GTX 32

Transponder
Installation Manual

190-00303-60 October, 2008 Revision F

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 © 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, KS 66062 USA
Telephone: 913.397.8200
Aviation Panel-Mount Technical Support Line (Toll Free) 1.888.606.5482
www.garmin.com

Garmin (Europe) Ltd.

Liberty House, Bulls Copse Road
Hounsdown Business Park
Southampton, SO40 9RB U.K.
+44/ (0) 870.8501241

Garmin AT, Inc.

2345 Turner Rd., SE
Salem, OR 97302 USA
Telephone: 503.581.8101

RECORD OF REVISIONS

Revision Revision Description

Date
A 8/10/03 Production Release
B 1/10/05 Revised to reflect software 2.08
C 1/9/06 Revised to add CG information for remote mount.
D 3/29/06 Revised to conform to standard, updated manual
E 04/04/08 Added GDL 90 interconnect info
F 10/07/08 Added caution regarding handle screw torque

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 This manual reflects the operation of software version 2. 10. Some differences in operation may be
observed when comparing the information in this manual to earlier or later software versions.

CURRENT REVISION DESCRIPTION

Page Section
Revision Description of Change
Number(s) Number
1-1 1.1 Replaced G1000 with Garmin Integrated Flight Deck
1-1 1.2 Replaced G1000 with Garmin Integrated Flight Deck
2-2 2.3 Replaced G1000 with Garmin Integrated Flight Deck
3-2 3.3 Replaced G1000 with Garmin Integrated Flight Deck
(3 places)
3-4 3.6 Added Final Installation Section, including caution for
F handle screw torque
3-5 3.7.1 Removed G1000 from 1st line
3-6 3.8 Replaced G1000 with Garmin Integrated Flight Deck
4-2 4.3 Replaced G1000 with Garmin Integrated Flight Deck
4-3 4.3.4 Replaced G1000 with Garmin Integrated Flight Deck
4-5 4.5 Replaced G1000 with Garmin Integrated Flight Deck
C-1 App C Replaced G1000 with Garmin Integrated Flight Deck

DOCUMENT PAGINATION

Section Page Range

Table of Contents i – vi
Section 1 1-1 – 1-6
Section 2 2-1 – 2-8
Section 3 3-1 – 3-6
Section 4 4-1 – 4-6
Appendix A A-1 – A-2
Appendix B B-1 – B-8
Appendix C C-1 – C-10

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 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.

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 TABLE OF CONTENTS

PARAGRAPH PAGE

1 GENERAL DESCRIPTION..............................................................................................................1-1
1.1 Introduction........................................................................................................................................1-1
1.2 Equipment Description .....................................................................................................................1-1
1.3 Mutual Suppression Pulses ................................................................................................................1-2
1.4 Identification of Installed Equipment ................................................................................................1-2
1.5 Interface Summary ............................................................................................................................1-2
1.6 Technical Specifications ....................................................................................................................1-3
1.7 License Requirements........................................................................................................................1-4
1.8 Certification .......................................................................................................................................1-5
1.9 Reference Documents ........................................................................................................................1-5
1.10 Limited Warranty...............................................................................................................................1-6

2 INSTALLATION OVERVIEW ........................................................................................................2-1

2.1 Introduction........................................................................................................................................2-1
2.2 Installation Materials .........................................................................................................................2-1
2.3 Installation Considerations ................................................................................................................2-2
2.4 Cabling and Wiring............................................................................................................................2-4
2.5 Installation Approval Considerations for Pressurized Aircraft..........................................................2-5
2.6 Cooling Air ........................................................................................................................................2-5
2.7 GTX 32 Mounting Requirements ......................................................................................................2-6

3 INSTALLATION PROCEDURE......................................................................................................3-1
3.1 Unpacking Unit..................................................................................................................................3-1
3.2 Wiring Harness Installation ...............................................................................................................3-1
3.3 Backshell Assembly...........................................................................................................................3-2
3.4 Weight and Balance ...........................................................................................................................3-3
3.5 Electrical Load Analysis....................................................................................................................3-4
3.6 Final Installation ................................................................................................................................3-4
3.7 Post Installation Configuration and Checkout ...................................................................................3-5
3.8 Continued Airworthiness ...................................................................................................................3-6

4 SYSTEM INTERCONNECTS..........................................................................................................4-1
4.1 Pin Function List................................................................................................................................4-1
4.2 Power Function ..................................................................................................................................4-2
4.3 Altitude Functions .............................................................................................................................4-2
4.4 Discrete Inputs/Outputs .....................................................................................................................4-4
4.5 RS-232 Input/Output, Software Update Connections........................................................................4-5

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 PARAGRAPH PAGE

APPENDIX A CONSTRUCTION AND VALIDATION OF STRUCTURES

A.1 Static Test Loading .......................................................................................................................... A-1
A.2 Determining Static Load Capability ................................................................................................. A-1

APPENDIX B OUTLINE AND INSTALLATION DRAWINGS

APPENDIX C INTERCONNECT DRAWINGS

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 LIST OF ILLUSTRATIONS

FIGURE PAGE

2-1 Antenna Installation Considerations ..................................................................................................2-3

2-2 GTX 32 G1000 Unit Rack .................................................................................................................2-7
2-3 GTX 32 Remote Stand-Alone Rack ..................................................................................................2-7
2-4 GTX 32 Remote Stand-Alone Rack, Suggested Mounting Locations...............................................2-8
3-1 Backshell Connector Assembly .........................................................................................................3-3
4-1 Rear Connector, J3271.......................................................................................................................4-1
4-2 GTX 32, Software Update Connections ............................................................................................4-5
A-1 Upward Static Load Test .................................................................................................................. A-2
A-2 Forward Static Load Test.................................................................................................................. A-2
B-1 GTX 32 Outline Drawing, in G1000 Rack, ...................................................................................... B-1
B-2 GTX 32 G1000 Rack/Connector Assembly Drawing ...................................................................... B-3
B-3 GTX 32 Remote Mounted Stand-Alone Rack/Connector Assembly Drawing (Sheet 1 of 2).......... B-5
B-3 GTX 32 Remote Mounted Stand-Alone Rack/Connector Assembly Drawing (Sheet 2) ................. B-7
C-1 GTX 32 Typical Garmin Integrated Flight Deck System Interconnect Wiring Diagram................. C-1
C-2 GTX 32 to GNS 480 (CNX80) Interconnect Wiring Diagram ........................................................ C-3
C-3 GTX 32 to GDL 90, Typical Interconnect Wiring Diagram............................................................. C-5
C-4 Dual GTX 32 Transponders, Single Altitude Encoder, Interconnect Wiring
Diagram (Sheet 1 of 2)...................................................................................................................... C-7
C-4 Dual GTX 32 Transponders, Single Altitude Encoder, Interconnect Wiring
Diagram (Sheet 2)............................................................................................................................. C-9

LIST OF TABLES

TABLE PAGE

3-1 Pin Contact Part Numbers..................................................................................................................3-1

3-2 Recommended Crimp Tools ..............................................................................................................3-1
3-3 Unit Power Loads ..............................................................................................................................3-4
4-1 P3271 Pin Assignments .....................................................................................................................4-1
4-2 Aircraft Power Pin Assignments........................................................................................................4-2
4-3 Encoded Altitude Pin Assignments ...................................................................................................4-3
4-4 Discrete Input/Output Pin Assignments.............................................................................................4-4
4-5 RS-232 Input/Output Pin Assignments..............................................................................................4-5
A-1 Static Test Load ................................................................................................................................ A-1

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 GTX 32 HARDWARE MOD LEVEL HISTORY

The following table identifies hardware modification (Mod) Levels for the GTX 32
Transponder. 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 SERVICE SERVICE PURPOSE OF MODIFICATION

LEVEL BULLETIN BULLETIN
NUMBER DATE

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 1 GENERAL DESCRIPTION

1.1 Introduction
This manual presents mechanical and electrical installation requirements for installing the Garmin
GTX 32 Transponder as part of a Garmin Integrated Flight Deck.

The GTX 32 can also be incorporated as a remote mounted unit in installations with other compatible
control/display units such as the Garmin GNS 480 (CNX80).

The information in this manual is STC approved. Only the equipment interfaces covered in this manual
are within the scope of the STC. Other equipment may be suitable for use with the GTX 32 but additional
FAA approval may be required. After installation of the GTX 32 in an aircraft not covered by an airframe
manufacturer’s TC, FAA Form 337 must be completed by an appropriately certificated agency to return
the aircraft to service.

1.2 Equipment Description

The Garmin GTX 32 rack-mounted transponder is a radio transmitter and receiver that operates on radar
frequencies, receiving ground radar or TCAS interrogations at 1030 MHz and transmitting a coded
response of pulses to ground-based radar on a frequency of 1090 MHz. The GTX 32 is equipped with
IDENT capability that activates the Special Position Identification (SPI) pulse for 18 seconds.

The GTX 32 replies to Mode A and Mode C interrogation. Mode A replies consist of framing pulses and
any one of 4,096 codes, which differ in the position and number of pulses transmitted. Mode C replies
include framing pulses and encoded altitude.

By replying to ground transmissions or TCAS interrogations, the GTX 32 enables ATC to display aircraft
identification, altitude and groundspeed on ATC radar screens or TCAS traffic indicators.

The GTX 32 is configured to be turned on by the aircraft avionics master bus. Transponder code entry
and function control are accessed through keys on the GDU Primary Flight Displays or the GNS 480
(CNX80).

The GTX 32 features transmit/receive RS-232 data ports. The unit concentrates data from gray code,
RS-232 input data and discrete inputs to the high-speed RS-232 data ports for display on the Garmin
Integrated Flight Deck displays. The unit is designed to feed all outgoing data via RS-232 data ports that
send and receive data to/from the GIA 63 Integrated Avionics Units (IAU) or GNS 480 (CNX80) display.
The GTX 32 can also be incorporated to act as the controller for a GDL 90.

Provision is made for unit software upgrade by means of RS-232 data through rear connector pins. In
installations where the transponder interfaces with a GNS 480 (CNX80) the installation of an optional
connector is highly recommended. If the optional connector is placed in the aircraft, transponder removal
and reinstallation for software upgrade is not required. The software can be changed while the unit is still
mounted inside the aircraft.

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 1.3 Mutual Suppression Pulses
Other equipment on board the aircraft may transmit in the same frequency band as the transponder, such
as DME or another transponder. Mutual suppression is a synchronous pulse that is sent to the other
equipment to suppress transmission of a competing transmitter for the duration of the pulse train
transmission. The transponder transmission is suppressed by an external source and other equipment on
board is suppressed by the GTX 32 transponder. This feature is designed to limit mutual interference.

1.4 Identification of Installed Equipment

The STC for the installation of a GTX 32 system in an aircraft may contain interfaces into the aircraft’s
existing equipment. This GTX 32 installation manual identifies an installation to include:

• GTX 32 Transponder
• Transponder Antenna
• Control and Display unit
• An Altitude Encoder

The STC includes all the data needed to support the installation of the GTX 32 in all the aircraft identified
on the AML. Although the interface to other equipment is present in the manual, the STC does not
include data for the installation of the Transponder Antenna, Control/Display, or Altitude Encoder. The
installation of the GNS 480 (CNX80) or GDU Multifunction Display, or any other interfaced equipment
is assumed to be covered under the aircraft original TC, another STC, or field approval and is not
modified by or covered under the GTX 32 STC.

1.5 Interface Summary

The GTX 32 provides the following interface connections via the rear connector:

• Ten (10) encoding altimeter inputs.

• Serial altitude output.
• External IDENT input.
• External STBY input.
• External suppression pulse input and output.
• Aircraft power input (14/28 Vdc).
• Switched power output of up to 1.5 amps (for digital altitude encoder power).
• Remote power turn on.
• Serial airdata or GPS groundspeed input.
• Serial altitude input. (Reduces wire count vs. parallel wire gray code altimeter interface.)
• Software update input.
• Outputs 4096 code and current operating mode to GDL90

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 1.6 Technical Specifications
It is the responsibility of the installing agency to obtain the latest revision of the GTX 32 Environmental
Qualification Form. This form is available directly from Garmin under the following part number:

GTX 32 Environmental Qualification Form, Garmin part number 005-00174-02

To obtain a copy of this form, see the dealer/OEM portion of the Garmin web site (www.garmin.com).

1.6.1 Physical Characteristics

Characteristic Specification
G1000 Rack Width 1.71 Inches (43 mm)
G1000 Rack Height 6.30 Inches (160 mm)
Remote Mount Stand-Alone Rack Width 1.73 Inches (44 mm)
Remote Mount Stand-Alone Rack Height 6.85 Inches (174 mm)
Depth Including Connectors (measured from 8.78 Inches (223 mm)
face of unit to rear of connector backshells) (G1000 and Remote Mount Rack)
GTX 32 Unit Weight 2.2 lbs. (1.00 kg)
GTX 32 Weight (Installed with G1000 rack 2.8 lbs. (1.27 kg)
and connectors)
GTX 32 Weight (Installed with remote mount 3.4 lbs. (1.54 kg)
stand-alone rack and connectors)

1.6.2 Electrical Specifications

Characteristic Specification
FCC Authorization Emission Designator 11M0M1D
Unit Software RTCA DO-178B Level D
Temperature Range -20°C to +55°C (Continuous Operation)
Altitude 55,000 Feet
Transmitter Frequency 1090 MHz ±1 MHz
Transmitter Power 125 Watts minimum, 150 Watts nominal at the antenna
through 1.5 dB coax.
Receiver Frequency 1030 MHz
Receiver Sensitivity -74 dBm Nominal for 90% replies
Mode A Capability 4096 Identification Codes
Mode C Capability 100 Foot Increments from -1000 to 63,000 feet
External Suppression Input Low ≤ 0.5 V; High ≥ 8 V

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 1.6.3 Power Requirements

Characteristic Specification
Input Voltage 14/28 Vdc See the Environmental Qualification Form
for details on surge ratings and minimum/maximum
operating voltages.
Power Input 15 Watts Typical, 22 Watts Maximum
Maximum Full TSO Reply 0.95 A @ 27.5 Vdc, 1.85 A @ 13.75 Vdc
Rate; 1200 PRF, Code 7777
Maximum Quiescent 0.50 A @ 27.5 Vdc, 0.90 A @ 13.75 Vdc

1.7 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 GTX 32 installation must comply
with current transmitter licensing requirements. 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. The GTX 32
owner accepts all responsibility for obtaining the proper licensing before using the GTX 32.

CAUTION
The UHF 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.

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 1.8 Certification
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.

1.8.1 TSO/ETSO Compliance

Applicable LRU
Function TSO/ETSO Category SW Part
Numbers
006-B0125-00
Airborne ATC Transponder TSO-C74c
Class 1A and later
Equipment ETSO-C74c
006-B0125-()

1.8.2 TSO/ETSO Deviations

None.

1.9 Reference Documents

The following publications are sources of additional information for installing the GTX 32. Before
installing the unit, the technician should read all relevant referenced materials along with this manual.

Part Number Document

190-00303-00 G1000 System Installation Manual
190-00303-04 G1000 Line Maintenance and Configuration Manual
560-0982-01 GNS 480 (CNX80) Installation Manual
560-1049-02 GDL 90 Installation Manual

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 1.10 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: 913/397.8200 Southampton, SO40 9RB, U.K.
FAX: 913/397.8282 Phone: +44/0870.851241
FAX: +44/0870.851251

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 2 INSTALLATION OVERVIEW

2.1 Introduction
This section provides hardware equipment information for installing the GTX 32 Transponder, related
hardware and optional accessories. Installation of the GTX 32 should follow the data detailed in this
manual. Cabling is fabricated by the installing agency to fit each particular aircraft. The guidance of
FAA advisory circulars AC 43.13-1B and AC 43.13-2A, where applicable, may be found useful for
making retro-fit installations that comply with FAA regulations.

Refer to the G1000 System Installation Manual, Garmin part number 190-00303-00 for further details on
the mechanical aspects. For installation in an aircraft using the remote mounted stand-alone rack refer to
Appendix B for rack drawings and dimensions.

2.2 Installation Materials

The GTX 32 is available as a single unit under the following part numbers:

Item Catalog Part Number

GTX 32 (011-00768-00) 010-00265-00

2.2.1 Equipment Available

Each of the following accessories is provided separately for the GTX 32 unit and is required for
installation.

Item Garmin Catalog Part Number

G1000 Install Rack, GTX 32 115-00439-00
G1000 Nutplate Kit 011-00915-01 (preferred) or
011-01148-01
Or
GTX 32 Remote Stand-Alone Install Rack 115-00628-00
(Alternate Configuration)
Connector Kit, GTX 32 011-01013-00 (SPIDER) or
011-01013-01 (Shield Block)
Backplate Assembly, GTX 32 011-00677-01
Garmin Transponder Antenna kit* 010-10160-00
*Note: A transponder antenna approved to TSO C66( ) or C74( ) that has been installed to meet
the requirements of this manual may be used with the GTX 32.

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 2.2.2 Additional Equipment Required
The following installation accessories are required but not provided:

• Cables – The installer will supply all system cables including circuit breakers. Cable
requirements and fabrication is detailed in Section 3 of this manual.
• Hardware – #6-32 x 100° Flathead SS Screw [(MS24693, AN507R or other approved fastener)
(4 ea.)] for horizontal mounting.
• Hardware – #8-32 x 100° Panhead Machine Screw [(MS35206, AN526 or other approved
fastener) (4 ea.).] for vertical mounting of the remote stand-alone rack
• Encoding Altitude Digitizer – For GNS 480 (CNX80) installation. Use encoding altimeter
manufacturer’s instructions. The Garmin GAE 43 (Garmin P/N 013-00066-00) can provide
altitude data in either serial or parallel gray code format.

2.3 Installation Considerations

When installed as part of a Garmin Integrated Flight Deck system, the GTX 32 interfaces with
GIA 63/GIA 63W units. Optional available discrete line interfaces are shown in Section 4.4 Discrete
Inputs/Outputs.

In other system installations, the GTX 32 can interface with equipment including altimeters and Air Data
Computer (ADC). RS-232 provides a serial communication path between interfacing equipment.
Fabrication of a wiring harness is required.

Optional available discrete line interfaces are described in Section 4.4 Discrete Inputs/Outputs, and shown
in the Interconnect Drawings provided in Appendix C.

2.3.1 Preservation of Previous Systems

It is the installer’s responsibility to preserve the essential characteristic of the aircraft being modified with
this equipment to be in accordance with the aircraft manufacturer’s original design. This includes the
preservation of multiple power buses, which reduces the probability of interrupting power to essential
instruments and avionics.

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 2.3.2 Antenna Location Considerations
Antenna mounting should utilize the aircraft manufacturer’s Type Certificated antenna location and style
of antenna. The antenna installation should be installed in accordance with AC 43.12-2A Chapter 3.
Note that penetration of the pressure vessel on the pressurized aircraft requires additional data not
contained in this manual (see Section 2.5).

Figure 2-1. Antenna Installation Considerations

A. The antenna (Garmin P/N 010-10160-00) or equivalent should be mounted away from major
protrusions, such as engine(s), propeller(s), and antenna masts. It should also be as far as
practical from landing gear doors, access doors or other openings that could affect the
radiation pattern.

B. The main antenna should be mounted vertically on the bottom of the aircraft.

C. Avoid mounting the antenna within three feet of the ADF sense antenna or any other
communication antenna and six feet from the DME antenna.

D. To prevent RF interference, the antenna must be physically mounted a minimum distance of

three feet from the GTX 32.

NOTE
If the antenna is being installed on a composite aircraft, sufficient ground plane
material must be added. Conductive wire mesh, radials, or thin aluminum sheets
embedded in the composite material provide the proper ground plane allowing the
antenna pattern (gain) to be maximized for optimum transponder performance.

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 2.4 Cabling and Wiring
Use MIL-W-22759/16 or other approved wire, AWG #24 or larger wire for all interface connections. The
standard pin contacts supplied in the connector kit are compatible with up to AWG #22 wire. In cases
where some installations have more than one unit sharing a common circuit breaker, sizing and wire
gauge is based on aircraft circuit breaker layout, length of wiring, current draw of units, and internal unit
protection characteristics. Do not attempt to combine more than one unit on the same circuit breaker
unless it is specified on aircraft manufacturer approved drawings.

In some cases, a larger gauge wire such as AWG #18 or #16 may be needed for power connections. If
using #16 or #18 barrel contacts, ensure that no two contacts are mounted directly adjacent to each other.
This minimizes the risk of contacts touching and shorting to adjacent pins or to ground.

Ensure that routing of the wiring does not come in contact with sources of heat, RF or EMI interference.
Check that there is ample space for the cabling and mating connectors. Avoid sharp bends in cabling and
routing near aircraft control cables.

The following table lists examples of the recommended antenna cable vendors and the type of cable to be
used for specific lengths of cable. Any cable meeting specifications is acceptable for the installation.

The maximum coaxial cable attenuation at 1090 MHz must not exceed 1.5 dB, including connectors.

The following table is for reference only, and lists some suitable cable types, along with the maximum
length based on an assumed loss figure of 0.2 dB per connector. Any 50 Ω, double shielded coaxial cable
assembly that meets airworthiness requirements and the 1.5 dB maximum loss figure (including
connectors) may be used.

Max. Length Insertion loss ECS Type MIL-C-17 Type RG Type

(feet – [m]) (dB/100ft)
6' 1.3" [1.86m] 18.0 M17/128-RG400 RG-400
7' 7.3" [2.32m] 14.45 3C142B
9' 2.0" [2.79m] 12.00 M17/112-RG304 RG-304
12' 6.0" [3.81m] 8.80 311601 M17/127-RG393 RG-393
15' 5.4" [4.71m] 7.12 311501
19' 9.4" [6.03m] 5.56 311201
30' 3.6" [9.24m] 3.63 310801
Supplier Vendor: Electronic See current issue RG types are
Information Cable Specialists of Qualified obsolete and
5300 W. Franklin Products List are shown for
Drive QPL-17. reference only;
Franklin, WI 53132 replaced by
Tel: 800-327-9473 M17 type
414-421-5300 numbers.
Fax: 414-421-5301
www.ecsdirect.com

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 2.4.1 Cable Routing Considerations
When routing cables, observe the following precautions:
• All cable routing should be kept as short and as direct as practical.
• Avoid sharp bends.
• Avoid routing cables near power sources (e.g., 400 Hz generators, trim motors, etc.) or near
power for fluorescent lighting.
• Avoid routing antenna cables near ADF antenna cable (allow at least a 12-inch separation).

2.5 Installation Approval Considerations for Pressurized Aircraft

Antenna and cable installations on pressurized cabin aircraft require FAA approved installation design
and engineering substantiation data whenever such installations incorporate alteration (penetration) of the
cabin pressure vessel by connector holes and/or mounting arrangements. Use of existing bulkhead
connectors previously approved by other means is permissible without additional approval.

For needed engineering support pertaining to the design and approval of such pressurized aircraft antenna
installations, it is recommended that the installer proceed according to any of the following listed options:

1. Obtain approved antenna installation design data from the aircraft manufacturer.

2. Obtain an FAA approved Supplemental Type Certificate (STC) pertaining to and valid for the subject
antenna installation.

3. Contact the FAA Aircraft Certification Office in the appropriate Region and request identification of
FAA Designated Engineering Representatives (DERs) who are authorized to prepare and approve the
required antenna installation engineering data.

4. Obtain FAA Advisory Circular AC-183C and select (and contact) a DER from the roster of
individuals identified thereunder.

5. Contact an aviation industry organization such as the Aircraft Electronics Association and request
their assistance.

Antenna installation in the pressure vessel of pressurized aircraft is beyond the scope of the GTX 32 STC.
Additional manufacturer’s data may be necessary and FAA approval may be required to cover the
installation of the antenna.

2.6 Cooling Air

Refer to the G1000 System Installation manual, Garmin part number 190-00303-00, for information on
cooling requirements. For remote mounted units, forced air cooling is not required. However, the
application of forced air cooling is recommended to provide beneficial cooling if the unit is located in a
confined space or near a source of heat.

A 5/8 inch air fitting is provided on the rear of the backplate for the purpose of admitting cooling air
under such conditions. If a form of forced air cooling is installed, make certain that rainwater or
condensation cannot enter and be sprayed on the equipment.

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 2.7 GTX 32 Mounting Requirements
The GTX 32 mounting surface must be capable of providing structural support and electrical bond to the
aircraft to minimize radiated EMI and provide protection from High-Intensity Radiation Fields (HIRF).
The GTX 32 can be mounted using the G1000 main system rack, or may be mounted remotely if desired.
Figure 2-2 shows the GTX 32 unit rack. The unit rack is fastened to the main system rack using the
nutplate kit listed in Section 2.2. Refer to Figure B-2, GTX 32 Rack/Connector Assembly Drawing, for
nutplate placement locations. The installer must provide any additional remote mounting equipment.

2.7.1 Remote Mounted Stand-Alone Rack Considerations

Figure 2-3 and Figure B-3 Sheets 1 & 2 show the GTX 32 remote mounted stand-alone rack. The remote
rack can be installed in a variety of locations, such as the electronics bay, under a seat or on an avionics
shelf behind the rear baggage area. Refer to Figure 2-4 for suggested location. Leave sufficient clearance
between the GTX 32 and any obstruction. Install the rack in accordance with AC 43.13-2A Chapter 2
“Radio Installations.” The rack should be mounted to a surface known to have sufficient structural
integrity to withstand additional inertia forces imposed by a 3.4-pound (1.54 kg) unit. If it is necessary to
build a shelf or bracket to mount the GTX 32 stand-alone rack or it is not certain that the chosen location
is of sufficient structural integrity, refer to Appendix A for validation of rack mounting structures and
determining static load capability.

Figure B-3 Sheet 2 gives the GTX 32 stand-alone rack dimensions. The rack can be mounted vertically
using four 8-32 pan head screws (MS35206, AN526 or other approved fastener). It can also be mounted
horizontally using four 6-32 100° counter-sunk flathead screws (MS24693, AN507R or other approved
fastener). Ensure that the GTX 32 chassis has a ground path to the airframe by having at least one
mounting screw in contact with the airframe. If more water-resistance is desired, the rack should be
installed in the upright vertical orientation only, otherwise, the rack may be mounted in either vertical or
horizontal orientation.

After the cable assemblies are made and wiring installed to the rack back plate, route wiring bundle as
appropriate. Use cable ties to secure the cable assemblies and coax to provide strain relief for the cable
assemblies.

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 Figure 2-2. GTX 32 G1000 Unit Rack (115-00439-00)

Figure 2-3 shows the remote rack (P/N 115-00628-00) for use in a stand-alone installation. The installer
must provide any additional mounting hardware required for the remote stand-alone rack.

Figure 2-3. GTX 32 Remote Stand-Alone Rack (115-00628-00)

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 Figure 2-4. GTX 32 Remote Stand-Alone Rack, Suggested Mounting Locations

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 3 INSTALLATION PROCEDURE

3.1 Unpacking Unit

Carefully unpack the equipment and make a visual inspection of the unit for evidence of damage incurred
during shipment. If the unit is damaged, notify the carrier and file a claim. To justify a claim, save the
original shipping container and all packing materials. Do not return the unit to Garmin until the carrier
has authorized the claim.

Retain the original shipping containers for storage. If the original containers are not available, a separate
cardboard container should be prepared that is large enough to accommodate sufficient packing material
to prevent movement.

3.2 Wiring Harness Installation

Allow adequate space for installation of cables and connectors. The installer shall supply and fabricate all
cables. All electrical connections to the GTX 32 are made through one 25-pin D-subminiature connector.
Section 4 defines the electrical characteristics of all input and output signals. Required connectors and
associated hardware are supplied with the connector kit.

See Appendix C for examples of interconnect wiring diagrams. Construct the actual harnesses in
accordance with the aircraft manufacturer authorized interconnect standards.

CAUTION
Check wiring connections for errors before inserting the GTX 32 into the rack. Incorrect
wiring could cause internal component damage.

Table 3-1 Pin Contact Part Numbers

25 pin D-Subminiature connector (P3271)
Manufacturer
18 AWG 20-24 AWG
(Power Only)
Garmin P/N 336-00023-00 336-00022-00
Military P/N N/A M39029/63-368
AMP N/A 205090-1
Positronic FC6018D M39029/63-368
ITT Cannon See Note 3 031-1007-42

Table 3-2 Recommended Crimp Tools

18 AWG 20-24 AWG
Manufacturer Hand
Positioner Insertion/ Positioner Insertion/
Crimping Tool
Extraction Tool Extraction Tool

Military P/N M22520/2-01 N/A M81969/1-02 M22520/2-08 M81969/1-02

Positronic 9507 9502-11 M81969/1-02 9502-5 M81969/1-02
ITT Cannon 995-0001-584 N/A N/A 995-0001-604 980-2000-426
AMP 601966-1 N/A N/A 601966-5 91067-2
Daniels AFM8 K774 M81969/1-02 K13-1 M24308/1-02
Astro 615717 N/A M81969/1-02 615724 M81969/1-02

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 NOTES
1. Insertion/Extraction 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 alternative to the Positronic contacts listed (and
provided in the installation kit), the installer may use contacts made by ITT Cannon under P/N
031-1007-001. 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 980-0005-722.
4. Extracting the #16, #18 and #20 contact requires that the expanded wire barrel be cut off from
the contact. It may also be necessary to push the pin out from the face of the connector when
using an extractor due to the absence of the wire. A new contact must be used when
reassembling the connector.
5. For applications using 16 AWG wire, contact Garmin for information regarding connector
crimp positioner tooling.
6. All wires must be passed through the backshell before being assembled to connector.

3.3 Backshell Assembly

The GTX 32 connector kit includes one Garmin backshell assembly. Garmin’s backshell connectors give
the installer the ability to quickly and easily terminate shield grounds at the backshell housing using one
of two methods available (SPIDER or Shield Block).

NOTE
The SPIDER grounding method is permitted for previous installations; however Garmin
recommends the use of the Shield Block grounding method for all new installations.

Garmin Integrated Flight Deck Installations:

To assemble the backshell and grounding system, refer to instructions provided in the G1000 System
Installation Manual (190-00303-00), as well as the SPIDER Installation Instructions (190-00313-02) and
Shield Block Installation Instructions (190-00313-09).

Non- Garmin Integrated Flight Deck Installations:

GTX 32 installations that are not installed with the Garmin Integrated Flight Deck, the connector and
backshell assembly is shown in Figure 3-1. Refer to the SPIDER Installation Instructions (190-00313-02)
and Shield Block Installation Instructions (190-00313-09) for grounding instructions.
1. Backshell Cast Housing. Provides a mounting point for connector accessories.
2. D-Subminiature 25 pin connector.
3. Ground System (SPIDER ground shown). Allows shield grounds to be made to the backshell
housing.
4. Strain Relief Tab. Fastens wiring bundle to housing.
5. Backshell Lid. Provides access when servicing the connector.

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 5

Figure 3-1. Backshell Connector Assembly

(Top: Exploded View Bottom: Assembled)

3.4 Weight and Balance

Weight and balance computation is required after the installation of the GTX 32. Follow the guidelines
as established in AC 43.13-1B, Chapter 10, Section 2. Make appropriate entries in the equipment list
indicating items added, removed or relocated along with the date accomplished. Include your name and
certificate number in the aircraft records. Section 1.6.1 identifies the weight of the new GTX 32
equipment, Figure B-1 shows the center of gravity.

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 3.5 Electrical Load Analysis
An electrical load analysis should be completed on each aircraft prior to installation in accordance with
AC43.13-1B, Chapter 11. See Section 1.6.3 for Power Requirements. Use the following values for
Power Loads computation:

Table 3-3. Unit Power Loads

1 14 VDC 28 VDC
GTX 32 Input
2 Typical Max. Typical Max.

GTX 32 Main Power 1.1 A 1.85 A 0.6 A 0.9 A

3.5.1 Circuit Breaker Placard

Install a Circuit Breaker Placard labeled Transponder or Transponder 1, Transponder 2 as appropriate as
indicated in AC 43.13-2A, Paragraph 27c(4).

3.6 Final Installation

For final installation and assembly, refer to the outline and installation drawings shown in Appendix B of
this manual.
1. Assemble the connector backshell as described in Section 3.3.
2. Attach the connector to the rear plate using the screws provided in the connector kit.
3. Mount the unit rack to the main system rack or other suitable mounting location using the provided
nutplates.
4. Assemble the rear plate into the GTX 32 unit rack.
5. Insert the GTX 32 into the rack, noting proper orientation as shown on the installation drawing in
Appendix B.
CAUTION
Do not use excessive force when inserting the GTX 32 into the rack. This may cause
damage to occur to the connectors, unit, and/or unit rack. If heavy resistance is felt
during installation, stop! Remove the GTX 32 and identify the source of resistance. The
rear plate is designed to float in the unit rack. Check to ensure the rear plate is not bound
by the connector harness.

6. Lock the GTX 32 in place using the lever-locking handle. Fasten the handle to the GTX 32 body
using the provided Phillips screw. (Note that some early GTX 32’s use D-ring ¼-turn fastener)

CAUTION
Start the handle screw into the hole carefully, to avoid cross-threading. Do not apply
torque in excess of 14 in-lbs to the handle screw. The application of torque exceeding 14
in-lbs to this screw will damage the LRU case and/or retaining hardware.

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 3.7 Post Installation Configuration and Checkout

NOTE
The GTX 32 Transponder will not provide valid outputs until the aircraft
post installation configuration procedures are completed.

3.7.1 Configuration
When installed as part of a Garmin Integrated Flight Deck, the GTX 32 transponder must have FAA
approved configuration data. Configuration data is loaded to the GTX 32 from an aircraft-specific SW
Loader Card. Transponder settings are predetermined for a specific aircraft and are typically contained
within the file named ‘GTX1’.

The GDU PFD serves as the graphics user interface to the installer configuring the system. For basic
configuration information, refer to the G1000 Line Maintenance and Configuration Manual, Garmin part
number 190-00303-04. For actual aircraft installation/checkout, use only aircraft manufacturer approved
checkout procedures.

Verify proper operation of the transponder by testing in accordance with Appendix F to 14 CFR Part 43 –
ATC Transponder Tests and Inspections.

For transponder installations operating with a Garmin GNS 480 (CNX80) system refer to GNS 480
(CNX80) Installation Manual 560-0982-01 for configuration procedures and operation checks.

For transponder installations operating with a Garmin GDL 90 system refer to GDL 90 Installation
Manual 560-1049-02 for configuration procedures and operation checks.

3.7.2 Interference Check

Turn on and verify operation of all avionics equipment except GTX 32. Then power GTX 32 on and
verify there is no interference with any other equipment in the aircraft. The operation/performance
checks should be made with all other avionics turned on. Verify that there is no interference during any
mode of transponder operation.

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 3.7.3 Operation/Performance Checkout

CAUTION
If the unit is removed from the aircraft and operated, always connect J3272 to an
antenna or a 50 Ω, 5-Watt load.

Verify proper operation of the transponder by testing as specified in Appendix F of 14 CFR, Part 43, to
AC 43-6B, and/or other appropriate regulations. The test is typically done as a ramp test using a
transponder ramp test set, such as the TIC TR-210, IFR ATC-600A or other suitable transponder test set.

Self Test
Verify that the unit does not display a failure indication when turned on.
Altitude Input
Verify that the displayed altitude matches the altimeter pressure altitude (at 29.92).
External Inputs
If the external ident or standby inputs are connected, verify operation by:
a) Verify that the unit goes to standby when the external standby input is pulled low.
b) Verify that the ident indication turns on when the external ident button is pressed
(must be in the “ON” or “ALT” modes).

3.7.4 Performance (Ramp) Test

After installation, the transponder should be tested as specified in 14 CFR Part 43 Appendix F,
AC 43-6B, and other appropriate regulations. The test is typically done as a ramp test using a transponder
ramp test set, such as the IFR ATC-600A or TIC TR-210. The ramp test includes checks as follows:

a) Reply Frequency
b) Suppression
c) Receiver Sensitivity
d) Reply RF Output Power
e) Altitude Reporting

3.8 Continued Airworthiness

Test according to Title 14 CFR §§ 91.411 and 91.413 as well as Part 43 Appendix F. Other than for
regulatory checks, maintenance of the GTX 32 is ‘on condition’ only.

Aircraft covered under the GTX 32 STC AML should use ICA document number 190-00303-63.

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 4 SYSTEM INTERCONNECTS

4.1 Pin Function List

4.1.1 P3271
1 13
+ + + + + + + + + + + + +

+ + + + + + + + + + + +

14 25
Figure 4-1. Rear Connector, J3271

Table 4-1. P3271 Pin Assignments

Pin Pin Name I/O
1 XPDR RE MOTE POWER OFF In
2 RS-232 IN 2 In
3 ALTITUDE A1 In
4 ALTITUDE C2 In
5 ALTITUDE A2 In
6 ALTITUDE A4 In
7 ALTITUDE C4 In
8 EXTERNAL IDENT SELECT* In
9 ALTITUDE B1 In
10 ALTITUDE C1 In
11 ALTITUDE B2 In
12 ALTITUDE B4 In
13 POWER GROUND --
14 SWITCHED POWER OUTPUT Out
15 AIRCRAFT POWER 1 In
16 XPDR SYSTEM ID PROGRAM* In
17 EXTERNAL SUPPRESSION I/O I/O
18 ALTITUDE D4 In
19 RS-232 IN 1 In
20 RS-232 OUT 1 Out
21 (RESERVED FOR SOFTWARE UPLOAD) --
22 AIRBORNE SENSE (SQUAT SWITCH) In
23 AIRCRAFT POWER 2 In
24 RS-232 OUT 2 Out
25 SIGNAL GROUND --

* Denotes Active Low (Ground to activate).

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 4.2 Power Function
Power Input requirements are listed in the following tables. The power-input pins accept 14/28 Vdc.
Switched Power Out is a power source available for devices such as a remote digital altitude encoder.
Refer to Appendix C for power interconnections.

4.2.1 Aircraft Power

Table 4-2. Aircraft Power Pin Assignments
Pin Name Connector Pin I/O
AIRCRAFT POWER 1 P3271 15 In
AIRCRAFT POWER 2 P3271 23 In
SWITCHED POWER OUT P3271 14 Out
POWER GROUND P3271 13 --
SIGNAL GROUND P3271 25 --

4.3 Altitude Functions

Altitude functions with pin assignments are shown for reference in connection to the GNS 480 (CNX80)
system. When installed as part of a Garmin Integrated Flight Deck system, altitude data is received from
the GIA 63 in RS-232 format.

Parallel gray code altitude inputs are considered active if either the voltage to ground is < 1.9 V or the
resistance to ground is < 375 Ω. These inputs are considered inactive if the voltage to ground is
11-33 Vdc. Refer to figures in Appendix C for parallel gray code and serial data altitude interconnection.
Carefully check encoder input lines for correct connection after wiring is complete.

NOTES
The GTX 32 contains internal altitude code line isolation diodes to prevent
the unit from pulling the encoder lines to ground when the transponder is
turned off.
If two separate altimeters are connected to the GTX 32, one providing
parallel gray code and the other, serial data, the unit selects only one for use
at a time, with serial data input receiving the highest priority.
For altimeters that can be connected in both serial data and parallel gray code
format, such as the Garmin GAE 43 (Garmin P/N 013-00066-00), select one
or the other but not both wiring connections.
When connecting two GTX 32 transponders to a GPS, the unit can only
receive RS-232 serial data from one unit at a time. Use a DPDT switch to
connect both serial data and External Standby Select. Refer to Figure C-4
Sheets 1 and 2.

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 4.3.1 Altimeter Inputs
Table 4-3. Encoded Altitude Pin Assignments
Pin Name Connector Pin I/O
ALTITUDE D4 P3271 18 In
ALTITUDE A1 P3271 3 In
ALTITUDE A2 P3271 5 In
ALTITUDE A4 P3271 6 In
ALTITUDE B1 P3271 9 In
ALTITUDE B2 P3271 11 In
ALTITUDE B4 P3271 12 In
ALTITUDE C1 P3271 10 In
ALTITUDE C2 P3271 4 In
ALTITUDE C4 P3271 7 In
ALTITUDE COMMON SIGNAL GROUND P3271 25 --

4.3.2 Altimeter Interconnect, Dual GTX 32 Installation

Refer to Figure C-4 Sheets 1 and 2 for Dual GTX 32 altimeter interconnections. A dual GTX 32
installation can accept either parallel wire gray code altimeter input or RS-232 serial data input as shown.

For a complete dual installation containing two encoders, it is best to connect one encoder to each
transponder.

4.3.3 Altimeter Calibration and Checkout

Refer to GNS 480 (CNX80) Installation Manual 560-0982-01 for calibration procedures and gray code
altitude checkout.

4.3.4 Altimeter Selection Priority

When connecting the transponder to a GNS 480 (CNX80), the installer must be aware of the GTX 32
priority for selecting encoded altimeter interconnections. The GTX 32 searches in this sequence for
altitude, and stops when it finds a valid pressure altitude input.

Altitude reporting equipment order of precedence:

1) RS-232 data from GNS 480 (CNX80) or Garmin Integrated Flight Deck system
2) RS-232 Fuel/Air Data Computer (if configured W/ALT.)
3) Parallel wire Gray Code input
4) Shadin Altitude Serializer/Encoder
5) Icarus Altitude Serializer/Encoder

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 Only approved devices may provide altitude to the GTX 32 in accordance with 14 CFR Part 91.217. In
addition, all altitude reporting devices installed in the aircraft must meet certification requirements of
14 CFR Part 91.413. The installer must select an altitude reporting device that is a certified altitude
source for the particular aircraft.

For additional information, refer to GNS 480 (CNX80) Installation Manual 560-0982-01 for the altitude
data reporting configuration.

4.4 Discrete Inputs/Outputs

Table 4-4. Discrete Input/Output Pin Assignments
Pin Name Connector Pin I/O
EXTERNAL IDENT SELECT* P3271 8 In
XPDR SYSTEM ID PROGRAM* P3271 16 In
AIRBORNE SENSE (SQUAT SWITCH) P3271 22 In
EXTERNAL SUPPRESSION (TXP/DME) P3271 17 I/O
* INACTIVE: 10 ≤ Vin ≤ 33VDC or Rin ≥100kΩ
ACTIVE: Vin ≤ 1.9VDC with ≥ 75 uA sink current, or Rin ≤ 375Ω
Sink current is internally limited to 200 uA max for a grounded input

EXTERNAL IDENT SELECT (remote IDENT) is a momentary input. Refer to Figures C-1, C-2, & C-3
for the remote IDENT switch interconnect.

AIRBORNE SENSE (SQUAT SWITCH) is an ON or OFF input. The squat switch is one of the
Airborne Determination methods available for sensing airborne status. Input for Airborne Determination
allows automatic start and stop of the flight timer and enables automatic STBY mode selection. Refer to
figures C-2 & C-3 for the squat switch interconnect.

XPDR SYSTEM ID PROGRAM* (remote STBY) is an ON or OFF input used typically for dual
transponder installations. When grounded, the GTX 32 is placed in standby.

EXTERNAL SUPPRESSION should be connected if a DME is installed in the aircraft avionics system.
The GTX 32 suppression I/O pulses may not be compatible with all models of DME. Known
incompatible units include the Bendix/King KN 62, KN 64 and KNS 80. These models have an output-
only suppression port and can be damaged by the GTX 32 mutual suppression output. In this case, leave
the suppression pin open. Refer to figures C1, C-2, & C-3 for the external suppression interconnect.

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 4.4.1 RS-232 Serial Data Electrical Characteristics
The GTX 32 can be configured to include GPS, Altitude, and Airdata data inputs on two RS-232 input
lines. Altitude data supplied to the GTX 32 can be output to the GNS 480 (CNX80) on an RS-232 output
line.

Refer to Figure C-3 (of this document) and the GDL 90 Installation Manual 560-1049-02 for information
when connecting to a GDL 90.

Table 4-5. RS-232 Input/Output Pin Assignments

Pin Name Connector Pin I/O
RS-232 OUT 1 P3271 20 Out
RS-232 OUT 2 P3271 24 Out
RS-232 IN 1 P3271 19 In
RS-232 IN 2 P3271 2 In

The RS-232 outputs conform to EIA Standard RS-232C with an output voltage swing of at least ±5 V
when driving a standard RS-232 load. Refer to Appendix C for RS-232 serial data interconnect.

4.5 RS-232 Input/Output, Software Update Connections

When the GTX 32 is installed in a system other than a Garmin Integrated Flight Deck system an optional
RS-232 serial data connector should be installed in the aircraft for future software upgrades, negating the
need to remove the transponder from the aircraft. The connector can be mounted anywhere convenient
for access, such as under the instrument panel, on a remote avionics shelf next to the unit or in the
instrument panel itself. Be sure to label the connector for Software Update. Do not include the Test
Mode Select switch in the aircraft. See Figure 4-2 for software update connections.

If the GTX 32 installation interfaces with a GNS 480 (CNX80) in the aircraft, the GNS 480 (CNX80)
must be turned off during GTX 32 software upload, due to loading of RS-232 port 1.

Figure 4-2. GTX 32 Software Update Connections

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 APPENDIX A CONSTRUCTION AND VALIDATION OF STRUCTURES

A.1 Static Test Loading

This appendix includes information necessary for testing load-carrying capabilities of equipment
mounting structures, such as shelves, mounting plates and mounting brackets, used to mount the GTX 32
remote mounting tray.

Baggage compartments and cabins or cockpit floors are good mounting platforms providing the floor
attachments meet the strength requirements. If support racks, brackets or shelves need to be fabricated,
they should be fabricated and attached to the aircraft structure in accordance with the methods outlined in
AC 43.13-2A Chapter 2. After the structure is installed, it should be tested as outlined in AC 43.13-2A
Chapter 1 to verify that it is capable of supporting the required loads.

The GTX 32 installation must be capable of withstanding the Ultimate Load Factors listed in Table A-1
for at least 3 seconds in each direction specified without damage or permanent deformation. Note that
these required loads differ somewhat from those normally required for equipment installations.

Since the combined weight of the GTX 32 and its equipment mounting rack and connector is 3.4 lbs, the
static loads which must be applied (Load Factor x 3.4 lbs.) will be as follows:

Table A-1. Static Test Load

Direction of Force Load Factor Static Test Load
(Load Factor x GTX 32 Weight)
DOWNWARD 6.6 G (6.6 x 3.4) = 22.5 lbs.
UPWARD 6.0 G (6.0 x 3.4) = 20.4 lbs.
SIDEWARD 4.5 G (4.5 x 3.4) = 15.3 lbs.
FORWARD 18.0 G (18.0 x 3.4) = 61.2 lbs.

A.2 Determining Static Load Capability

A recommended method of determining the static load capability is as follows:

1. Mark and drill the holes where the GTX 32 equipment rack will be mounted.

2. Install four 8-32 machine screws (MS35206, AN526 or equivalent) in the four holes which
will be used to mount the GTX 32 equipment rack using washers, nuts and nutplates to
mount the equipment rack to the mounting surface. Note that some means of locking
fastener must be used, e.g. either lock nuts or steel nuts with lock washers.

3. For testing downward loading, place shot bags or other suitable weights totaling 22.5 pounds
within the footprint outlined by the four screw holes (assuming the mounting surface is
horizontal) or use a calibrated force gauge at the location of the center of gravity when the
unit is mounted.

4. Verify there is no damage or permanent deformation of the structure after 3 seconds.

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 5. Fasten a 36 inch loop of suitable material such as fishing line, braided wire, or other similar
material having a breaking strength of at least 100 lbs., diagonally between two of the
screws. Then fasten another loop diagonally between the other two screws, adjusting the
length of the loop so it exactly matches the first.

6. Hook a calibrated force gauge through both loops and apply a sustained pull for at least 3
seconds in each of the other three directions (upward, sideward and forward) at the above
calculated forces (i.e. 20.4 lb. upward, 15.3 lb. sideward and 61.2 lb. forward).

7. Examine the support structure carefully. If there has been damage or permanent deformation,
the structure is not suitable and must be replaced with one that is strong enough to withstand
the test loads. Examine all aircraft stringers, bulkheads and skin surfaces, which may have
direct or indirect contact with the fabricated shelf. If it is determined that no damage or
permanent deformation has occurred, the structure is of sufficient strength and the GTX 32
equipment rack may be permanently mounted on it.

Figure A-1. Upward Static Load Test

Figure A-2. Forward Static Load Test

Page A-2 GTX 32 Installation Manual

Revision F 190-00303-60

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 APPENDIX B OUTLINE AND INSTALLATION DRAWINGS

3.6 92

P3271

7.26 184.4

6.90 175.26 6.300 160.02

FORCED-AIR
TYP COOLING PORT

4.75 120.7

2.9 72
3.18 80.8

7.26 184.5
MOUNTING HOLE FOR
#6 100 FLAT HEAD SCREW 8.03 203.9 1.710 43.43
18 PLACES
8.77 222.8

9.11 231.3 N O TE S :
.39 9.78
1 . D I ME N S I ON S : I N C HE S [ m m]
2 . T O LE R A N CE S : INCH mm
.X ± 0. 1 X ±3
. XX ± 0. 0 4 .X ±1 . 0
.48 12.19 TYP . X XX ± 0. 0 2 0 . XX ±0 . 5 1

.37 9.27 .377 9.58

TYP

3.727 94.67
TYP

Figure B-1. GTX 32 Outline Drawing, in G1000 Rack

GTX 32 Installation Manual Page B-1 (Page B-2 blank)
190-00303-60 Revision F

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 APPENDIX B OUTLINE AND INSTALLATION DRAWINGS

3 115-00657-01
2 PLACES

2 4
211-63234-12
211-00084-00 #4-40 x .500 100 FLAT HEAD
2 PLACES
3 #6-32 x .375 100 FLAT HEAD 011-01013-XX
12 PLACES
CONNECTOR KIT ASSEMBLY 2

1 211-60234-06
4 #4-40 X .187 PAN HEAD PHILLIPS
4 PLACES

011-00677-01
BACK PLATE ASSEMBLY

115-00439-00
MODULAR INSTALL RACK

NOTES:
011-00768-00 1. PART OF 011-00677-01 BACK PLATE ASSEMBLY
GTX 32 2. PART OF 011-01013-XX CONNECTOR KIT ASSEMBLY (-01 SHOWN)
3. PART OF 011-00915-01 NUT PLATE KIT (PREFERRED). ALTERNATE KIT: 011-01148-01 NOT SHOWN.
WITH EITHER KIT, AT LEAST 2 OF 3 FASTENERS MUST BE USED IN EACH NUT PLATE POSITION.
4. APPLY THREAD LOCKING COMPOUND TO THREADED FASTENERS IF PRE-APPLIED PATCH IS DAMAGED

Figure B-2. GTX 32 G1000 Rack/Connector Assembly Drawing

GTX 32 Installation Manual Page B-3 (Page B-4 blank)
190-00303-60 Revision F

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 APPENDIX B OUTLINE AND INSTALLATION DRAWINGS

211-60234-06
4 PLACES 1

GROUNDING WIRES
125-00032-04
011-00980-01
1
2
211-63234-12
2 PLACES 011-00950-02
2 2

330-00184-25
336-00022-00
336-00023-00
AS NEEDED
2

232-00013-01
1

212-20014-00
1
NOTES:
234-10002-00
1. PART OF 011-00677-01 BACK PLATE ASSEMBLY
1
2. PART OF 011-01013-00 CONNECTOR KIT ASSEMBLY.

3. APPLY THREAD LOCKING COMPOUND TO ALL THREADED

330-00326-00 FASTENERS.
1
115-00628-00

Figure B-3. GTX 32 Remote Mounted Stand-Alone Rack/Connector Assembly Drawing (Sheet 1 of 2)
GTX 32 Installation Manual Page B-5 (Page B-6 blank)
190-00303-60 Revision F

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 APPENDIX B OUTLINE AND INSTALLATION DRAWINGS

4.25 1.69
[108.0] [42.9]

6.84
[173.9]
5.27
[133.8]
3.70
3.30 [93.9]
[83.7]

8.01 [203.5]
8.77 [222.7]

1.67 [42.3] 4.75 [120.6]

1.05
[26.6]

0.32 4X Ø0.18 [Ø4.6]

[8.2]
Figure B-3. GTX 32 Remote Mounted Stand-Alone Rack/Connector Assembly Drawing (Sheet 2)
GTX 32 Installation Manual Page B-7 (Page B-8 blank)
190-00303-60 Revision F

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 APPENDIX C INTERCONNECT DRAWINGS

Figure C-1. GTX 32 Typical Garmin Integrated Flight Deck System Interconnect Wiring Diagram
GTX 32 Installation Manual Page C-1 (Page C-2 blank)
190-00303-60 Revision F

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 APPENDIX C INTERCONNECT DRAWINGS

Figure C-2. GTX 32 to GNS 480 (CNX80) Interconnect Wiring Diagram

GTX 32 Installation Manual Page C-3 (Page C-4 blank)
190-00303-60 Revision F

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 APPENDIX C INTERCONNECT DRAWINGS

P1 P2 P2
CH2 CH6 CH7 GDL 90
12 33 15 RS232 RxD

5 24 7 GND

8. THE GTX 32 WILLL REMOTELY CONTROL THE GDL 90 DATALINK.

9.

Figure C-3. GTX 32 to GDL 90, Typical Interconnect Wiring Diagram

GTX 32 Installation Manual Page C-5 (Page C-6 blank)
190-00303-60 Revision F

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 APPENDIX C INTERCONNECT DRAWINGS

Figure C-4. Dual GTX 32 Transponders, Single Altitude Encoder, Interconnect Wiring Diagram (Sheet 1 of 2)
GTX 32 Installation Manual Page C-7 (Page C-8 blank)
190-00303-60 Revision F

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 APPENDIX C INTERCONNECT DRAWINGS

Figure C-4. Dual GTX 32 Transponders, Single Altitude Encoder, Interconnect Wiring Diagram (Sheet 2)
GTX 32 Installation Manual Page C-9 (Page C-10 blank)
190-00303-60 Revision F

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