sp>12345<CR>
Where:
ALT ASCII characters
<sp> space (0x20)
12345 altitude in feet
<CR> carriage return (0x0d)
Page B-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
B.2.4 Shadin Fuel Flow Sentence
The Garmin GTN is capable of receiving the following 55-byte message from the Shadin Fuel Flow
Indicator:
<STX>K0543.2<sp>0100.0<sp>0040.0<sp>0060.0<sp>0123.4<sp>0045.4<sp>0078.0<sp>123<ETX>
Where:
<STX> start-transmit character (0x02)
K units designation (i.e., Gallons, Liters, Kilograms, B[pounds])
0543.2 total fuel remaining (i.e., ASCII-coded decimal format: 0x30, 0x35, 0x34, 0x33, 0x2e,
0x32)
<sp> space (0x20)
0100.0 fuel flow rate, total (formatted as for total fuel remaining)
0040.0 fuel flow rate, engine one (or asterisks["∗∗∗∗∗∗"], in the case of single engine aircraft)
0060.0 fuel flow rate, engine two (asterisks, in the case of single engine aircraft)
0123.4 fuel used, total
0045.4 fuel used, engine one (asterisks, in the case of single engine aircraft)
0078.0 fuel used, engine two (asterisks, in the case of single engine aircraft)
123 checksum (of bytes 2 through 51)
<ETX> end-transmit character (0x03)
Note: Checksum is calculated by adding each byte in the message (2 through 51), such that carries are
discarded to give a one byte result. The ASCII-coded decimal representation of that byte is given,
ranging from 0 (0x30, 0x30, 0x30) to 255 (0x32, 0x35, 0x35).
B.2.5 ARNAV/EI Fuel Flow Sentence
The Garmin GTN is capable of receiving the following 13-byte message from the ARNAV or Electronics
International (“EI”) Fuel Flow Indicators:
<STX>G0245100550<ETX>
Where:
<STX> start-transmit character (0x02 hex)
G units designation (i.e., Gallons, Imperial gallons, Liters, Kilograms, B[pounds])
0245 total fuel remaining in reverse order (i.e., ASCII-coded decimal format: 0x30, 0x32,
0x34, 0x35)
1 fuel remaining checksum (modulo 10 sum of four "total fuel remaining" digits)
0055 total fuel flow rate in reverse order
0 fuel flow checksum
<ETX> end-transmit character (0x03)
Note: Fuel remaining and fuel flow are [∗ 10] when units designation is gallons or imperial gallons. For
example, 0245 gallons indicates 542 gallons; 0245 liters indicates 5420 liters. Checksum is the modulo 10
sum of the four fuel flow decimal digits, converted to an ASCII numerical character (e.g., checksum for
"5678" would be ASCII "6").
GTN 725/750 TSO Installation Manual Page B-7
190-01007-02 Rev. A
B.2.6 Shadin Fuel/Air Data Computer Sentence
The Garmin GTN is capable of receiving the following message strings from the Shadin Fuel/Air Data or
Air Data Computer:
SHADIN “z” FORMAT
<STX>
ZA012<CR><LF> "ZA" (ASCII characters); "012" represents indicated Air Speed (knots)
ZB345<CR><LF> "ZB" (ASCII characters); "345" represents true Air Speed (knots)
ZC678<CR><LF> "ZC" (ASCII characters); "678" represents Mach Speed (thousandths)
ZD<+/->9012<CR><LF> "ZD" (ASCII characters); sign; "9012" represents pressure altitude (tens of
feet)
ZE<+/->3456<CR><LF> "ZE" (ASCII characters); sign; "3456" represents density altitude (tens of feet)
ZF<+/->78<CR><LF> "ZF" (ASCII characters); sign; "78" represents outside air temperature
(Celsius)
ZG<+/->90<CR><LF> "ZG" (ASCII characters); sign; "90" represents true air temperature (Celsius)
ZH123<CR><LF> "ZH" (ASCII characters); "123" represents wind direction (degrees from north)
ZI456<CR><LF> "ZI" (ASCII characters); "456" represents wind speed (knots)
ZJ<+/->78<CR><LF> "ZJ" (ASCII characters); sign; "78" represents rate of turn (degrees per second)
ZK<+/->901<CR><LF> "ZK" (ASCII characters); sign; "901" represents vertical speed (tens of
ft/minute)
ZL234<CR><LF> "ZL" (ASCII characters); "234" represents heading (degrees from north)
ZM5678<CR><LF>† "ZM" (ASCII characters); "5678" represents fuel flow, right (tenths
gallons/hour)
ZN90123<CR><LF>† "ZN" (ASCII characters); "90123" represents fuel used, right (tenths gallons)
ZO4567<CR><LF>† "ZO" (ASCII characters); "4567" represents fuel flow, left (tenths gallons/hour)
ZP89012<CR><LF>† "ZP" (ASCII characters); "89012" represents fuel used, left (tenths gallons)
ZQ345<CR><LF> "ZQ" (ASCII characters); "345" represents error log/reason indicator
ZR678<CR><LF> "ZR" (ASCII characters); "678" represents checksum
<ETX>
Where:
<STX> start-transmit character (0x02)
<CR> carriage-return character (0x0d)
<LF> line-feed character (0x0a)
<+/-> sign indicator (0x2b["+"] or 0x2d["-"])
<ETX> end-transmit character (0x03)
† Not available from Air Data Computer
Note: Checksum is calculated by adding each byte in the message (including all characters from <STX>
up to and including the error log/reason indicator), such that carries are discarded to give a one byte
result. The ASCII-coded decimal representation of that byte is given, ranging from 0 (0x30, 0x30, 0x30)
to 255 (0x32, 0x35, 0x35).
Page B-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
SHADIN “G” FORMAT
<STX>
GA012<CR><LF> "GA" (ASCII characters); "012" represents indicated Air Speed (knots)
GB345<CR><LF> "GB" (ASCII characters); "345" represents true Air Speed (knots)
GC678<CR><LF> "GC" (ASCII characters); "678" represents Mach Speed (thousandths)
GD<+/->9012<CR><LF> "GD" (ASCII characters); sign; "9012" represents pressure altitude (tens of feet)
GE<+/->3456<CR><LF> "GE" (ASCII characters); sign; "3456" represents density altitude (tens of feet)
GF<+/->78<CR><LF> "GF" (ASCII characters); sign; "78" represents outside air temperature (Celsius)
GG<+/->90<CR><LF> "GG" (ASCII characters); sign; "90" represents true air temperature (Celsius)
GH123<CR><LF> "GH" (ASCII characters); "123" represents wind direction (degrees from north)
GI456<CR><LF> "GI" (ASCII characters); "456" represents wind speed (knots)
GJ<+/->78<CR><LF> "GJ" (ASCII characters); sign; "78" represents rate of turn (degrees per second)
GK<+/->901<CR><LF> "GK" (ASCII characters); sign; "901" represents vertical speed (tens of
ft/minute)
GL234<CR><LF> "GL" (ASCII characters); "234" represents heading (degrees from north)
GM5678<CR><LF>† "GM" (ASCII characters); "5678" represents fuel flow, right (Twin only) (tenths
gallons/hour)
GN90123<CR><LF>† "GN" (ASCII characters); "90123" represents fuel used, right (Twin only)
(tenths gallons)
GO4567<CR><LF> "GO" (ASCII characters); "4567" represents fuel flow, left (or Single) (tenths
gallons/hour)
GP89012<CR><LF> "GP" (ASCII characters); "89012" represents fuel used, left (or Single) (tenths
gallons)
GQ001<CR><LF> "GQ" (ASCII characters); "001" represents error log/reason indicator (001 =
temp. sensor error, 000 = no errors)
GR6789.0<CR><LF>† "GR" (ASCII characters); "6789.0" represents fuel remaining (gallons)
Ga<+/->1234<CR><LF> "Ga" (ASCII characters); sign; "12.34" represents barometric corrected altitude
(tens of feet)
Gb56.78<CR><LF> "Gb" (ASCII characters); "56.78" represents current barometric pressure setting
(inches Hg)
G*901<CR><LF> "G*" (ASCII characters); "901" represents checksum
<ETX>
Where:
<STX> start-transmit character (0x02)
<CR> carriage-return character (0x0d)
<LF> line-feed character (0x0a)
<+/-> sign indicator (0x2b["+"] or 0x2d["-"])
<ETX> end-transmit character (0x03)
† Not available from Airdata Computer
Note: Checksum is calculated by adding each byte in the message (including all characters from <STX>
up to and including the error log/reason indicator), such that carries are discarded to give a one byte
result. The ASCII-coded decimal representation of that byte is given, ranging from 0 (0x30, 0x30, 0x30)
to 255 (0x32, 0x35, 0x35).
GTN 725/750 TSO Installation Manual Page B-9
190-01007-02 Rev. A
SHADIN “S” FORMAT
<STX>
SA012<CR><LF> "SA" (ASCII characters); "012" represents indicated Air Speed (knots)
SB345<CR><LF> "SB" (ASCII characters); "345" represents true Air Speed (knots)
SC678<CR><LF> "SC" (ASCII characters); "678" represents Mach Speed (thousandths)
SD<+/->9012<CR><LF> "SD" (ASCII characters); sign; "9012" represents pressure altitude (tens of feet)
SE<+/->3456<CR><LF> "SE" (ASCII characters); sign; "3456" represents density altitude (tens of feet)
SF<+/->78<CR><LF> "SF" (ASCII characters); sign; "78" represents outside air temperature (Celsius)
SG<+/->90<CR><LF> "SG" (ASCII characters); sign; "90" represents true air temperature (Celsius)
SH123<CR><LF> "SH" (ASCII characters); "123" represents wind direction (degrees from north)
SI456<CR><LF> "SI" (ASCII characters); "456" represents wind speed (knots)
SJ<+/->78<CR><LF> "SJ" (ASCII characters); sign; "78" represents rate of turn (degrees per second)
SK<+/->901<CR><LF> "SK" (ASCII characters); sign; "901" represents vertical speed (tens of ft/minute)
SL234<CR><LF> "SL" (ASCII characters); "234" represents heading (degrees from north)
SM5678<CR><LF> "SM" (ASCII characters); "5678" represents fuel flow, right (tenths gallons/hour)
SN90123<CR><LF> "SN" (ASCII characters); "90123" represents fuel used, right (tenths gallons)
SO4567<CR><LF> "SO" (ASCII characters); "4567" represents fuel flow, left (tenths gallons/hour)
SP89012<CR><LF> "SP" (ASCII characters); "89012" represents fuel used, left (tenths gallons)
SQ345<CR><LF> "SQ" (ASCII characters); "345" represents error log/reason indicator
SR67890<CR><LF> "SR" (ASCII characters); "67890" represents fuel remaining (tenths gallons)
SS123<CR><LF> "SS" (ASCII character); "123" represents ground speed (knots)
ST456<CR>LF> "ST" (ASCII character); "456" represents track (degrees)
SU789012<CR><LF> "SU" (ASCII character); "789012" represents distance to waypoint (hundredths nautical miles)
SV<E/W>345<CR><LF> "SV" (ASCII character); “E” represents East, “W” represents West; "345" represents magnetic
variation (tenths degrees)
SW<N/S>67 8901<CR><LF>"SW" (ASCII character); “N” represents North, “S” represents South; "67 8910" represents current
latitude (degrees, minutes, hundredths of minutes)
SX<E/W>234 5678<CR><LF>"SX" (ASCII character); “E” represents East, “W” represents West; "234 5678" represents
current longitude (degrees, minutes, hundredths of minutes)
SY<L/R>90<CR><LF> "SY" (ASCII character); “L” represents Left, “R” represents Right; "90" represents drift angle
(degrees)
Sa<+/->1234<CR><LF> "Sa" (ASCII character); sign; "1234" represents barometric corrected altitude (tens of feet)
Sb56.78<CR><LF> "Sb" (ASCII character); "56.78" represents current barometric pressure setting (inches Hg)
S*901<CR><LF> “S*” (ASCII character); "901" represents checksum
<ETX>
Where:
<STX> start-transmit character (0x02)
<CR> carriage-return character (0x0d)
<LF> line-feed character (0x0a)
<+/-> sign indicator (0x2b["+"] or 0x2d["-"])
<ETX> end-transmit character (0x03)
Note: Checksum is calculated by adding each byte in the message (including all characters from <STX>
up to and including the error log/reason indicator), such that carries are discarded to give a one byte
result. The ASCII-coded decimal representation of that byte is given, ranging from 0 (0x30, 0x30, 0x30)
to 255 (0x32, 0x35, 0x35).
Page B-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
This page intentionally left blank
GTN 725/750 TSO Installation Manual Page C-1
190-01007-02 Rev. A
Appendix C MECHANICAL DRAWINGS
C.1 Drawing List
The following drawings are included in this section.
Figure C-1. GTN Mounting Rack Dimensions
Figure C-2. GTN Mounting Rack Installation
Figure C-3. GTN Mounting Rack Assembly
Figure C-4. GTN Recommended Panel Cutout Dimensions
Page C-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
This page intentionally left blank
GTN 725/750 TSO Installation Manual Page C-3
190-01007-02 Rev. A
Figure C-1. GTN Mounting Rack Dimensions
Page C-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure C-2. GTN Mounting Rack Installation
GTN 725/750 TSO Installation Manual Page C-5
190-01007-02 Rev. A
Figure C-3. GTN Mounting Rack Assembly
Page C-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure C-4. GTN Recommended Panel Cutout Dimensions
GTN 725/750 TSO Installation Manual Page D-1
190-01007-02 Rev. A
Appendix D INTERCONNECT DIAGRAMS
D.1 Drawing List
The following drawings are included in this section:
Figure D-1. GTN System Interface Diagram
Figure D-2. GTN 750 Typical Installation
Figure D-3. GTN 725 Typical Installation
Figure D-4. GTN Power Lighting Configuration Interconnect
Figure D-5. GTN – Antenna Interconnect
Figure D-6. GTN - Main Indicator Interconnect
Figure D-7. GTN - Autopilot Interconnect
Figure D-8. GTN - Traffic Interconnect
Figure D-9. GTN - Transponder Interconnect
Figure D-10. Dual GTN to Single GDU Interconnect
Figure D-11. GTN - GDU/AHRS Interconnect
Figure D-12. GTN - ARINC 429 EFIS Interconnect
Figure D-13. GTN - GDL 69/69A Interconnect
Figure D-14. Audio Panel Interconnect
Figure D-15. Air Data/IRU/AHRS RS-232 Interconnect
Figure D-16. Air Data/IRU/AHRS ARINC 429 Interconnect
Figure D-17. GAD 42 Interconnect
Figure D-18. VOR/ILS Indicator Interconnect
Figure D-19. RMI OBI Interconnect
Figure D-20. GTN – WX-500 Interconnect
Figure D-21. GTN 750 - DME Interconnect
Figure D-22. GTN 750 – Remote DME Interconnect
Figure D-23. Parallel 2 of 5 DME Tuning
Figure D-24. Parallel Slip Code DME Tuning Interconnect
Figure D-25. Heading Synchro Interconnect
Figure D-26. GPS Annunciator Interconnect
Figure D-27. NAV Source Select Annunciator Interconnect
Figure D-28. TAWS Interconnect
Figure D-29. Switches Interconnect
Page D-2 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
This page intentionally left blank
GTN 725/750 TSO Installation Manual Page D-3
190-01007-02 Rev. A
Figure D-1. GTN System Interface Diagram
Page D-4 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
GTN 750
P1001
1
21
40
2
41
60
MAIN OBS ROTOR C
MAIN OBS STATOR D
MAIN OBS STATOR E GND
MAIN OBS STATOR F
MAIN OBS STATOR G GND
MAIN OBS ROTOR H GND
49
68
MAIN LATERAL +LEFT
MAIN LATERAL +RIGHT
11
30
MAIN +TO OUT
MAIN +FROM OUT
50
69
MAIN LATERAL +FLAG OUT
MAIN LATERAL -FLAG OUT
51
70
MAIN VERTICAL +FLAG OUT
MAIN VERTICAL -FLAG OUT
12
31
MAIN VERTICAL +UP OUT
MAIN VERTICAL +DOWN OUT
s
s
s
s
s
s
s
s
NAVIGATION
INDICATOR
OBS RESOLVER {H/A}
OBS RESOLVER {C}
OBS RESOLVER {D}
OBS RESOLVER {E}
OBS RESOLVER {F}
OBS RESOLVER {G}
CDI+ L
CDI+ R
+TO FLAG
+FROM FLAG
NAV+ FLAG
NAV- FLAG
G/S- FLAG
G/S+ FLAG
+ UP
+ DOWN
NAV/GPS
AIRCRAFT POWER
AIRCRAFT POWER 5A
ESSENTIAL BUS
22 AWG
20
19
AIRCRAFT GND
AIRCRAFT GND 78
77 22 AWG AIRCRAFT
GROUND
LIGHTING BUS 1 HI
LIGHTING BUS 1 LO TO AIRCRAFT
LIGHTING BUS
18
17
LIGHTING BUS 2 LO
LIGHTING BUS 2 HI 61
42
AUDIO PANEL
COM 1 MIC AUDIO HI
COM 1 MIC KEY OUT
COM 1 AUDIO HI
COM 1 AUDIO LO
NAV 1 AUDIO HI
NAV 1 AUDIO LO
500 Ω VOR/LOC AUDIO OUT HI
500 Ω VOR/LOC AUDIO OUT LO
P1004
16
17
MIC AUDIO IN LO
COM MIC 1 KEY
COM MIC 1 AUDIO IN HI
500 Ω COM AUDIO LO
500 Ω COM AUDIO HI 7
18
5
11
20
P1003
AIRCRAFT POWER
AIRCRAFT POWER 43
30
AIRCRAFT GND
AIRCRAFT GND 38
37
44
40
5A (28 VDC)
ESSENTIAL BUS
10A (14 VDC)
AIRCRAFT POWER
AIRCRAFT GND
COM
20 AWG (5A C/B, 28VDC)
18 AWG (10A C/B, 14 VDC)
AIRCRAFT
GROUND
20 AWG (5A C/B, 28VDC)
18 AWG (10A C/B, 14 VDC)
P1006 GPS/WAAS
ANTENNA
P1007 COM
ANTENNA
P1008 NAV
ANTENNA
TRANSPONDER
RS232 OUT 1
RS232 IN 1
GROUND
s
27RS-232 IN 1
RS-232 OUT 1 8
46RS-232 GND 1
AIRCRAFT GND 61
GPS/WAAS ANTENNA
COM ANTENNA
NAV ANTENNA
AIRCRAFT POWER 51 ESSENTIAL BUS
22 AWG
NAV
5A
AUDIO OUT LO
AUDIO OUT HI
23
HI
LO
ALERT 1
AUDIO IN
P1001
4
RS-232 IN
RS-232 OUT
RS-232 OUT 2
RS-232 IN 2
7
26
RS-232 GND 2 45
s
s
s
s
s
s
Figure D-2. GTN 750 Typical Installation
Sheet 1 of 2
GTN 725/750 TSO Installation Manual Page D-5
190-01007-02 Rev. A
Figure D-2. GTN 750 Typical Installation
Sheet 2 of 2
Page D-6 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-3. GTN 725 Typical Installation
Sheet 1 of 2
GTN 725/750 TSO Installation Manual Page D-7
190-01007-02 Rev. A
Figure D-3. GTN 725 Typical Installation
Sheet 2 of 2
Page D-8 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
P1001
GTN 7XX
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. ALL POWER LEADS AND GROUND LEADS ARE REQUIRED.
4. CONFIGURATION MODULE IS MOUNTED IN THE BACKSHELL OF THE P1001 CONNECTOR.
5. CONFIGURATION MODULE HARNESS USES 28 AWG WIRES. CONTACTS SUPPLIED WITH CONFIGURATION MODULE
MUST BE USED FOR CONNECTING CONFIGURATION MODULE HARNESS TO P1001.
6. OPTIONAL CONNECTION. LIGHTING CAN BE CONTROLLED BY THE INTEGRATED PHOTOCELL, A SINGLE LIGHTING
BUS, OR DUAL LIGHTING BUSES. REFER TO SECTION TBD FOR MORE DETAILS.
7. CIRCUIT BREAKER SHOULD BE LABELED AS SHOWN.
8. CIRCUIT BREAKER SHOULD BE LABELED AS: “GPS” FOR THE GTN 725, AND “NAV/GPS” FOR THE GTN 750
s
CONFIG MODULE POWER
CONFIG MODULE GND
CONFIG MODULE DATA
CONFIG MODULE CLOCK
4
1
3
2
RED
BLK
YEL
WHT
LIGHTING BUS 1 HI
LIGHTING BUS 1 LO TO AIRCRAFT
LIGHTING BUS
65
64
62
63
18
17
NAV/GPS
AIRCRAFT POWER
AIRCRAFT POWER
AIRCRAFT GND
AIRCRAFT GND
5A (28 VDC)
ESSENTIAL BUS
AIRCRAFT
GROUND
7.5A (14 VDC)
20 AWG
20
19
78
77
AIRCRAFT POWER
AIRCRAFT POWER 43
30
AIRCRAFT GND
AIRCRAFT GND 38
37
44
40
P1003
5A (28 VDC)
ESSENTIAL BUS
10A (14 VDC)
AIRCRAFT POWER
AIRCRAFT GND
COM
LIGHTING BUS 2 LO
LIGHTING BUS 2 HI 61
42
P1004
AIRCRAFT POWER
AIRCRAFT POWER
AIRCRAFT GND
AIRCRAFT GND
52
51
62
61
20 AWG
20 AWG AIRCRAFT
GROUND
20 AWG (5A C/B, 28VDC)
18 AWG (10A C/B, 14 VDC)
AIRCRAFT
GROUND
20 AWG (5A C/B, 28VDC)
18 AWG (10A C/B, 14 VDC)
20 AWG
3
3
3
4
6
8
5
7
Figure D-4. GTN Power Lighting Configuration Interconnect
Sheet 1 of 2
GTN 725/750 TSO Installation Manual Page D-9
190-01007-02 Rev. A
P1001
GTN 7XX
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. ALL POWER LEADS AND GROUND LEADS ARE REQUIRED.
4. CONFIGURATION MODULE IS MOUNTED IN THE BACKSHELL OF THE P1001 CONNECTOR.
5. CONFIGURATION MODULE HARNESS USES 28 AWG WIRES. CONTACTS SUPPLIED WITH CONFIGURATION MODULE
MUST BE USED FOR CONNECTING CONFIGURATION MODULE HARNESS TO P1001.
6. OPTIONAL CONNECTION. LIGHTING CAN BE CONTROLLED BY THE INTEGRATED PHOTOCELL, A SINGLE LIGHTING
BUS, OR DUAL LIGHTING BUSES. REFER TO SECTION TBD FOR MORE DETAILS.
7. CIRCUIT BREAKER SHOULD BE LABELED AS SHOWN.
8. CIRCUIT BREAKER SHOULD BE LABELED AS: “GPS” FOR THE GTN 725, AND “NAV/GPS” FOR THE GTN 750.
9. TVS ASSEMBLY PROTECTION IS ONLY REQUIRED ON ONE GTN IN A DUAL NAV/COM INSTALLATION.
s
CONFIG MODULE POWER
CONFIG MODULE GND
CONFIG MODULE DATA
CONFIG MODULE CLOCK
4
1
3
2
RED
BLK
YEL
WHT
LIGHTING BUS 1 HI
LIGHTING BUS 1 LO TO AIRCRAFT
LIGHTING BUS
65
64
62
63
18
17
NAV/GPS
AIRCRAFT POWER
AIRCRAFT POWER
AIRCRAFT GND
AIRCRAFT GND
5A (28 VDC)
ESSENTIAL BUS
AIRCRAFT
GROUND
7.5A (14 VDC)
20 AWG
20
19
78
77
AIRCRAFT POWER
AIRCRAFT POWER 43
30
AIRCRAFT GND
AIRCRAFT GND 38
37
44
40
P1003
5A (28 VDC)
ESSENTIAL BUS
10A (14 VDC)
AIRCRAFT POWER
AIRCRAFT GND
COM
LIGHTING BUS 2 LO
LIGHTING BUS 2 HI 61
42
P1004
AIRCRAFT POWER
AIRCRAFT POWER
AIRCRAFT GND
AIRCRAFT GND
52
51
62
61
20 AWG
20 AWG AIRCRAFT
GROUND
20 AWG (5A C/B, 28VDC)
18 AWG (10A C/B, 14 VDC)
AIRCRAFT
GROUND
20 AWG (5A C/B, 28VDC)
18 AWG (10A C/B, 14 VDC)
20 AWG
3
3
3
4
6
8
5
7
+
-
TVS1
+
-
TVS ASSY
NON-METAL AIRCRAFT
+
-
TVS1
+
-
TVS ASSY
99
99
(VFR-ONLY INSTALLATIONS EXCLUDED)
Figure D-4. GTN Power Lighting Configuration Interconnect
Sheet 2 of 2
Page D-10 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-5. GTN – Antenna Interconnect
Sheet 1 of 3
GTN 725/750 TSO Installation Manual Page D-11
190-01007-02 Rev. A
Figure D-5. GTN – Antenna Interconnect
Sheet 2 of 3
Page D-12 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-5. GTN – Antenna Interconnect
Sheet 3 of 3
GTN 725/750 TSO Installation Manual Page D-13
190-01007-02 Rev. A
Figure D-6. GTN - Main Indicator Interconnect
Page D-14 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-7. GTN - Autopilot Interconnect
GTN 725/750 TSO Installation Manual Page D-15
190-01007-02 Rev. A
Figure D-8. GTN - Traffic Interconnect
Page D-16 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-9. GTN - Transponder Interconnect
GTN 725/750 TSO Installation Manual Page D-17
190-01007-02 Rev. A
Figure D-10. Dual GTN to Single GDU Interconnect
Page D-18 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
GTN 7XX
RS-232 OUT 1
RS-232 GND 1
8
46
4
P1001
s
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS PRACTICAL.
4. FOR GTN 7XX CONFIGURATION SETTINGS, SEE SECTION TBD.
s
P1004
VOR/ILS ARINC 429 OUT A
VOR/ILS ARINC 429 OUT B
24
23
ARINC 429 OUT 1A
ARINC 429 OUT 1B
10
29
ARINC 429 IN 1A
ARINC 429 IN 1B
48
67
s
s
s
GDU
RS-232 IN 2
ARINC 429 IN 1A
ARINC 429 IN 1B
ARINC 429 IN 2A
ARINC 429 IN 2B
ARINC 429 OUT 1A
ARINC 429 OUT 1B
AHRS/ADC
Figure D-11. GTN - GDU/AHRS Interconnect
GTN 725/750 TSO Installation Manual Page D-19
190-01007-02 Rev. A
GTN 7XX
# 1
48ARINC 429 IN 1 A
P1001
P1004
67ARINC 429 IN 1 B
10ARINC 429 OUT 1A
29ARINC 429 OUT 1B
24VOR/ILS ARINC 429 OUT A
23VOR/ILS ARINC 429 OUT B
ARINC 429 EFIS
DISPLAY # 1
LNAV TRANSMITTER A
LNAV TRANSMITTER B
LRN/LNAV 1 RECEIVER A
LRN/LNAV 1 RECEIVER B
LRN/LNAV 2 RECEIVER A
LRN/LNAV 2 RECEIVER B
NAV 1 RECEIVER A
NAV 1 RECEIVER B
NAV 2 RECEIVER A
NAV 2 RECEIVER B
GTN 7XX
# 2
48ARINC 429 IN 1 A
P1001
P1004
67ARINC 429 IN 1 B
10ARINC 429 OUT 1A
29ARINC 429 OUT 1B
24VOR/ILS ARINC 429 OUT A
23VOR/ILS ARINC 429 OUT B
ARINC 429 EFIS
DISPLAY # 2
LNAV TRANSMITTER A
LNAV TRANSMITTER B
LRN/LNAV 1 RECEIVER A
LRN/LNAV 1 RECEIVER B
LRN/LNAV 2 RECEIVER A
LRN/LNAV 2 RECEIVER B
NAV 1 RECEIVER A
NAV 1 RECEIVER B
NAV 2 RECEIVER A
NAV 2 RECEIVER B
4
4
6
6
7
7
s
s
s
s
s
s
Figure D-12. GTN - ARINC 429 EFIS Interconnect
Sheet 1 of 2
Page D-20 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-12. GTN - ARINC 429 EFIS Interconnect
Sheet 2 of 2
GTN 725/750 TSO Installation Manual Page D-21
190-01007-02 Rev. A
Figure D-13. GTN - GDL 69/69A Interconnect
Page D-22 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. THE 500 OHM AUDIO OUTPUTS ARE BALANCED OUTPUTS, AND THE LO OUTPUTS MUST BE CONNECTED. IF THE
AUDIO PANEL DOES NOT HAVE A LO INPUT, THE LO OUTPUT SHOULD BE CONNECTED TO A GROUND LUG AT
THE AUDIO PANEL.
3. THE COM REMOTE TRANSFER INPUT MAY BE USED FOR EMERGENCY OPERATION OF THE COM TRANSMITTER.
IF THE REMOTE TRANSFER SWITCH IS ACTIVE FOR TWO SECONDS, THE ACTIVE COM FREQUENCY WILL CHANGE
TO 121.50 MHZ.
4. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION.
PINOUTS OF OTHER UNITS SHOWN FOR REFERENCE ONLY.
5. SHIELDS FOR AUDIO CABLES SHOULD BE GROUNDED AT ONE END (WITH LEADS LESS THAN 3.0 INCHES) AND
LEFT FLOATING AT THE OTHER END. IF SHIELDED AUDIO CABLE IS CARRIED THROUGH A DISCONNECT, CARRY
THE SHIELD GROUND THROUGH THE DISCONNECT ON A SEPARATE PIN.
6. CONNECTING TWO MICROPHONES TO MIC AUDIO HI/LO AT THE SAME TIME MAY RESULT IN WEAK OR
DISTORTED AUDIO. MIC ISOLATION RELAYS ARE RECOMMENDED SO THAT ONLY ONE MIC IS ACTIVE AT A TIME.
7. USE THE AUDIO INHIBIT IN DISCRETE INPUT TO INHIBIT GTN 7XX AURAL ALERTS WHEN A HIGHER PRIORITY
SYSTEM IS PLAYING AUDIO MESSAGES.
8. USE THE AUDIO ACTIVE OUT DISCRETE OUTPUT TO INHIBIT AURAL ALERTS FROM LOWER PRIORITY SYSTEMS
WHENEVER THE GTN 7XX IS PLAYING AUDIO MESSAGES.
GTN 7XX
MIC 1 AUDIO IN HI
MIC 1 TRANSMIT
MIC AUDIO LO
500 Ω COM AUDIO LO
500 Ω COM AUDIO HI
500 Ω VOR/LOC AUDIO OUT HI
500 Ω VOR/LOC AUDIO OUT LO
7
18
5
11
20
COM REMOTE
TRANSFER SWITCH
27COM REMOTE TRANSFER
P1003
P1004
16
17
2
3
6
P1001
AUDIO OUT HI
AUDIO OUT LO
4
23
RS-232 OUT 2
RS-232 IN 2
7
26
RS-232 GND 2 45
35TAWS AUDIO ACTIVE OUT
36TAWS AUDIO INHIBIT IN 7
8
AUDIO PANEL
COM 1/(COM 2) MIC AUDIO
COM 1/(COM 2) MIC KEY
COM 1/(COM 2) AUDIO HI
COM 1/(COM 2) AUDIO LO
COM 1/(COM 2) MIC AUDIO LO
NAV 1/(NAV 2) AUDIO HI
NAV 1/(NAV 2) AUDIO LO
UNSWITCHED AUDIO IN HI
UNSWITCHED AUDIO IN LO
RS-232 IN
RS-232 OUT
Figure D-14. Audio Panel Interconnect
Sheet 1 of 2
GTN 725/750 TSO Installation Manual Page D-23
190-01007-02 Rev. A
Figure D-14. Audio Panel Interconnect
Sheet 2 of 2
Page D-24 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-15. Air Data/IRU/AHRS RS-232 Interconnect
Sheet 1 of 2
GTN 725/750 TSO Installation Manual Page D-25
190-01007-02 Rev. A
Figure D-15. Air Data/IRU/AHRS RS-232 Interconnect
Sheet 2 of 2
Page D-26 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-16. Air Data/IRU/AHRS ARINC 429 Interconnect
GTN 725/750 TSO Installation Manual Page D-27
190-01007-02 Rev. A
Figure D-17. GAD 42 Interconnect
Page D-28 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-18. VOR/ILS Indicator Interconnect
GTN 725/750 TSO Installation Manual Page D-29
190-01007-02 Rev. A
RADIO MAGNETIC
INDICATOR
OBI SYNC
OBI CLOCK
OBI DATA
P1004
25
27
26 VOR OBI SYNC
VOR OBI DATA
VOR OBI CLOCK
GTN 750
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0 ". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS
PRACTICAL.
4. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION.
s
s
s
s
Figure D-19. RMI OBI Interconnect
Page D-30 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
L3 Communications
WX-500
8 RS-232 RX
20 RS-232 TX
P3
5RS-232 GROUND
6EXTERNAL CLEAR
GTN 7XX
5RS-232 OUT 4
P1001
5RS-232 IN 4 24
s
OPTIONAL EXTERNAL
CLEAR SWITCH
P2
RS-232 GND 4 43
4
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS PRACTICAL.
4. FOR WX-500 DATA TO BE DISPLAYED ON THE GTN 7XX MAP PAGE THE GTN 7XX MUST HAVE A DIGITAL HEADING
SOURCE, OR THE WX-500 MUST HAVE A SYNCHRO OR SERIAL HEADING SOURCE. A STEPPER HEADING SOURCE WILL
NOT ALLOW WX-500 DATA TO BE DISPLAYED ON THE MAP PAGE.
5. ANY AVAILABLE RS-232 PORT MAY BE USED. REFER TO SECTION TBD FOR RS-232 CHANNEL SETTINGS.
6. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION. PINOUTS
OF OTHER UNITS SHOWN FOR REFERENCE ONLY.
7. ANY AVAILABLE ETHERNET PORT MAY BE USED. REFER TO FIGURE TBD FOR HSDB ARCHITECTURE OPTIONS.
NOTES:
s
Figure D-20. GTN – WX-500 Interconnect
GTN 725/750 TSO Installation Manual Page D-31
190-01007-02 Rev. A
GTN 7XX
VOR/LOC +LEFT
VOR/LOC +RIGHT
VOR/LOC +TO
VOR/LOC +FROM
VOR/LOC +FLAG
VOR/LOC -FLAG
VOR/LOC SUPERFLAG
GLIDESLOPE SUPERFLAG
VOR OBS STATOR D
VOR OBS STATOR E (GROUND)
GLIDESLOPE +FLAG
GLIDESLOPE +DOWN
VOR OBS ROTOR H (GROUND)
VOR OBS ROTOR C
VOR OBS STATOR G (GROUND)
VOR OBS STATOR F
VOR/LOC COMPOSITE OUT
ILS ENERGIZE
GLODESLOPE +UP
GLIDESLOPE -FLAG
5
6
1
2
3
4
15
55
32
34
10
9
38
53
11
13
14
12
29
8
P1004
s
s
s
s
s
s
s
s
s
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS PRACTICAL.
4. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION. PINOUTS
OF OTHER UNITS SHOWN FOR REFERENCE ONLY.
5. THIS INTERCONNECT APPLIES ONLY WHEN IT IS DESIRED FOR A SEPARATE INDICATOR TO DISPLAY GTN 750 VOR/ILS
INFORMATION REGARDLESS OF THE CDI BUTTON STATUS.
s
+LEFT
+RIGHT
+TO
+FROM
NAV +FLAG
NAV -FLAG
NAV SUPERFLAG
NAV SUPERFLAG LO
GLIDESLOPE SUPERFLAG
GLIDESLOPE SUPERFLAG LO
OBS D (COS HI)
OBS E (COS LO)
GLIDESLOPE +FLAG
+DOWN
OBS A/H
OBS C
OBS G (SIN LO)
OBS F (SIN HI)
VOR/LOC COMPOSITE
ILS ENERGIZE
+UP
GLIDESLOPE -FLAG
NAVIGATION
INDICATOR
Figure D-21. GTN 750 - DME Interconnect
Page D-32 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
REMOTE DME
DME REQUEST
CLOCK BUS
DATA BUS
DME INDICATOR
RNAV REQUEST
CLOCK BUS
DATA BUS
NAV 1 COMMON
DME REQUEST
NAV 2 COMMON
P1004
18
19
20
SERIAL DME-RNAV/CH REQ
SERIAL DME-DATA
SERIAL DME-CLOCK
GTN 750 #1
41DME COMMON
s
s
s
P1004
18
19
20
SERIAL DME-RNAV/CH REQ
SERIAL DME-DATA
SERIAL DME-CLOCK
GTN 750 #2
41DME COMMON
s
s
s
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 750, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS PRACTICAL.
4. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION.
5. THE GTN 750 MUST BE CONFIGURED AT INSTALLATION TO OUTPUT DME TUNING DATA UNDER THE DME CHANNEL
MODE.
s
10 BIT/50 BIT SELECTN/C
Figure D-22. GTN 750 – Remote DME Interconnect
GTN 725/750 TSO Installation Manual Page D-33
190-01007-02 Rev. A
DME
1 MHZ-A
1 MHZ-B
1 MHZ-C
1 MHZ-D
1 MHZ-E
100 KHZ-A
100 KHZ-B
100 KHZ-C
2 X 5 CODE SELECT
SLIP CODE SELECT
10 MHZ-A
DME COMMON
BCD CODE SELECT
100 KHZ-D
100 KHZ-E
50 KHZ
10 MHZ-E
GTN 750
PARALLEL DME 1MHZ-A
PARALLEL DME 1MHZ-B
PARALLEL DME 1MHZ-C
PARALLEL DME 1MHZ-D
PARALLEL DME 1MHZ-E
PARALLEL DME 100KHZ-A
PARALLEL DME 100KHZ-B
PARALLEL DME 100KHZ-C
DME COMMON
PARALLEL DME 100KHZ-D
PARALLEL DME 100KHZ-E
PARALLEL DME 50KHZ
45
46
47
33
56
37
39
40
41
43
54
42
N/C
N/C
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 750, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS PRACTICAL.
4. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT.
s
P1004
Figure D-23. Parallel 2 of 5 DME Tuning
Page D-34 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-24. Parallel Slip Code DME Tuning Interconnect
GTN 725/750 TSO Installation Manual Page D-35
190-01007-02 Rev. A
Figure D-25. Heading Synchro Interconnect
Page D-36 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
Figure D-26. GPS Annunciator Interconnect
GTN 725/750 TSO Installation Manual Page D-37
190-01007-02 Rev. A
Figure D-27. NAV Source Select Annunciator Interconnect
Page D-38 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
P1001
71TERRAIN WARNING ANNUNCIATE
72TERRAIN NOT AVAILABLE ANNUNCIATE
s
6
7
GTN 7XX
57TAWS INHIBIT ANNUNCIATE
73TERRAIN CAUTION ANNUNCIATE
37TAWS INHIBIT IN
23AUDIO OUT LO
4AUDIO OUT HI
35TAWS AUDIO ACTIVE OUT
NOTES:
1. ALL WIRES 24 AWG OR LARGER UNLESS OTHERWISE SPECIFIED.
2. GROUND DESIGNATIONS: SHIELD BLOCK GROUND AIRFRAME GROUND
3. AT THE GTN 7XX, CONNECT SHIELD GROUNDS TO THE CONNECTOR BACKSHELL -- THE SHIELD LEADS MUST BE LESS
THAN 3.0". CONNECT OTHER SHIELD GROUNDS TO AIRCRAFT CHASSIS WITH AS SHORT A CONDUCTOR AS PRACTICAL.
4. REFER TO MANUFACTURER’S DOCUMENTATION FOR COMPLETE PINOUT AND INTERCONNECT INFORMATION.
5. IF EXTERNAL TAWS ANNUNCIATION IS REQUIRED, THE ANNUNCIATOR PANELS ON THIS PAGE ARE SUITABLE TO MEET
THE ANNUNCIATION REQUIREMENT. REFER TO SECTION TBD TO DETERMINE IF EXTERNAL TAWS ANNUNCIATION IS
REQUIRED.
6. ONLY ONE GTN SHOULD HAVE TAWS ENABLED TO PREVENT CONFLICTING AUDIO MESSAGES. REFER TO SECTION TBD
FOR ADDITIONAL INFORMATION.
7. CONNECT TO THE AUDIO INHIBIT INPUTS OF OTHER SYSTEMS WITH LOWER PRIORITY AURALS THAN TAWS.
8. OTHER UNSWITCHED INPUTS ON THE AUDIO PANEL MAY BE USED IN LIEU OF THOSE SHOWN.
s
5
TAWS ANNUNCIATOR PANEL
TERR PULL UP ANNC IN
TAWS INHIBIT ANNC IN
TERR CAUTION ANNC IN
AIRCRAFT GROUND
TAWS INHIBIT OUT
AIRCRAFT GROUND
AIRCRAFT GROUND
AIRCRAFT GROUND
AIRCRAFT GROUND
TERR N/A ANNC IN
AUDIO PANEL
UNSWITCHED IN HI
UNSWITCHED IN LO
8
Figure D-28. TAWS Interconnect
GTN 725/750 TSO Installation Manual Page D-39
190-01007-02 Rev. A
Figure D-29. Switches Interconnect
Page D-40 GTN 725/750 TSO Installation Manual
Rev. A 190-01007-02
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