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MAINTENANCE MANUAL
136-174 MHz, 110 WATT POWER AMPLIFIER
19D902797G1
TABLE OF CONTENTS
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front Cover
SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
POWER AMPLIFIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Exciter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Low Level Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
PA Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Drive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Power Amplifier Finals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
POWER CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Signal Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
TROUBLESHOOTING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
IC DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
LOW PASS FILTER MODULE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
OUTLINE DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
POWER AMPLIFIER ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
POWER AMPLIFIER SCHEMATIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
DESCRIPTION
The VHF Power Amplifier Assembly is a wide band RF
power amplifier operating over the entire 136 to 174 MHz
range without tuning or band splitting. Its main function is
to amplify the 10 mW FM signal from the Transmitter
Synthesizer to the rated RF output of 110 watts at the antenna
port. The output of the Power Amplifier Assembly is adjust-
able from 65 to 135 watts at the PA output J104. This
corresponds to a rated RF output of 55 to 110 watts at the
antenna.
The assembly consists of a printed wiring board (A1)
and associated components, including a power module and
three RF power transistors, mounted to the heat sink assem-
bly. The printed wiring board (A1) contains both the power
LBI-38531A
Page
amplifier circuitry (100 series components) and the power
control circuitry (200 series components).
Unfiltered supply voltage, A+, for the power amplifier
circuits enters the assembly via feedthrough capacitor, C1.
Power cable W4 routes the A+ from CI 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.
The Power Control circuitry sets the output power level
by adjusting the PA Power Set level. It keeps the output
power constant despite variations in input power, power
amplifier gain, or temperature through the use of a feedback
control loop in the PA assembly.
Printed in U.S.A.
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Summary of Contents for Ericsson 19D902797G1
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Page 1: Table Of Contents
LBI-38531A MAINTENANCE MANUAL 136-174 MHz, 110 WATT POWER AMPLIFIER 19D902797G1 TABLE OF CONTENTS Page DESCRIPTION ..........Front Cover SPECIFICATIONS . -
Page 2: Specifications
Power The MMIC requires a 5 volt supply source. The 8 volt Amplifier Finals, Q102 and Q103. regulator (U100) provides the 5 volts to the MMIC via a dropping resistor R103. Copyright© February 1992, Ericsson GE Mobile Communications Inc. -
Page 3: Power Amplifier Finals
LBI-38531 drop to zero (0) volts and the PA alarm light on the station power (zero watts) corresponds to 2.5 volts while maximum Power Amplifier Finals (Q102, Q103) will turn on. power corresponds to 4.5 volts. This voltage is not temperature compensated and no effort is made to calibrate this signal to an Each of the Power Amplifier Final devices is capable of absolute power level. -
Page 4: Troubleshooting Guide
LBI-38531 VHF POWER AMPLIFIER VOLTAGE CHART TROUBLESHOOTING GUIDE PARAMETER REFERENCE READINGS SYMBOL (volts DC) (50 OHM, -30° TO +60° C) SYMPTOM AREAS TO CHECK INDICATIONS 13.4 V ±20% SUPPLY VOLTAGE 1. No Power or low Power at 1. Measure the transmitter output power The presence of power at this port is an Antenna Port before the duplexer or antenna switch... -
Page 5: Ic Data
IC DATA PARTS LIST LBI-38531 U100 19A705532P2 VOLTAGE REGULATOR U101 344A3221P1 MMIC AMPLIFIER U102 19A70532P1 PA AMPLIFIER MODULE... - Page 6 PARTS LIST LBI-38531...
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Page 7: Low Pass Filter Module
ASSEMBLY & SCHEMATIC DIAGRAM LBI-38531 LOW PASS FILTER MODULE 19D902856G1 (19D902856 Sh. 1, Rev. 0) (19D902855, Sh. 1, Rev. 1) -
Page 8: Outline Diagrams
OUTLINE DIAGRAMS LBI-38531 POWER AMPLIFIED BOARD A1 LOW PASS FILTER MODULE 19D902794G1 19D902856G1 (19D902794, Sh.1, Rev. 3) (19D902853, Sh.1, Rev. 2) (19D902793, Comp. Side, Rev. 4) (19D902854, Comp. Side, Rev. 9) -
Page 9: Power Amplifier Assembly
ASSEMBLY DIAGRAM LBI-38531 (19B801659, Sh. 2, Rev. 3) POWER AMPLIFIER ASSEMBLY POWER AMPLIFIER ASSEMBLY 19D902797G1 19D902797G1 (19D902797, Sh. 1, Rev. 6) (19D902797, Sh. 2, Rev. 6) -
Page 10: Power Amplifier Schematic
SCHEMATIC DIAGRAM LBI-38531 POWER AMPLIFIER ASSEMBLY 19D902797G1 (19D902798, Sh. 1, Rev. 3)
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