Garmin GNS 400W User manual

190-00356-05 October 2008 Revision A
GNS 400W SERIES
MAINTENANCE MANUAL
GPS 400W, GNC 420W/AW, and GNS 430W/AW

_________________________________________________________________
GNS 400W Series Maintenance Manual Page A-1
190-00356-05 Rev. A
© Copyright 2008
Garmin Ltd. or its subsidiaries
All Rights Reserved
Except as expressly provided below, 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 Corporation. Garmin Corporation grants permission to download a single copy
of this manual and of any revision to this manual onto a hard drive or other electronic storage medium to
be viewed and to print one copy of this manual or of any revision hereto, provided that such electronic or
printed copy of this manual or revision must contain the complete text of this copyright notice and
provided further that any unauthorized commercial distribution of this manual or any revision hereto is
strictly prohibited.
Garmin International Inc.
1200 E. 151st Street, Olathe, Kansas 66062
Order Desk/Technical Support
Telephone: [phone]
Telephone Toll Free: [phone]
Facsimile: [phone]
Facsimile Toll Free: [phone]
e-mail: [email protected]
[email protected]
Garmin (Europe) Ltd.
Liberty House
Bulls Copse Road
Hounsdown Business Park
Southampton, SO40 9RB, UK
Order Desk/Technical Support
Telephone: [phone]
Facsimile: [phone]
e-mail: [email protected]
Garmin AT, Inc., 2345 Turner Road SE, Salem, OR 97302
Phone: [phone] (US)
Fax: [phone]
e-mail:
[email protected]

______________________________________________________________
GNS 400W Series Maintenance Manual Page i
190-00356-05 Rev. A
WARNING
Observe all safety regulations at all times. Do not replace components inside
the unit when potentially lethal voltages are present. Turn off system power
before making or breaking electrical connections. Regard any exposed
connector, terminal board, or circuit board as a possible shock hazard.
Components which retain a charge shall be discharged only when such
grounding does not result in equipment damage. If a test connection to
energized equipment is required, make the test equipment ground connection
before probing the voltage or signal to be tested. Do not reach into or enter
any enclosure for the purpose of servicing or adjusting the equipment without
immediate presence or assistance of another person capable of rendering aid.
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, refer to the
Garmin web site at www.garmin.com/prop65.

NOTE
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.

NOTE
The lens is coated with a special anti-reflective coating that is very sensitive
to skin oils, waxes and abrasive cleaners. Cleaners containing ammonia will
harm the anti-reflective coating. It is very important to clean the lens using a
clean, lint-free cloth and an eyeglass lens cleaner that is specified as safe for
anti-reflective coatings.

NOTE
This product contains a lithium battery that must be recycled or disposed of
properly. Battery replacement and removal must be performed by professional
services.

______________________________________________________________
Page ii GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
RECORD OF REVISIONS
Revision Date Section Page Description
A 10/2/08 ------ ------ Initial Release
DOCUMENT PAGINATION
Section Pages
Table of Contents i-vi
Section 1 1-1 to 1-2
Section 2 2-1 to 2-10
Section 3 3-1 to 3-6
Section 4 4-1 to 4-58
Section 5 5-1 to 5-18
Section 6 6-1 to 6-4
Appendix A A-1 to A-8
SERVICE BULLETIN HISTORY
The following table identifies hardware service bulletins for the GNS 400W series of units. The
table below is subject to change without notice. Authorized Garmin Sales and Service Centers
are encouraged to access the most up-to-date bulletin and advisory information on the Garmin
Dealer Resource web site at www.garmin.com using their Garmin-provided user name and
password. Mod Level changes are listed with the associated service bulletin number, service
bulletin date, and the purpose of the bulletin in the table below.
Bulletin # Date of Publication Name/Summary/MOD Level
740 11/29/07 400W Series Unit’s software upgrade to Main
Software version 3.00 & GPS. There was no mod
level change associated with this upgrade.
628 1/17/08 NAV Software Version 5.02 for the GNS 430W
Series Units. There was no mod level change
associated with this upgrade.

______________________________________________________________
GNS 400W Series Maintenance Manual Page iii
190-00356-05 Rev. A
This manual provides board-level maintenance information for the GNS 400W units listed in the
table below.
UNIT PART NUMBER COLOR NOTES
GPS 400W 011-01057-00 BLACK
011-01057-10 GRAY
011-01057-40 BLACK NOTE 1
011-01057-50 GRAY NOTE 1
GNC 420W 011-01058-00 BLACK
011-01058-10 GRAY
011-01058-40 BLACK NOTE 1
011-01058-45 BLACK 28 VDC UPGRADE UNIT
011-01058-50 GRAY NOTE 1
GNC 420AW 011-01059-00 BLACK
011-01059-10 GRAY
011-01059-40 BLACK NOTE 1
011-01059-50 GRAY NOTE 1
GNS 430W 011-01060-00 BLACK
011-01060-10 GRAY
011-01060-40 BLACK NOTE 1
011-01060-45 BLACK 28 VDC UPGRADE UNIT
011-01060-50 GRAY NOTE 1
GNS 430AW 011-01061-00 BLACK
011-01061-10 GRAY
011-01061-40 BLACK NOTE 1
011-01061-50 GRAY NOTE 1
Designations: A— 28 VDC Unit with 16 watt comm transmitter.
Note 1—The unit is an upgrade of the non-WAAS unit.

______________________________________________________________
Page iv GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
TABLE OF CONTENTS
SECTION 1—INTRODUCTION
1.1 Maintenance/Support Philosophy............................................................................. 1-1
1.2 Unit Upgrades........................................................................................................... 1-1
1.3 Factory Repair........................................................................................................... 1-1
1.4 Warranty Information ............................................................................................... 1-2
SECTION 2—UNIT DESCRIPTION
2.1 Introduction............................................................................................................... 2-1
2.2 Front Panel Layout.................................................................................................... 2-2
2.3 Unit Functions........................................................................................................... 2-2
2.4 Technical Specifications........................................................................................... 2-4
SECTION 3—THEORY OF OPERATION
3.1 Main Board............................................................................................................... 3-1
3.2 VHF Communications Transceiver (Com Board) .................................................... 3-3
3.3 Nav Board................................................................................................................. 3-4
3.4 Glideslope Receiver.................................................................................................. 3-4
3.5 WAAS GPS Receiver............................................................................................... 3-4
3.6 Inverter Board........................................................................................................... 3-4
3.7 Interface Board ......................................................................................................... 3-5
3.8 Video Board.............................................................................................................. 3-5
3.9 Keyboard................................................................................................................... 3-5
SECTION 4—TROUBLESHOOTING/TESTING
4.1 Introduction............................................................................................................... 4-1
4.2 Limitation/Scope....................................................................................................... 4-1
4.3 Troubleshooting Method I – Failure Messages ........................................................ 4-1
4.4 Troubleshooting Method II – Minimum Performance Tests .................................... 4-7
4.5 Comm Board Tests ................................................................................................. 4-20
4.6 VOR/LOC Receiver Testing................................................................................... 4-44
4.7 Glideslope Receiver Tests....................................................................................... 4-53
4.8 Testing Failures....................................................................................................... 4-56
4.9 Return To Service Tests..........................................................................................4-57

______________________________________________________________
GNS 400W Series Maintenance Manual Page v
190-00356-05 Rev. A
SECTION 5—REPLACEMENT PROCEDURES
5.1 Tools ......................................................................................................................... 5-1
5.2 Inspection..................................................................................................................5-1
5.3 Unit Description........................................................................................................ 5-1
5.4 Replacement Procedures........................................................................................... 5-2
5.5 Periodic Maintenance ............................................................................................. 5-18
SECTION 6—SERVICE PARTS LIST
6.1 GPS 400W ................................................................................................................ 6-1
6.2 GNC 420W............................................................................................................... 6-2
6.3 GNC 420AW ............................................................................................................ 6-2
6.4 GNS 430W................................................................................................................ 6-3
6.5 GNS 430AW............................................................................................................. 6-3
APPENDIX A—SYSTEM INTERCONNECTS
A.1 P4001 Main Connector............................................................................................ A-1
A.2 P4002 Comm Connector.......................................................................................... A-5
A.3 P4006 Connector...................................................................................................... A-6

______________________________________________________________
Page vi GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
FIGURES
2-1 GPS 400W ................................................................................................................ 2-1
2-2 GNC 420W............................................................................................................... 2-1
2-3 GNS 430W................................................................................................................ 2-1
3-1 GNS 400W Block Diagram...................................................................................... 3-1
4-1 Typical Fault Messages ............................................................................................ 4-1
4-2 Main Analog Input Test Page................................................................................. 4-11
4-3 Display Pattern Test Page....................................................................................... 4-11
4-4 WAAS GPS Status Page......................................................................................... 4-12
4-5 Main CDI/OBS Configuration Page....................................................................... 4-13
4-6 Main Discrete Outputs Page ................................................................................... 4-15
4-7 Main Discrete Inputs Page...................................................................................... 4-15
4-8 Main ARINC 429 Configuration Page ................................................................... 4-16
4-9 Main RS232 Configuration Page............................................................................ 4-17
4-10 Main CDI/OBS Configuration Page....................................................................... 4-25
5-1 Data Card Slot Locations.......................................................................................... 5-3
5-2 Data Card Insertion/Removal Detail......................................................................... 5-3
5-3 Top Assembly........................................................................................................... 5-5
5-4 Main and Nav Chassis .............................................................................................. 5-7
5-5 Fan Replacement....................................................................................................... 5-8
5-6 Main Chassis Bottom Cavity.................................................................................. 5-10
5-7 Main Chassis Top Cavity........................................................................................ 5-12
5-8 Memory Battery Location on Main Board.............................................................. 5-15
5-9 Nav Chassis Cavity................................................................................................. 5-17
A-1 Rear Panel Connectors............................................................................................. A-1
TABLES
2-1 Unit Configuration.................................................................................................... 2-1
2-2 General Specifications.............................................................................................. 2-4
2-3 GPS Specifications ................................................................................................... 2-5
2-4 Comm Specifications................................................................................................ 2-6
2-5 VOR Specifications .................................................................................................. 2-7
2-6 LOC Specifications................................................................................................... 2-8
2-7 Glideslope Specifications.......................................................................................... 2-9
4-1 Fault Messages and Recommended Actions............................................................. 4-2
4-2 Configuration and Test Page Names......................................................................... 4-8
4-3 Unit Input Power Requirements................................................................................ 4-9
4-4 Unit Board Configurations...................................................................................... 4-13
4-5 Com Power Requirements ...................................................................................... 4-23
4-6 Testing Failures-Main Board.................................................................................. 4-56

___________________________________________________________
GNS 400W Series Maintenance Manual Page 1-1
190-00356-05 Rev. A
SECTION 1
INTRODUCTION
This manual contains maintenance information for the GNS 400 “W” (WAAS) series of units. All
units in the GNS 400W series affected by this manual are listed in the table on page iii.
1.1 MAINTENANCE/SUPPORT PHILOSOPHY
Avionics shop repair is limited to replacing the parts listed in Section 6. All repairs can be made
at the bench with an appropriate replacement spare part. Faulty parts listed in Section 6 (or a
complete unit) can be returned to Garmin for repair. For information pertaining to spares
stocking (suggested quantities, etc.) contact Garmin at one of the addresses listed on the inside
cover.
This manual is written for field shops not equipped with Garmin Automated Test Equipment
(ATE) and not having access to Garmin proprietary repair documentation. Component level
repair is not authorized. Send the unit to Garmin for repair when any troubleshooting, testing, or
repair falls outside the scope of this manual (paragraph 1.3).
1.2 UNIT UPGRADES
This manual does not contain procedures for upgrading “legacy” GNS 400 series units to WAAS
units. Contact Garmin aviation product support for upgrade information and instructions. If field
shops should encounter a WAAS upgraded unit, refer to the table on page iv which lists all
upgrade part numbers.
1.3 FACTORY REPAIR
A "Return Merchandise Authorization" (RMA) number must be requested from Garmin before a
unit is returned. Units returned without an RMA will be refused and returned at the sender's
expense. Send units with assigned RMA numbers to the following address:
Garmin International, Inc.
Factory Repair
1200 E. 151st St.
RMA Number: _______
Dock Door #1
Olathe, KS 66062

___________________________________________________________
Page 1-2 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
1.4 WARRANTY INFORMATION
This Garmin product is warranted to be free from defects in materials or workmanship for two
years from the date of purchase. For WAAS upgrade of this product, the warranty is separate and
described in the service record or statement.
Products bought through online auctions are not eligible for rebates or other special offers from
Garmin. Online auction confirmations are not acceptable 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.
Within a warranty 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 is responsible for any transportation cost. This
warranty does not cover failures due to abuse, misuse, accident or unauthorized alteration or
repairs. SUCH REMEDY SHALL BE YOUR SOLE AND EXCLUSIVE REMEDY FOR ANY
BREACH OF WARRANTY
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.

___________________________________________________________
GNS 400W Series Maintenance Manual Page 2-1
190-00356-05 Rev. A
SECTION 2
UNIT DESCRIPTION
This section gives a brief decsription of each unit in the GNS 400W series.
2.1 INTRODUCTION
All units in the 400W series are 6.25 inches wide and 2.66 inches high. The display on all units is
a 240 by 128 pixel color LCD. All units include two removable data cards, one with a Jeppesen
database (which is inserted in the left card slot), and the second a terrain database (which is
inserted in the right card slot). The GPS 400W is a GPS/WAAS unit that meets the requirements
of Technical Standard Order (TSO)-C146a and is approved for IFR en route, terminal, non-
precision, and precision approach operations.
The GNC 420W/(AW) includes all the features of the GPS 400W but includes a VHF
communications transceiver. The “AW” designates a 28 V dc unit with a 16 watt COM
transmitter. The GNS 430W/(AW) includes all the features of the GNC 420W/(AW), but includes
airborne VOR/localizer (LOC) and glideslope (G/S) receivers. The “AW” model designates a 28
V dc unit with a 16 watt com transmitter.
Table 2-1 summarizes the board configuration for each unit.
Table 2-1. Unit Configuration
Main
Board
Inverter
Board
Interface
Board
WAAS
GPS
Module
COM
Board
NAV
Board
GS
Board
GPS 400W • • • •
GNC 420W • • • • •
GNC 420AW • • • • •
GNS 430W • • • • • • •
GNS 430AW • • • • • • •

___________________________________________________________
Page 2-2 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
2.2 FRONT PANEL LAYOUT
Figures 2-1 through 2-3 show the front bezel layout for each unit.
Figure 2-1. GPS 400W
Figure 2-2. GNC 420W
Figure 2-3. GNS 430W
2.3 UNIT FUNCTIONS
2.3.1 GPS 400W
The GPS 400W performs the following functions:
•Position and velocity determination using signals transmitted by Global Positioning
System (GPS) Satellites.
•Display of the stored navigation and map database for use by the pilot/flight crew.
•Area navigation functions using the determined position/velocity and stored navigation
data.
•Approach navigation functions including WAAS precision approaches and the associated
database.
•Interfacing with other flight instruments such as a moving map, autopilot, CDI/HIS
(including OBS), indicators, altitude encoder/serializer, fuel management system, and
annunciators.
•Operation from 11 to 33 volts.
•Terrain situational awareness (TERRAIN) functions and associated databases.

___________________________________________________________
GNS 400W Series Maintenance Manual Page 2-3
190-00356-05 Rev. A
2.3.2 GNC 420W
The GNC 420W performs the following functions:
•All functions of the GPS 400W.
•Communications transceiver tuning from 118.00 to 136.975 MHz in 25 kHZ or 8.33 kHZ
increments.
•10-watt (420W) or 16-watt (420AW) transmitter designed to meet the German FTZ
requirements (an external filter may be required to achieve the harmonic requirement).
2.3.3 GNS 430W
The GNS 430W performs the following functions:
•All functions of a GNC 420W.
•The VOR/ILS localizer receiver tuning from 108.00 to 117.95 MHz in 50 kHZ
increments.
•The ILS glideslope receiver tuning from 328.6 to 335.4 MHz as paired with the
frequency tuned on the VOR / ILS localizer receiver.
•VOR audio Morse code identifier output.
•Remote DME channeling.
•Interface with other flight instruments such as autopilot, CDI/HSI (including OBS) and
OBI.

___________________________________________________________
Page 2-4 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
2.4 TECHNICAL SPECIFICATIONS
Table 2-2. General Specifications
Operating Temperature Range -20° C to +55° C. For more details see
Environmental Qualification Form on the
Dealers Only page on www.garmin.com.
Humidity 95% non-condensing
Altitude Range -1,500 ft. to 50,000 ft.
Input Power Requirements
Input Voltage Range - All Units (Main
Connector)
10 to 33.2 V dc
Input Voltage Range GNC 420W, GNS
430W (COM Connector)
11 to 33 V dc
Input Voltage Range GNC 420AW, GNS
430AW (COM Connector)
24.1 to 33 V dc
GPS 400W (Main Connector) 700 mA @ 28 V dc (maximum) 1.4 A @ 14 V
dc (maximum)
GNC 420W, GNC 420AW, (Main Connector) 1.2 A @ 28 V dc (maximum) 2.5 A @ 14 V dc
(maximum)
GNS 430W, GNS 430AW, (Main Connector) 1.2 A @ 28 V dc (maximum) 2.5 A @ 14 V dc
(maximum)
GNC 420W, GNS 430W (COM Connector) 15 mA @ 28 V dc (receive) 3.0 A @ 28 V dc
(transmit) 15 mA @ 14 V dc (receive) 6.0 A @
14 V dc (transmit)
GNC 420AW, GNS 430AW (COM
Connector)
15 mA @ 28 V dc (receive) 3.0 A @ 28 V dc
(transmit)
Superflag Power Requirements 500 mA maximum per superflag output
Environmental Testing See Environmental Qualification Form on the
Dealers Only page on www.garmin.com.
Display Size 3.8” diagonal
Active Area 3.29” (W) x 1.75” (H)
Resolution 240 x 128 pixels
Viewing Angle (with a 2:1 contrast ratio, min) Left/Right: Up: Down: 40° 40° 40°
Viewing Distance 36 inches maximum

___________________________________________________________
GNS 400W Series Maintenance Manual Page 2-5
190-00356-05 Rev. A
Table 2-3. GPS Specifications
Number Of Channels 15 (12 GPS and 3 GPS/WAAS/SBAS)
Frequency 1575.42 MHz L1, C/A code
Sensitivity (Acquisition, No Interference) -134.5 dBm GPS -135.5 dBm WAAS
Sensitivity (Drop Lock) -144 dBm
Dynamic Range > 20 dB
Lat/Lon Position Accuracy < 1.25 meter RMS horizontal, < 2 meter vertical, with
WAAS
Velocity 1000 knots maximum (above 60,000 ft.)
TTFF (Time To First Fix) 1:45 min. typical with current almanac, position, and
time
Reacquisition 10 seconds typical
Position Update Interval 0.2 sec (5 Hz)
1 PPS (Pulse Per Second) ± 275 nanoseconds of UTC second
Datum WGS-84
SATCOM Compatibility SATCOM compatibility is dependent upon antenna
selection.
Antenna Power Supply 35 mA typical, 40 mA max at 4.7 V dc

___________________________________________________________
Page 2-6 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
Table 2-4. COMM Transceiver Specifications (GNC 420W and GNS 430W Only)
Audio Output 100 mW minimum into a 500 ohm load.
Audio Response Less than 6 dB of variation between 350 and 2500 Hz.
Audio Distortion The distortion in the receiver audio output shall not
exceed 15% at all levels up to 100 mW.
AGC Characteristics The audio output will not vary by more than 6 dB when
the level of the RF input signal, modulated 30% at 1000
Hz, is varied from 5 μV to 450,000 μV.
Sensitivity (S+N)/N on all channels shall be greater than 6 dB
when the RF level is 2 μV (hard) modulated 30% at
1000 Hz at rated audio.
Squelch 2 μv ± 6 dB for 25 kHz channels. 3 μv ± 6 dB for 8.33
kHz channels.
Selectivity
6 dB BW is greater than ± 8 kHz for 25 kHz channeling.
60 dB BW is less than ± 25 kHz for 25 kHz channeling.
6 dB BW is greater than ± 2.778 kHz for 8.33 kHz
channeling. 60 dB BW is less than ± 7.37 kHz for 8.33
kHz channeling.
Spurious Response Greater than 85 dB.
Modulation AM double sided, Emission Designator 6K00A3E
Frequency Band 118.00 to 136.99 MHz 25 kHz and 8.33 kHz channel
spacing
Transmitting Power
GNS 420W, GNS 430W 10 watts minimum, 15 watts
maximum GNS 420AW, GNS 430W 16 watts minimum,
20 watts maximum
Transmitter Duty Cycle Recommended 10% maximum.
Modulation Capability
The modulation is not less than 70% and not greater
than 98% with a standard modulator signal applied to
the transmitter.
Carrier Noise Level At least 45 dB (S+N)/N.
Frequency Stability 0.0005%
Demodulated Audio Distortion Less than 10% distortion when the transmitter is
modulated at least 70%.
Sidetone 1.4 Vrms into a 500 ohm load when the transmitter is
modulated at least 70%.
Demodulated Audio Response Less than 6 dB when the audio input frequency is varied
from 350 to 2500 Hz.
* C37d Class 4 & 6 may not provide suitable COM transmit range for some high-altitude aircraft.
**Specifications shown apply at nominal input voltages of 13.75 V dc or 27.5 V dc, as
applicable, and with a nominal 50 ohm resistive load at the antenna connector.

___________________________________________________________
GNS 400W Series Maintenance Manual Page 2-7
190-00356-05 Rev. A
Table 2-5. VOR Specifications (GNS 430W Only)
Receiver Audio Sensitivity At -103.5 dBm (S+N)/N shall not be less than 6
dB.
Course Deviation Sensitivity -103.5 dBm or less for 60% of standard
deflection.
Flag The VOR Course Deviation Flag must be
flagged: a) in the absence of an RF signal. b) in
the absence of the 9960 Hz modulation. c) in
the absence of either one of the two 30 Hz
modulations. d) When the level of a standard
VOR deviation test signal produces less than a
50% of standard deflection.
AGC Characteristics From -99 to -13 dBm input of a Standard VOR
Audio Test Signal, audio output levels shall not
vary more than 3 dB.
Spurious Response Greater than 80 dB.
VOR OBS Bearing Accuracy The bearing information as presented to the
pilot does not have an error in excess of 2.7°
as specified by RTCA DO-196 and EuroCAE
ED-22B.
Audio Output A minimum 100 mW into a 500 ohm load.
Audio Response Less than 6 dB of variation between 350 and
2500 Hz. Except the 1020 Hz Ident Tone is at
least 20 dB down in voice mode.
Audio Distortion The distortion in the receiver audio output does
not exceed 10% at all levels up to 100 mW.

___________________________________________________________
Page 2-8 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
Table 2-6. LOC Specifications (GNS 430W Only)
Receiver Audio Sensitivity At -103.5 dBm (S+N)/N shall not be less than 6
dB.
Course Deviation Sensitivity -103.5 dBm or less for 60% of standard
deflection.
Flag The LOC Course Deviation Flag must be
flagged: a) in the absence of an RF signal. b)
When either the 90 or 150 Hz modulating
signals is removed and the other is maintained
at its normal 20%. c) In the absence of both 90
and 150 Hz modulation. d) When the level of a
standard localizer deviation test signal
produces less than a 50% of standard
deflection.
AGC Characteristics From -86 dBm and -33 dBm input of a
Standard VOR Audio Test Signal, audio output
levels does not vary more than 3 dB.
Selectivity Nose Bandwidth: The input signal level
required to produce the reference AGC voltage
does not vary more than 6 dB over the input
signal frequency range of ± 9 kHz from the
assigned channel frequency. Skirt Bandwidth:
The input signal level required to produce
reference AGC voltage will be at least 70 dB
greater than the level required to produce
reference AGC voltage at the assigned
channel frequency at ± 36 kHz from the
assigned channel frequency.
Spurious Response Greater than 80 dB.
Centering Accuracy Typical 0 ± 3 mV (Max error 9.9 mV per RTCA
DO-195).
Audio Output A minimum 100 mW into a 500 ohm load.
Audio Response Less than 6 dB of variation between 350 and
2500 Hz. Except the 1020 Hz Ident Tone is at
least 20 dB down in voice mode.
Audio Distortion The distortion in the receiver audio output does
not exceed 10% at all levels up to 100 mW.

___________________________________________________________
GNS 400W Series Maintenance Manual Page 2-9
190-00356-05 Rev. A
Table 2-7. Glideslope Specifications (GNS 430W Only)
Sensitivity -87 dBm or less for 60% of standard deflection.
Centering Accuracy 0 ± .0091 ddm or 0 ± 7.8 mV
Selectivity The course deviation shall be 0 ddm ±
.0091ddm when using the Glideslope
Centering Test Signal as the RF frequency is
varied ±17 kHz from the assigned channel. At
frequencies displaced by ± 132 kHz or greater,
the input signal is at least 60 dB down.
Standard deflection a) With a standard deflection ‘FLY DOWN’
condition (90 Hz dominant), the output shall be
-78 mV ± 7.8 mV. b) With a standard deflection
‘FLY UP’ condition (150 Hz dominant), the
output shall be +78 mV ± 7.8 mV.
Flag The unit flags when: a) the level of a standard
deviation test signal produces 50% or less of
standard deflection of the deviation indicator. b)
In the absence of 150 Hz modulation. c) In the
absence of 90 Hz modulation. d) In the
absence of both 90 Hz and 150 Hz modulation.
e) In the absence of RF.

___________________________________________________________
Page 2-10 GNS 400W Series Maintenance Manual
Rev. A 190-00356-05
Blank Page