Maintenance Manual
LBI-38674L
450-470 MHz,
110 WATT POWER AMPLIFIER
19D902797G3
403-425 MHz,
90 WATT POWER AMPLIFIER
19D902797G6
425-450 MHz,
90 WATT POWER AMPLIFIER
19D902797G7
380-400 MHz,
75 WATT POWER AMPLIFIER
19D902797G8
470-494 MHz,
90 WATT POWER AMPLIFIER
19D902797G9
492-512 MHz,
90 WATT POWER AMPLIFIER
19D902797G10
410-430 MHz,
90 WATT POWER AMPLIFIER
19D902797G11
TABLE OF CONTENTS
Section
Page
1.0 SPECIFICATIONS...................................................................................................................................................3
2.0 DESCRIPTION ........................................................................................................................................................4
3.0 CIRCUIT
ANALYSIS..............................................................................................................................................5
3.1 POWER
AMPLIFIER ..........................................................................................................................................5
3.1.1 Exciter
(U7) ..................................................................................................................................................5
3.1.2 Small
Signal Gain Stage ...............................................................................................................................5
3.1.3
Low Level Amplifier (U1)............................................................................................................................5
3.1.4 Driver
(Q1) ...................................................................................................................................................5
3.1.5
Power Amplifier Finals (Q2 & Q3) ..............................................................................................................6
3.1.6 Low
Pass Filter .............................................................................................................................................6
3.2 POWER
CONTROL ............................................................................................................................................7
3.2.1 Keying
and
Unkeying the PA .......................................................................................................................7
3.2.2 PA
Output Power Set....................................................................................................................................7
3.2.3 PA
Protection................................................................................................................................................7
3.2.4 Theory
of
Operation......................................................................................................................................7
3.2.5 Signal
Interface.............................................................................................................................................8
4.0 TROUBLESHOOTING .........................................................................................................................................10
4.1 TROUBLESHOOTING
GUIDE ........................................................................................................................10
4.2
LOW PASS FILTER TEST PROCEDURE .......................................................................................................13
4.2.1 Recommemded
Test
Equipment .................................................................................................................13
4.2.2 Test
Set-Up and Procedure .........................................................................................................................13
5.0 PARTS
LIST ..........................................................................................................................................................14
6.0 PRODUCTION
CHANGES...................................................................................................................................23
7.0 IC
DATA ................................................................................................................................................................26
8.0 ASSEMBLY
DIAGRAMS.....................................................................................................................................29
8.1
POWER AMPLIFIER 19D902797G3 & G6 THROUGH G11..........................................................................29
8.2 COVER
ASSEMBLY 19B801659G3 ................................................................................................................30
9.0
ASSEMBLY, OUTLINE & SCHEMATIC DIAGRAMS FOR LOW PASS FILTER MODULE 19D902856G331
10.0 OUTLINE
DIAGRAM...........................................................................................................................................32
10.1 POWER AMPLIFIER BOARD A1 19D902856G3, G6, G7, G8, G9, G10 & G11...........................................32
11.0 SCHEMATIC DIAGRAM .....................................................................................................................................33
11.1 POWER AMPLIFIER ASSEMBLY 19D902 797G3 & G6 THROUGH G11 ..................................................33
12.0 OUTLINE & SCHEMATIC DIAGRAM FOR 470-512 MHz LOW PASS FILTER MODULE 19D902856G9 .34
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