Garmin GPS 155XL User manual

190-00067-22 February, 2008 Revision F
GPS 155XL/GNC 300XL
Installation Manual

Page A GPS 155XL/GNC 300 XL Installation Manual
Revision F 190-00067-22
© Copyright 2008
Garmin Ltd. or its subsidiaries
All Rights Reserved
Except as expressly provided herein, no part of this manual may be reproduced, copied, transmitted,
disseminated, downloaded or stored in any storage medium, for any purpose without the express prior
written consent of Garmin. Garmin hereby grants permission to download a single copy of this manual
and of any revision to this manual onto a hard drive or other electronic storage medium to be viewed and
to print one copy of this manual or of any revision hereto, provided that such electronic or printed copy of
this manual or revision must contain the complete text of this copyright notice and provided further that
any unauthorized commercial distribution of this manual or any revision hereto is strictly prohibited.
Garmin International, Inc.
1200 E. 151st Street
Olathe, Kansas 66062 U.S.A.
Aviation Dealer Technical Support Line (Toll Free): [phone]
Web Site Address: www.garmin.com
E-mail: [email protected]
Garmin (Europe) Ltd
Liberty House
Bulls Copse Road
Hounsdown Business Park
Southampton, SO40 9RB, UK
Telephone: [phone]
RECORD OF REVISIONS
Revision Date Description
A 02/0/98 Initial Release
B 03/31/98 Misc Changes
C 06/22/98 Changes to Figure 5-1, Misc Changes
D 10/12/99 Added TSO/ETSO compliance table
E 09/07/00 Added German Certification, JTSO, Plus Misc Changes
F 02/20/08 Updated document and added perchlorate statement
DOCUMENT PAGINATION
Section Page Range
Table of Contents i–iv
Section 1 1-1–1-6
Section 2 2-1–2-4
Section 3 3-1–3-8
Section 4 4-1–4-12
Section 5 5-1–5-4
Appendix A A-1–A-4
Appendix B B-1–B-2
Appendix C C1–C-4
Appendix D D-1–D-18

GPS 155XL/GNC 300XL Installation Manual Page i
190-00067-22 Revision F
GENERAL MAINTENANCE PRECAUTIONS
The following are general safety precautions that are not related to any specific procedure and therefore
do not appear elsewhere in this maintenance manual. These are recommended precautions that personnel
should understand and apply during the many phases of maintenance and repair.
KEEP AWAY FROM LIVE CIRCUITS. Maintenance personnel shall observe all safety regulations
at all times. Do not replace components inside the equipment when potentially lethal voltages are present.
Turn off system power before making or breaking electrical connections. Regard any exposed connector,
terminal board, or circuit board as a possible shock hazard. Components that retain a charge shall be
discharged only when such grounding does not result in equipment damage. If a test connection to
energized equipment is required, make the test equipment ground connection before probing the voltage
or signal to be tested.
DO NOT SERVICE ALONE. Personnel shall not under any circumstances reach into or enter any
enclosure for the purpose of servicing or adjusting the equipment without immediate presence or
assistance of another person capable of rendering aid.
NOTE
Specialized. test equipment and extensive depot level repair training are required for
testing the equipment covered in this namual. Therefore, this manual may not be used to
test or repair the subject equipment unless the using facility has been specifically
authorized by Garmin to do so. This manual does not need to be kept current if used only
for reference purposes.
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
States without first obtaining an export license. The preceding statement is required to be included on
any and all reproductions in whole or in part of this manual.
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.
WARNING
Perchlorate Material –special handling may apply, see
www.dtsc.ca.gov./hazardouswaste/perchlorate.

Page ii GPS 155XL/GNC 300XL Installation Manual
Revision F 190-00067-22
TABLE OF CONTENTS
PARAGRAPH PAGE
1 GENERAL DESCRIPTION .......................................................................................................1-1
1.1 Introduction.................................................................................................................................1-1
1.2 Technical Characteristics.............................................................................................................1-1
1.3 License Requirements .................................................................................................................1-4
1.4 Certification.................................................................................................................................1-5
1.5 Limited Warranty ........................................................................................................................1-6
2 INSTALLATION........................................................................................................................2-1
2.1 Introduction.................................................................................................................................2-1
2.2 Antenna Considerations...............................................................................................................2-1
2.3 Rack Considerations....................................................................................................................2-3
2.4 Cabling And Wiring....................................................................................................................2-3
2.5 Cooling Air..................................................................................................................................2-3
2.6 Minimum Installation Requirements...........................................................................................2-4
2.7 External Altitude Input................................................................................................................2-4
3 INSTALLATION PROCEDURE ...............................................................................................3-1
3.1 Installation Accessories...............................................................................................................3-1
3.2 Data Base Options.......................................................................................................................3-2
3.3 Annunciator Options ...................................................................................................................3-2
3.4 Miscellaneous Options ................................................................................................................3-2
3.5 Required Installation Accessories Not Supplied .........................................................................3-3
3.6 Antenna Installation ....................................................................................................................3-3
3.7 Cable Installation.........................................................................................................................3-4
3.8 Rack Installation..........................................................................................................................3-5
3.9 GPS 155XL/GNC 300XL Installation And Removal .................................................................3-6
3.10 J101 & J102 Pin Functions..........................................................................................................3-7
3.11 Comm Antenna Installation Check (GNC 300XL).....................................................................3-8
4 POST-INSTALLATION CONFIGURATION & CHECKOUT PROCEDURE........................4-1
4.1 Introduction.................................................................................................................................4-1
4.2 Test Mode Operations .................................................................................................................4-1
4.3 Installation Configuration............................................................................................................4-1
4.4 Ground Test.................................................................................................................................4-8
4.5 VHF Comm Interference Check................................................................................................4-12
4.6 VHF Comm Check (GNC 300XL)............................................................................................4-12
5 CONTINUED AIRWORTHINESS............................................................................................5-1
5.1 Continued Airworthiness.............................................................................................................5-1

GPS 155XL/GNC 300XL Installation Manual Page iii
190-00067-22 Revision F
TABLE OF CONTENTS
PARAGRAPH PAGE
A APPENDIX A CERTIFICATION DOCUMENTS...................................................................A-1
A.1 General .......................................................................................................................................A-1
A.2 Environmental Qualification Form—GPS 155XL/GNC 300XL...............................................A-1
A.3 Environmental Qualification Form—GA 56 GPS Aviation Antenna........................................A-3
B APPENDIX B CONNECTOR CHANGES...............................................................................B-1
B.1 Remote Battery Pin Assignments...............................................................................................B-1
C APPENDIX C STC PERMISSION...........................................................................................C-1
C.1 GPS 155XL ................................................................................................................................C-1
C.2 GNC 300XL...............................................................................................................................C-1
D APPENDIX D OUTLINE AND INSTALLATION DRAWINGS
LIST OF FIGURES
FIGURE PAGE
2-1 GPS Antenna Installation Considerations ...................................................................................2-2
2-2 Switch/Annunciator Layout ........................................................................................................2-4
3-1 Coax Cable Installation ...............................................................................................................3-5
3-2 View Of J101 From Back of Rack ..............................................................................................3-7
3-3 View Of J102 From Back of Rack ..............................................................................................3-8
D-1 GA 56 Antenna Installation Drawing.........................................................................................D-1
D-2 Aviation Rack Dimensions.........................................................................................................D-3
D-3 Aviation Rack Installation..........................................................................................................D-5
D-4 Interconnect Wiring Diagram, Remote Battery And Encoding Altimeter Connections ............D-7
D-5 Interconnect Wiring Diagram, Navigation Indicator Connections.............................................D-9
D-6 Interconnect Wiring Diagram, Bendix/King KI 209A Connections........................................D-11
D-7 Interconnect Wiring Diagram, Switch Annunciator Connections............................................D-13
D-8 Interconnect Wiring Diagram, Optional Accessory Connections ............................................D-15
D-9 Interconnect Wiring Diagram, Audio Connections..................................................................D-17
LIST OF TABLES
TABLE PAGE
3-1 Contact Part Numbers and Recommended Crimp Tools.............................................................3-4
3-2 J101 Pin Functions ......................................................................................................................3-7
3-3 J102 Pin Functions ......................................................................................................................3-8

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GPS 155XL/GNC 300XL Installation Manual Page 1-1
190-00067-22 Revision F
1GENERAL DESCRIPTION
1.1 Introduction
This manual describes the physical, mechanical, and electrical characteristics and the installation
requirements for the GPS 155XL/GNC 300XL Aviation Kit. After installation of the GPS 155XL/GNC
300XL system, FAA Form 337 must be completed by an appropriately certified agency to return the
aircraft to service.
1.2 Technical Characteristics
The conditions and tests required for TSO C129a approval of the GPS 155XL/GNC 300XL are minimum
performance standards. It is the responsibility of the agency installing this system either on or within a
specific type or class of aircraft to determine that the aircraft installation conditions are within the TSO
standards. The system may be installed only if evaluation by the applicant documents an acceptable
installation and is approved by the administrator. For TSO/JTSO Compliance, see Appendix A.
1.2.1 Physical Characteristics
1.2.2 Operational Characteristics
Characteristic Specification
Operating Temperature Range -20°C to +55°C
Humidity 95% non-condensing
Altitude Range -1,500 to 50,000 ft.
Power Range (GNC 300XL) 10 to 15.1 VDC
Power Range (GPS 155XL) 10 to 33 VDC
Power Requirements (GNC 300XL) 1.35A @ 13.8V (not transmitting); 5.5A @
13.8V (transmitting)
Power Requirements (GPS 155XL) 0.95A @ 13.8V
Characteristic Specification
Width 6.25 inches
Height 2 inches
Depth 5.65 inches
GPS 155XL Weight (Unit Only) 2.05 lbs.
GNC 300XL Weight (Unit Only) 2.55 lbs.
GA 56 Antenna Weight 0.25 lbs.
Aviation Rack Weight (w/connector) 0.83 lbs.
Max Air Speed(Structural rating for antenna) Subsonic

Page 1-2 GPS 155XL/GNC300 XL Installation Manual
Revision F 190-00067-22
1.2.3 Interfaces
The GPS 155XL/GNC 300XL provides an interface to various general aviation instruments. Table 3-2
defines the function of each pin on the 37-pin DSUB connector located at the back of the rack. Table 3-3
lists the function of each pin in the 26-pin HD-DSUB connector (J102) located above the 37-pin
connector at the back of the rack. Figures D-4 through D-9 define the interconnects between the rack and
other instruments. J101 and J102 pin functions are provided in paragraphs 1.2.4 and 1.2.5.
1.2.4 J101 Connector Pin Functions (37-pin)
Pin(s) Pin Function
CDI
(Pins 1 and 4)
Capable of driving up to three 1000 ohm parallel loads, +150
millivolts full scale deflection with a maximum output of +300
millivolts.
To/From
(Pins 2 and 4)
Capable of driving up to three 200 ohm parallel loads, +190
millivolts full scale deflection.
Nav Flag
(Pins 3 and 4)
Capable of driving up to three 1000 ohm parallel loads, 375
millivolts for flag out-of-view, and +40 millivolts for flag in-view.
OBI Data
(Pins 7, 8, and 23)
Output providing bearing to waypoint data for a Bendix/King RMI
(KI 229 or equivalent).
Message Annunciator
(Pin 20)
Output capable of driving negative logic message annunciators by
sinking up to 500 mA.
RS232 Chan 1 Output
Data
(Pin 24)
Output capable of driving devices as listed in Section 4. Conforms
to the EIA specification RS-232C.
RS232 Chan 2 Output
Data
(Pin 19)
Output capable of driving devices as listed in Section 4. Conforms
to the EIA specification RS-232C.
RS232 Chan 1 Input Data
(Pin 17)
Input capable of receiving data from devices listed in Section 4.
Conforms to the EIA specification RS-232C.
RS232 Chan 2 Input Data
(Pin 18)
Input capable of receiving data from devices listed in Section 4.
Conforms to the EIA specification RS-232C.
Arrival Annunciator
(Pin 12)
Output capable of driving negative logic annunciator by sinking up
to 500 mA.
GPS Approach Active
Annunciator (Pin 13)
Output capable of driving negative logic annunciator by sinking up
to 500 mA. See GPS 155XL/GNC 300XL Pilot's Guide (GPN 190-
00067-20 and 190-00067-30), for more information.
GPS Approach Arm
Annunciator (Pin 28)
Output capable of driving negative logic annunciator by sinking up
to 500 mA. See GPS 155XL/GNC 300XL Pilot's Guide (GPN 190-
00067-20 and GPN 190-00067-30), for more information.
ARINC 429 Output A & B
(Pins 15 and 16)
Output capable of interfacing with any device that has an input
conforming to the GAMA ARINC 429 (low speed) specification.
NAV Super Flag Output
(Pin 10)
Output capable of driving positive logic NAV Super Flag by
sourcing up to 500 mA for flag out of view (NAV valid).
GPS Approach Arm Low
(Pin 9)
Input, when grounded, controls approach mode.
GPS OBS
(Pins 4, 14, 35 and 37)
Capable of interfacing with a standard OBS resolver.

GPS 155XL/GNC 300XL Installation Manual Page 1-3
190-00067-22 Revision F
J101 Connector Pin Functions (37-pin) continued
Pin(s) Pin Function
ARINC 429 Input A & B
(Pins 32 and 33)
Input capable of receiving data from ARINC 429 (low speed)
devices as listed in Section 4.
Battery +,-, Charge Enable
(Pins 30, 34, and 29)
Connection for Garmin remote battery accessory.
1.2.5 J102 Connector Pin Functions (26 pin)
Pin(s) Pin Function
MIC Audio Hi and Lo
(Pins 2 and 3, GNC 300XL Only)
Input requiring 275mV RMS into 470 ohm load (Standard
carbon or dynamic MIC containing transistorized
pre-amp).
MIC Key
(Pin 4, GNC 300XL Only)
Input, when grounded, keys the transmitter.
COMM Audio Hi and Lo (Pins 5
and 6, GNC 300XL Only)
Output capable of driving a 500-ohm load with 100mW.
MIC Intercom
(Pin 8, GNC 300XL Only)
Input requiring 125 mV RMS into 470 ohm load (Standard
carbon or dynamic MIC containing transistorized
pre-amp).
Remote Transfer
(Pin 10, GNC 300XL Only)
Input, when grounded, swaps the active and standby
COMM frequencies.
TX Interlock
(Pin 12, GNC 300XL Only)
Input, when grounded, reduces receiver sensitivity so
squelch will not break when another transceiver is keyed.
Altimeter input
(Pins 14-24)
Capable of receiving encoded output data from any
parallel altimeter device.
Remote Enter
(Pin 26)
Input, when ground, functions the same as the enter key
on the GPS 155XL/GNC 300XL front panel.
Sequence Hold Low
(Pin 13)
Input, when grounded, activates HOLD mode. See GPS
155XL Pilot’s Guide (GPN 190-00067-20) or the GNC
300XL Pilot's Guide (GPN 190-00067-30) for more
information.
1.2.6 Comm Antenna Connector (J4, GNC 300XL Only)
Capable of providing 5 watts, minimum, at 13.8V sensitivity of 6 dB SNR, minimum, at 2 uV hard. The
COMM antenna shall be approved to TSO C37( ) and C38( ).

Page 1-4 GPS 155XL/GNC300 XL Installation Manual
Revision F 190-00067-22
1.3 LICENSE REQUIREMENTS
If any of these devices are connected to a personal computer used in home or in office, then the four
following paragraphs are applicable.
These devices comply with Part 15 of the FCC limits for Class B digital devices. This equipment
generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance
with the instructions, may cause harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If this equipment does cause
harmful interference to other equipment, which can be determined by turning the equipment off and
on, the user is encouraged to try and correct the interference by relocating the equipment or
connecting the equipment to a different circuit than the affected equipment.
Consult an authorized dealer or other qualified avionics service technician for additional help if these
remedies do not correct the problem. These devices comply with Part 15 of the FCC rules. Operation
is subject to the following conditions: (1) This device may not cause harmful interference, and (2) this
device must accept any interference received, including interference that may cause undesired
operation.
These units do not contain any user-serviceable parts. Repairs should only be made by an authorized
Garmin service center. Unauthorized repairs or modifications could void your warranty and your
authority to operate this device under Part 15 Regulations.
The FCC requires Garmin to inform users that these units meet the more stringent requirements "For
Home or Office Use".
The following guidance is provided to help ensure the proper licensing of the GNC 300XL Comm.
1. The Telecommunications Act of 1996 effective February 8, 1996 provides the FCC discretion
to eliminate radio station license requirements for aircraft. At present, an individual license to
operate the GNC 300XL aboard a private aircraft is not needed in many circumstances. Please
see FCC Fact Sheet PR5000 or contact the FCC at 1-800-322-1117 for more information.
2. No license change is required for aircraft that already have a station license per FCC 404
Instructions dated 1994.
3. If an aircraft license is required or desired, contact the FCC at 1-800-322-1117 to request FCC
form 404, “Application for Aircraft Radio Station License,” to apply for FCC authorization.
The FCC also has a "Fax on Demand" service to provide forms by fax at 202-418-0177.

GPS 155XL/GNC 300XL Installation Manual Page 1-5
190-00067-22 Revision F
1.4 CERTIFICATION
The GNC 300XL/GPS 155XL is certified for IFR enroute, terminal, and non-precision approaches. The
GNC 300XL/GPS 155XL initial certification was accomplished via an STC by Garmin in a Piper PA32
aircraft. See Appendix C for a copy of the STCs.
All installations must be certified. For more information, see FAA Advisory Circular "Airworthiness
Approval of Global Positioning System (GPS) Navigation Equipment for use as a VFR and IFR
Supplemental Navigation System," Appendix 1. All new certifications after Garmin's Piper PA32
installation will be "Follow-On."
1.4.1 German Certification
For installations required to meet German regulation REG TP 321 ZV 034, Lowpass Filter (GPN 330-
00157-00) must be installed on the GNC 300XL COM RF connector, J4, instead of the GPS Notch Filter
(GPN 330-00067-00).

Page 1-6 GPS 155XL/GNC300 XL Installation Manual
Revision F 190-00067-22
1.5 LIMITED WARRANTY
This Garmin product is warranted to be free from defects in materials or workmanship for two years from
the date of purchase. Within this 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
cover failures due to abuse, misuse, accident or unauthorized alteration or repairs.
THE WARRANTIES AND REMEDIES CONTAINED HEREIN ARE EXCLUSIVE AND IN LIEU OF
ALL OTHER WARRANTIES EXPRESS OR 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 THIS 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 the unit 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.
To obtain warranty service, contact your local Garmin Authorized Service Center. For assistance in
locating a Service Center near you, call Garmin Customer Service at one of the numbers shown below.
Products sold through online auctions are not eligible for rebates or other special offers from Garmin.
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.
Garmin International, Inc. Garmin (Europe) Ltd.
1200 East 151st Street Liberty House, Bulls Copse Road
Olathe, Kansas 66062, U.S.A. Hounsdown Business Park
Phone: [phone] Romsey, SO40 9RB, U.K.
FAX: [phone] Phone: 44/ (0) 870.8501241
FAX: 44/ (0) 870.8501251

GPS 155XL/GNC 300XL Installation Manual Page 2-1
190-00067-22 Revision F
2INSTALLATION
2.1 Introduction
Careful planning and consideration of the suggestions in this section are required to achieve the desired
performance and reliability from the GPS 155XL/GNC 300XL.
2.2 Antenna Considerations
2.2.1 GPS Antenna Location
The GPS 155XL/GNC 300XL GA 56 Antenna must be mounted on top of the aircraft. For best
performance, select a location with an unobstructed view of the sky above the aircraft when in level
flight. Figure 2-1 illustrates a typical GPS antenna installation. The antenna should be located at least 3
feet from transmitting antennas such as VHF Comm, HF transmitter, DME, Transponder, and Radar.
For rotorcraft, locate the GA 56 Antenna as far as possible from the main rotor hub. This reduces the
percentage of time the blade blocks the antenna. Also mount it as far below the blade surface as possible
if installing the antenna under the blade. This reduces signal distortion caused by the blades.
2.2.2 Communication Antenna Location (GNC 300XL)
The COMM 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 inches
square minimum). The antenna should be mounted a minimum of 6 feet from any DME antennas, 4 feet
from any ADF sense antennas, and 3 feet from the GNC 300XL and its GPS antenna.
The GNC 300XL COMM antenna connector is specified to have a 1.57542 GHz notch filter installed
(GPN 330-00067-00) to minimize interfering harmonics.
Installations required to meet German regulation REG TP 321 ZV 034, must have Lowpass Filter
(GPN 330-00157-00) installed on the GNC 300XL COM RF connector J4 instead of the GPS Notch
Filter (GPN 330-00067-00).
2.2.3 Electrical Bonding
No special precautions need to be taken to provide a bonding path between the GPS antenna and the
aircraft structure. Follow the manufacturer’s instructions for the COMM antenna (GNC 300XL).
2.2.4 Antenna Limitations
Garmin’s GA 56 Antennas are recommended for installations where the airspeed of the aircraft will be
subsonic.
In such installations, Garmin's GA 56—Mod 1 or later—must be used. See the COMM antenna
specification for its limitations (GNC 300XL).

Page 2-2 GPS 155XL/GNC300 XL Installation Manual
Revision F 190-00067-22
2.2.5 VHF Comm Interference of GPS
On many panel-mounted aircraft installations, VHF Communication radios can radiate strong harmonics
from the comm transceivers and their antenna. The GNC 300XL COMM section will not interfere with
its GPS section. However, placement of the GNC 300XL GPS antenna relative to a COMM and COMM
antenna, including its own, is critical.
Figure 2-1. GPS Antenna Installation Considerations
Use the following guidelines, in addition to others in this document, when locating the GPS 155XL/GNC
300XL and its antenna(s).
•GPS Antenna—Locate as far as possible from all COMM antennas and all COMMs (including
the GNC 300XL). The GPS antenna will be much less sensitive to COMM antennas that use a
1.57542 GHz notch filter.
•GPS 155XL/GNC 300XL—Locate as far as possible from all COMM antennas.
If a COMM antenna is found to be the problem, a 1.57542 GHz notch filter (GPN 330-00067-00) may be
installed in the VHF COMM coax, as close to the COMM as possible. This filter (GPN 330-00067-00) is
required for the GNC 300XL transmitter.
If a COMM is found to be radiating, the following can be done:
•Replace or clean the VHF COMM rack connector to ensure a good coax ground.
•Place a grounding brace between the GNC 300XL, the VHF COMM, and ground.
•Shield the VHF COMM wiring harness.
2.2.6 Comm Antenna Installation Instructions (GNC 300XL)
Install the COMM antenna according to the manufacturer's recommendations.

GPS 155XL/GNC 300XL Installation Manual Page 2-3
190-00067-22 Revision F
2.3 RACK CONSIDERATIONS
2.3.1 Accessibility
Plan a location that gives the pilot comfortable access to the keypad and provides good visibility from the
pilot's perspective. Check that there is adequate depth for the rack in the instrument panel. A location
away from heating vents or other sources of heat generation is optimal. Figure 2-1 illustrates a typical
aviation rack installation.
2.4 CABLING AND WIRING
The recommended antenna cable type for both antennas is M17/155-0001 (RG-58A/U) per MIL-C-17.
Maximum allowable length for the GPS antenna using this cable type is 40 feet. Other cable types with
50 ohms nominal impedance and longer lengths can be used for the GPS antenna, provided the installer
insures that the attenuation does not exceed 10 dB at 1.5 GHz for the specific installation.
Check that there is ample space for the cabling and mating connectors. Avoid sharp bends in cabling,
particularly the GNC 300XL COMM antenna cable, and routing near aircraft control cables. Cabling for
the GPS 155XL/GNC 300XL should not be routed near components or cabling which are sources of
electrical noise. Do not route the GNC 300XL COMM antenna cable near any ADF antenna cables.
Route the GPS antenna cable as far as possible away from all COMMs and COMM antenna cable.
2.5 COOLING AIR
The GPS 155XL/GNC 300XL units meet 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 15-20 °C (25 to 35 °F) doubles the mean time between failure
(MTBF). Recommended airflow rating is 1 CFM (cubic foot per minute) at a pressure equivalent to 0.1
inches of water.
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. A 5/8” diameter air fitting is provided on the rear of the mounting rack for the purpose of
admitting cooling air under such conditions. If a form of forced air cooling is installed, make certain that
rainwater cannot enter and be sprayed on the equipment.

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Revision F 190-00067-22
2.6 MINIMUM INSTALLATION REQUIREMENTS
The following is a list of required devices for A1 and A2 certification. For a specific list of equipment
used in the initial STC, see GPN 190-00067-26 for the GPS 155XL and GPN 190-00067-36 for the GNC
300XL. Deviations from this equipment should be approved by the FAA or the governing organization.
•Pressure Altitude Device—This device delivers pressure altitude data to the GPS 155XL/GNC
300XL. This data comes from an encoder or altitude data digitizer.
•Manual Course Device—This device delivers the manual course selected to the GPS
155XL/GNC 300XL. Course information can come from an analog resolver or from an EFIS via
the ARINC 429 bus.
•HSI/CDI Device—This device displays Nav Flag, Left/Right, and To/From information. This
can be displayed on the EFIS, HSI or CDI.
•External Annunciators and Switches:
•NAV Annunciator
•GPS Annunciator
•NAV/GPS Switch
•HOLD Annunciator
•AUTO Annunciator
•GPS Sequence Switch
•Approach Active Annunciator (not required for A2)
•Approach Arm Annunciator (not required for A2)
•GPS Approach Switch (not required for A2)
•Message Annunciator
•Arrival Annunciator
The installer is advised to ensure that the switches and annunciators are the functional equivalent to and
perform at least as well as the Garmin devices used in the initial STC. The Garmin switches and
annunciators are sunlight readable and in the primary view of the pilot. Figure 2-2 shows what the
Garmin switch/annunciators look like. For other information concerning switch/annunciators see the
Generic Airplane Flight Manual Supplement (GPN 190-00067-24 for the GPS 155XL and GPN
190-00067-34 for the GNC 300XL) as well as current FAA directives.
•Qualified GPS Antenna—This antenna must be one of those listed in the accessories list.
2.7 EXTERNAL ALTITUDE INPUT
Pressure altitude input from an external source may be derived from a RS-232 compatible serial altitude
input or Parallel Gray Code/Gillham Altitude as described in Section 4 of this manual. Gillham Altitude
is not required when serial altitude is used.
Figure 2-2. Switch/Annunciator Layout

GPS 155XL/GNC 300XL Installation Manual Page 3-1
190-00067-22 Revision F
3INSTALLATION PROCEDURE
3.1 INSTALLATION ACCESSORIES
The following installation accessories are available:
1.Antenna and Rack Options:
•GA 56 Antenna Kit, without cable (Mod 1 or later, P/N 010-10040-01). This kit contains the
following items:
DESCRIPTION GPN QTY
GA 56 ANTENNA SUB-ASSEMBLY 011-00134-00 1
BACKING PLATE 115-00031-00 1
NUT, SELF-LOCKING, #8-32 210-10004-09 4
ANTENNA GASKET 253-00002-00 1
•GA 56 Flange Mount Antenna Kit, (Mod 1 or later, P/N 010-10040-02). This kit contains the
following items:
DESCRIPTION GPN QTY
FLANGE MOUNT GA 56 ANTENNA
SUB-ASSEMBLY
011-00147-00 1
NUT PLATE 115-00080-00 1
SCREW, # 10-32 X 5/8 211-62212-14 4
ANTENNA GASKET 253-00011-00 1
2. Other accessories include the following:
•Connector, BNC, Male, Clamp, (P/N 330-00087-00)
•Low-Loss Aviation Antenna Extension Cable with Right Angle BNC Connector, 15 ft., (P/N
320-00003-00)
•Low-Loss Aviation Antenna Extension Cable with Right Angle BNC Connector, 30 ft., (P/N
320-00003-02)
NOTE
One cable assembly and one BNC connector are required to make the antenna cable, or it can be
fabricated by the installer from materials meeting the requirements of paragraph 2.4.
•Mounting Rack (without connectors), P/N 011-00154-00
NOTE
A mounting rack is required for approved installations. The following hardware is required for
installation of the mounting rack, but is not provided—#6-32 Flat Head Screw (4 ea.) #6-32
Self-locking Nut (4 ea.)
•Connector, (JI and J2) Kit, P/N 011-00313-00
•Sample Flight Manual Supplement, Garmin GPS 155XL, P/N 190-00067-24
•Sample Flight Manual Supplement, Garmin GNC 300XL, P/N 190-00067-34
•Pilot’s Guide, Garmin GPS 155XL, P/N 190-00067-20
•Pilot’s Guide, Garmin GNC 300XL, P/N 190-00067-30

Page 3-2 GPS 155XL/GNC300 XL Installation Manual
Revision F 190-00067-22
3.2 DATA BASE OPTIONS
DESCRIPTION GPN
MEMORY CARD - WORLDWIDE DATABASE 010-10051-00
MEMORY CARD - AMERICAS DATABASE 010-10051-01
MEMORY CARD - INTERNATIONAL DATABASE 010-10051-02
MEMORY CARD - USER 010-10032-03
3.3 ANNUNCIATOR OPTIONS
DESCRIPTION GPN MID-CONTINENT P/N
INTEGRATED SW/ANN UNIT. HOR. 28V 013-00029-10 MD41-448
INTEGRATED SW/ANN UNIT, HOR. 14V 013-00029-11 MD41-444
INTEGRATED SW/ANN UNIT, HOR, 28V
(5V LIGHTING)
013-00029-12 MD41-448 (5V)
INTEGRATED SW/ANN UNIT, VERT. 28V 013-00029-15 MD41-458
INTEGRATED SW/ANN UNIT, VERT, 14V 013-00029-16 MD41-454
INTEGRATED SW/ANN UNIT, VERT. 28V
(5V LIGHTING)
013-00029-17 MD41-458 (5V)
3.4 MISCELLANEOUS OPTIONS
DESCRIPTION GPN
PC KIT 010-10075-00
GPS 155XL PILOT’S GUIDE 190-00067-20
GPS 155XL QUICK REFERENCE GUIDE 190-00067-21
GPS 155XL IN PIPER PA32 DOCUMENTED INSTALLATION 190-00067-26
GNC 300XL PILOT’S GUIDE 190-00067-30
GNC 300XL QUICK REFERENCE GUIDE 190-00067-31
GNC 300XL IN PIPER PA32 DOCUMENTED INSTALLATION 190-00067-36
GPS 1.57542 GHz NOTCH FILTER (GNC 300XL ONLY) 330-00067-00
WALL ADAPTER - 110 VAC 362-00014-00
28 TO 14V CONVERTER (GNC 300XL ONLY) (CONSISTS OF
011-00181-00)
010-10057-00
REMOTE BATTERY PACK (CONSISTS OF 011-00182-00) 010-10074-00

GPS 155XL/GNC 300XL Installation Manual Page 3-3
190-00067-22 Revision F
3.5 REQUIRED INSTALLATION ACCESSORIES NOT SUPPLIED
The following installation accessories are required but not provided (GNC 300XL only).
•Comm Antenna—Broad Band 50 Ohm Vertically Polarized with Coaxial Cable
•Headphones—500 Ohm Nominal Impedance
•Microphone—Low Impedance Carbon or Dynamic with Transistorized Preamp
3.6 ANTENNA INSTALLATION
For the COMM antenna, follow the manufacturer's instructions (GNC 300XL). The remainder of this
section applies to the GPS antenna. The GA 56 Antenna outline and footprint dimensions are shown in
Figure D-1.
1. Using the backing plate as a template, mark the location of the mounting holes and the through
hole for the coaxial cable. Drill or punch the holes.
2. The antenna installation must provide adequate support for the antenna considering a
maximum drag load of 5 lbs. for the GA 56 antennas (at subsonic speed). Install a doubler
plate to reinforce thin skinned aircraft. Observe guidelines for acceptable installation practices
as outlined in AC 43.13-2A.
3. Seal the antenna and gasket to the fuselage using a good quality electrical grade sealant. Use
caution to ensure that the antenna connector is not contaminated with sealant. Ensure that the
mounting screws are fully tightened and that the antenna base is well seated against the gasket.
CAUTION
Do not use construction grade RTV sealant or sealants containing acetic acid. These
sealants may damage the electrical connections to the antenna. Use of these types
sealants may void the antenna warranty.

Page 3-4 GPS 155XL/GNC300 XL Installation Manual
Revision F 190-00067-22
3.7 CABLE INSTALLATION
1. Route the coaxial cable to the rack location keeping in mind the recommendations of Section 2.
Secure the cable in accordance with good mechanical practices.
2. Trim the coaxial cable to the desired length and install the BNC connector (330-0087-00) per
the cabling instructions in Figure 3-1. If the connector is provided by the installer, follow the
connector manufacturer's instructions for cable preparation.
3. Contacts for the 37 and 26 pin connectors must be crimped into the individual wires of the
aircraft wiring harness.
Table 3-1 lists contact part numbers (for reference) and crimp tools.
Table 3-1. Contact Part Numbers and Recommended Crimp Tools
Notes regarding the table:
1. Insert/Extract tools from ITT Cannon are all plastic, others are plastic with metal tip.
2. Non-Garmin part numbers shown are not maintained by Garmin and consequently are subject to change
without notice.
3. Alternate contacts for 18 AWG wire: As an alternate to the Positronic contacts listed (and provided in the
install kit), the installer may use contacts made by ITT Cannon as follows:
•Socket Contact - ITT Cannon P/N 031-10007-001
•Pin Contact - ITT Cannon P/N 330-5291-055. (These contacts require the use of a different crimp
tool positioner than shown in the table, with the part numbers as follows: Daniels P/N K250,
Astro P/N 616245, or ITT Cannon P/N: 980-00005-722.)