Maintenance Manual

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Maintenance Manual

LBI-38641F

VHF RECEIVER SYNTHESIZER MODULE

19D902781G1 & G2

DESCRIPTION

The Receiver Synthesizer Module provides the local

oscillator signal (LO) to the Receiver Front End Module

of the MASTR III base station. The module also provides

the reference oscillator signal to the transmitter synthe-

sizer. Receiver Synthesizer Module 19D902781G1

(Group 1) generates an output injection signal in the 157

to 172 MHz range, and 19D902781G2 (Group 2) gener-

ates a signal in the 129 to 152 MHz Range.

The Receiver Synthesizer Module is a phase-locked

loop (PLL) design, as shown in the block diagram (Figure

1). Its output is generated directly by the VCO Q1 and

buffered by Monolithic Microwave Integrated Circuits

(MMIC) U1 and U3.

The logic signals from controller (U10, 12, and 13)

determine the synthesizer frequency. Frequency stability

is maintained by either using the internal reference oscil-

lator Y1 or by applying a high precision reference signal

to the EXT Reference Oscillator Port J4. The internal

reference oscillator is a temperature controlled crystal

oscillator (TCXO) operating at 12.8 MHz. The oscillator

has a stability of

1.5 ppm over the temperature range of

-30

C to +75

C. See the table containing General Speci-

fications for the minimum external oscillator specifica-

tions.

The buffered VCO output is sampled by the resistive

splitter and conditioned by buffer amplifier U2. It is then

fed to the divide by 64/65 dual modulus prescaler U5. The

divided output from the prescaler is connected to the F

input of the PLL U6. Within the PLL the divided VCO

input signal F

is divided again. The PLL also divides

down the 12.8 MHz reference signal. Three inputs from

the controller; ENABLE, CLOCK, and serial DATA pro-

gram the PLL divider circuits.

TABLE OF CONTENTS

Page

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

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

CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

VOLTAGE CONTROLLED OSCILLATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

REFERENCE OSCILLATOR AND BUFFER . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

LOOP FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

DIGITAL CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

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

MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

TEST AND ALIGNMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

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

ASSEMBLY DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

OUTLINE DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

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

PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

PRODUCTION CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

IC DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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.

Summary of content (16 pages)

PAGE 1
Maintenance Manual LBI-38641F VHF RECEIVER SYNTHESIZER MODULE 19D902781G1 & G2 TABLE OF CONTENTS Page DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front Cover GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 CIRCUIT ANALYSIS . . . . . . . . . . . . . . . VOLTAGE CONTROLLED OSCILLATOR . BUFFER AMPLIFIERS . . . . . . . . . . . . REFERENCE OSCILLATOR AND BUFFER PRESCALER AND SYNTHESIZER . . . . .
PAGE 2
LBI-38641F The divided reference signal and the divided VCO signal are compared in the PLL phase detector. When the reference and VCO signals are identical the PLL phase detector generates a constant DC output voltage. This voltage is buffered by U8 and filtered by the loop filter circuit. It is then applied to Q1 setting the VCO on frequency. If the compared frequencies (phases) differ, an error voltage is generated which adjusts the VCO frequency.
PAGE 3
LBI-38641F Integrated circuits U1 and U3 provide amplification of the local oscillator signal. The output of U1 is fed to a resistive signal splitter composed of R13 through R18. One of the resistive signal splitter outputs drives amplifier U3. The U3 output signal is coupled by C17 to a low-pass filter network (C24 and C25, L6, L8, and L9) and a resistive pad (R25, R26 and R30) for isolation. The local oscillator signal is finally routed to J2, LO OUT, for connection to the Receiver Front End Assembly.
PAGE 4
LBI-38641F Synthesizer Loading SERVICE NOTES The following service information applies when aligning, testing, or troubleshooting the RX Synthesizer: • Unground the ENABLE TEST line (pin 22A). Load the synthesizer IC Group 1 - 170 MHz. Group 2 - 150 MHz. Logic Levels: Logic 1 = high Logic 0 = Low • • = = TROUBLESHOOTING CHART SYMPTOM I. Loop Fails To Lock Verify the lock indicator (CR1) is off or the FLAG 2 line is high. 4.5 to 5.5 Vdc 0 to 0.
PAGE 5
LBI-38641F ASSEMBLY DIAGRAM TROUBLESHOOTING CHART (Continued) SYMPTOM III. LO power low or tuned out of band. IV. LO signal not present. (i.e. Q1 does not oscillate) AREAS TO CHECK INDICATIONS 1. Check tuning with 6 Vdc applied using test procedure. FLO±5 MHz LO tuning incorrect. Retune following test procedure. 2. Check DC bias at Buffer Amplifiers U1, U2, & U3 pin 3 Typ. 3.2 Vdc. Bad Buffer Amplifier. Replace bad part. 1. Check DC bias at Q1 drain. (Typ. +8Vdc) Replace Q1. 2.
PAGE 6
OUTLINE DIAGRAM LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G1 & G2 (19D902664, Sh. 1, Rev.
PAGE 7
LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G1 (19D903621, Sh. 1, Rev.
PAGE 8
SCHEMATIC DIAGRAM LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G1 (19D903621, Sh. 2, Rev.
PAGE 9
LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G1 (19D903621, Sh. 3, Rev.
PAGE 10
SCHEMATIC DIAGRAM LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G2 (19D903769, Sh. 1, Rev.
PAGE 11
LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G2 (19D903769, Sh. 2, Rev.
PAGE 12
SCHEMATIC DIAGRAM LBI-38641F RECEIVER SYNTHESIZER BOARD 19D902664G2 (19D903769, Sh. 3, Rev.
PAGE 13
PARTS LIST LBI-38641F RECEIVER SYNTHESIZER MODULE 19D902781G1-G2 ISSUE 4 SYMBOL PART N0. DESCRIPTION ——— MISCELLANEOUS — — PART NO. DESCRIPTION 19B802690P1 RF Shielding Grommet. C36 19A703902P3 Metal: 0.047 µF ±10%, 50 VDCW. RF Casting. C37 19A702052P14 Ceramic: 0.01 µF ±10%, 50 VDCW. 11 19A702381P508 Screw, thd. form: No. 3.5-0.6 x 8. (Used in G1, G2, G1 and G2). C38 19A702052P26 Ceramic: 0.1 µF ±10%, 50 VDCW. 17 19D902664G2 C39 and C40 19A702052P3 Ceramic: 470 pF ±10%, 50 VDCW.
PAGE 14
PARTS LIST & PRODUCTION CHANGES SYMBOL PART NO. DESCRIPTION R70 thru R72 19B800607P102 Metal film: 1K ohms ±5%, 1/8 w. R73 thru R76 19B800607P103 Metal film: 10K ohms ±5%, 1/8 w. R77 and R78 19B800607P101 Metal film: 100 ohms ±5%, 1/8 w. R79 thru R88 19B800607P102 Metal film: 1K ohms ±5%, 1/8 w.
PAGE 15
LBI-38641F U8 & U9 19A702293P2 Dual Operational Amplifier IC DATA U14 19A702705P4 Quad Analog Switch U10 19A703471P120 Decoder/Demux U15 19A704971P8 +5 Regulator U12 & U13 19A703483P302 Logic Gate/Inverter 14 Y1 19B801351P12 Crystal Oscillator U16 19A70497P10 +8V Regulator
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