Aeroflex IFR 2975 User manual

Radio Test Set
Maintenance Manual
1002-4250-4P0
Issue-3
IFR 2975

MAINTENANCE MANUAL
RADIO TEST SET
IFR 2975
PUBLISHED BY
Aeroflex
COPYRIGHT ©Aeroflex 2006
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical, photocopying, recording or
otherwise without the prior permission of the publisher.
Original Printing Jul 2004
Issue-2 Apr 2005
Issue-3 Jul 2006
10200 West York / Wichita, Kansas 67215 U.S.A. / [phone] / FAX [phone]

WARNING:
HIGH VOLTAGE EQUIPMENT
THIS EQUIPMENT CONTAINS CERTAIN CIRCUITS AND/OR
COMPONENTS OF EXTREMELY HIGH VOLTAGE POTENTIALS,
CAPABLE OF CAUSING SERIOUS BODILY INJURY OR DEATH. WHEN
PERFORMING ANY OF THE PROCEDURES CONTAINED IN THIS
MANUAL, HEED ALL APPLICABLE SAFETY PRECAUTIONS.
SAFETY FIRST: TO ALL SERVICE PERSONNEL
REFER ALL SERVICING OF UNIT TO QUALIFIED TECHNICAL PERSONNEL.
CASE, COVER OR PANEL REMOVAL
Removing protective covers, casings or panels from this unit exposes the technician to electrical hazards that
can result in electrical shock or equipment damage.
SAFETY IDENTIFICATION IN TECHNICAL MANUAL
This manual uses the following terms to draw attention to possible safety hazards, that may exist when
operating or servicing this equipment.
CAUTION: THIS TERM IDENTIFIES CONDITIONS OR ACTIVITIES THAT, IF IGNORED, CAN RESULT IN
EQUIPMENT OR PROPERTY DAMAGE (e.g., FIRE).
WARNING: THIS TERM IDENTIFIES CONDITIONS OR ACTIVITIES THAT, IF IGNORED, CAN RESULT IN
PERSONAL INJURY OR DEATH.
SAFETY SYMBOLS IN MANUALS AND ON UNITS
CAUTION: Refer to accompanying documents.
AC TERMINAL: Terminal that may supply or be supplied with ac or alternating voltage.
SWITCH OFF: AC line power to the device is OFF.
SWITCH ON: AC line power to the device is ON.
DANGEROUS VOLTAGE: Indicates electrical shock hazard due to high voltage levels.
EQUIPMENT GROUNDING PRECAUTION
Improper grounding of equipment can result in electrical shock.
USE OF PROBES
Check the specifications for the maximum voltage, current and power ratings of any connector on the unit
before connecting it with a probe from a terminal device. Be sure the terminal device performs within these
specifications before using it for measurement, to prevent electrical shock or damage to the equipment.
POWER CORDS
Power cords must not be frayed or broken nor expose bare wiring when operating this equipment.
USE RECOMMENDED FUSES ONLY
Use only fuses specifically recommended for the equipment at the specified current and voltage ratings.

CAUTION: INTEGRATED CIRCUITS AND SOLID STATE DEVICES SUCH AS MOS FETS, ESPECIALLY CMOS
TYPES, ARE SUSCEPTIBLE TO DAMAGE BY ELECTROSTATIC DISCHARGES RECEIVED FROM
IMPROPER HANDLING, THE USE OF UNGROUNDED TOOLS AND IMPROPER STORAGE AND
PACKAGING. ANY MAINTENANCE TO THIS UNIT MUST BE PERFORMED WITH THE FOLLOWING
PRECAUTIONS:
OBEFORE USE IN A CIRCUIT, KEEP ALL LEADS SHORTED TOGETHER EITHER BY THE USE OF
VENDOR-SUPPLIED SHORTING SPRINGS OR BY INSERTING LEADS INTO A CONDUCTIVE
MATERIAL.
OWHEN REMOVING DEVICES FROM THEIR CONTAINERS, GROUND THE HAND BEING USED
WITH A CONDUCTIVE WRISTBAND.
OTIPS OF SOLDERING IRONS AND/OR ANY TOOLS USED MUST BE GROUNDED.
ODEVICES MUST NEVER BE INSERTED INTO NOR REMOVED FROM CIRCUITS WITH POWER
ON.
OPC BOARDS, WHEN TAKEN OUT OF THE SET, MUST BE LAID ON A GROUNDED CONDUCTIVE
MAT OR STORED IN A CONDUCTIVE STORAGE BAG. REMOVE ANY BUILT-IN POWER
SOURCE, SUCH AS A BATTERY, BEFORE LAYING PC BOARDS ON A CONDUCTIVE MAT OR
STORING IN A CONDUCTIVE BAG.
OPC BOARDS, IF BEING SHIPPED TO THE FACTORY FOR REPAIR, MUST BE PACKAGED IN A
CONDUCTIVE BAG AND PLACED IN A WELL-CUSHIONED SHIPPING CONTAINER.
CAUTION
THIS EQUIPMENT CONTAINS PARTS
SENSITIVE TO DAMAGE
BY ELECTROSTATIC DISCHARGE (ESD)
CAUTION: SIGNAL GENERATORS CAN BE A SOURCE OF ELECTROMAGNETIC INTERFERENCE (EMI) TO
COMMUNICATION RECEIVERS. SOME TRANSMITTED SIGNALS CAN CAUSE DISRUPTION AND
INTERFERENCE TO COMMUNICATION SERVICES OUT TO A DISTANCE OF SEVERAL MILES.
USERS OF THIS EQUIPMENT SHOULD SCRUTINIZE ANY OPERATION THAT RESULTS IN
RADIATION OF A SIGNAL (DIRECTLY OR INDIRECTLY) AND SHOULD TAKE NECESSARY
PRECAUTIONS TO AVOID POTENTIAL COMMUNICATION INTERFERENCE PROBLEMS.
CAUTION: KEEP ALL VENT OPENINGS CLEAR AND UNOBSTRUCTED FOR PROPER EQUIPMENT COOLING
AND CONTINUED RELIABILITY. DO NOT OPERATE EQUIPMENT IN THE VERTICAL POSITION ON
PLUSH CARPET OR UPHOLSTERY TO AVOID IMPAIRING THE AIR EXHAUST. WHEN OPERATING
THE TEST SET IN THE NORMAL HORIZONTAL OR TILT BAIL POSITION, MAINTAIN AT LEAST
1.6 INCHES (FOUR CENTIMETERS) OF CLEARANCE BETWEEN THE EQUIPMENT REAR EXHAUST
FAN SCREEN AND OBJECTS OR WALLS.

i
PREFACE
SCOPE
This manual contains maintenance instructions for the 2975. The information in this manual enables
servicing technicians to:
OService, test or replace any major assembly within the 2975.
OMaintain operating conditions of the 2975 to the expected performance standards.
OUnderstand principles of operation, relating to the overall operation of the 2975 as well as
functional operation within the major assemblies.
ORGANIZATION
The 2975 Maintenance Manual is composed of the following sections:
SECTION 1 - THEORY OF OPERATION
Describes how the 2975 operates on three levels of complexity: system level, functional level
and functionally at a module (assembly) level.
SECTION 2 - CALIBRATION/VERIFICATION
Provides the step by step procedures for calibrating and verifying the performance of the
2975.
SECTION 3 - REPLACEMENT PROCEDURES
Provides step by step procedures for removing and installing major assemblies within the
2975.
SECTION 4 - PARTS LIST
Provides part lists and diagrams for ordering replaceable parts within the 2975.
SECTION 5 - ASSEMBLIES
Contains the 2975 system interconnect diagram and diagrams of all major assemblies.

ii
TABLE OF CONTENTS
PARAGRAPH TITLE PAGE
SECTION 1 - THEORY OF OPERATION
1-1 General................................................................................................ 1-1
1-2 System Overview................................................................................... 1-1
1-3 Module Overview................................................................................... 1-5
1-3-1 Backplane PCB Assy (42A1A1A1) ...................................................... 1-13
1-3-2 Front Panel Audio PCB Assy (42A1A1A2) ........................................... 1-14
1-3-3 CPU Adapter Assy (42A1A1A5) .......................................................... 1-15
1-3-4 Power Supply Assy (42A1A1A6) ......................................................... 1-16
1-3-5 Power Termination Assy (42A1A1A7).................................................. 1-17
1-3-6 Disk I/O PCB Assy (42A1A1A9).......................................................... 1-20
1-3-7 Attenuator Assy (42A1A3) ................................................................. 1-21
1-3-8 Generator Assy (42A1A4).................................................................. 1-22
1-3-9 IF/Video PCB Assy (42A1A5) ............................................................. 1-23
1-3-10 Multifunction I/O PCB Assy (42A1A6) ................................................. 1-24
1-3-11 Receiver Assy (42A1A7) ................................................................... 1-25
1-3-12 CAI PCB Assy (42A1A8).................................................................... 1-26
SECTION 2 - CALIBRATION
2-1 General................................................................................................ 2-1
2-1-1 Calibration/Verification Schedule ....................................................... 2-1
2-1-2 Controls and Connectors................................................................... 2-1
2-1-3 Test Equipment Requirements ........................................................... 2-1
2-1-4 Test Record..................................................................................... 2-1
2-2 Precautions .......................................................................................... 2-2
2-2-1 Safety............................................................................................. 2-2
2-2-2 ESD................................................................................................ 2-2
2-3 Disassembly Requirements..................................................................... 2-2
2-4 Verification Procedures.......................................................................... 2-3
2-4-1 Initial Setup .................................................................................... 2-3
2-4-2 Generator Output Frequency ............................................................. 2-4
2-4-3 Generator Output Power ................................................................... 2-5
2-4-4 Generator Level Flatness .................................................................. 2-6
2-4-5 Generator T/R Power Level Accuracy ................................................. 2-7

iii
TABLE OF CONTENTS (cont)
PARAGRAPH TITLE PAGE
SECTION 2 - CALIBRATION (cont)
2-4-6 Generator T/R Power Level Flatness .................................................. 2-8
2-4-7 RF Power Meter Accuracy ................................................................. 2-9
2-4-8 RSSI Meter Accuracy........................................................................ 2-10
2-4-9 Analyzer Level Accuracy ................................................................... 2-11
2-4-10 Generator FM Residual ..................................................................... 2-13
2-4-11 Generator AM Residual ..................................................................... 2-14
2-4-12 Generator FM Deviation Accuracy ...................................................... 2-15
2-4-13 Generator FM Modulation Rate .......................................................... 2-16
2-4-14 Generator FM Modulation Distortion ................................................... 2-17
2-4-15 Generator AM Modulation Accuracy.................................................... 2-18
2-4-16 RF Error Meter Accuracy................................................................... 2-19
2-4-17 AF Meter Accuracy ........................................................................... 2-20
2-4-18 FM Deviation Meter Accuracy ............................................................ 2-21
2-4-19 AM Modulation Meter Accuracy .......................................................... 2-22
2-4-20 Analyzer Frequency and Span Accuracy.............................................. 2-23
2-4-21 Analyzer Bandwidth Switching Error ................................................... 2-24
2-4-22 Oscilloscope Amplitude Accuracy ....................................................... 2-25
2-4-23 Digital Voltmeter DC Accuracy........................................................... 2-27
2-4-24 Digital Voltmeter AC Accuracy ........................................................... 2-28
2-4-25 Function Generator Level Accuracy .................................................... 2-29
2-4-26 Function Generator Frequency Accuracy............................................. 2-30
2-4-27 Function Generator Total Harmonic Distortion ..................................... 2-31
2-4-28 AF Counter Accuracy........................................................................ 2-32
2-4-29 SINAD/Distortion Meter Accuracy ....................................................... 2-33
2-5 Verification Data Sheet .......................................................................... 2-34
2-6 Calibration Procedures .......................................................................... 2-41
2-6-1 Power Supply Voltages ..................................................................... 2-41
2-6-2 Generator / Analyzer / TCXO ............................................................. 2-44
2-7 Calibration Data Sheet........................................................................... 2-46

iv
TABLE OF CONTENTS (cont)
PARAGRAPH TITLE PAGE
SECTION 3 - REPLACEMENT PROCEDURES
3-1 General................................................................................................ 3-1
3-1-1 Safety Precautions ........................................................................... 3-1
3-1-2 ESD Precautions.............................................................................. 3-1
3-2 Tool Requirements ................................................................................ 3-1
3-3 Replacement Procedures........................................................................ 3-2
3-3-1 Remove Case Assy........................................................................... 3-3
3-3-2 Replace Handle ............................................................................... 3-4
3-3-3 Replace Attenuator Assy................................................................... 3-5
3-3-4 Replace Generator Assy ................................................................... 3-6
3-3-5 Replace Receiver Assy ..................................................................... 3-7
3-3-6 Replace IF/Video PCB Assy............................................................... 3-8
3-3-7 Replace Multifunction I/O PCB Assy ................................................... 3-9
3-3-8 Replace CAI PCB Assy ..................................................................... 3-10
3-3-9 Replace CPU Adapter Assy ............................................................... 3-11
3-3-10 Replace Rear Panel Assy.................................................................. 3-12
3-3-11 Replace Rear Panel PCB Assy........................................................... 3-13
3-3-12 Replace Power Supply Assy .............................................................. 3-16
3-3-13 Replace Disk I/O Assy ...................................................................... 3-19
3-3-14 Replace Front Panel Assy ................................................................. 3-20
3-3-15 Replace Front Panel Audio PCB Assy ................................................. 3-23
3-3-16 Replace Power Termination Assy ....................................................... 3-24
3-3-17 Replace Floppy Drive Assy................................................................ 3-26
3-3-18 Replace Backplane PCB Assy............................................................ 3-27
SECTION 4 - PARTS LIST
4-1 General ............................................................................................... 4-1
4-2 Parts Lists ........................................................................................... 4-2
4-2-1 Accessories..................................................................................... 4-2
4-2-2 Composite Assy ............................................................................... 4-3
4-2-3 Chassis Assy ................................................................................... 4-4
4-2-4 CPU Adapter Assy............................................................................ 4-5

v
TABLE OF CONTENTS (cont)
PARAGRAPH TITLE PAGE
SECTION 5 - ASSEMBLIES
APPENDIX A - I/O CONNECTORS AND PIN-OUT TABLES
A-1 Table of I/O Connectors ......................................................................... A-1
A-2 Pin-Out Table for MIC Connector ............................................................ A-2
A-3 Pin-Out Table for AUDIO I/O Connector ................................................... A-3
A-4 Pin-Out Table for GPIB Connector........................................................... A-4
A-5 Pin-Out Table for RS-232 Connector ....................................................... A-5
A-6 Pin-Out Table for PRINTER Connector..................................................... A-6
A-7 Pin-Out Table for TEST PORT Connector ................................................. A-7
A-8 Pin-Out Table for VGA Connector............................................................ A-8
A-9 Pin-Out Table for MOUSE Connector ....................................................... A-9
A-10 Pin-Out Table for KEYBOARD Connector ................................................. A-10
A-11 Pin-Out Table for USB Connector............................................................ A-11
A-12 Pin-Out Table for ETHERNET Connector.................................................. A-12
APPENDIX B - REPACKING FOR SHIPMENT
B-1 Shipping Information ............................................................................. B-1
B-1-1 Authorization ................................................................................... B-1
B-1-2 Tagging Test Sets ............................................................................ B-1
B-1-3 Shipping Containers ......................................................................... B-1
B-1-4 Freight Costs................................................................................... B-1
B-2 Repacking Procedure............................................................................. B-1
APPENDIX C - CONTROLS AND CONNECTORS
C-1 Controls ............................................................................................... C-1
C-2 Connectors........................................................................................... C-3
C-2-1 2975 Front Panel ............................................................................. C-3
C-2-2 2975 Rear Panel .............................................................................. C-5
APPENDIX D - SPECIFICATIONS

vi
TABLE OF CONTENTS (cont)
PARAGRAPH TITLE PAGE
APPENDIX E - TEST EQUIPMENT REQUIREMENTS
E-1 General................................................................................................ E-1
E-2 Recommended Test Equipment ............................................................... E-1
APPENDIX F - ETHERNET CROSSOVER CABLE

vii
LIST OF ILLUSTRATIONS
FIGURE NO. TITLE PAGE
1-1 2975 System Overview........................................................................... 1-3
1-2 2975 Module Overview........................................................................... 1-7
1-3 Front Panel Audio PCB Assy Block Diagram ............................................. 1-14
1-4 Power Supply Assy Block Diagram .......................................................... 1-16
1-5 Power Termination Assy Block Diagram ................................................... 1-18
1-6 Disk I/O PCB Assy Block Diagram ........................................................... 1-20
1-7 Attenuator Assy Block Diagram ............................................................... 1-21
1-8 Multifunction I/O Assy Block Diagram ...................................................... 1-24
1-9 CAI PCB Assy Block Diagram.................................................................. 1-26
2-1 Power Supply Voltages .......................................................................... 2-43
2-2 Calibration Test Equipment Configuration ................................................ 2-47
2-3 Generator Calibration Setup ................................................................... 2-48
2-4 Analyzer Calibration Setup ..................................................................... 2-49
2-5 TCXO Calibration Setup ......................................................................... 2-50
4-1 Accessory Kit Contents .......................................................................... 4-3
4-2 2975 Composite Assy ............................................................................ 4-9
4-3 2975 Chassis Assy ................................................................................ 4-11
4-4 CPU Adapter Assy ................................................................................. 4-12
5-1 2975 System Interconnect ...................................................................... 5-3
5-2 Chassis Assy ........................................................................................ 5-4
5-3 Backplane PCB Assy ............................................................................. 5-5
5-4 Front Panel Audio PCB Assy................................................................... 5-10
5-5 Rear Panel PCB Assy ............................................................................ 5-11
5-6 Front Panel Assy................................................................................... 5-12
5-7 CPU Adapter Assy ................................................................................. 5-13
5-8 Power Supply Assy ................................................................................ 5-14
5-9 Power Termination Assy......................................................................... 5-15
5-10 Floppy Drive Assy ................................................................................. 5-16
5-11 Disk I/O PCB Assy................................................................................. 5-17
5-12 Rear Panel Assy ................................................................................... 5-18
5-13 Attenuator Assy .................................................................................... 5-19
5-14 Generator Assy ..................................................................................... 5-20
5-15 IF/Video PCB Assy ................................................................................ 5-21

viii
LIST OF ILLUSTRATIONS (cont)
FIGURE NO. TITLE PAGE
5-16 Multifunction I/O PCB Assy..................................................................... 5-22
5-17 Receiver Assy....................................................................................... 5-23
5-18 CAI PCB Assy ....................................................................................... 5-24
5-19 Handle Assy ......................................................................................... 5-25
B-1 Repacking for Shipment ......................................................................... B-2

SECTION 1 - THEORY OF OPERATION
1-1
1-1 GENERAL
The 2975 digital radio test platform integrates over 20 radio-testing instruments into a single user-
friendly instrument that offers the interconnectivity normally expected from a personal computer.
The 2975 digital test platform, created with modular design, is simple to support and upgrade. The
2975 provides comprehensive transmitter and receiver testing, while the full-range spectrum analyzer
and tracking generator make possible base site component testing. The dual channel oscilloscope
and internal DEMOD scope provide comprehensive viewing of signals.
This following sections, System Overview and Module Overview, provide the maintenance technician
with a concept of how the 2975 operates.
1-2 SYSTEM OVERVIEW
RECEIVE SYSTEM OVERVIEW
The 2975 is capable of receiving modulated or unmodulated signals ranging form 1 MHz to 2.7 GHz.
Signals are received through the Power Termination Assy at the ANT Connector (low power signals,
<-10 dBm) or T/R Connector (high power signals, >-10 to +50 dBm). A diode detector serves to
measure RF power applied to the T/R Connector. The ANT Connector and GEN Connector are
protected from high power levels by a limiter circuit. Refer to the Generate System Overview for
more details on the GEN Connector. The RF signal is routed to the Receiver Assy.
The Receiver Assy has selectable attenuators and provides reference signals of 10, 40, 80 and
400 MHz to the system. External 10 MHz I/O is routed from the Receiver Assy to the Rear Panel
Assy. In the Receiver Assy, the incoming signal is converted to an IF (immediate frequency) of
10.7 MHz and signal conditioning is started. The 10.7 MHz IF signal is passed on to the Video/IF
PCB Assy.
The IF/Video PCB Assy has selectable 10.7 MHz IF filtering of 30 kHz, 300 kHz and 6 MHz. Both the
CAI (Common Air Interface) PCB Assy and the IF/Video PCB Assy work together to provide the AGC
(automatic gain control) for the Receiver Assy. The CAI PCB Assy sends data to the IF/Video PCB
Assy to increase or decrease the gain automatically, providing the correct level to the CAI PCB Assy.
The IF/Video PCB Assy also is responsible for Analyzer resolution bandwidth filters in the “Look and
Listen” mode of 300 Hz, 3 kHz and 60 kHz. When the dedicated Analyzer mode is selected, all
combinations of IF filtering are used to provide a fully functional Spectrum Analyzer. Additional
functions of the IF/Video PCB Assy are: 10.7 MHz IF output to the Rear Panel Assy, Video output to
the Rear Panel Assy and IF Count to the Multifunction PCB Assy. The final destination of the
10.7 MHz IF signal is routed to the CAI PCB Assy.
The CAI PCB Assy receives the 10.7 MHz IF signal and digitally performs the demodulation process.
Demodulation types include FM, AM, P25 and P25Encr. During the demodulation process, the signal
is measured for correct power strength. If the incoming power is incorrect, data is provided back to
the IF/Video PCB Assy for AGC control as previously discussed in the IF/Video PCB section above.
The CAI PCB Assy provides digitally demodulated signals to the system for meter functions such as:
Receiver Level Meter, Deviation Meter, C4FM Meter, Demod Output, Internal Demod Scope and
Speaker. Other CAI PCB Assy functions are discussed in the Generate System Overview.

1-2
GENERATE SYSTEM OVERVIEW
The Generate System path starts with the CAI PCB Assy. The CAI PCB Assy digitally modulates an
11.4 MHz IF signal. The Modulation sources are M1, M2, Mic and Audio. The Modulation types
include FM, AM, P25 and P25Encr.
Primarily Digital audio sources begin in the Multifunction PCB Assy and are transferred to the CAI
PCB Assy, however; the CAI PCB Assy provides P25 and P25Encr (encrypted) digital audio sources.
The 11.4 MHz IF signal is routed to the Generator Assy.
The Generator Assy is designed to convert the 11.4 MHz IF signal to the desired output frequency
between 1 MHz to 2.7 GHz. The variable attenuator in the Generator Assy provides 9.9 dB
attenuation in 0.1 dB steps between the 10 dB steps of the Attenuator Assy. The signal is amplified
to a level high enough to overcome the losses of the Attenuator Assy and Power Termination Assy
and to meet the specified maximum output power level. The desired RF signal is then routed to the
Attenuator Assy.
The Attenuator Assy consists of six relay-attenuator sections and a driver board. One relay-
attenuator section is 10 dB and the other five relay-attenuator sections are 20 dB for a total
attenuation of 110 dB. After the Attenuator Assy, the RF signal goes to the Power Termination Assy.
The RF signal can be routed out the GEN Connector or the T/R Connector in the Power Termination
Assy. The GEN Connector provides a maximum output signal of +10 dBm and the T/R Connector
provides a maximum output signal of -30 dBm over the 1 MHz to 2.7 GHz range.

1-3
042M-037
T/R Connector
Gen Connector
Attenuation
Mixer
Mixer
Mixer
3410.7 MHz IF
210.7 MHz IF
Mixer
Mixer
Mixer
90.7 MHz IF
80 MHz
400 MHz
Mixer 610.7 MHz IF
3411.7 MHz IF
10.7 MHz
Mixer
300 Hz
3 kHz
60 kHz
30 kHz
300 kHz
6 MHz
LOG AMP
AntConnector
DAC
ADC
Harris Up
Convertor
Harris
Down
Convertor
Parametric
DSP
Layer 1
DSP
I Out
DAC
Q Out
DAC
Q
Q
I
I
I
Q
Digitized Audio In
Digitized Audio Out
Generator Assy
Power Termination
Assy
Receiver Assy
IF/Video PCB Assy
CAI PCB Assy
(Common Air Interface)
110 dB Step
Attenuator
10 MHz
10 MHz
10.7 MHz IF
5.3 MHz
IF
RJ-11 and Test Connector
Front Panel Audio PCB Assy
Front Panel Assy
O-Scope Channel 1
Multifunction I/O PCB Assy
O-Scope Channel 2
DVM
3.5" Disk Drive
Disk I/O PCB Assy
Ribbon Cable
11.4MHz
40 MHz
ADC
IF Count
I/O BUS
CPU and
CPU Adapter Assy
Display and
Inverter Supply
Display Power Supply
Video
Filter
Audio In +/-
Filter
Mic In
Tone or
Data Filter
DAC
ADC
ADC
Audio Out 2
Programable
Resistor
Voltage
Reg
Test Connector I/O
Audio
DAC
Audio
Volume
Control
Dual
DAC
Backlight
Control
Ref
Control
DSP FPGA
DSP
Signal
Conditioning
DAC
Signal
Conditioning
DAC
DVM
Loads
Signal
Conditioning
DVM/Scope
Control
20 dB
CPU
Hard Disk
Drive
Rear Panel Assy
10.7 MHz Out
Analyzer Video Out
GPIB
USB
Parallel
RS-232
EXT
Keyboard
Mouse
VGA
Ethernet
Battery
Sense
EXT
REF I/O
SA IF
SA
Video
CPU
ADAPTER
PCB ASSY
Front Panel
Keypad PCB
Assy
Tone or Data
Filter
Audio Out 1
Bal or Unbal
Bal /1 or /10
Bal or
Unbal
Electric or
Dynamic
3.5" Disk
Control
10 MHz
Power Supply Assy
Fan
Power Entry
Power Supply
Power Supply
Interface
Power
On / Off Battery Sense
+15 V
+5 V Digital
+5 V Analog
Ground
Track LO
IF Count
External 10 MHz I/O
I/O BUS
External 10 MHz I/O
40 MHz
Shielded
Coaxial Cables
ADC
VAR
Atten
20 dB
20 dB
20 dB
20 dB
10 dB
10.7 MHz
Figure 1-1 2975 System Overview

1-4
THIS PAGE INTENTIONALLY LEFT BLANK.

1-5
1-3 MODULE OVERVIEW
Page
Backplane PCB Assy (42A1A1A1) ....................................................... 1-13
Front Panel Audio PCB Assy (42A1A1A2) ............................................ 1-14
CPU Adapter Assy (42A1A1A5) .......................................................... 1-15
Power Supply Assy (42A1A1A6) ......................................................... 1-16
Power Termination Assy (42A1A1A7) .................................................. 1-17
Disk I/O PCB Assy (42A1A1A9) .......................................................... 1-20
Attenuator Assy (42A1A3).................................................................. 1-21
Generator Assy (42A1A4) .................................................................. 1-22
IF/Video PCB Assy (42A1A5) ............................................................. 1-23
Multifunction I/O PCB Assy (42A1A6) .................................................. 1-24
Receiver Assy (42A1A7) .................................................................... 1-25
CAI PCB Assy (42A1A8) .................................................................... 1-26

1-6
THIS PAGE INTENTIONALLY LEFT BLANK.

1-7
TEMP-1
RXT/R_IN
40 MHz - Not Used
W7
W8
GEN
A1A1A7J3
TXBIAS_IN
T/R
A1A1A7J1
RXBIAS_IN
ANT
A1A1A7J2
Freq
Cal
DAC
TXOLDET_OUT
Output
Protect
(TX Overload
Sense)
Power
Pad
Temp
20 dB
Splitter
20 dB
125 W
RXOLDET_OUT
(RX Overload
Sense)
Input
Protect
LNA_BIAS
W10
Detector
Ambient
Temp
TEMP-2
Broadband
Power Detector
Divide
by 4
80 MHz
System
Clock
10 MHz
Input
Divide
by N
YIG
Driver
(Cal - Not
Used)
Divide
by 4
X8
Mult
Divide
by 2
Snap Diode
Comb Ckt
3410.7 MHz
1st LO
Null Ckt
Divide
by 2
3rd LO - 200 MHz
3200 MHz
2nd LO
Receive System
Hardware Gain
Cal 200 MHz
3rd LO
042M-021
W4
Low
Power
Detector
10 MHz
LPF
180 to 185 MHz
Sythesizer
To 110 dB Step Attentuator Output
Cal On/Off
80 MHz
W9
400 MHz (to Generator Assy)
40 MHz - Not Used
GENAMP_BIAS
Disk I/O
TXT/R_IN
To Multifunction
I/O Assy
12 Bit
A/D
High
Power
Detector
Power Termination
Divide
by 2
X 5
Mult
Frequency Distribution
670 MHz
Clean Loop
Osc
Step Loop Divide
by 8
Wide-Span
Sweep
4.8 MHz
DDS
3410.7 to
6110.7 MHz
YIG 1st LO
3410.7
MHz IF
Receive Module
80 MHz (to Generator Assy)
YIG Crossfeed
to Tracking Generator
Sweep Circuit
W6
15 MHz LPF
210.7 MHz BPF 10.7 MHz IF
Internal
10MHz
TCXO
Internal
Open-Loop
Temp
Comp
10 MHz
Cross-
Feed
50 dB
Step
Atten
10 MHz (to Generator YIG)
40 MHz (to Common Air Interface)
2nd LO - 3200 MHz
80 MHz (to 16 MHz Channel Analyzer Sweep DDS)
10 MHz (to Recieve 1st LO YIG Step Loop)
EXTERNAL REF I/O
A1A2J11 40 MHz (to Receive IF)
40 MHz (to Multifunction Board)
80 MHz (to Receive 1st LO YIG)
10.7 MHz IF
(To IF/Video Block)
Figure 1-2 2975 Module Overview

1-8
14 MHz LPF
40 MHz
7.5 MHz HPF
A_AMP-D_10dB
A_AMP-B_20dB
Log Gain/Offset
Line Driver
Line Driver
Gates
A/D OUT
IF Count
W2
W5
W1
DDS [+7 dBm]
A_AMP-C_20dB
DAC
12 Bit
DAC
12 Bit
TEMP
SENSOR
12 Bit
A/D
BW=30 kHz
6 Poles
14 MHz LPF
BW=3 kHz
6 Poles
14 MHz LPF
Video
12 Bit
A/D
Line Driver
Video Out
10.7 MHz IF Out
(to CAI PCB Assy)
10.7 MHz IF Out
(to Rear Panel Assy)
BW=60 kHz
2 of 6 Poles
BW=300 Hz
6 Poles
7 MHz LPF
W4
A_AMP-A_20 dB
A/D OUT
R_AMP-C_20 dB
R_AMP-B_20 dB
14 MHz LPF
042M-022
[-20 dBm]
[-20 dBm
Top of Scale]
BW=300 kHz
4 of 6 Poles
14 MHz LPF
BW=60 kHz
4 of 6 Poles
R_AMP-D_10 dB
IF/Video PCB Assy
TOS
+6 dBm
Video Filter
Line Driver
7.5 MHz HPF
BW=300 kHz
2 of 6 Poles
10.7 MHz IF
(From Rec Block) Logarithmic
Amplifier
R_AMP-A_20 dB
Figure 1-2 2975 Module Overview (cont)