Northern Airborne Technology SM240 User manual

Northern Airborne Technology Ltd.
1925 Kirschner Road
Kelowna, BC, Canada.
V1Y 4N7
Telephone [phone]
Facsimile [phone]
Issued on the authority of Northern Airborne Technology Ltd.
Copyright 2005
Installation and Operation Manual
Model 240
Passenger Speaker Amplifier
SM240
ISSUE 4.12

Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Installation and Operation Manual Page ii
ENG-FORM: 820-0115.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Prepared By: Checked By: Certification: Approved By:
The status of this installation and operation manual is controlled by issue shown on the title page. The
status of each section is controlled by revision shown in the footer of each page. All revisions affecting
sections of this manual have been incorporated into the latest issue.
ISSUE/REVISION RECORD
Manual Issue
Number Section Revision Number Revision Description Issue Date
4.12 Section 2 Rev: 1.01 MOD D WED label change May 26, 2010
4.11 Section 1 Rev: 1.00
Section 2 Rev: 1.00
Section 3 Rev: 1.00
Rewritten in latest format Sep 8, 2008
4.10 N/A Initial release May 27, 2005

Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Installation and Operation Manual Page iii
ENG-FORM: 820-0115.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Table of Contents
Section Title Page
1. Description
1.1 Introduction 1-1
1.2 Product Description 1-1
1.3 Design Features 1-1
1.4 Specifications 1-1
1.4.1 Electrical Specifications 1-1
1.4.2 Physical Specifications 1-3
1.4.3 Environmental Specifications 1-3
1.4.4 Product Approval 1-3
1.5 Unit Nomenclature 1-3
2. Installation
2.1 Introduction 2-1
2.2 Unpacking and Inspection 2-1
2.2.1 Warranty 2-1
2.3 Continued Airworthiness 2-1
2.4 Installation Procedures 2-1
2.4.1 Warnings 2-2
2.4.2 Cautions 2-2
2.4.3 Cabling and Wiring 2-2
2.4.4 Mounting 2-2
2.4.5 Mode Selection 2-3
2.4.6 Numerical Pin Identification 2-3
2.4.7 Post Installation Checks 2-4
2.5 Adjustments and Connections 2-5
2.6 Accessories Required But Not Supplied 2-5
2.7 Installation Drawings 2-5
3. Operation
3.1 Introduction 3-1
3.2 General Information 3-1

Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Section 1 Rev: 1.00 Issue 4 Page 1-1
ENG-FORM: 800-0114.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Section 1 Description
1.1 Introduction
Information in this section consists of product description, design features and specifications for the
Model 240 Passenger Speaker Amplifier. All derivative product information shall be contained in the
applicable manual supplement, which may be obtained from NAT as required.
Review all notes, warnings and cautions.
1.2 Product Description
The Model 240 Passenger Speaker Amplifier mixes audio from various sources for output to cabin
speakers. It is a remotely controlled, electronic unit, which operates upon command from switches and
potentiometers in the cockpit or cabin of the aircraft.
1.3 Design Features
The Model 240 provides left/right audio taken from an external stereo receiver/music source, to the cabin
speakers.
The Model 240 provides Fasten Seat Belt and No Smoking sign chime tones, a Cabin Call ringer tone,
ADF, Pilot Select Com (PSC), TV, Briefer and Cabin Paging audio, to the cabin speakers.
All inputs and operating modes are electronically switched. Ground signals, supplied by manual switches
in the cockpit, enable the electronic switches in the Model 240. The circuitry is arranged to provide Paging
and Briefer audio priority; the PA MIC or Briefer switch signals essentially open the Stereo Left, Stereo
Right, ADF 1, ADF 2, PSC and TV audio inputs. Microphone bias current is available from the Model 240
for the PA MIC microphone input.
A musical chime tone is provided to the cabin speakers to alert the passengers of a change in the Fasten
Seat Belt or No Smoking sign status. A Cabin Call ringer tone is also provided to the cabin speakers for
the cockpit to cabin intercom system.
1.4 Specifications
1.4.1 Electrical Specifications
Input specifications are expressed in volts RMS (Vrms), rather than milliwatts, to avoid any misunderstanding.
Input Signals:
ADF: Two single, switched audio inputs for ADF, etc. Input level is 7.75 Vrms.
PSC: One single, switched audio input compatible with the Pilot Select
Com (PSC) output of dB Systems Model 418, which provides a
1.00 Vrms signal, produced from a summation of selected COM,
DME and MKR receivers.
TV: One single, switched audio input for TV etc. Input level is 1.00 Vrms.

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SM240 Installation and Operation Manual
Section 1 Rev: 1.00 Issue 4 Page 1-2
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CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Stereo Left: One single, switched differential audio input from the Left channel of
the stereo audio from a stereo receiver/ music source. Input level is
maximum 1.00 Vrms (at max. source volume) and audio LO is not
common to that of other inputs.
Stereo Right: One single, switched differential audio input from the Right channel
of the stereo audio from a stereo receiver/music source. Input level is
maximum 1.00 Vrms (at max. source volume) and audio LO is not
common to that of other inputs.
Briefer: One single, switched audio input from Briefer audio, etc. Input level
is 1.00 Vrms
PA MIC: The microphone input, used for Cabin Paging audio, supplies bias
current and is compatible with carbon and amplified dynamic
microphones.
Paging Volume: Controls the level of PA MIC and Briefer audio inputs to the PA
Sidetone and Left and Right Speaker outputs. Volume control range
is 30 dB (minimum) controlled by a 10 kOhm ½ watt, linear
potentiometer. When the potentiometer is at maximum, the level is at
maximum.
Receiver Volume: Controls level of ADF, PSC and TV audio inputs to the Left and Right
Speaker outputs. Range and control same as Paging Volume
specification.
Power Supply: 28 Vdc, 3A maximum.
Output Signals:
Left/Right Speaker: The Left and Right Speaker Amplifier output ratings are each
20 watts into 2 Ohms. This is a peak rating, intended for speech and
music. The continuous rating of the amplifier output is 2 watts into
2 Ohms for sine wave operation. Power ratings are as follows:
Load Rated Power Continuous Power
2 Ohm 20 W 2W
4 Ohm 10 W 1W
PA Sidetone: This output will deliver 6.7 mW into 600 Ohms continuously. Rated
and continuous power ratings are the same.
Chime Tone: Generated and supplied to Left and Right Speaker outputs when 12 to 32
Vdc is applied to and removed from connector pins P50-31 and P50-32.
Provides a 790 ±20 Hz tone, followed by a decaying 610 ±20 Hz tone.
Factory set for 3.5 VP-P into 2 Ohms, adjustable from 1.0 to 6.9 VP-P.
Ringer Tone: Generated and supplied to Left and Right Speaker outputs when a
ground signal is applied to connector pin P50-33. 700 ±75 Hz tone,
ON for 1.8 ±0.1 seconds, then OFF for 3.2 ±0.1 seconds, repeating.
Factory set for 1.5 VP-P (700 Hz component) into 2 Ohms,
adjustable from 0 to 5.2 VP-P.
Frequency Response: Stereo inputs to Speaker outputs – Flat within 3 dB from 85 Hz to
20,000 Hz. All other inputs to Speaker or PA Sidetone outputs – Flat
within 3 dB from 350 Hz to 6,000 Hz.
Harmonic Distortion: Less than 3 percent distortion, all outputs.
Isolation Between Channels: 60 dB, minimum.
Output Noise: Greater than 75dB below rated, all outputs.

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Section 1 Rev: 1.00 Issue 4 Page 1-3
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CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
1.4.2 Physical Specifications
Height: 1.90" [48.26 mm]
Length: 7.80" [198.12 mm]
Width: 4.90" [124.46 mm]
Weight: 1.4 lbs. [0.635 kg]
1.4.3 Environmental Specifications
Temperature: -55 to +70 degrees C.
Altitude: up to 70,000 feet.
Qualification of the Model 240 Passenger Speaker Amplifier was completed in accordance with
DO-160 B Env. Cat. F2-BA[JLO]XXXXXXX[BZ]AAAAAL
Note: Refer to Environmental Qualification Form located in Section 2 of this Manual for complete details
of the environmental categories.
1.4.4 Product Approval
FAA: TSO – C50c (RTCA/DO-170 Class Ib)
1.5 Unit Nomenclature
Model 240 Derivative Part Number Descriptions:
The following is a tabulation of all Derivative Part Numbers available for the Model 240 Passenger Speaker
Amplifier. A Model 240 with an associated Derivative Part Number is designated as a Model 240-xxx, where xxx
is the applicable three digit Derivative Part Number.
Derivative Part No. Description of Derivative
240-001 Physically and electrically identical to base Model 240 except for the following
changes:
Left and Right SPKR level shall be 3.3 ±6 Vrms.
Minimum RCVR volume shall be ≤100mVrms.
The Cabin Call Left and Right SPKR levels shall be 8 ±2 Vpp.
The Seat Belt/No Smoking Chime Left and Right SPKR levels shall be 1.6 ±2 Vpp.
Right and Left SPKR crosstalk shall be ≤7mVrms.
Right and Left SPKR noise shall be ≤4mVrms.
240-002 Physically and electrically identical to the Base Model 240.
Section 1 ends

Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Section 2 Rev: 1.01 Issue 4 Page 2-1
ENG-FORM: 805-0121.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Section 2 Installation
2.1 Introduction
Information in this section consists of unpacking and inspection procedures, installation procedures, post-
installation checks and installation drawings for the Model 240 Passenger Speaker Amplifier.
Review all notes, warnings and cautions.
2.2 Unpacking and Inspection
Unpack the equipment carefully and locate the warranty card. Inspect the unit visually for damage due to
shipping and report all such claims immediately to the carrier involved. Check that all items listed below
are present before proceeding and report any shortage immediately to your supplier:
- Warranty Card
- Certificate of Conformity or Release Certification
2.2.1 Warranty
All Northern Airborne Technology Ltd. products are warranted for 2 years from date of installation by an
authorized Northern Airborne Technology Ltd. dealer, to be free of defects in workmanship or
performance. This warranty covers all materials and labour, but is exclusive of any transport to deliver the
defective unit to and from Northern Airborne Technology Ltd. or its designated warranty repair center, or
any labour to remove or re-install the defective unit in the aircraft. Contact Northern Airborne Technology
Ltd. for any questions regarding this warranty, its applicability to your units and/or for return authorization.
Northern Airborne Technology Ltd. is the final arbitrator concerning warranty administration. Units which
have been physically damaged, burned, immersed in water or otherwise abused beyond the scope of
normal use will not be considered for warranty. WARRANTY IS VOID UNLESS THE PRODUCT IS
INSTALLED BY AN AUTHORIZED NORTHERN AIRBORNE TECHNOLOGY LTD. DEALER. Product
for which a warranty card is not returned shall be warranted from date of manufacture.
2.3 Continued Airworthiness
Maintenance of the Model 240 Passenger Speaker Amplifier is ‘on condition’ only. Periodic maintenance
of this product is not required.
2.4 Installation Procedures
Installation Notice
This product must be installed in accordance with the installation instructions provided in the latest issue
of this Installation and Operation Manual. Check the Publication Index at www.northernairborne.com for
the issue status of the manual. The latest issue of the manual may be downloaded from the same
website. All risk associated with installation of this product contrary to these instructions shall be the
responsibility of the installing agency.

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SM240 Installation and Operation Manual
Section 2 Rev: 1.01 Issue 4 Page 2-2
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CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.1 Warnings
WARNING:
High volume settings can cause hearing damage.
Set the headset volume control to the minimum volume setting prior to
conducting tests, and slowly increase the headset volume to a
comfortable listening level.
2.4.2 Cautions
CAUTION:
Do not remove components from the product while the unit is turned on. This
could cause damage to the component or unit.
2.4.3 Cabling and Wiring
All wire shall be selected in accordance with the original aircraft manufacturer's Maintenance Instructions
or AC43.13-1B Change 1, Paragraphs 11-76 through 11-78. Unshielded wire types shall qualify to
MIL-W-22759 as specified in AC43.13-1B Change 1, Paragraphs 11-85, 11-86, and listed in Table 11-11.
For shielded wire applications, use Tefzel MIL-C-27500 shielded wire with solder sleeves (for shield
terminations) to make the most compact and easily terminated interconnect. Follow the Installation Wiring
Diagram in Section 2.7 as required.
Allow 3" from the end of the shielded wiring to the shield termination to allow the connector hood to be
easily installed. Maintain wire segregation and route wiring in accordance with the original aircraft
manufacturers Maintenance Instructions.
Maintain wire segregation and route wiring in accordance with the original aircraft manufacturers
Maintenance Instructions.
Unless otherwise noted, all wiring shall be a minimum of 24 AWG, except power and ground lines, and
speaker amplifier outputs (P40 pins 1 – 14, 18, 19, 20 and 25), which shall be a minimum of 20 AWG.
Refer to the Installation Wiring Diagram for additional specifications.
The control switches shown will switch low current loads and should have a DC rating of 28 Vdc. Typical
switches for this application include Alco MTA series.
2.4.4 Mounting
The Model 240 may be mounted in any orientation. Shock or vibration isolators are not required.
Installation dimensions are shown on the Model 240 Outline drawing. The amplifier may be mounted to a
metal or plastic surface, but it is necessary to ground the case to the airframe. When mounting to a plastic
surface, use a grounding strap. The case is finished with an electrically conductive film so it is not
necessary to remove the film for electrical bonding.

Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Section 2 Rev: 1.01 Issue 4 Page 2-3
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CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.4.5 Mode Selection
The operating modes of the Model 240 are established when either a ground (low) signal or a 12 to 32
Vdc (high) signal is applied to the relevant pin of the 37 pin connector as listed below:
Pin No. Control
Signal Identification Function
P50-16 Low ADF 1 Switch Connects ADF 1 input audio to Left and Right Speaker outputs.
P50-15 Low ADF 2 Switch Connects ADF 2 input audio to Left and Right Speaker outputs.
P50-14 Low PSC Switch Connects Pilot Select COMM input audio to Left and Right
Speaker outputs.
P50-13 Low TV Switch Connects TV input audio to Left and Right Speaker outputs.
P50-5 Low Stereo Switch
Connects Stereo Left and Right Input audio to Left and Right
Speaker outputs, respectively.
P50-24 Low PA Key PSC, TV and Stereo input audio circuits.
P50-25 Low Briefer Switch
Connects Briefer input audio to PA Sidetone and Left and Right
Speaker outputs. Opens ADF, PSC, TV and Stereo input audio circuits.
P50-31 *High No Smoking Chime tone to Left and Right Stereo outputs.
P50-32 *High Seat Belt Chime tone to Left and Right Stereo outputs.
P50-33 Low Cabin Call Ringer tone to Left and Right Stereo outputs.
P50-34 Low Hook Switch Disables ringer tone.
* An application or removal of a High signal at pins P50-31 and P50-32 will provide a chime tone at Left
and Right speaker outputs.
2.4.6 Numerical Pin Identification
Pin Identification, P40 (25 pin connector):
1. Left Spkr Out Hi 14. Left Spkr Out Hi
2. Left Spkr Out Hi 15. No Connection
3. Left Spkr Out Lo 16. No Connection
4. Left Spkr Out Lo 17 No Connection
5. Left Spkr Out Lo 18. Power Ground
6. 28 VDC 19. Power Ground
7. 28 VDC 20. Power Ground
8. 28 VDC 21. No Connection
9. Right Spkr Out Lo 22. Chassis Ground
10. Right Spkr Out Lo 23. No Connection
11 Right Spkr Out Lo 24. No Connection
12. Right Spkr Out Hi 25. Right Spkr Out Hi
13. Right Spkr Out Hi

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Section 2 Rev: 1.01 Issue 4 Page 2-4
ENG-FORM: 805-0121.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Pin Identification, P50 (37 pin connector):
1. Audio Common (except stereo) 20 Audio Common (except stereo)
2. PA MIC Hi 21. Audio Common (except stereo)
3. Paging Volume 22. Audio Common (except stereo)
4. Briefer Audio Hi 23. No Connection
5. Stereo Switch 24. PA Key
6. Left Input Hi 25. Briefer Switch
7. Left Input Lo 26. No Connection
8. Right Input Lo 27. Audio Common (except stereo)
9. Right Input Hi 28. Audio Common (except stereo)
10. No Connection 29. No Connection
11. Receiver Volume Control 30. No Connection
12. No Connection 31. Smoking Sign Switch
13. TV Switch 32. Seat Belt Sign Switch
14. PSC Switch 33. Cabin Call Switch
15. ADF 2 Switch 34. Hook Switch
16. ADF 1 Switch 35. PA Sidetone Hi
17. ADF 1 Audio Hi 36. Audio Common (except stereo)
18. TV Audio Hi 37. ADF 2 Audio Hi
19. PSC Audio Hi
2.4.7 Post-Installation Checks
2.4.7.1 Voltage/Resistance Checks
Do not attach the Model 240 until the following conditions are met.
Use the pin identification information in Section 2.4.5 above and the Installation Procedures Wiring
Diagrams in the drawings section to check all the pins for the correct line voltages or continuity to ground.
2.4.7.2 Post Installation Information
The Right and Left Speaker Amplifier is designed for speech and music signals and has both a Rated and
a Continuous Power specification. The Continuous rating is the power the amplifier can continuously
deliver with a sine wave. The Rated Power specification is the peak power it can deliver without clipping.
Bench testing and adjustments may require brief periods of sine wave operation above the Continuous
rating; those periods should be limited to 1 minute to prevent amplifier damage. Power ratings are as
follows:
Load Rated Power Continuous Power
2 Ohm 20 W 2 W
4 Ohm 10 W 1 W
2.4.7.3 Power On Checks
Power up the aircraft’s systems and confirm normal operation of all functions of the Model 240.
Upon satisfactory completion of all performance checks, make all required log book entries, electrical
load, weight and balance amendments and other documentation as required by your local regulatory
agency before releasing the aircraft for service.

Model 240 Passenger Speaker Amplifier
SM240 Installation and Operation Manual
Section 2 Rev: 1.01 Issue 4 Page 2-5
ENG-FORM: 805-0121.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
2.5 Adjustments and Connections
All internal screwdriver potentiometer adjustments of the Model 240 are set to factory standards. If it is
necessary to change a setting, refer to the calibration and maintenance section of this manual.
2.6 Accessories Required But Not Supplied
Installation kit 240-IKC, consisting of p/n D25SMV-1KC (for 25-pin P40) and D37SMV-1KC (for 37-pin P50),
is required to complete the installation. The kits consist of the following:
D25SMV-IKC
Quantity Description NAT Part #
1 D-min 25 Socket housing 20-21-025
25 MS Crimp Socket 20-26-901
1 25 pin JVL Hood/Locklever 20-28-125
1 D-min Cable Clamp 20-27-189
D37SMV-IKC
Quantity Description NAT Part No
1 D-min 37 Socket Housing 20-21-037
37 MS Crimp Socket 20-26-901
1 37 Pin JVL Hood/Locklever 20-28-005
1 D-min Cable Clamp 20-27-189
2.7 Installation Drawings
DOCUMENT REV. DESCRIPTION TYPE
Installation Wiring Page 1 – Installation Wiring Diagram Block Diagram
Installation Wiring Page 2 – Installation Wiring Diagram - Continued Block Diagram
Installation Wiring Page 3 – Installation Wiring Diagram - Continued Block Diagram
240\521-0 1.01 Passenger Speaker Amplifier Environmental Qual Form
240\240 1.70 Passenger Speaker Amplifier Outline
Section 2 ends following the above documents

Page 1

Page 2

Page 3

ENVIRONMENTAL QUALIFICATION FORM
Description: Passenger Speaker Amplifier Document #: 240\521-0
NAT Part #: 240-xxx TSO #: : TSO-C50c
Manufacturer’s Specification and/or Other Applicable Specification: RTCA DO-160B
Manufacturer: Wulfsberg Electronics Division
Address: 6400 Wilkinson Drive, Prescott, AZ USA 86301
Prepared By: Checked By: Approved By:
Rev: 1.01 May 21, 2010 Page 1 of 2
ENG-FORM: 521-0102.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
CONDITIONS DO-160B SECTION/
PARAGRAPH
DESCRIPTION OF CONDUCTED TESTS
Temperature and Altitude
Low temperature
High temperature
In-flight loss of cooling
Altitude
4.0
4.5.1
4.5.3
4.5.4
4.6.1
Category F2
-55°C Operating Low Temperature
+70°C Operating High Temperature
No cooling required
+70,000 feet
Temperature Variation 5.0 Category B
Humidity 6.0 Category A
Operational Shocks and Crash Safety
Operational Shocks
Crash Safety
7.0
7.2
7.3
Operational and Crash shocks per DO-160B,
paragraphs. 7.2.1, 7.3.1, 7.3.2 and 7.3.2.2
(without shock mounts)
Vibration 8.0 Categories J, L, and O (DO-160B, Table 8-1)
without shock mounts
Explosion Proofness 9.0 Category X, no test performed
Waterproofness 10.0 Category X, no test performed
Fluids Susceptibility 11.0 Category X, no test performed
Sand and Dust 12.0 Category X, no test performed
Fungus Resistance 13.0 Category X, no test performed
Salt Spray 14.0 Category X, no test performed

240-xxx Environmental Qualification Form
Rev: 1.01 May 21, 2010 Page 2 of 2
ENG-FORM: 521-0102.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
CONDITIONS DO-160B SECTION/
PARAGRAPH
DESCRIPTION OF CONDUCTED TESTS
Magnetic Effect 15.0 Category X, no test performed
Power Input
16.0 Categories B and Z
Equipment met requirements for Emergency
Electrical System Operation per DO-160B
subparagraph 16.5.2.1 b (3)
Voltage Spike 17.0 Category A
Audio Frequency Conducted
Susceptibility 18.0 Category A
Induced Signal Susceptibility 19.0 Category A
Radio Frequency Susceptibility 20.0 Category A
Emission of Radio Frequency Energy 21.0 Category A
Lightning Induced Transient
Susceptibility 22.0 Category L
Remarks:
Model 240-xxx was qualified to the environmental test requirements of RTCA DO-160B by similarity to the
Model 218 Amplifier and the Model 207 Amplifier.
•Tests of DO-160B, Sections 4.0 (paragraphs 4.5.1 and 4.5.3), 5.0, 16.0 and 18.0 were conducted on
the Model 218 Amplifier at dB Systems, Inc. in Redmond, Washington.
•Tests of DO-160B, Sections 4.0 (paragraph 4.6.1), 7.0, 8.0, 17.0, 19.0, 20.0 and 21.0 were conducted
on the Model 218 Amplifier at Sundstrand Data Control, Inc. in Redmond, Washington.
•Tests of DO-160A, Section 6.0 were conducted on the Model 207 Amplifier at Sundstrand Data
Control, Inc. in Redmond, Washington.
•Tests of DO-160B, Section 22.0 were conducted on the Model 218 Amplifier at Beech Aircraft
Corporation in Wichita, Kansas.
End of Environmental Qualification Form

Model 240 Passenger Speaker Amplifier
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Section 3 Rev: 1.00 Issue 4 Page 3-1
ENG-FORM: 806-0112.DOT
CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.
Section 3 Operation
3.1 Introduction
Information in this section consists of functional and operational procedures for the Model 240 Passenger
Speaker Amplifier.
3.2 General Information
The Model 240 Passenger Speaker Amplifier provides Seat Belt and No Smoking sign time chimes, a
Cabin Call ringer tone, ADF, Pilot Select Com (PSC), TV, Briefer and Cabin Paging Audio to the cabin
speakers.
The Model 240 provides left/right audio taken from an external stereo receiver/music source to the cabin
speakers.
The Model 240 is a remotely controlled electronic unit, which operates upon command from switches and
potentiometers in the cockpit or cabin of the aircraft.
The 240 has no operator accessible controls. During installation, or if the unit has been exchanged, it may
be a requirement to change internal adjustments. This should be performed only by fully qualified
personnel.
Section 3 ends