M/A-Com 19D902797G5 Maintenance Manual
Maintenance Manual
LBI-39127H
851-870 MHz, 110 WATT POWER AMPLIFIER
19D902797G5, Revision A only
TABLE OF CONTENTS
Page
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front Page
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
POWER AMPLIFIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Small Signal Gain Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Driver Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Final Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Power Sense and Isolation Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
POWER CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Signal Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
POWER AMPLIFIER READINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
IC DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
ASSEMBLY DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
OUTLINE DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
ASSEMBLY DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Back Cover
PRODUCTION CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Back Cover
SYMBOL
PART NO.
DESCRIPTION
4
SBS 123 01/10
Spring nut.
5
19A702339P510
Screw, thread forming,
flat head.
6
19A701312P5
Washer, plain steel, 3.5
mm.
7
19A702381P510
Screw, thread forming,
pan head.
9
19A700136P19
Sleeve
10
105 8567/1
Guard, fan.
11
19A701863P12
Clamp, loop.
13
19A700033P6
Washer, lock, ext tooth.
14
19A700034P5
Nut, hex, steel.
B1
and
B2
BKV 301 216/02
DC fan.
W1
344A3337P4
Cable.
WT1
and
WT2
7142645P1
Conductor, splice.
PRODUCTION CHANGES
Changes in the equipment to improve or to simplify circuits are identi-
fied by a "Revision Letter", which is stamped after the model number
of the unit. The revision stamped on the unit includes all previous
revisions. Refer to the Parts List for descriptions of parts affected by
these revisions.
REV. A - POWER AMPLIFIER 19D902797G5
Incorporated into production radios.
PA FAN PLATE ASSEMBLY
188D6127G1
DESCRIPTION
The 800 MHz MASTR III Power Amplifier Assem-bly is
a wide band RF power amplifier operating over the 851-870
MHz range without tuning. Its main function is to amplify the
10mW FM signal from the Transmitter Synthesizer to the
rated RF output at the antenna port. The output of the Power
Amplifier Assembly is adjust-able from rated power to 10dB
below rated power at the PA output J104.
The assembly consists of a printed wiring board (A1) and
associated components, including a power module and an RF
power transistor, mounted to the heat sink assembly. The
printed wiring board (A1) contains both the power amplifier
circuitry and the power control cir-cuitry. The heatsink as-
sembly includes a copper heat spreader for the power transis-
tor.
Unfiltered supply voltage, A+, for the power ampli-fier
circuits enters the assembly via feedthrough capaci-tor, C1.
Power cable W4 routes the A+ from C1 to J103 on the PWB.
Filtered A+ voltage for the power control circuit enters the
assembly via control cable W13 which connects to the PWB
at J201.
M/A-COM Wireless Systems
3315 Old Forest Road
Lynchburg, Virginia 24501
(Outside USA, 434-385-2400) Toll Free 800-528-7711
www.macom-wireless.com
Printed in U.S.A.