Nat LD08, Installation And Operation Manual

SM15 Rev. 4.00 

LD08 Lamp Dimmer Manual 

Nov 21, 2003 

Page 1-1 

ENG-FORM: 800-0106.DOT 
 

CONFIDENTIAL AND PROPRIETARY TO NORTHERN AIRBORNE TECHNOLOGY LTD.

Section 1.0 Description 

1.1 Introduction 

This manual contains information on the LD08 Lamp Dimmer.  
  
Information in this section consists of purpose of equipment, features and specifications.  

1.2 

Purpose of Equipment 

The LD08 is a bulkhead mounted dimming and lamp test unit, specifically designed to 
handle the complex annunciator requirements of LORAN C/GPS systems sharing an 
existing NAV system indicator.   
 
The correct dimming and lamp test interface is provided for the RS08/PB08 
combination, as well as six (6) additional discrete annunciators.  This permits simple 
integration of systems such as the Bendix/King Loran or Trimble GPS/Loran with the 
nav switching functions of the RS08.  It also provides central annunciation dimming 
(day/night) selection and a central lamp test function, all on a single panel mounted 
toggle switch.  Optional interconnect permits adjustment of the annunciator dimming 
with an external 10 k

Ω 

potentiometer. 

1.3  

Features 

Internal logic is provided to interface both the floating lamp connections of the PB08, 
and annunciators triggered by a ground output.  An adjustable lamp dimmer is provided 
to drive eight separate 28 Vdc/40 mA lamp lines, each with individual short circuit 
protection, surge limiting, and lamp test logic. 
 
The dimmer may be operated in the preset mode (typically set in the 8-19 V range), or 
as an adjustable dimmer via an external control.  A single switch can be used to select 
day, night, and lamp test functions.  
 
The day operation mode also provides regulated 24 Vdc for all lamps, to prevent early 
lamp failure and internal lamp blackening from excessive voltage. 
 
All interconnect and relay contacts are gold plated.  Relays are sealed, high vibration 
rated (50 g shock), dry nitrogen filled units. 
 
Circuit boards are constructed of G10-FR (flame retardant) material, with solder masks, 
reflowed tin plating, and environmental post-coating.