Northern Airborne Technology AA24 User Manual

SM18

AA24/AA25 Series

Single User Audio Controller

INSTALLATION AND OPERATION MANUAL

REV 4.00 November 21, 2003

Northern Airborne Technology Ltd.

1925 Kirschner Road

Kelowna BC, Canada

V1Y 4N7

Telephone [phone]

Facsimile [phone]

Copyright 2003 by Northern Airborne Technology

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.

SM18 Rev 4.00 AA24/AA25 Single Series Audio Controller Manual

Performed at factory

Periodically NAT will release manual amendments. In order to maintain the most
accurate and up to date manual these amendments should be carried out immediately
upon receipt and recorded on the following amendment record.

AMENDMENT RECORD

Amendment

Number

#1 Jan 23/06 2

Amendment

Date

Section(s)

Changed

Date

Entered

Entered By

Insert any Amendment Instruction sheets after this page.

Nov 21, 2003 Page ii

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INSTALL_OPS
MANUAL AMENDMENT

Manual: SM18 (AA24/AA25) Amendment #: 1
Document # SM18\Install_Ops\809-0001 Amendment Date: Jan 23, 2006

The purpose of this amendment is to add the most recent revisions of drawings to the
manual.

Amendment Instructions:

1

2-5 Rev 4.00 2-5 Rev 4.00 Amendment # 1

2

AA24-001\405-0 Rev 1.01 AA24-001\405-0 Rev 1.02
AA25-001\405-0 Rev 1.01 AA25-001\405-0 Rev 1.02

Note: Ensure that all drawings are inserted in the order shown on the latest drawing lists.

Remove Drawings (Section 2) Replace or add Drawings (Section 2)

3 Update the Amendment Record sheet at the front of the manual.

4 Insert this page into the manual after the Amendment Record sheet (page ii).

Manual Amendment ends after the following amended pages

Remove Pages Replace With Pages

Amendment # 1 Jan 23, 2006 Page 1

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SM18 Rev 4.00 AA24/AA25 Single Series Audio Controller Manual

Table of Contents

Section Title Page

1.0 Description

1.1 Introduction 1-1

1.2 Purpose of Equipment 1-1

1.3 Features 1-1

1.4 Specifications 1-2

1.4.1 Electrical Specifications 1-2

1.4.2 Physical Specifications 1-3

1.4.2 Environmental Specifications 1-4

1.5 Unit Nomenclature 1-4

2.0 Installation

2.1 Introduction 2-1

2.2 Unpacking and Inspection 2-1

2.2.1 Warranty 2-1

2.3 Installation Procedures 2-1

2.3.1 Warnings 2-1

2.3.2 Cautions 2-2

2.3.3 Cabling and Wiring 2-2

2.3.4 Fuses and Breakers 2-2

2.3.5 Adjustments 2-2

2.3.6 Post-Installation Checks 2-3

2.4 Continued Airworthiness 2-3

2.5 Accessories Required But Not Supplied 2-4

2.6 Installation Drawings 2-5

3.0 Operation

3.1 Introduction 3-1

3.2 General 3-1

3.3 Controls and Indicators 3-1

3.3.1 Transmit selection 3-1

3.3.2 Receiver/Transceiver Selection 3-2

3.3.3 Volume Control 3-2

3.3.4 VOX Mode Control 3-2

3.3.5 Audio Alerting Functions 3-2

Nov 21, 2003 Page iii

ENG-FORM: 820-0109.DOT

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SM18 Rev. 4.00 AA24/AA25 Series Single User Audio Controller Manual

Section 1.0 Description

1.1 Introduction

This manual contains information on the AA24/AA25 Series Single User Audio Controller.
All derivatives will be covered by manual supplements which can be obtained from NAT
as required.

Information in this section consists of purpose of equipment, features and specifications.

1.2 Purpose of Equipment

The AA24/AA25 series single-user Audio Controllers support one headset per box.
Connection to other users in the system is made through the ICS Tie line. The small
size and extensive radio and ICS functions make this unit an excellent choice for multi­station aircraft.

The AA24/AA25 series systems provide full boom-mic transmit and ICS functions for the
user. The front panel controls permit user adjustment of frequently needed signals, such
as intercom audio level, VOX threshold, and individual radio receive levels. Internal
adjustments set default values for direct audio level and artificial side tone.

1.3 Features

The AA24/AA25 series systems employ NAT's unique audio processing which reduces
noise and tailors the frequency response to produce clean, crisp intercom audio.
Having high output power and low distortion results in better on-board communication.

Inputs are fully floating and include a dedicated alerting input. The tie line of the
AA24/AA25 series is fully compatible with other NAT systems including AA80, AA82,
AMS40 and AA95 series units. By keeping ‘ICS TIE LINE’ characteristics fully
compatible with existing NAT products, it is possible to chain multiple systems together
to a maximum of 4 units. The AA24/AA25 series have over-voltage and reverse-voltage
protection, to ensure operability in severe aircraft environments. A front panel
annunciator allows easy visual setting of the ‘VOX’ threshold, and also indicates
transmit operation. In addition to all common features the AA25 also provides
independent radio volume adjustment of up to 6 sources.

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AA24/AA25 Series Single User Audio Controller Manual SM18 Rev. 4.00

1.4 Specifications

1.4.1 Electrical Specifications

Power supply

Voltage 28 Vdc (reverse and over voltage protection)

Current 400 ma. max.

Lighting 28 Vdc @ 160 mA.

Headset Power Phone output is nominal 600 Ω load
Short circuit protected
Typical 200 mW into headset
David Clark H10-30/40 series recommended

Microphone Industry standard ‘carbon equivalent’ type
250 mVrms for full output

Amplified dynamic microphone preferred

David Clark M1/DC, M3, M4 recommended

(For low Z microphones, AA24-801 or AA25­801 are recommended)

Indicators Transmit (green LED)
VOX ICS triggered by ICS Tie Line (red LED)

Input Signals:

4 aircraft transceiver radio inputs
5 navigational receiver inputs

2.5 V rms for full output

4.7 kΩ input impedance

1 bi-directional ICS tie line
1 Vpp for full output

2.2 kΩ input impedance

Keylines Transmit key is active low (33 ma. of current)
Intercom key is active low (1 ma. of current)

Intercom line NAT ICS tie line compatible 2k input impedance
(340 mVrms level)

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SM18 Rev. 4.00 AA24/AA25 Series Single User Audio Controller Manual

Output signals:

Transmitter audio lines Non-adjustable, microphone connected directly

to radio. (mic bias supplied by radio)

Transmitter key lines Hard ground output (relay contacts 1 amp.

max.)

Green L.E.D. annunciator

Intercom line 340 mVrms into 2 k ohms
(freq. response +/- 6 db from 250 to 4000 Hz)

Headset output 200 mW max. into 600 ohms (floating output)
300 mW max. into 150 ohms

Receive channel freq. response +/- 6 dB from 300 to 5000 Hz

Intercom channel freq. response +/- 6 dB from 500 to 3100 Hz

Sidetone channel freq. response +/- 6 db from 225 to 5000 Hz

Direct input freq. response +/- 6 db from 275 to 3100 Hz

Distortion <2% THD

Isolation /crosstalk >60 db min.

Signal/noise ratio 70 db min.

1.4.2 Physical Specifications

AA24 AA25

Height 1.49" 37.8 mm 2.62" 66.7 mm

Depth (max.) 7.55" 191.8 mm 7.44" 188.8 mm

Depth behind panel 5.84" 148.3 mm 5.83" 148.0 mm

Width (max.) 5.75" 146.0 mm 5.75" 146.0 mm

Width behind panel 4.9" 124.5 mm 4.9" 124.5 mm

Weight 1.2 lbs 500 g 1.5 lbs 680 g

Mounting standard Dzus rails standard Dzus rails

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AA24/AA25 Series Single User Audio Controller Manual SM18 Rev. 4.00

1.4.3 Environmental Specifications

Operating Temperature -40° C to +70° C

Storage Temperature -55° C to +85° C

Altitude 25,000 ft. max.

Humidity 95 % Non-Condensing

Vibration DO-160B category P, panel mounting 6g.

Shock 12 g. (any axis)

1.5 Unit Nomenclature

Model Description / Distinction

AA24-001 COM1, COM2, COM3, COM4 + PA
NAV, ADF, DME, MKR, & AUX receive switches
+28 Vdc lights and +28 Vdc power
high impedance headset and mic

ICS, RX volume and VOX sq. controls

AA25-001 COM1, COM2, COM3, COM4 + PA
NAV, ADF, DME, MKR, & AUX receive switches
COM1 - 4, NAV & ADF level controls
+28 Vdc lights and +28 Vdc power
high impedance headset and mic

ICS, RX volume and VOX sq. controls

End of section 1.0

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SM18 Rev. 4.00 AA24/AA25 Series Single User Audio Controller Manual

Section 2.0 Installation

2.1 Introduction

Information in this section consists of: unpacking and inspection procedures, installation
procedures, post-installation checks, and installation drawings.

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. Note that each unit should have the following:

- AA24-001 or AA25-001 Audio Controller

- Warranty Card

- Operator’s Manual

- Release certification

Verify that all items are present before proceeding and report any shortage immediately
to your supplier.

2.2.1 Warranty

Complete the warranty card information and send it to NAT when the installation is
complete. If you fail to complete the warranty card, the warranty will be activated on
date of shipment from NAT.

Note: An appropriately rated facility, e.g. Certified Aircraft Repair Station, must install

this equipment in accordance with applicable regulations. NAT Ltd’s warranty is
not valid unless the equipment is installed by an authorized NAT Dealer. Failure
to follow any of the installation instructions, or installation by a non-certified
individual or agency will void the warranty, and may result in a non-airworthy
installation.

2.3 Installation Procedures

2.3.1 Warnings

Do not bundle any lines from this unit with transmitter coax lines. Do not bundle any
logic, audio, or DC power lines from this unit with 400 Hz synchro wiring or AC power
lines. Do not position this unit next to any device with a strong alternating magnetic field
such as an inverter, motor or blower, or significant interference to operation will result.

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AA24/AA25 Series Single User Audio Controller Manual SM18 Rev. 4.00

2.3.2 Cautions

In all installations, use shielded cable exactly as shown and ground as indicated. Significant
ground loop and noise problems may result from not following these guidelines.

Do not ground the microphone or headphone jacks.

Do not connect the microphone and headphone shields together.

Use caution when routing microphone and ICS Tie Line wiring, as they are low level
signals prone to coupling from other sources.

Do not take a ground from the instrument panel or similar location that shares a ground
return with a turn and bank, horizon or other motor driven instrument. This may cause
the InterVox unit to pick up the sound of the motor as ground loop interference.

For best results, all headsets/microphones in the system should be of the same type to
avoid VOX problems and uneven volume.

2.3.3 Cabling and Wiring

All unshielded wire should be Tefzel MIL-M-22759/16 or equivalent. For shielded wire
applications, use Tefzel MIL-M-27500 shielded wire with solder sleeves (for shield
terminations) to make the most compact and easily terminated interconnect. Follow the
wiring diagrams in Section 2.6 as required.

Allow 3 inches from the end of the wire to the shield termination to allow the hood to be
easily installed. Note that the hood is a ‘clamshell’ hood, and is installed after the wiring
is complete.

All wiring should be at least 22 AWG, except power and ground lines which should be at
least 20 AWG. Ensure that all ground connections are clean and well secured.

2.3.4 Fuses and Breakers

Power protection should be provided through a 1.0 A breaker, and not attached to any
other existing breaker without additional protection.

2.3.5 Adjustments

See 3D drawing AA24\001\903-0 at the end of this section of the manual for the
adjustment locations.

The unit ships from the factory with all internal adjustments set to the normal test levels.
Once installed in the aircraft, it may be desirable to change some of these settings to
best suit the local operating environment.

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SM18 Rev. 4.00 AA24/AA25 Series Single User Audio Controller Manual

The Direct Audio level (DIR AUD LEVEL) and sidetone level (S/T LEVEL) can be
adjusted at the time of installation. The adjustment pots are accessed through holes in
the upper cover, and can be rotated clockwise to increase the level, and
counterclockwise to decrease it.

2.3.6 Post-Installation Checks

2.3.6.1 Voltage/resistance checks

Do not attach the AA24 or AA25 until the following conditions are met.

Check the following:

a) Check J101, pin <1> for +28 Vdc relative to ground.

b) Check J101, pin <9> for continuity to ground (less than 0.5 Ω).

2.3.6.2 Power On checks

Install the AA24 or AA25 and power up the ship’s systems. Verify normal operation of
all functions. Refer to Section 3 for specific operation details.

a) Run through all installed functions, and check the ICS and TX functions for all users.

b) Different headsets models may have significantly different mic characteristics,

which will affect ‘VOX’ squelch settings. The David Clark M-7 mic is much more
active than the M-4 or M-1 mics, and may aggravate headset imbalance if used
in a mixed system.

Note: Unusual buzzes, hums or other background audio are symptomatic of

multiple grounds, or noisy external systems such as blowers or pumps
sharing wiring with the audio system. Failure to key or correctly modulate
a transmitter is often the result of forgetting to connect all required
grounds to the radio or external audio system.

c) To verify proper operation, all functions and levels should be checked in-flight.

If the unit functions satisfactory, make the required log entries and complete the
required MOT/FAA paperwork, before releasing the aircraft for service.

2.4 Continued Airworthiness

Maintenance of the AA24-001 or AA25-001 Single User Audio Controller is ‘on
condition’ only. Periodic maintenance of this product is not required.

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AA24/AA25 Series Single User Audio Controller Manual SM18 Rev. 4.00

2.5 Accessories Required But Not Supplied

Both the AA24 and the AA25 Series Audio Controllers require Installation kit p/n AA24-IKC
(crimp) or AA24-IKS (solder) to complete the installation. They consist of the following:

AA24-IKC 37-pin and 15-pin D-min Female Crimp Kit (NAT Part No. D37S15SL-IKC)

Quantity Description NAT Part #

1 D-min 37 Socket Housing 20-21-037
37 MS Crimp Socket 20-26-901
1* Jack Screw Set 20-27-002
1* Lock Clip Set 20-27-004
1 37 Pin Connector Hood 20-29-038
1 D-min 15 Socket Housing 20-21-015
15 MS Crimp Socket 20-26-901
1* Jack Screw Set 20-27-002
1* Lock Clip Set 20-27-004
1 15 Pin Connector Hood 20-29-015

* Use as required.

AA24-IKS 37-pin and 15-pin D-min Female solder Kit (NAT Part No. D37S15SL-IKS)

Quantity Description NAT Part #

1 D-min 37 Socket Solder Cup 20-20-037
1* Jack Screw Set 20-27-002
1* Lock Clip Set 20-27-004
1 37 Pin Connector Hood 20-29-038
1 D-min 15 Socket Solder Cup 20-20-015
1* Jack Screw Set 20-27-002
1* Lock Clip Set 20-27-004
1 15 Pin Connector Hood 20-29-015

* Use as required.

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SM18 Rev. 4.00 AA24/AA25 Series Single User Audio Controller Manual

2.6 Installation Drawings

DRAWING REV. DESCRIPTION TYPE SERIAL #

AA24-001

AA24-001\40324001 - Single User Audio Controller Interconnect 1005 – 1127

AA24-001\403-0 1.01 Single User Audio Controller Interconnect 1128 and up

AA24-001\405-0 1.02 Single User Audio Controller Connector Map All

AA24-001\90324001 - Single User Audio Controller Mechanical 1005 – 1127

AA24-001\903-0 1.01 Single User Audio Controller 3-D 1128 and up

AA24-001\905-0 1.02 Single User Audio Controller (1 of 2) Faceplate All

AA24-001\922-0 1.01 Single User Audio Controller Mech. Installation All

AA25-001

AA25-001\403-0 1.00 Single User Audio Controller Interconnect 1001 – 1056

AA25-001\403-0 1.10 Single User Audio Controller Interconnect 1057 and up

AA25-001\405-0 1.02 Single User Audio Controller Connector Map All

AA25-001\905-0 1.01 Single User Audio Controller (1 of 2) Faceplate All

AA25-001\922-0 1.01 Single User Audio Controller Mech. Installation All

Section 2.0 ends after these Drawings

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Confidential and Proprietary to NAT

Confidential and Proprietary to NAT

Confidential and Proprietary to NAT

Confidential and Proprietary to NAT

SM18 Rev 4.00 AA24/AA25 Series Single User Audio Controller Manual

t

Section 3.0 Operation

3.1 Introduction

Information in this section consists of the functional and operational procedures for the
AA24/AA25 Series Single User Audio Controller.

3.2 General

The AA24/AA25 series single user audio controllers allow selection of transmit and
receive audio, and LIVE, VOX or PTT intercom. One direct alerting input is provided to
allow emergency alerting audio to pass unmuted to the user's headset. After
transmitting on the radios the user's microphone automatically reverts back to intercom
mode. The AA25 audio controller also provides central volume adjustment for all the
aircraft audio.

3.3 Controls and Indicators

TX Annunciator LED

Transmi

Selection

Control

RX Volume

Controls

RX/TX Select Switches

VOX Control

RX and ICS
Volume Control

3.3.1 Transmit selection

The rotary selector switch at the lower left of the panel selects the desired transmit
function. When the radio PTT switch is activated, the microphone will be coupled to the
radio or PA channel selected. Receive audio is automatically selected with the transmit
selection, and no additional switching is needed to establish outside communication.

During transmission, the TX annunciator LED on the front panel will illuminate green.

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AA24/AA25 Series Single User Audio Controller Manual SM18 Rev 4.00

3.3.2 Receiver/Transceiver Selection

The Receiver/Transceiver audio is selected from a double row of color-coded toggle
switches. Receiver switch bats are blue, and transceiver switch bats are white. To
connect the desired radio to the headphones, the relevant switch is toggled upwards.

On the AA25, independent volume controls are provided for the transceivers and the
first two NAV aids.

3.3.3 Volume Control

The Volume control is a dual concentric knob.

3.3.3.1 ICS Volume Control

The inner knob of the dual control is ICS VOL and controls the intercom volume for all
headsets. An internal trimpot sets the minimum level. With ICS VOL set fully ccw
intercom volume will be at a minimum. As the operator rotates the control cw, intercom
volume will increase.

In multiple station systems, the ICS volume adjusts only the local ICS audio level.

3.3.3.2 RX Volume Control

The outer knob of the dual control is RX VOL and controls the RX volume for all
selected radios. With RX VOL fully ccw, volume will be at a minimum. As the operator
rotates the control cw, volume will increase.

3.3.4 VOX Mode Control

The VOX Control selects the mode of operation of the intercom mic. When the control
is in the centre of its range, the intercom is in the VOX mode (voice activated). As the
control is rotated counterclockwise, the system becomes more sensitive, until in the fully
counterclockwise position it is in LIVE mode (on constantly). As the control is rotated
clockwise, the sensitivity decreases, until at the fully clockwise position it is in PTT
mode (activated by cyclic or foot switch closure).

3.3.5 Audio Alerting Functions

The user receives audio alerting signals connected to the Direct Audio under all
operating conditions of the AA24/AA25.

End of Section 3.0

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