Garmin GDU 37X User manual

190-01054-01 March, 2011 Revision C
GDU 37X
Installation Manual

Page A GDU 37X Installation Manual
Revision C 190-01054-01
© Copyright 2011
Garmin Ltd. or its subsidiaries
All Rights Reserved
Except as expressly provided herein, no part of this manual may be reproduced, copied, transmitted, dis-
seminated, 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 unauthor-
ized commercial distribution of this manual or any revision hereto is strictly prohibited.
Garmin International, Inc.
1200 E. 151st Street
Olathe, KS 66062 USA
Telephone: [phone]
Aviation Dealer Technical Support Line (Toll Free): [phone]
www.garmin.com
Garmin (Europe) Ltd
Liberty House
Bulls Copse Road
Hounsdown Business Park
Southampton, SO40 9RB, UK
Telephone: [phone]
RECORD OF REVISIONS
DOCUMENT PAGINATION
Revision Revision Date Description
A 03/09/09 Initial Release
B 08/21/09 Changed doc name to GDU 37X, added system ID info to
database section, and added GA 57X info
C 03/31/11 Corrected Fig D-1.1, various updates
Section Page Range
Table of Contents i – vi
Section 1 1-1 – 1-6
Section 2 2-1 – 2-6
Section 3 3-1 – 3-28
Section 4 4-1 – 4-14
Section 5 5-1 – 5-2
Appendix A A-1 – A-4
Appendix B B-1 – B-14
Appendix C C-1 – C-10
Appendix D D-1 – D-2

GDU 37X Installation Manual Page i
190-01054-01 Revision C
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.
References to the GDU 37X throughout this manual apply equally to the GDU
370 and GDU 375 except where specifically noted.
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 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.
CURRENT REVISION DESCRIPTION
WARNING
NOTE
Revision Page
Number(s)
Section
Number Description of Change
C
4-1 4.2.1 Updated text and screenshot per new software
4-6 4.4.4 Updated screenshot per new software
4-10, 4-11 4.4.7 Added MapMX and SL40 information
4-13 4.5.2 Added Chartview information
D-1 Appdx D Corrected pin number of RS-232 RX3

Page ii GDU 37X Installation Manual
Revision C 190-01054-01
TABLE OF CONTENTS
PARAGRAPH PAGE
Section 1 GDU 37X Installation Overview ...................................................... 1-1
Unpacking Unit ................................................................................................................................... 1-1
Introduction ......................................................................................................................................... 1-1
System Overview................................................................................................................................. 1-1
General GDU 37X LRU Specifications ..............................................................................................1-2
Garmin LRU Part Numbers .......................................................................................................... 1-2
Power Specifications..................................................................................................................... 1-2
Physical Specifications ................................................................................................................. 1-2
Cooling Requirements .................................................................................................................. 1-3
Mounting ............................................................................................................................................. 1-3
Wiring/Cabling Considerations........................................................................................................... 1-3
Wiring Harness Installation .......................................................................................................... 1-3
Cable Location Considerations..................................................................................................... 1-4
Cable Installation .......................................................................................................................... 1-5
Backshell Assemblies ................................................................................................................... 1-5
Section 2 GDU 37X ............................................................................................ 2-1
Equipment Description........................................................................................................................ 2-1
Navigation Functions.................................................................................................................... 2-1
Interface Summary........................................................................................................................ 2-1
Electrical Specifications ...................................................................................................................... 2-2
Electrical Characteristics .............................................................................................................. 2-2
Power Consumption...................................................................................................................... 2-2
GPS Specifications........................................................................................................................ 2-2
Antennas ....................................................................................................................................... 2-3
Environmental Specifications.............................................................................................................. 2-3
Installation Requirements................................................................................................................... 2-4
Required Accessories.................................................................................................................... 2-4
Additional Equipment Required ...................................................................................................2-4
Installation Considerations .................................................................................................................. 2-5
Mounting Requirements ...................................................................................................................... 2-5
Unit Installation................................................................................................................................... 2-5
Continued Airworthiness..................................................................................................................... 2-5
Panel Cutout Template ........................................................................................................................ 2-6
Section 3 Garmin GPS/XM Antennas.............................................................. 3-1
GPS Antennas...................................................................................................................................... 3-1
XM Antennas....................................................................................................................................... 3-1
Antenna Mounting Considerations...................................................................................................... 3-2
VHF COM/GPS Interference........................................................................................................3-2
GPS/XM Antenna Mounting Location ......................................................................................... 3-3
Buried Antenna (below the skin covering or glareshield) Mounting .......................................... 3-5
Antenna Doubler/Backing Plate ...................................................................................................3-6
Antenna Grounding Plane............................................................................................................. 3-6
Antenna Grounding....................................................................................................................... 3-7

GDU 37X Installation Manual Page iii
190-01054-01 Revision C
PARAGRAPH PAGE
Teardrop Footprint Antenna Installation (GA 55 and GA 56)............................................................ 3-7
Preparation of Doubler.................................................................................................................. 3-7
Antenna Installation Instructions .................................................................................................. 3-8
Reference Figures ......................................................................................................................... 3-8
ARINC 743 Footprint Antenna Installation (GA 55A, GA 57X) ..................................................... 3-13
Preparation of Doubler................................................................................................................ 3-14
Antenna Installation Instructions ................................................................................................ 3-14
Reference Figures ....................................................................................................................... 3-15
Non-Structural Mount Installation .................................................................................................... 3-22
Generic Non-structural Antenna Installation .............................................................................. 3-22
Considerations for Non-Structural Mounting ............................................................................. 3-23
Non-structural Installation to Glareshield................................................................................... 3-23
Non-structural Installation to Airframe ...................................................................................... 3-25
Section 4 Software, Configuration, Databases, and XM Activation ............. 4-1
Configuration Mode ............................................................................................................................ 4-1
Software/Audio Data Identification .................................................................................................... 4-1
LRU Software and Audio Data Version Identification................................................................. 4-1
Software Loading Procedure ............................................................................................................... 4-2
GDU Software Loading Procedure............................................................................................... 4-2
Configuration Pages ............................................................................................................................ 4-3
Main Configuration Page.............................................................................................................. 4-3
ACFT Configuration Page ............................................................................................................ 4-4
W/B (Weight/Balance) Configuration Page ................................................................................. 4-5
UNITS Configuration Page........................................................................................................... 4-6
DSPL (Display) Configuration Page ............................................................................................ 4-7
SOUND Configuration Page......................................................................................................... 4-9
COMM Configuration Page........................................................................................................ 4-10
Garmin Database Updates ................................................................................................................. 4-11
Updating Garmin Databases .......................................................................................................4-11
Available Databases.................................................................................................................... 4-13
XM Activation Instructions (GDU 375 only) ................................................................................... 4-14
Section 5 Post-Installation Checkout Procedure............................................. 5-1
Required Test Equipment.................................................................................................................... 5-1
GDU 37X Test Procedure ................................................................................................................... 5-1
Appendix A GDU 37X Pinouts ........................................................................ A-1
GDU 37X ............................................................................................................................. A-1
P3701 Connector...........................................................................................................................A-1
Aircraft Power...............................................................................................................................A-2
Demo Mode Selection...................................................................................................................A-2
Serial Data.....................................................................................................................................A-3
Lighting.........................................................................................................................................A-3
Audio.............................................................................................................................................A-3

Page iv GDU 37X Installation Manual
Revision C 190-01054-01
PARAGRAPH PAGE
Appendix B Connector Installation Instructions............................................B-1
Jackscrew Backshell Installation Instructions...................................................................... B-1
Shield Block Installation Parts......................................................................................................B-1
Shield Termination Technique – Method A.1 (Standard) ............................................................B-3
Shield Termination Technique - Method A.2 (Daisy Chain) .......................................................B-7
Shield Termination – Method B.1 (Quick Term) .........................................................................B-8
Shield Termination-Method B.2 (Daisy Chain-Quick Term).....................................................B-10
Daisy Chain between Methods A and B.....................................................................................B-11
Double-Shield Termination Technique - Method C.1 ................................................................B-12
Double-Shield Termination Technique (Quick Term) - Method C.2.........................................B-13
ID Program Pins (Strapping) ......................................................................................................B-13
Splicing Signal Wires .................................................................................................................B-14

GDU 37X Installation Manual Page v
190-01054-01 Revision C
LIST OF FIGURES
FIGURE PAGE
Section 1 GDU 37X Installation Overview .......................................................1-1
Coax Cable Installation.......................................................................................................... 1-5
Section 2 GDU 37X .............................................................................................2-1
GDU 37X............................................................................................................................... 2-1
GDU 37X Mounting Accessories .......................................................................................... 2-4
GDU 37X Panel Cutout Template ......................................................................................... 2-6
Section 3 Garmin GPS/XM Antennas...............................................................3-1
Recommended Antenna Placement ...................................................................................... 3-4
Carbon/Glass Buried Antenna Area ..................................................................................... 3-5
Glare Shield Buried Antenna Area ....................................................................................... 3-6
Doubler Design, Teardrop Footprint Antenna, Skin Thickness 0.032" to 0.049" ................ 3-8
Doubler Design, Teardrop Footprint Antenna, Skin Thickness 0.049" to 0.051" ................ 3-9
Doubler Design, Teardrop Footprint Antenna, Skin Thickness 0.051" to 0.063" ................ 3-9
Sample Doubler Location, Teardrop Footprint Antenna, Metal Skin Aircraft................... 3-10
Skin Cutout Detail, Teardrop Footprint Antenna, Skin Thickness 0.032" to 0.049" ......... 3-10
Skin Cutout Detail, Teardrop Footprint Antenna, Skin Thickness 0.049" to 0.051" ......... 3-11
Skin Cutout Detail, Teardrop Footprint Antenna, Skin Thickness 0.051" to 0.063" ......... 3-11
Doubler Installation, Teardrop Footprint Antenna, Skin Thickness 0.032" to 0.049" ....... 3-12
Doubler Installation, Teardrop Footprint Antenna, Skin Thickness 0.049" to 0.051" ....... 3-12
Doubler Installation, Teardrop Footprint Antenna, Skin Thickness 0.051" to 0.063" ....... 3-13
Doubler Design, ARINC 743 Footprint Antenna, Skin Thickness 0.032" to 0.049" ........ 3-15
Doubler Design, ARINC 743 Footprint Antenna, Skin Thickness 0.049" to 0.051" ........ 3-16
Doubler Design, ARINC 743 Footprint Antenna, Skin Thickness 0.051" to 0.063" ......... 3-17
Sample Doubler Location, ARINC 743 Antenna, Metal Skin Aircraft.............................. 3-18
Skin Cutout Detail, ARINC 743 Footprint Antenna, Skin Thickness 0.032" to 0.049"..... 3-18
Skin Cutout Detail, ARINC 743 Footprint Antenna, Skin Thickness 0.049" to 0.051"..... 3-19
Skin Cutout Detail, ARINC 743 Footprint Antenna, Skin Thickness 0.051" to 0.063"..... 3-19
Doubler Installation, ARINC 743 Footprint Antenna, SkinThickness 0.032" to 0.049"... 3-20
Doubler Installation, ARINC 743 Footprint Antenna, SkinThickness 0.049" to 0.051"... 3-20
Doubler Installation, ARINC 743 Footprint, Skin Thickness 0.051" to 0.063" ................. 3-21
Installation of ARINC 743 Footprint Antenna ................................................................... 3-21
Generic Non-structural ARINC 743 Footprint Antenna Installation.................................. 3-22
Example Bracket Antenna Mounting Under Glareshield ................................................... 3-23
Example Non-structural Antenna Mounting Under Glareshield ........................................ 3-24
Example Teardrop Antenna Installation In Airframe Under Fabric Skin........................... 3-25
Example ARINC 743 Footprint In Airframe Under Fabric Skin ....................................... 3-25
Example Non-structural Antenna Mounting On Airframe ................................................. 3-26
Example Teardrop Footprint Antenna Mounting Under Fabric Skin................................. 3-27

Page vi GDU 37X Installation Manual
Revision C 190-01054-01
FIGURE PAGE
Appendix A GDU 37X Pinouts ........................................................................ A-1
View of J3701 Connector from Back of Unit ...................................................................... A-1
Appendix B Connector Installation Instructions............................................B-1
Shield Install onto a Jackscrew Backshell (78 pin example) ............................................... B-2
Method A.1 for Shield Termination..................................................................................... B-3
Insulation/Contact Clearance ............................................................................................... B-5
Method A.2 (Daisy Chain) for Shield Termination ............................................................. B-7
Method B.1 (Quick Term) for Shield Termination.............................................................. B-9
Method B.2 (Daisy Chain-Quick Term) for Shield Termination....................................... B-10
Daisy Chain between Methods A and B ............................................................................ B-11
Method C.1 Double-Shield Termination............................................................................ B-12
Method C.2 Double-Shield Termination............................................................................ B-13
D-Sub Spliced Signal Wire illustration.............................................................................. B-14
Appendix C Outline and Installation Drawings ........................................... C-1
GDU 37X Outline Drawing ................................................................................................. C-1
GDU Panel Cutout Drawing ................................................................................................ C-2
GA 55/55A Installation Drawing ......................................................................................... C-3
GA 56 Installation Drawing ................................................................................................. C-4
GA 57X Installation Drawing .............................................................................................. C-5
Appendix D Interconnect Drawing (example only)....................................... D-1
GDU 37X Interconnect Drawing ......................................................................................... D-1

GDU 37X Installation Manual Page vii
190-01054-01 Revision C
LIST OF TABLES
TABLE PAGE
Section 1 GDU 37X Installation Overview ...................................................... 1-1
GDU 37X LRU Part Numbers ............................................................................................... 1-2
Contents of GDU 37X Assembly (010-00667-XX)............................................................... 1-2
GDU 37X LRU Power Requirements.................................................................................... 1-2
GDU 37X LRU Physical Specifications ................................................................................ 1-2
Pin Contact and Crimp Tools Part Numbers.......................................................................... 1-4
Section 2 GDU 37X ............................................................................................ 2-1
GDU 37X Supply Voltages.................................................................................................... 2-2
GDU 37X Power Requirements............................................................................................. 2-2
GDU 37X GPS Specifications ............................................................................................... 2-2
GDU 37X Supported Antennas.............................................................................................. 2-3
GDU 37X Required Accessories ........................................................................................... 2-4
Contents of GDU 37X Connector Kit (011-01921-00)*........................................................ 2-4
Section 3 Garmin GPS/XM Antennas.............................................................. 3-1
GPS Antennas ....................................................................................................................... 3-1
GPS Antenna Minimum Requirements................................................................................. 3-1
XM Antennas ........................................................................................................................ 3-1
XM Satellite Radio Antenna Minimum Requirements......................................................... 3-2
Teardrop Footprint Antenna Doubler Design and Installation .............................................3-7
ARINC 743 Footprint Antenna Doubler Design and Installation....................................... 3-13
Minimum Distance Required Between Tube Structure and Antenna.................................3-27
Appendix B Connector Installation Instructions............................................B-1
Parts supplied for a Shield Block Installation (Figure B-1)................................................. B-1
Parts not supplied for a Shield Block Installation (Figure B-1)........................................... B-1
Shielded Cable Preparations for Garmin Connectors .......................................................... B-3
Shielded Cable Preparations – (Quick Term) ...................................................................... B-9
Shielded Cable Preparations for Garmin Connectors ........................................................ B-12

Page viii GDU 37X Installation Manual
Revision C 190-01054-01
Limited Warranty
This Garmin product is warranted to be free from defects in materials or workmanship for one year 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] Southampton, SO40 9RB, U.K.
FAX: [phone] Phone: [phone]
FAX: [phone]

GDU 37X Installation Manual Page 1-1
190-01054-01 Revision C
1 GDU 37X Installation Overview
1.1 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.
1.2 Introduction
This manual provides an overview of the GDU 37X and its mechanical and electrical installation aspects.
The Garmin GDU 37X is not a TSO-certified product and has received no FAA
approval or endorsement, and is therefore not suitable for installation in a type-
certificated aircraft.
The following outline describes the organization of this manual:
Section 1 This section gives a basic overview of the GDU 37X system and interface. This
section contains generic information that pertains to all components of the GDU
37X system, such as wiring and backshell considerations.
Section 2 This section describes the electrical and installation aspects of the GDU 37X.
Section 3 This section describes the electrical and installation aspects of the Garmin GPS
and XM antennas.
Section 4 This section contains software, configuration, database, and XM activation
information.
Section 5 This section contains post-installation checkout for the GDU 37X.
Appdx A This section contains pinout information for all GDU 37X LRU’s.
Appdx B This section contains outline and installation drawings for the Garmin Antennas
and GDU 37X units.
Appdx C This section connector installation instructions.
Appdx D This section contains interconnect drawings for the Garmin GDU 37X.
1.3 System Overview
The GDU 37X is a Non-TSO’d multifunction display designed for retrofit installation in light sport (LSA)
and experimental aircraft. It features a built-in XM weather audio receiver (GDU 375 only), 7” WVGA
high-resolution screen, and dual power inputs.
NOTE

Page 1-2 GDU 37X Installation Manual
Revision C 190-01054-01
1.4 General GDU 37X LRU Specifications
1.4.1 Garmin LRU Part Numbers
1.4.2 Power Specifications
All LRUs are capable of operating at either 14 or 28 VDC. See Table 1-3 for current draw specifications.
1.4.3 Physical Specifications
All width, height, and depth measurements are taken with unit rack (if applicable) and connectors.
Table 1-1 GDU 37X LRU Part Numbers
LRU Unit Only Part Number Assembly Part Number
GDU 370 Americas DB 011-01747-15 010-00667-15
GDU 370 Atlantic DB 011-01747-20 010-00667-20
GDU 370 Pacific DB 011-01747-35 010-00667-35
GDU 375 Americas DB 011-01747-30 010-00667-25
Table 1-2 Contents of GDU 37X Assembly (010-00667-XX)
Item Garmin P/N Quantity
GDU 37X 011-01747-XX 1
GDU 37X Connector Kit 011-01921-00 1
GDU 37X Nutplate 115-01054-00 1
SD Card, Dummy 145-00561-00 1
Important Safety and Product Information 190-00720-50 1
GDU 37X Quick Reference Guide 190-01055-00 1
Jeppesen Free Single Update 190-10003-03 1
Table 1-3 GDU 37X LRU Power Requirements
LRU Supply Voltage Current Draw
GDU 37X 10-29 Vdc 1.10 Amp @ 14Vdc
0.55 Amp @ 28Vdc
Table 1-4 GDU 37X LRU Physical Specifications
LRU Width Height Depth Unit Weight
Unit Weight
w/Nutplate
& Connector
Weight
GDU 370 6.04 inches
(153.4 mm)
7.83 inches
(198.8 mm)
3.41 inches
(86.7 mm)
1.6 lbs
(0.713 kg)
1.8 lbs
(0.803 kg)
GDU 375 6.04 inches
(153.4 mm)
7.83 inches
(198.8 mm)
3.41 inches
(86.7 mm)
1.7 lbs
(0.753 kg)
1.9 lbs
(0.843 kg)

GDU 37X Installation Manual Page 1-3
190-01054-01 Revision C
1.4.4 Cooling Requirements
While no forced cooling air is required for the GDU 37X, it is highly recommended that the air behind the
panel be kept moving (by ventilation or a fan).
Avoid installing the GDU 37X LRUs near heat sources. If this is not possible,
ensure that additional cooling is provided. Allow adequate space for installation
of cables and connectors. The installer will supply and fabricate all of the cables.
All wiring should be in accordance with FAA AC 43.13?1B and AC 43.13?2A.
1.5 Mounting
Refer to Sections 2 and 3 for specific mounting instructions for each component of the GDU 37X, and to
Appendix C for Outline & Installation Drawings.
1.6 Wiring/Cabling Considerations
Use MIL-W-22759/16 (or other approved wire) AWG #24 or larger wire for all connections unless
otherwise specified. 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 LRU sharing a common circuit
breaker, sizing and wire gauge is based on aircraft circuit breaker layout, length of wiring, current draw on
units, and internal unit protection characteristics. Do not attempt to combine more than one unit on the
same circuit breaker.
RG400 or RG142 coaxial cable with 50 W nominal impedance and meeting applicable aviation regulations
should be used for the installation.
1.6.1 Wiring Harness Installation
Allow adequate space for installation of cables and connectors. Ensure that routing of the wiring does not
come in contact with sources of heat, RF or EMI interference. Analog Input wires routed too close to
spark plugs, plug wires, or magnetos may result in erratic readings.
The installer shall supply and fabricate all of the cables. The connector is available in the GDU 37X
Connector Kit (011-01921-00). Electrical connections are made through D subminiature connectors for
the GDU 37X units. Appendix A defines the electrical characteristics of all input and output signals.
Required connectors and associated hardware are supplied with the connector kit.
Check wiring connections for errors before connecting any wiring harnesses.
Incorrect wiring could cause internal component damage.
NOTE
CAUTION

Page 1-4 GDU 37X Installation Manual
Revision C 190-01054-01
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.
1.6.2 Cable Location Considerations
Use cable meeting the applicable aviation regulation for the interconnect wiring. Any cable meeting
specifications is acceptable for the installation. When routing cables, observe the following precautions:
• All cable routing should be kept as short and as direct as possible.
• Check that there is ample space for the cabling and mating connectors.
• Avoid sharp bends in cabling.
• Avoid routing near aircraft control cables.
• Avoid routing cables near power sources (e.g., 400 Hz generators, trim motors, etc.) or near power for
fluorescent lighting.
• Route the GPS antenna cable as far as possible away from all COM transceivers and antenna cables.
Table 1-5 Pin Contact and Crimp Tools Part Numbers
LRU Contact
Type
Garmin
Contact Part
Number
Recommended
Positioner
Recommended
Insertion/
Extraction Tool
Recommended
Hand Crimping
Tool
GDU 37X
Socket,
MilCrimp,
Size 20
336-00094-00 M22520/2-08,
Daniels K13-1
M81969/1-04
for size 22D
pins and
M81969/1-02
for size 20 pins
M22520/2-01
NOTES

GDU 37X Installation Manual Page 1-5
190-01054-01 Revision C
1.6.3 Cable Installation
1. Route the coaxial cable to the unit location. Secure the cable in accordance with good aviation prac-
tices.
2. Trim the coaxial cable to the desired length and install the BNC connector (330-00087-00) per the
cabling instructions on Figure 1-1. If the connector is provided by the installer, follow the connector
manufacturer’s instructions for cable preparation.
Figure 1-1 Coax Cable Installation
3. Contacts for the 50 pin connectors must be crimped onto the individual wires of the aircraft wiring har-
ness. Table 1-5 list contact part numbers (for reference) and recommended crimp tools.
1.6.4 Backshell Assemblies
Connector kits include backshell assemblies. Garmin’s backshell connectors give the installer the ability
to quickly and easily terminate shield grounds at the backshell housing. The instructions needed to
assemble the backshell connector w/Shield Block grounding system are located in Appendix B.

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Revision C 190-01054-01
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GDU 37X Installation Manual Page 2-1
190-01054-01 Revision C
2 GDU 37X
Figure 2-1 GDU 37X
2.1 Equipment Description
The GDU 37X is not suitable for installation in a type-certificated aircraft.
The GDU 37X is mounted flush to the aircraft instrument panel using four #6 screws. The GDU 37X is
available in two models, GDU 370 and GDU 375. The GDU 370 is a Garmin Display Unit with a GPS
receiver. The GDU 375 provides these same features plus an XM receiver.
2.1.1 Navigation Functions
• Display of position and ground speed
• Display of stored navigation and map databases
• Area navigation functions using the determined position/velocity and stored navigation data
• Advisory approach navigation functions and associated databases
2.1.2 Interface Summary
The GDU 37X uses RS-232 communications interfaces. The GDU 37X communicates with the following
Garmin LRUs:
• SL30 Nav/Comm Transceiver
• SL40 Comm Transceiver
• GNS 400/500 Series Units
• GTX 327/330 Transponder

Page 2-2 GDU 37X Installation Manual
Revision C 190-01054-01
2.2 Electrical Specifications
2.2.1 Electrical Characteristics
2.2.2 Power Consumption
2.2.3 GPS Specifications
The GDU 37X uses a high-sensitivity GPS receiver that continuously tracks and uses up to 12 satellites to
compute and update its position.
Table 2-1GDU 37X Supply Voltages
Characteristics Specifications
Power Requirements 14/28 VDC
Table 2-2 GDU 37X Power Requirements
LRU 14V (Maximum) 14V (Typical) 28V (Maximum) 28V (Typical)
GDU 370 15W, 1.10 Amp 8.5W, .600 Amp 15W, 0.540 Amp 8.5W, .300 Amp
GDU 375 15W, 1.10 Amp 9.5W, .675 Amp 15W, 0.540 Amp 9.25W, .330 Amp
Table 2-3 GDU 37X GPS Specifications
Characteristics Specifications
Acquisition Time
a) Warm Start (position known to 10 nm, time known to 10 minutes, with
valid almanac and ephemeris): Less than 5 seconds
b) Cold Start (position known to 300 nm, time known to 10 minutes, with
valid almanac): Less than 45 seconds
c) AutoLocate™ (with almanac, without initial position or time): Less than
60 seconds
Update Rate 5/second, continuous
Positional Accuracy <10 meters
Antenna Power
Supply Voltage (4.5 to 5.0), current (50 mA max)

GDU 37X Installation Manual Page 2-3
190-01054-01 Revision C
2.2.4 Antennas
Table 2-4 lists Garmin and non-Garmin antennas currently supported by the GDU 37X. Refer to Section 3
for Garmin antenna installation information. For non-Garmin antennas, follow the manufacturer’s
installation instructions.
[1] The GPS antenna connector is TNC type. The VHF COM antenna connector is BNC type.
[2] The GPS antenna connector is BNC type. The XM antenna connector is TNC type.
The GPS antenna should provide a gain of 16 to 25dB, and requires a 4.5V to 5V
supply voltage that can provide 50mA max.
2.3 Environmental Specifications
The GDU 37X has an Operating Temperature Range of -20°C to +60°C.
Table 2-4 GDU 37X Supported Antennas
Model Mount
Style Conn Type Antenna
Type Mfr Antenna Part
Number
Garmin Order
Number
Comant
2480-201
VHF/GPS
[1]
Screw
Mount,
Teardrop
Footprint
BNC
TNC
VHF COM,
GPS Comant CI 2480-201 N/A
Comant
420-10 XM
only
Antenna
Screw
Mount,
ARINC 743
Footprint
TNC XM Comant CI 420-10 N/A
GA 26C
Suction
Cup,
Magnetic or
Flange Mt
BNC GPS Garmin 011-00149-04 010-10052-04
GA 26XM Ground
Plane Mt TNC XM Garmin 013-00268-10 010-11373-00
GA 55 Stud Mount TNC XM Garmin 011-01033-00 010-10600-01
GA 55A ARINC 743 TNC XM Garmin 011-01153-00 010-10598-00
GA 56 Stud Mount BNC GPS Garmin 011-00134-00 010-10040-01
GA 57X [2]
Screw
Mount,
ARINC 743
Footprint
BNC
TNC GPS XM Garmin 011-01032-10 010-11370-10
NOTE

Page 2-4 GDU 37X Installation Manual
Revision C 190-01054-01
2.4 Installation Requirements
2.4.1 Required Accessories
Each of the following accessories is provided with the GDU 37X unit. The connector kit is required to
install the unit (Figure 2-2). The GDU 37X Nutplate is available to reinforce the panel cutout in thin panel
installations.
*Included in GDU 37X Assembly (010-00667-XX) Table 1-1
*Included in GDU 37X Assembly (010-00667-XX) Table 1-1
2.4.2 Additional Equipment Required
A 3/32” hex drive tool is required to secure the GDU 37X to the panel as described in Section 2.7 Unit
Installation.
Figure 2-2 GDU 37X Mounting Accessories
Table 2-5 GDU 37X Required Accessories
Item Garmin P/N Quantity
GDU 37X Connector Kit* 011-01921-00 1
GDU 37X Nutplate* 115-01054-00 1
Table 2-6 Contents of GDU 37X Connector Kit (011-01921-00)*
Item Garmin P/N Quantity
Sub-Assy,bkshl w/Hdw,Jackscrew 011-01855-04 1
Conn, Rcpt,D-Sub, Crimp Socket, C 330-00625-50 1
Contact, Sckt, D-Sub, Crimp, Size 20 336-00094-00 20
GDU 37x UNIT
011-01747-( )
CONNECTOR KIT
011-01921-00