Northern Airborne Technology RA User Manual

Installation and Operation Manual

RA Series

Remote Attenuator

SM30

ISSUE 4.01

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 2003

RA Series Remote Attenuator

SM30 Installation and Operation Manual

Prepared By: Checked By: 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

4.00 N/A N/A Nov 19, 2003

Section

Revision Number

Revision Description Issue Date

4.01 Section 1 Rev #: 1.00
Section 2 Rev #: 1.00

Revised manual using latest
templates.

Aug 6, 2008

Section 3 Rev #: 1.00

Installation and Operation Manual Page ii

ENG-FORM: 820-0114.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIR BORNE TECHNOLOGY LTD.

RA Series Remote Attenuator

SM30 Installation and Operation Manual

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 1-2

1.4.1 Electrical Specifications 1-2

1.4.2 RF Signal Specifications 1-2

1.4.3 Physical Specifications 1-2

1.4.4 Environmental Specifications 1-2

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 Cabling and Wiring 2-1

2.4.2 Post-Installation Checks 2-2

2.5 Adjustments and Connections 2-2

2.6 Accessories Required But Not Supplied 2-3

2.7 Installation Drawings 2-3

3. Operation

3.1 Introduction 3-1

3.2 General Information 3-1

3.3 Controls and Indicators 3-1

3.4 Optional Features 3-1

3.5 Emergency Operation 3-1

Installation and Operation Manual Page iii

ENG-FORM: 820-0114.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIR BORNE TECHNOLOGY LTD.

RA Series Remote Attenuator

SM30 Installation and Operation Manual

Section 1 Description

1.1 Introduction

Information in this section consists of product description, design features and specifications for the RA
Series Remote Attenuator. 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 RA-series of remote attenuators reduce the RF transmit power from a transceiver under logic control
from a Tac/Com control head or a switch. The attenuator may also be enabled and perform the same
function during receive operations. The attenuator is normally enabled when the control line is unactuated
(not grounded). A ground (<1 Vdc) on the control line will bypass the attenuator and allow RF to pass at
full power. When enabled, the remote attenuator will reduce the incoming signal by a factor of 10
(RA10-xxx) to 1000 (RA30-xxx). There is a remote attenuator model that can handle up to 1 W
continuous power (RAxx-001) and another model that can handle up to 20 W continuous (RAxx-020).

The RA series Remote Attenuators are bulkhead mounted units specifically designed to allow attenuation
of aircraft radio transmissions. This is desirable under some conditions where the radio exceeds output
power limits of altitude. If the radios were simply adjusted to output the lower level, they may become
unstable and difficult to control tightly to the output tolerances. By installing a RA series Remote
Attenuator, radio operation is not impaired and the required output power is achieved.

RA units also normally attenuate the receive signals to reduce some channel interference from nearby
stations when at altitude.

1.3 Design Features

RA series Remote Attenuators are easy to install with an uncomplicated interconnect.
They are powered from a +28 Vdc aircraft supply and available in a variety of configurations.
A ground seeking keying circuit enables RF signals to pass eithe r attenuated or unattenuated.
All interconnect and relay contacts are gold plated. The relays are sealed, high vibration rated (50g

shock), dry nitrogen filled.
The circuit boards are constructed of G10-FR (flame retardant) material, with solder masks ref lowed tin

plating and environmentally post-coated.

Section 1 Rev: 1.00 Issue 4 Page 1-1

ENG-FORM: 800-0114.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIR BORNE TECHNOLOGY LTD.

RA Series Remote Attenuator

SM30 Installation and Operation Manual

1.4 Specifications

1.4.1 Electrical Specifications

Input Power +20 to +33 Vdc at 160 mA max.
Case is internally grounded

Logic Ground seeking input for keyline capable of sinking 5 mA.

1.4.2 RF Signal Specifications

Frequency DC to 600 Mhz.
Insertion Loss 0.5 dB typical.
Attenuation

Keyed Less than 0.3 dB.
Unkeyed 10 – 30 dB nominal.

RF Power Input

-001 1 Watt continuous max.

-020 20 Watts continuous max.

1.4.3 Physical Specifications

RA10-001/RA30-001

Height 1.60" (41.0 mm) 1.60" (41.0 mm)
Length 4.60" (117.0 mm) 9.50" (241.0 mm)
Width 2.50" (64.0 mm) 2.50" (64.0 mm)
Weight 7.0 ounce s (210.0 g) 19.0 ounces (530.0 g)
Mounting Bulkhead Bulkhead

1.4.4 Environmental Specifications

Temperature -40 to +70° C
Altitude 16,500 feet max.
Humidity 95% Non-condensing
Shock 12g (any axis)
Vibration Conforms to DO-160B category ‘P’

RA10-020

Section 1 Rev: 1.00 Issue 4 Page 1-2

ENG-FORM: 800-0114.DOT

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIR BORNE TECHNOLOGY LTD.