Maintenance Manual

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Maintenance Manual

LBI-38640G

VHF TRANSMITTER SYNTHESIZER MODULE

19D902780G1

TABLE OF CONTENTS

Page

DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front Cover

GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

VOLTAGE CONTROLLED OSCILLATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

RF AMPLIFIERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

REFERENCE BUFFER AMPLIFIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

PRESCALER AND SYNTHESIZER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

LOOP BUFFER AMPLIFIERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

AUDIO FREQUENCY AMPLIFIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

VOLTAGE REGULATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

LOGIC CIRCUITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

TEST PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

ALIGNMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

OUTLINE DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

ASSEMBLY DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

PRODUCTION CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

IC DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

DESCRIPTION

The principle function of the Transmitter Synthesizer

Module is to provide the RF excitation for input to the

MASTR III station power amplifier. The output of the syn-

thesizer is a frequency modulated signal at the desired fre-

quency. The module contains the following functional

blocks:

•

A voltage controlled oscillator.

•

A chain of integrated circuit RF Amplifiers.

•

A reference buffer amplifier.

•

Dual modulus prescaler and synthesizer integrated

circuits.

•

Loop amplifiers and passive loop filter.

•

An audio amplifier and a pre-modulation integrator.

•

IC voltage regulators for +5 and -5 Vdc. A discrete

component regulator for +8 Vdc, and an Opera-

tional Amplifier regulator for +4 Vdc.

•

Logic circuitry: address decoder, input signal gates,

and a lock indicator circuit.

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Summary of content (12 pages)

PAGE 1
Maintenance Manual LBI-38640G VHF TRANSMITTER SYNTHESIZER MODULE 19D902780G1 TABLE OF CONTENTS DESCRIPTION . . . . . . . . . . . . . . . . . . . . . GENERAL SPECIFICATIONS . . . . . . . . . . . . BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . VOLTAGE CONTROLLED OSCILLATOR RF AMPLIFIERS . . . . . . . . . . . . . . REFERENCE BUFFER AMPLIFIER . . . PRESCALER AND SYNTHESIZER . . . . LOOP BUFFER AMPLIFIERS . . . . . . . AUDIO FREQUENCY AMPLIFIER . . . .
PAGE 2
LBI-38640G Table 1 - General Specifications ITEM SPECIFICATION FREQUENCY RANGE in 4 bands 136 to 174 MHz 136 to 144 MHz 142 to 152 MHz 150 to 162 MHz 160 to 174MHz RF POWER OUT(50 Ohm load) 10 to 13 dBm (10 to 20 mW) RF HARMONICS <-30 dBc NON-HARMONIC SPURS 1 to 200 MHz 200 MHz to 1 GHz <-90 dBc <-60 dBc CARRIER ATTACK TIME <50 ms REFERENCE INPUT input level input impedance frequency 0 dBm ±1.5dB 50 Ohm 5 to 17.
PAGE 3
LBI-38640G The other output of the resistive splitter drives U202. U202 is a buffer amplifier with a gain of about 10 dB. U202 drives the synthesizer prescaler (i.e. it provides a signal to the PLL). REFERENCE BUFFER AMPLIFIER Transistor Q401 and associated components comprise a buffer amplifier for the reference oscillator signal. (The reference oscillator signal is produced by the receiver synthesizer module of a MASTR III station.
PAGE 4
LBI-38640G c. Open switches SW1A and SW1C and close switches SW1B and SW1D. SERVICE NOTES The following service information applies when aligning, testing, or troubleshooting the TX Synthesizer: d. Program synthesizer at 147 MHz. Verify LED is off. • Standard Modulating Signal = 1 kHz sinusoidal voltage, 1.0 Vrms at the module input terminals (600 ohm Rin). e. Close switches SW1A, SW1B, SW1C and SW1D. • The input audio level for setting the 4.5 kHz or 10 Hz (or 7 Hz) deviation should always be 1.
PAGE 5
OUTLINE DIAGRAM LBI-38640G Figure 2 - Test Point Locations VHF TRANSMITTER SYNTHESIZER BOARD 19D902779G1 (19D902779, Sh. 1, Rev.
PAGE 6
ASSEMBLY DIAGRAM LBI-38640G VHF TRANSMITTER SYNTHESIZER MODULE 19D902780G1 (19D902780, Sh. 1, Rev.
PAGE 7
LBI-38640G VHF TRANSMITTER SYNTHESIZER 19D902780G1 (19D902622 Sh. 1, Rev.
PAGE 8
SCHEMATIC DIAGRAM LBI-38640G VHF TRANSMITTER SYNTHESIZER 19D902780G1 (19D902622, Sh. 2,Rev.
PAGE 9
LBI-38640G VHF TRANSMITTER SYNTHESIZER 19D902780G1 (19D902622, Sh. 3, Rev.
PAGE 10
PARTS LIST LBI-38640G 9
PAGE 11
LBI-38640G PARTS LIST & PRODUCTION CHANGES PRODUCTION CHANGES Changes to the equipment to improve performance or to simplify circuits are identified 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 partls List for the descriptions of parts affected by this revision. Rev.
PAGE 12
IC DATA U201 & U203 19A705927P11 Silicon Bipolar MMIC U301 19A704971P9 +5V Regulator U402 19B800902P5/P7 Synthesizer LBI-38640G U701 & U705 19A703483P302 Quad 2-Input NAND Gate U702 19A703471P320 Address Decoder U302 & U601 19A116297P7 Dual Wide Band Op-Amp U303 19A704971P7 -5V Regulator U501 344A3070P1 Operational Amplifier U401 19A149944P201 Dual Modulus Prescaler U502 19A702705P4 Quad Analog Switch 11