Northern Airborne Technology AA20 - Manual (Page 5)

AA20 Series PA/Siren System
SM33-1 Installation and Operation Manual
Section 1 Rev: 1.00 Issue 4 Page 1-1
ENG-FORM: 800-0113.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 AA20
Series PA/Siren System. 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 AA20 PA/Siren systems are compact, self-contained systems capable of 30 W of output power.
They provide a centralized control for audio paging both inside and outside the aircraft.
The AA20 PA/Siren systems are usually used for sling load control and local external paging in smaller
airframes, or internal paging in larger airframes.
1.3 Design Features
The main functions of the AA20 include selection of audio sources for the paging audio and siren for
alerting. Microphone interfacing is accomplished from either an AA9X/AMS4X series audio controller, or a
‘carbon equivalent’ microphone. An external radio feed is provided. The internal siren is adjustable for
tone, rate and level. Provision is made for external power switching to allow PA110/220 power amplifiers
to be connected for increased power output.
All external interconnects and switches are gold plated for maximum reliability. All switches are sealed.
G10-FR flame-retardant circuit boards are post coated for maximum moisture resistance and corrosion
prevention.
1.4 Specifications
1.4.1 Electrical Specifications
Power +22 to 32 Vdc (28 Vdc nominal) at 2.2 A max. (excluding lamps),
0.25 A idle current
Lamps
2 lamps for 28 Vdc operation @ 80 mA max load
Input
2.5 Vrms at 600
Ω (Radio and PA). Impedance 1 kΩ
Output
30 Wrms max. @ 1 kHz into 8
Ω
Microphone Industry
standard ‘carbon equivalent’ amplified dynamic
microphone preferred.
Min. 200 mV output required into 150
Ω
David Clark M1/DC, or M4 recommended