Aeroflex 3500 User manual

EXPORT CONTROL WARNING: This document contains controlled technology or technical data
under the jurisdiction of the Export Administration Regulations (EAR), 15 CFR 730-774. It cannot
be transferred to any foreign third party without the specific prior approval of the U.S. Department
of Commerce, Bureau of Industry and Security (BIS). Violations of these regulations are punishable
by fine, imprisonment, or both.
Communications
Test Set
3500 / 3500A
Maintenance Manual
Issue-4

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MAINTENANCE MANUAL
COMMUNICATIONS TEST SET
3500 / 3500A
PUBLISHED BY
Aeroflex
COPYRIGHT ©Aeroflex 2011
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.
Reissued Jan 2010
Issue-2 Apr 2010
Issue-3 May 2010
Issue-4 Mar 2011
10200 West York / Wichita, Kansas 67215 U.S.A. / [phone] / FAX [phone]

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Electromagnetic Compatibility:
For continued EMC compliance, all external cables must be shielded and three meters or less in
length.
Nomenclature Statement:
In this manual, 3500 / 3500A, Test Set or Unit refers to the 3500 / 3500A Communications Test Set.

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THIS PAGE INTENTIONALLY LEFT BLANK.

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SAFETY FIRST: TO ALL SERVICE PERSONNEL
REFER ALL SERVICING OF UNIT TO QUALIFIED TECHNICAL PERSONNEL.
WARNING: USING THIS EQUIPMENT IN A MANNER NOT SPECIFIED BY THE ACCOMPANYING
DOCUMENTATION MAY IMPAIR THE SAFETY PROTECTION PROVIDED BY THE EQUIPMENT.
CASE, COVER OR PANEL REMOVAL
Opening the Case Assembly exposes the operator to electrical hazards that can result in electrical shock or
equipment damage. Do not operate this Test Set with the Case Assembly open.
SAFETY IDENTIFICATION IN TECHNICAL MANUAL
This manual uses the following terms to draw attention to possible safety hazards that may exist when
operating 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. (This symbol refers to specific CAUTIONS
represented on the unit and clarified in the text.)
AC OR DC TERMINAL: Terminal that may supply or be supplied with AC or DC voltage.
DC TERMINAL: Terminal that may supply or be supplied with DC voltage.
AC TERMINAL: Terminal that may supply or be supplied with AC or alternating voltage.
EQUIPMENT GROUNDING PRECAUTION
Improper grounding of equipment can result in electrical shock.
USE OF PROBES
Check specifications for the maximum voltage, current and power ratings of any connector on the Test Set
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, 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.
WARNING: THE 3500 / 3500A USES A LITHIUM ION BATTERY PACK. THE FOLLOWING WARNINGS
CONCERNING LITHIUM ION BATTERIES MUST BE HEEDED:
•DO NOT RECHARGE OUTSIDE THE 3500 / 3500A.
•DO NOT CRUSH, INCINERATE OR DISPOSE OF IN NORMAL WASTE.
•DO NOT SHORT CIRCUIT OR FORCE DISCHARGE AS THIS MIGHT CAUSE THE BATTERY TO
VENT, OVERHEAT OR EXPLODE.

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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:
•BEFORE 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.
•WHEN REMOVING DEVICES FROM THEIR CONTAINERS, GROUND THE HAND BEING USED
WITH A CONDUCTIVE WRISTBAND.
•TIPS OF SOLDERING IRONS AND/OR ANY TOOLS USED MUST BE GROUNDED.
•DEVICES MUST NEVER BE INSERTED INTO NOR REMOVED FROM CIRCUITS WITH POWER
ON.
•PC 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.
•PC 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 ENSURE COMPLIANCE WITH
INSTRUCTIONS IN FAA CIRCULAR AC 170-6C, DATED FEBRUARY 19, 1981.

PREFACE
Subject to ITAR, see Cover Page for details. i
SCOPE
This Manual contains instructions for maintaining the 3500 / 3500A. It is strongly recommended that
the technician be thoroughly familiar with this manual before attempting to perform maintenance on
the equipment.
ORGANIZATION
The Manual is composed of the following Chapters:
CHAPTER 1 - INTRODUCTION
Provides an Introduction and Functional Descriptions for each assembly in the 3500 / 3500A.
CHAPTER 2 - MAINTENANCE INSTRUCTIONS
Identifies and explains Routine Service, Troubleshooting, Calibration/Verification,
Remove/Replace and Shipping/Storage Procedures.

TABLE OF CONTENTS
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PARAGRAPH PAGE
CHAPTER 1 - INTRODUCTION
1-1 General Information .................................................................................. 1-1
1-1A Scope.................................................................................................. 1-1
1-1B Nomenclature Cross-Reference List ........................................................ 1-1
1-2 Equipment Description............................................................................... 1-1
1-2A Equipment Characteristics, Capabilities and Features............................... 1-1
1-2B Equipment Data .................................................................................... 1-1
1-2C Safety, Care and Handling ..................................................................... 1-1
1-3 Principles of Operation .............................................................................. 1-2
1-3-1 General Description .............................................................................. 1-2
1-3-2 Detailed Description.............................................................................. 1-3
1-3-2A Power Supply PCB Assy (62A1A1) ...................................................... 1-3
1-3-2B Keypad PCB Assy (62A1A2A1) ........................................................... 1-7
1-3-2C RF Digitizer PCB Assy (62A1A2A2)..................................................... 1-7
1-3-2D Multi-Function PCB Assy (62A1A2A3) ................................................. 1-7
1-3-2E LCD Assy (62A1A2A4)....................................................................... 1-8
1-3-2F Flex Assy (62A1A2A6)....................................................................... 1-8
1-3-2G Audio I/O PCB Assy (62A1A2A7) (3500A Only)..................................... 1-9
1-3-2H RF Assy (62A1A3) ............................................................................ 1-10
CHAPTER 2- MAINTENANCE INSTRUCTIONS
2-1 Service Upon Receipt ................................................................................ 2-1
2-1-1 Service Upon Receipt of Materiel................................................................ 2-1
2-1-1A Unpacking............................................................................................ 2-1
2-1-1B Checking Unpacked Equipment............................................................... 2-1
2-1-2 Preliminary Servicing and Adjustment of Equipment...................................... 2-1
2-2 Troubleshooting........................................................................................ 2-2
2-2-1 Troubleshooting Guidelines.................................................................... 2-2
2-2-2 Equipment Inspection ............................................................................ 2-2
2-2-3 Troubleshooting Precautions .................................................................. 2-3
2-2-4 EMC / Safety Compliance ...................................................................... 2-3
2-2-5 Battery Precautions............................................................................... 2-4
2-3 Calibration / Verification Procedures ........................................................... 2-15
2-3-1 Calibration / Verification Schedule.......................................................... 2-15
2-3-2 Testing Conditions ................................................................................ 2-15
2-3-3 Test Equipment .................................................................................... 2-16
2-3-4 Verification Procedures ......................................................................... 2-17
2-3-4A Generator Verification ....................................................................... 2-17
2-3-4B Receiver RSSI Verification................................................................. 2-20
2-3-4C TCXO Verification ............................................................................. 2-22
2-3-4D RF Power Meter Verification .............................................................. 2-23
2-3-4E SWR Meter Verification ..................................................................... 2-28
2-3-4F Audio Level Meter Verification ........................................................... 2-29
2-3-4E Verification Data Sheets.................................................................... 2-31
2-3-5 Calibration Procedures .......................................................................... 2-35
2-3-5A Calibration Setup.............................................................................. 2-35
2-3-5B Generator Calibration........................................................................ 2-37
2-3-5C Receiver Calibration ......................................................................... 2-39
2-3-5D TXCO Calibration.............................................................................. 2-41
2-3-5E RF Power Meter Calibration ............................................................... 2-42
2-3-5F SWR Phase Detector Calibration ........................................................ 2-50
2-3-5G Audio Level Meter Calibration ............................................................ 2-51

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PARAGRAPH PAGE
CHAPTER 2- MAINTENANCE INSTRUCTIONS (cont)
2-4 Remove/Replace Procedures...................................................................... 2-53
2-4A Battery ............................................................................................ 2-54
2-4B Fuse ............................................................................................... 2-57
2-4C Open Case Assembly ........................................................................ 2-60
2-4D Power Supply PCB Assy (62A1A1) ...................................................... 2-62
2-4E Keypad PCB Assy (62A1A2A1) ........................................................... 2-64
2-4F RF Digitizer PCB Assy (62A1A2A2)..................................................... 2-65
2-4G Multi-Function PCB Assy (62A1A2A3) (3500) ....................................... 2-67
2-4G Multi-Function PCB Assy (62A1A2A3) (3500A) ..................................... 2-69
2-4H LCD Assy (62A1A2A4) (3500)............................................................. 2-71
2-4H LCD Assy (62A1A2A4) (3500A)........................................................... 2-73
2-4E Keypad Assy (62A1A2A5) .................................................................. 2-75
2-4I Flex Assy (62A1A2A6)....................................................................... 2-76
2-4I Audio I/O PCB Assy (62A1A2A7) ........................................................ 2-77
2-4J RF Assy (62A1A3) ............................................................................ 2-79
2-4K ANT Connector ................................................................................. 2-82
2-4L T/R Connector .................................................................................. 2-83
2-4M DC IN Connector .............................................................................. 2-84
2-4N AUDIO Connector ............................................................................. 2-85
2-4N AUDIO Connector ............................................................................. 2-86
2-4O SWR Connector ................................................................................ 2-87
2-4O DVM Connector ................................................................................ 2-88
2-4O AUDIO IN Connector ......................................................................... 2-89
2-4O AUDIO OUT Connector ...................................................................... 2-90
2-5 Preparation for Storage or Shipment ........................................................... 2-91
2-5A Packaging ............................................................................................ 2-91
2-5B Environment ......................................................................................... 2-91
APPENDICES
A Replacement Parts .................................................................................... A-1
B Connector Pin-Out Tables .......................................................................... B-1
C Test Equipment Requirements .................................................................... C-1
D Abbreviations ........................................................................................... D-1
E Assembly Drawings / Schematics ................................................................ E-1

LIST OF ILLUSTRATIONS / TABLES
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LIST OF ILLUSTRATIONS
TITLE PAGE
System Block Diagram.................................................................................................... 1-2
Power Supply PCB Assy Block Diagram............................................................................ 1-5
Multi-Function PCB Assy Block Diagram........................................................................... 1-6
RF Digitizer PCB Assy Block Diagram .............................................................................. 1-7
Audio I/O PCB Assy Block Diagram.................................................................................. 1-9
RF Assy Block Diagram .................................................................................................. 1-13
3500 ............................................................................................................................ A-15
3500A .......................................................................................................................... A-16
Chassis Assy (3500) ...................................................................................................... A-17
Chassis Assy (3500A) .................................................................................................... A-18
3500 / 3500A................................................................................................................. E-3
Power Supply PCB Assy ................................................................................................. E-7
Chassis Assy ................................................................................................................ E-8
Keypad PCB Assy .......................................................................................................... E-10
RF Digitizer PCB Assy.................................................................................................... E-11
Multi-Function PCB Assy ................................................................................................ E-12
LCD Assy...................................................................................................................... E-13
Keypad Assy ................................................................................................................. E-14
Flex Assy...................................................................................................................... E-15
Audio I/O PCB Assy ....................................................................................................... E-16
RF Assy........................................................................................................................ E-17
LIST OF TABLES
TITLE PAGE
3500 I/O Connectors ...................................................................................................... B-1
3500A I/O Connectors .................................................................................................... B-2
3500 AUDIO Connector Pin-Out Table.............................................................................. B-3
3500A AUDIO Connector Pin-Out Table............................................................................ B-4
3500 / 3500A REMOTE Connector Pin-Out Table............................................................... B-5
Comm Breakout Box - ETHERNET Connector Pin-Out Table ............................................... B-6
Comm Breakout Box - USB HOST Connector Pin-Out Table ................................................ B-7
Comm Breakout Box - RS-232 Connector Pin-Out Table ..................................................... B-8
Comm Breakout Box - REMOTE Connector Pin-Out Table................................................... B-9

CHAPTER 1 - INTRODUCTION
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1-1. GENERAL INFORMATION
A. Scope
Type of Manual: Maintenance Manual
Equipment Name and Model Number: 3500 / 3500A Communications Test Set
Purpose of Equipment: The 3500 / 3500A Communications Test Set is used for
testing radios and related equipment.
B. Nomenclature Cross-Reference List
COMMON NAME OFFICIAL NOMENCLATURE
3500 / 3500A 3500 / 3500A Communications Test Set
Test Set or Unit 3500 / 3500A Communications Test Set
1-2. EQUIPMENT DESCRIPTION
A. Equipment Characteristics, Capabilities and Features
Refer to the 3500 / 3500A Operation Manual for this information.
B. Equipment Data
Refer to the 3500 / 3500A Operation Manual for this information.
C. Safety, Care and Handling
Observe all WARNINGS, CAUTIONS and NOTES in this manual. This equipment can be extremely
dangerous if these instructions are not followed.
CAUTION
THIS EQUIPMENT CONTAINS PARTS
SENSITIVE TO DAMAGE
BY ELECTROSTATIC DISCHARGE (ESD)

1-2 Subject to Export Control, see Cover Page for details.
1-3. PRINCIPLES OF OPERATION
1-3-1 GENERAL DESCRIPTION
LCD T/R
KEYPAD
RF
DIGITIZER
POWER
SUPPLY
BATTERY
MULTI-
FUNCTION
RF SWR
ANT
REMOTE
DC IN
AUDIO
3500
LCD T/R
AUDIO I/O
RF
DIGITIZER
POWER
SUPPLY
BATTERY
MULTI-
FUNCTION
RF SWR
ANT
REMOTE
DC IN
KEYPAD
AUDIO
DVM
AUDIO IN
AUDIO OUT
3500A
Figure 1-1. System Block Diagram

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1-3-2 DETAILED DESCRIPTION
The System Block Diagram (Figure 1-1) and the System Interconnect Diagram (Figure E-1) shows the
relationship of all assemblies. The following paragraphs are detailed descriptions of the 3500 /
3500A assemblies.
A. Power Supply PCB Assy (62A1A1) (Figure 1-2)
The Power Supply PCB Assy is responsible for supplying power to the internal modules for operation
and for charging the internal batteries. The Power Supply PCB Assy operates from externally
supplied DC power and provides simultaneous run and battery charge, or battery charge only. The
battery charge time increases when in the run and charge mode. The Power Supply PCB Assy
consists of a DC-DC Converter, ON/OFF Control circuitry and the Battery Charger circuitry. The
external DC input is supplied from an External DC Power Supply (supplied).
The internal batteries are removable/replaceable Li Ion battery packs with an internal "gas-gauge"
feature that allows accurate determination of remaining battery life. Maximum operating and storage
temperature for Li Ion batteries is -20°C to +60°C and the maximum charging temperature is 0°C to
+45°C.
The Power Supply PCB Assy contains a synchronous buck converter to convert the input voltage to a
fixed output voltage (+10 Vdc). The Power Supply PCB Assy also contains a low-pass filter to reduce
the amount of internal emissions. The Input Converter Assembly is capable of providing enough
output current to charge the battery at full current and run the Test Set at the same time, as long as
the input voltage is within range.
Battery Charger
The battery charger is a boost type converter. The battery charger monitors the battery voltage and
temperature to determine if the battery is capable of being recharged, and if safe to attempt to
recharge the battery. The battery must be at least at a 9.2 V level and the temperature must be
between 0°and 45°C before a charge cycle initiates.
Output Circuitry
The output converters are comprised of a dual-phase synchronous buck converter for developing
+3.3 and +5 V outputs. The converter also has an auxiliary output that is used to generate +18 V
from the +VS source (either the battery or input converter). A separate buck/boost converter is used
to generate the -5 V output. A separate buck converter is used to generate the +5.5 V output. The
primary converter provides dual phase control, as well as gate drive for the switching MOSFETS and
over-current protection. The main converter runs at 220 kHz, while the auxiliary converter runs at
1.2 MHz.
Both +3.3 and +5 V outputs are capable of delivering up to 3 A of current and the 16 V output can
deliver up to 80 mA. If any of these three outputs experience a severe over-current, the supply turns
OFF.
The -5 V converter is a stand-alone buck/boost converter that runs at approximately 220 kHz and can
deliver up to 400 mA of current before starting to fold back. If the supply experiences a severe over-
current condition, the supply stays in fold-back mode until the short is removed.
The +5.5 V converter is a stand-alone buck converter that runs at approximately 500 kHz and can
deliver up to 500 mA of current before starting to fold back. If the supply experiences a severe over-
current condition, the supply stays in fold-back mode until the short is removed.

1-4 Subject to Export Control, see Cover Page for details.
A. Power Supply PCB Assy (62A1A1) (Figure 1-2) (cont)
ON/OFF Control
The ON/OFF control circuit provides debounce for the POWER Key and turn off delay, as well as
monitoring the protection circuitry.
Pressing the POWER Key shorts that point to ground providing a low to the ON/OFF control circuit
input, which turns the power supply circuits ON or OFF. To turn the unit ON, the POWER Key must
be pressed for a minimum of 128 ms. To turn the unit OFF, the PWR button must be pressed for
approximately 250 ms. After the 250 ms, an interrupt signal is sent by the ON/OFF circuit to the
software, indicating that the power supply circuits are shutting down and allowing the software to
perform an orderly shutdown. Approximately 500 ms after the generation of the interrupt the power
supply circuits shuts down.
The ON/OFF circuit also monitors the protection circuitry for a +3.3 V or +5 V over current condition
or a low battery condition, and shuts down the power supply circuits if any of these conditions are
present.
Source Select Circuitry
The source select circuitry is designed as a low-loss switch that selects the appropriate source when
the output of the ON/OFF circuitry is high. The external DC (+Vdc) is selected if present. If external
DC is not present, the battery (VBAT+) connects to +VS. If the Test Set is running the power source,
either external DC or battery may be switched without interrupting system operation.
The second function of the switching circuitry is to prevent battery current from flowing into the input
converter section when the Test Set is running on battery power. A low voltage cutoff is also
incorporated into the ON/OFF circuitry.
Protection Circuitry
The protection circuitry has four basic functions related to the DC input. The battery has internal
protection circuitry. The external DC input has a fuse, an over-voltage crowbar and reverse
protection diodes. The fuse is the primary disconnect to protect against any of the fault conditions.
If the DC input is too high (>32 V), the over-voltage crowbar triggers and the SCR opens the fuse. If
the DC input polarity is incorrect, the input clamp diodes forward bias and open the fuse. If the input
converter fails and the output of the converter is above 12 V, the SCR triggers and opens the fuse. If
the DC input voltage is too low, the input converter is disabled until the input voltage is within the
allowable range.

Figure 1-2. Power Supply PCB Assy
Block Diagram
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EXT DC IN
11 TO 32 Vdc
FUSE
CROWBAR
CHARGE
FULL CHARGE
PWR_ON_OFF
INPUT, OUTPUT
AND CHARGE
SUPERVISOR
PWM
BATTERY CHARGER
CHARGE
CONT
SOURCE
SELECT
PWM
CONT
INPUT
CONVERTER
10 Vdc
5 V CONVERTER
1 A TYPICAL
3.3 V CONVERTER
1 A TYPICAL
16 V CONVERTER
25 mA TYPICAL
-5 V CONVERTER
100 mA TYPICAL
+5.5 V CONVERTER
200 mA TYPICAL
PWM
CONT
-5 V
+16 Vdc
+3.3 V
+5 V
PWM
CONT
PWM
CONT
+5 V

FLASH
SRAM
RTC
EEPROM
HOST
PROCESSOR
COLDFIRE 5271
PROCESSOR
BUS
VOLTAGES
CHARGE/STATUS
POWER DOWN
JTAG
PHY
RS-232
XCVR
POWER PC
SIDE
POWER PC
SIDE
COLDFIRE
PC SIDE
COLDFIRE
PC SIDE
PHY
RS-232
XCVR
POWER
SUPPLY
JTAG DEV
PORT
RS-232
PORT
RS-232
PORT
ETHERNET
PORT
ETHERNET
PORT
DDC
FLASH
DDR
SDRAM
INT
DUC
FPGA
RF DIGITIZER PCB ASSY
TX
DAC
RCV
ADC
KEYPAD
I/F
BKLT
CNTRST
AUDIO
I/O
GP
I/O
LCD
I/F
USB
CNTLR
RS-232
XCVR
HOST
PERIPHERAL
COLDFIRE PC SIDE
MULTI I/O CONNECTOR
MIC
ASSY
PTT
MIC
SPEAKER
AUDIO IN
AUDIO OUT
DVM IN
LCD INTERFACE
LCD BACKLIGHT
KEYPAD, SYSTEM LEDs
RCV IF
TX IF
RF SPI CONTROL,
80 MHz CLOCK
Figure 1-3. Multi-Function PCB Assy
Block Diagram
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B. Keypad PCB Assy (62A1A2A1)
The Keypad PCB Assy controls the ON/OFF status of the Test Set and the manipulation of the
screens and menus. When a key is pressed, the Multi-Function PCB Assy interacts with the RF
Digitizer PCB Assy and RF Assy to display or manipulate the data on the LCD Display.
C. RF Digitizer PCB Assy (62A1A2A2) (Figure 1-4)
The RF Digitizer PCB Assy is used for generating the source 10.5 MHz (±500 kHz) output at
approximately -10 dBm from the DUC (Digital Up Converter), while the receive input to the A2D is
optimized for an input level of -10 dBm at 13 MHz (±500 kHz). All other RF signaling, filtering,
scaling and up/down conversion methodologies are accomplished in the RF Assy.
TX
DAC
RCV
ADC
TX IF
RCV IF
MULTI-FUNCTION
PCB ASSY
MULTI-FUNCTION
PCB ASSY
Figure 1-4. RF Digitizer PCB Assy Block Diagram
D. Multi-Function PCB Assy (62A1A2A3) (Figure 1-3)
The Multi-Function PCB Assy provides processor control of various digital, analog and RF sub-
circuits used to generate or receive RF signaling normally used in mobile radio communication. The
Multi-Function PCB Assy also contains the application specific circuits to control the other
assemblies. These circuits include interfaces to the LCD Assy, Keypad PCB Assy, Ethernet/RS-232/
USB, Power Supply PCB Assy, RF Digitizer PCB Assy, Audio I/O (3500A only) and RF hardware.
For the Generator, Audio I/O (3500A) and modulation signals are handled by the FPGA`s TDM
measurement bus. This bus runs at a 50 kHz-sample rate capable of delivering high quality audio to
the DUC (Digital Up Converter). The output of the DUC feeds a 14-Bit DAC for the digital-to-analog
conversion needed to form the output source RF signal.
For the Receiver, the output of the 14-Bit A2D is passed to the FPGA. The FPGA sends the data to
the DDC (Digital Down Converter) IC which processes the demodulation schemes needed and passes
the resultant data to the TDM audio bus for final interpretation by one of the system processors. The
system processors move the resultant modulation data to the LCD where the user can view the final
measurements.

1-8 Subject to Export Control, see Cover Page for details.
E. LCD Assy (62A1A2A4)
The LCD Assy is a 38 characters by 16 lines LCD display. The Multi-Function PCB Assy receives
signals and data from the Keypad PCB Assy, RF Digitizer PCB Assy and RF Assy. The processed
signals and data are sent to to the LCD Assy to display the various screens and menus with Soft Key
boxes at the bottom of the screen.
F. Flex Assy (62A1A2A6)
The Flex Assy forms the link between the REMOTE Connector and the Multi-Function PCB Assy. The
Test Set can be remotely controlled from the 44-Pin REMOTE Connector. Refer to Appendix C for the
REMOTE Connector Pin-Out definitions.

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G. Audio I/O PCB Assy (62A1A2A7) (Figure 1-5) (3500A Only)
The Audio I/O PCB Assy provides the DVM/Scope, Audio In and Audio Out signals to the 3500 /
3500A Front Panel.
The "DVM/Scope" input handles ±40 Vdc through a voltage divider network. AC signals are limited to
1/2 the 50 kHz bandwidth of the TDM audio digitizing bus.
The "Audio In" is specified at 3 Vrms with HIGH Z, 600 Ωor 150 Ωloads available. AM/FM external
signals are limited to 300 Hz to 5 kHz.
The "Audio Out" is rated to deliver 1.57 Vrms into a 600 Ωload with an output impedance of 100 Ω.
Driven by a sample rate of 50 kHz, the specified frequency range is 30 Hz to 5 kHz. The usable
frequency range is 0 to 20 kHz.
Audio In
10 MHz LPF
Div by 1
AC/DC Switch
1.0
M-Ohm
600
Ohm
53.2
k-Ohm
Div by 10
Ground
Switch
10 MHz LPF
From 24 bit D2A 50KSPS
10 MHz LPF
To 16 bit A2D 250KSPS
Scope
150
Ohm
Div by 1
Div by 20
Audio Out
To 24 bit A2D 50KSPS
1.0
k-Ohm
9.0
k-Ohm
Figure 1-5. Audio I/O PCB Assy Block Diagram

1-10 Subject to Export Control, see Cover Page for details.
H. RF Assy (62A1A3) (Figure 1-6)
The RF Assy consists of the RF Converter PCB Assy and the RF Controller PCB Assy. The RF Assy
receives power and control via the Multi-Function PCB Assy.
The RF Converter PCB Assy contains the RF termination for the T/R Connector, ANT Connector and
SWR Connector, as well as the frequency translation circuitry and step attenuator for both the
receive and generate paths. The RF Controller PCB Assy interfaces directly with the Multi-Function
PCB Assy to control the RF Assy. The RF Controller PCB Assy contains the 80 MHz TCXO system
clock and the RF synthesizers that generate the required Local Oscillator (LO) signals.
An 80 MHz TCXO with a stability of 1 ppm provides the reference signal for the RF Assy as well as
the Multi-Function PCB Assy. The 80 MHz TCXO provides the reference signal to the five Phase
Lock Loops (PLL) used to generate the required Local Oscillator (LO) signals.
The Generate path of the RF Assy receives a 10.5 MHz IF signal from the Multi-Function PCB Assy.
This signal is mixed with the 80 MHz Gen. 3rd LO to create a 69.5 MHz IF that is filtered to remove
unwanted mixing products and amplified before being input to the Generate leveler circuit. The
Generate leveler circuit is used to set the desired output signal level by compensating for variations
in flatness over the 2 to 1000 MHz output band. The 69.5 MHz IF is then mixed with the 1330 MHz
Generate 2nd LO to produce a 1399.5 MHz IF. The output of the mixer is filtered to remove unwanted
mixing products and amplified before being input to the last mixer. The Generate 1st LO, which
covers 1401.5 to 2399.5 MHz, is mixed with the 1399.5 MHz IF to produce an output frequency of 2 to
1000 MHz. Following the mixer the signal passes through a low-pass filter and into an amplifier. The
output of the amplifier is tapped off to the Generate Level detector. The output of the detector is
feed back to the Generate Leveler to level the generate system. The RF signal out of the amplifier
then passes through the step attenuators. The step attenuators provide 60 dB of attenuation in 1 dB
steps to set the signal level out of the Unit. The signal is then input to a RF switch. One port of the
switch goes to the T/R Connector via a 3 dB pad, 3 way resistive splitter, and the 20 dB power pad.
This attenuator allows the T/R Connector to accept signal levels up to 20 W directly into the Test Set.
The other port of the RF switch is input to a second RF switch which steers the signal to either the
ANT Connector or the SWR circuit. When the ANT Connector is selected, the signal passes through
another RF switch to insure sufficient isolation and is coupled to the ANT Connector through the ANT
Connector protection relay.
Connected to the ANT and SWR Connectors are the connector protection circuits. These circuits are
designed to protect the rest of the circuitry from damage if a high power signal is inadvertently input
to either of these connectors. If the signal level input to either connector is to high, the signal level
is detected by diode detector and the mechanical relay at the connector is opened. Additionally a
signal is sent to the software via the Multi-Function PCB Assy that alerts the operator that an
overload condition exists.
The SWR Connector can be used to measure SWR and Distance to Fault (DTF) or as a generate
connector providing up to -5 dBm output. When SWR or DTF testing is selected, the signal is
amplified and passes through a 6 dB pad to insure a good match at the SWR Connector. The signal
then goes through two directional couplers and the SWR connector protection relay. The coupler
couples off the forward and reverse power at the SWR Connector. The coupled signals are input to a
dual Log Amp that outputs video signal proportional to the amplitude and phase difference of the
forward and reverse power. From these measurement the software can calculate the SWR of the
UUT. It is necessary to calibrate the SWR circuitry by connecting a short, an open and a 50 Ω
termination to the end of the cable connected to the UUT.
When the 3500 / 3500A is in a Receive Mode, either Transmitter Test or Duplex Test, the signal may
be input to the T/R or ANT.