Garmin GTN 725 User 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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to 10 years imprisonment and a fine of up to $1,000,000 under Section 2410 of the Export Administration
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 50Ωload)
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 50Ωload)
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 500Ωload.
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 500Ωload.
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.