MAINTENANCE MANUAL FOR
21.4 MHz RECEIVER IF MODULE
12.5/25 kHz CHANNEL SPACING
19D902783G7 & G11
DESCRIPTION
The MASTR III Receiver IF Module provides amplifi-
cation and demodulation of the 21.4 MHz Intermediate
Frequency signal. The IF Module also includes the re-
ceiver squelch circuitry. However, it does not include de-
emphasis or squelch audio gating circuits. Figure 1 is a
block diagram showing the functional operation of the IF
Module.
The IF Module circuitry contains the following:
•
A 50 ohm input impedance IF Amplifier
•
A chain of two crystal filters and an integrated
circuit IF amplifier
•
An integrated circuit containing a crystal oscillator,
mixer, limiter, and quadrature detector
•
A variable gain AF amplifier
•
A squelch circuit
•
A fault detector circuit
•
An integrated circuit voltage regulator
•
An address decoder
TABLE OF CONTENTS
Page
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Front Cover
GENERAL SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
CIRCUIT ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
INPUT MATCHING NETWORK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
CRYSTAL FILTERS, IF AMPLIFIERS . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
OSCILLATOR/MIXER/DETECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
AUDIO AMPLIFIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
SQUELCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Buffer Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Bandpass Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Noise Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
DC Amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Schmitt Trigger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
FAULT DETECTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
VOLTAGE REGULATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
ADDRESS DECODER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
RECOMMENDED TEST EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
ALIGNMENT PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
ASSEMBLY DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
OUTLINE DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5
IC DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
PRODUCTION CHANGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Back Cover
LBI-39123E
ERICSSONZ
Ericsson Inc.
Private Radio Systems
Mountain View Road
Lynchburg, Virginia 24502
1-800-528-7711 (Outside USA, 804-592-7711)
Printed in U.S.A.
PRODUCTION CHANGES
Changes in 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 Parts List for the descriptions of parts
affected by these revisions.
REV. B - RECEIVER IF MODULE 19D902494G7
To improve production of Group 7 boards.
New schematic (193D1065).
REV. A - RECEIVER IF MODULE 19D902494G11
To ensure correct operation, U7 (19A701789P4) was replaced.
REV. B - RECEIVER IF MODULE 19D902494G11
To increase margins on squelch threshold sensitivity and 12 dB
SINAD in 12.5 kHz mode. C86 was 0.01
µ
F (19A702052P14),
R6 was 50 ohms (19B800607P510), R97 was 39 ohms
(19B801251P390) and R98 and R99 were 150 ohms
(19B801251P151). Added L6 (19A705430P24).
Summary of Contents for 19D902783G1
Page 6: ...SCHEMATIC DIAGRAM RECEIVER IF MODULE 19D902494G1 19D902504 Sh 1 Rev 6 LBI 38643C 5...
Page 7: ...SCHEMATIC DIAGRAM RECEIVER IF MODULE 19D902494G1 19D902504 Sh 2 Rev 6 LBI 38643C 6...
Page 42: ...RECEIVER FRONT END BOARD 19D902490G4 G7 OUTLINE DIAGRAM 19D902490 Sh 4 Rev 6A LBI 38673F 5...
Page 43: ...ASSEMBLY DIAGRAM RECEIVER FRONT END MODULE 19D902782G3 19D902782 Sh 1 Rev 6 LBI 38673F 6...
Page 44: ...ASSEMBLY DIAGRAM RECEIVER FRONT END MODULE 19D902782G4 G7 19D902782 Sh 2 Rev 6 LBI 38673F 7...
Page 45: ...SCHEMATIC DIAGRAM RECEIVER FRONT END MODULE 19D902782G4 G7 19D904768 Sh 1 Rev 6 LBI 38673F 8...
Page 47: ...SCHEMATIC DIAGRAM RECEIVER FRONT END MODULE 19D902782G3 19D903498 Rev 7 LBI 38673F 10...
Page 48: ...This page intentionally left blank LBI 38673F 11...
Page 56: ...ASSEMBLY DIAGRAMS LOW PASS FILTER MODULE 19D902856G3 19D902856 Sh 1 Rev 0 LBI 38674F 7...
Page 71: ...ACCESSORIES ANTENNA SWITCH 19B235897P2 LBI 38675E 9...
Page 80: ...SCHEMATIC DIAGRAM RECEIVER IF MODULE 19D902494G7 G11 193D1065 Sh 1 Rev 3 LBI 39123E 7...
Page 81: ...SCHEMATIC DIAGRAM RECEIVER IF MODULE 19D902494G7 G11 193D1065 Sh 2 Rev 3 LBI 39123E 8...
Page 82: ...SCHEMATIC DIAGRAM RECEIVER IF MODULE 19D902494G7 G11 193D1065 Sh 3 Rev 3 LBI 39123E 9...