DetailedService Manual

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CA, Motorola, Professional Radio, PRO Series and PRO Modelnumbers and HT Series and HT Model numbers are marks ofMotorola, Inc. LTR is a registered trademark of E.F. JohnsonCompany. Transcrypt is a registered trademark of TranscryptInternational, Inc. PassPort is a registered trademark of TridentMicro Systems, Inc.© 2000, 2001 Motorola, Inc. All rights reserved. Printed in U.S.A.

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Portable Radios

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SAFETY AND GENERAL INFORMATION

IMPORTANT INFORMATION ON SAFE AND EFFICIENT OPERATION

READ THIS INFORMATION BEFORE USING YOUR TWO-WAY RADIO

The information provided in this document supersedes the general safety information contained in userguides published prior to July 2000. For information regarding radio use and hazardous atmosphere pleaserefer to the Factory Mutual (FM) Approval Manual Supplement or Instruction Card, which is included withradio models that offer this capability.

RF Operational Characteristics

Your radio contains a transmitter and a receiver. When it is ON, it receives and transmits radio frequency (RF)energy.

Exposure To Radio Frequency Energy

Your Motorola Two-Way Radio, is designed to comply with the following National and International Standards andGuidelines regarding exposure of human beings to radio frequency electromagnetic energy (EME):

• United States Federal Communications Commission, Code of Federal Regulations(47 CFR part 2 sub-part J).

• American National Standards Institute (ANSI)/Institute of Electrical and Electronic Engineers (IEEE)(C95.1 - 1992)

• Institute of Electrical and Electronic Engineers (IEEE) (C95.1-1999 Edition)

• National Council on Radiation Protection and Measurements (NCRP) of the United States (Report 86,1986)

• International Commission on Non-Ionizing Radiation Protection (ICNRP - 1998)

• National Radiological Protection Board of the United Kingdom (1995)

• Ministry of Health (Canada) Safety Code 6. Limits of Human Exposure to Radio frequency ElectromagneticFields in the Frequency Range from 3 kHz to 300 GHz (1999)

• Australian Communications Authority Radiocommunications (Electromagnetic Radiation - Human Expo-sure) Standard (1999) (applicable to wireless phones only)

PORTABLE RADIO OPERATION AND EME EXPOSURE

To assure optimal radio performance and make sure human exposure to radio frequency electromagneticenergy is within the guidelines set forth in the above standards, always adhere to the following procedures:

Antenna Care

Use only the supplied or an approved replacement antenna. Unauthorized antennas, modifications, orattachments could damage the radio and may violate FCC regulations.

DO NOT hold the antenna when the two-way radio is “IN USE”. Holding the antenna affects call qualityand may cause the radio to operate at a higher power level than needed.

Two-Way Radio Operation

When using your radio as a traditional two-way radio, hold the radio in a vertical position with the microphone one to two inches (2.5 to 5 cm) away from the lips.

MAN WITH RADIO

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Body-Worn Operation

To maintain compliance with FCC RF exposure guidelines, if you wear a radio on your body whentransmitting, always place the radio in a Motorola supplied or approved clip, holder, holster, case, or body harness. Use of non-Motorola-approved accessories may exceed FCC RF exposure guidelines. If you do not use a body-worn accessory, ensure the antenna is at least one inch (2.5 cm) from your body when transmitting.

Data Operation

When using any data feature of the radio, with or without an accessory cable, position the antenna of the radio at least one inch (2.5 cm) from the body.

ELECTROMAGNETIC INTERFERENCE/COMPATIBILITY

Note: Nearly every electronic device is susceptible to electromagnetic interference (EMI) if inadequatelyshielded, designed or otherwise configured for electromagnetic compatibility.

• FACILITIES

To avoid electromagnetic interference and/or compatibility conflicts, turn off your radio in any facility whereposted notices instruct you to do so. Hospitals or health care facilities may be using equipment that issensitive to external RF energy.

• AIRCRAFT

When instructed to do so, turn off your radio when on board an aircraft. Any use of a radio must be inaccordance with applicable regulations per airline crew instructions.

• MEDICAL DEVICES

• Pacemakers

The Health Industry Manufacturers Association recommends that a minimum separation of 6 inches (15cm) be maintained between a handheld wireless radio and a pacemaker. These recommendations areconsistent with the independent research by, and recommendations of, Wireless Technology Research.

Persons with pacemakers should:

• ALWAYS keep the radio more than six inches (15 cm) from their pacemaker when the radio is turned ON.• not carry the radio in the breast pocket.• use the ear opposite the pacemaker to minimize the potential for interference.

• turn the radio OFF immediately if you have any reason to suspect that interference is taking place.

• Hearing Aids

Some digital wireless radios may interfere with some hearing aids. In the event of such interference, youmay want to consult your hearing aid manufacturer to discuss alternatives.

• Other Medical Devices

If you use any other personal medical device, consult the manufacturer of your device to determine if it isadequately shielded from RF energy. Your physician may be able to assist you in obtaining thisinformation.

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SAFETY AND GENERAL

• Use While Driving

Check the laws and regulations on the use of radios in the area where you drive. Always obey them

When using your radio while driving, please:

• Give full attention to driving and to the road.

• Use hands-free operation, if available.

• Pull off the road and park before making or answering a call if driving conditions so require.

OPERATIONAL WARNINGS

• FOR VEHICLES WITH AN AIR BAG

Do not place a portable radio in the area over an air bag or in the air bag deployment area. Air bags inflatewith great force. If a portable radio is placed in the air bag deployment area and the air bag inflates, the radiomay be propelled with great force and cause serious injury to occupants of the vehicle.

• POTENTIALLY EXPLOSIVE ATMOSPHERES

Turn off your radio prior to entering any area with a potentially explosive atmosphere, unless it is a radio typeespecially qualified for use in such areas as “Intrinsically Safe” (for example, Factory Mutual, CSA, or ULApproved). Do not remove, install, or charge batteries in such areas. Sparks in a potentially explosiveatmosphere can cause an explosion or fire resulting in bodily injury or even death.

Note: The areas with potentially explosive atmospheres referred to above include fueling areas such asbelow decks on boats, fuel or chemical transfer or storage facilities, areas where the air containschemicals or particles, such as grain, dust or metal powders, and any other area where you would nor-mally be advised to turn off your vehicle engine. Areas with potentially explosive atmospheres areoften but not always posted.

• BLASTING CAPS AND AREAS

To avoid possible interference with blasting operations, turn off your radio when you are near electricalblasting caps, in a blasting area, or in areas posted: “Turn off two-way radio”. Obey all signs and instructions.

OPERATIONAL CAUTIONS

• ANTENNAS

Do not use any portable radio that has a damaged antenna. If a damaged antenna comes into contactwith your skin, a minor burn can result.

• BATTERIES

All batteries can cause property damage and/or bodily injury such as burns if a conductive material such asjewelry, keys, or beaded chains touch exposed terminals. The conductive material may complete an electricalcircuit (short circuit) and become quite hot. Exercise care in handling any charged battery, particularly whenplacing it inside a pocket, purse, or other container with metal objects.

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Intrinsically Safe Radio Information

FMRC Approved EquipmentAnyone intending to use a radio in a location where hazardous concentrations of flammable materialexist (hazardous atmosphere) is advised to become familiar with the subject of intrinsic safety andwith the National Electric Code NFPA 70 (National Fire Protection Association) Article 500 (hazardous[classified] locations).

An Approval Guide, issued by Factory Mutual Research Corporation (FMRC), lists manufacturers andthe products approved by FMRC for use in such locations. FMRC has also issued a voluntaryapproval standard for repair service (“Class Number 3605”).

FMRC Approval labels are attached to the radio to identify the unit as being FM Approved forspecified hazardous atmospheres. This label specifies the hazardous Class/Division/Group alongwith the part number of the battery that must be used. Depending on the design of the portable unit,this FM label can be found on the back of the radio housing or the bottom of the radio housing.TheirApproval mark is shown below.

Radios must ship from the Motorola manufacturing facility with the hazardous atmosphere capability and FM Approval labeling. Radios will not be “upgraded” to this capability and labeled in the field.

A modification changes the unit’s hardware from its original design configuration. Modifications canonly be done by the original product manufacturer at one of its FMRC audited manufacturing facilities.

Unauthorized or incorrect modification of an FMRC Approved Product unit will negate the Approvalrating of the product.

WARNING: Do not operate radio communications equipment in a hazardous atmosphere unless it is a type especially qualified (e.g. FMRC Approved) for such use. An explosion or fire may result.

WARNING: Do not operate the FMRC Approved Product in a hazardous atmosphere if it has been physically damaged (e.g. cracked housing). An explosion or fire may result.

WARNING: Do not replace or charge batteries in a hazardous atmosphere. Contact sparking may occur while installing or removing batteries and cause an explosion or fire.

WARNING: Do not replace or change accessories in a hazardous atmosphere. Contact sparking may occur while installing or removing accessories and cause an explosion or fire.

WARNING: Do not operate the FMRC Approved Product unit in a hazardous location with the accessory contacts exposed. Keep the connector cover in place when accessories are not used.

WARNING: Turn radio off before removing or installing a battery or accessory.

WARNING: Do not disassemble the FMRC Approved Product unit in any way that exposes the internal electrical circuits of the unit.

WARNING: Failure to use an FMRC Approved Product unit with an FMRC Approved battery or FMRC Approved accessories specifically approved for that product may result in the dan-gerously unsafe condition of an unapproved radio combination being used in a hazardous location.

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APPROVED

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Repair of FMRC Approved Products

REPAIRS FOR MOTOROLA FMRC APPROVED PRODUCTS ARE THE RESPONSIBILITY OF THE USER.

You should not repair or relabel any Motorola manufactured communication equipment bearing theFMRC Approval label (FMRC Approved Product) unless you are familiar with the current FMRCApproval standard for repairs and service (Class Number 3605).

You may want to consider using a repair facility that operates under 3605 repair service approval.

FMRC’s Approval Standard Class Number 3605 is subject to change at any time without notice toyou, so you may want to obtain a current copy of 3605 from FMRC. Per the December, 1994publication of 3605, some key definitions and service requirements are as follows:

RepairA repair constitutes something done internally to the unit that would bring it back to its originalcondition Approved by FMRC. A repair should be done in an FMRC Approved facility.

Items not considered as repairs are those in which an action is performed on a unit which does notrequire the outer casing of the unit to be opened in a manner which exposes the internal electricalcircuits of the unit. You do not have to be an FMRC Approved Repair Facility to perform these actions.

RelabelingThe repair facility shall have a method by which the replacement of FMRC Approval labels arecontrolled to ensure that any relabeling is limited to units that were originally shipped from theManufacturer with an FM Approval label in place. FMRC Approval labels shall not be stocked by therepair facility. An FMRC Approval label shall be ordered from the original manufacturer as needed torepair a specific unit. Replacement labels may be obtained and applied by the repair facility providingsatisfactory evidence that the unit being relabeled was originally an FMRC Approved unit. Verificationmay include, but is not limited to: a unit with a damaged Approval label, a unit with a defective housingdisplaying an Approval label, or a customer invoice indicating the serial number of the unit andpurchase of an FMRC Approved model.

Do Not Substitute Options or AccessoriesThe Motorola communications equipment certified by Factory Mutual is tested as a system andconsists of the FM Approved portable, FM Approved battery, and FM Approved accessories oroptions, or both. This Approved portable and battery combination must be strictly observed. Theremust be no substitution of items, even if the substitute has been previously Approved with a differentMotorola communications equipment unit. Approved configurations are listed in the FM Approvalguide published by FMRC, or in the product FM Supplement. This FM Supplement is shipped with FMApproved radio and battery combination from the manufacturer. The Approval guide, or the Approvalstandard Class Number 3605 document for repairs and service, can be ordered directly throughFactory Mutual Research Corporation located in Norwood, Massachusetts.

WARNING: Incorrect repair or relabeling of any FMRC Approved Product unit could adversely affect the Approval rating of the unit.

WARNING: Use of a radio that is not intrinsically safe in a hazardous atmosphere could result in serious injury or death.

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Table of Contents

Chapter 1 Introduction

1.1 Scope of Manual ........................................................................................................... 1-11.2 Warranty and Service Support..................................................................................... 1-1

1.2.1 Warranty Period................................................................................................................... 1-11.2.2 Return Instructions .............................................................................................................. 1-11.2.3 After Warranty Period .......................................................................................................... 1-1

1.3 Related Documents ...................................................................................................... 1-21.4 Technical Support......................................................................................................... 1-2

1.4.1 Piece Parts Availability ........................................................................................................ 1-21.5 Radio Model Chart and Specifications........................................................................ 1-31.6 Radio Model Information .............................................................................................. 1-3

Chapter 2 Theory of Operation

2.1 Introduction ................................................................................................................... 2-12.2 Radio Power Distribution ............................................................................................. 2-1

Figure 2-1:DC Power Distribution Block Diagram ............................................................. 2-12.3 Keypad ........................................................................................................................... 2-2

Figure 2-2:Keypad Block Diagram .................................................................................... 2-22.4 Controller Board ........................................................................................................... 2-3

Figure 2-3:Controller Block Diagram................................................................................. 2-32.4.1 MCU Digital ......................................................................................................................... 2-32.4.1 Real Time Clock .................................................................................................................. 2-42.4.2 Circuit Description ............................................................................................................... 2-4Figure 2-4:RTC Circuit ...................................................................................................... 2-42.4.1 MODB/VSTBY Supply ......................................................................................................... 2-42.4.1 Audio/Signaling.................................................................................................................... 2-5

2.5 UHF Transmitter ............................................................................................................ 2-5Figure 2-5:UHF Transmitter Block Diagram...................................................................... 2-52.5.1 Power Amplifier (PA) ........................................................................................................... 2-52.5.2 Antenna Switch.................................................................................................................... 2-62.5.3 Harmonic Filter .................................................................................................................... 2-62.5.4 Antenna Matching Network ................................................................................................. 2-62.5.5 Power Control Integrated Circuit (PCIC) ............................................................................. 2-62.5.6 Temperature Cut Back Circuit ............................................................................................. 2-6

2.6 UHF Receiver................................................................................................................. 2-6Figure 2-6:UHF Receiver Block Diagram.......................................................................... 2-72.6.1 Receiver Front-End ............................................................................................................. 2-72.6.2 Receiver Back-End.............................................................................................................. 2-82.6.3 Automatic Gain Control (AGC) ............................................................................................ 2-82.6.4 Frequency Generation Circuit.............................................................................................. 2-9Figure 2-7:UHF Frequency Generation Unit Block Diagram............................................. 2-9

2.7 Synthesizer .................................................................................................................... 2-9Figure 2-8:UHF Synthesizer Block Diagram ................................................................... 2-10

2.8 Voltage Control Oscillator (VCO)............................................................................... 2-10Figure 2-9:UHF VCO Block Diagram .............................................................................. 2-11

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2.9 VHF Transmitter.......................................................................................................... 2-12Figure 2-10:VHF Transmitter Block Diagram.................................................................. 2-122.9.1 Power Amplifier.................................................................................................................. 2-122.9.2 Antenna Switch.................................................................................................................. 2-122.9.3 Harmonic Filter .................................................................................................................. 2-132.9.4 Antenna Matching Network................................................................................................ 2-132.9.5 Power Control Integrated Circuit (PCIC)............................................................................ 2-13

2.10 VHF Receiver............................................................................................................... 2-13Figure 2-11:VHF Receiver Block Diagram...................................................................... 2-142.10.1 Receiver Front-End............................................................................................................ 2-142.10.2 Receiver Back-End ............................................................................................................ 2-152.10.3 Automatic Gain Control (AGC) .......................................................................................... 2-152.10.4 Frequency Generation Circuit............................................................................................ 2-16Figure 2-12:VHF Frequency Generation Unit Block Diagram......................................... 2-16

2.11 Synthesizer.................................................................................................................. 2-16Figure 2-13:VHF Synthesizer Block Diagram ................................................................. 2-17

2.12 Voltage Control Oscillator (VCO) .............................................................................. 2-17Figure 2-14:VHF VCO Block Diagram ............................................................................ 2-18

2.13 Low Band Transmitter ................................................................................................ 2-19Figure 2-15:Low Band Transmitter Block Diagram......................................................... 2-192.13.1 Power Amplifier (PA) ......................................................................................................... 2-192.13.2 Antenna Switch.................................................................................................................. 2-192.13.3 Harmonic Filter .................................................................................................................. 2-202.13.4 Antenna Matching Transformer ......................................................................................... 2-202.13.5 Power Control Integrated Circuit (PCIC)............................................................................ 2-202.13.6 Temperature Cut Back Circuit ........................................................................................... 2-202.13.7 Electrostatic Discharge (ESD) Protection Circuit............................................................... 2-20

2.14 Low Band Receiver..................................................................................................... 2-20Figure 2-16:Low Band Receiver Block Diagram............................................................. 2-212.14.1 Receiver Front-End............................................................................................................ 2-212.14.2 Receiver Back-End ............................................................................................................ 2-222.14.3 Automatic Gain Control (AGC) .......................................................................................... 2-222.14.4 Frequency Generation Circuit............................................................................................ 2-22Figure 2-17:Low Band Frequency Generation Unit Block Diagram................................ 2-23

2.15 Synthesizer.................................................................................................................. 2-23Figure 2-18:Low Band Synthesizer Block Diagram ........................................................ 2-24

2.16 Voltage Control Oscillators (VCO) ............................................................................ 2-242.16.1 Receive VCO..................................................................................................................... 2-242.16.2 Transmit VCO.................................................................................................................... 2-242.16.3 Buffer ................................................................................................................................. 2-242.16.4 Diplexer/Output Filters ....................................................................................................... 2-242.16.5 Prescalar Feedback........................................................................................................... 2-25

2.17 800 MHz Transmitter................................................................................................... 2-25Figure 2-19:800 MHz Transmitter Block Diagram........................................................... 2-252.17.1 Power Amplifier.................................................................................................................. 2-252.17.2 Antenna Switch.................................................................................................................. 2-262.17.3 Harmonic Filter .................................................................................................................. 2-262.17.4 Power Control Integrated Circuit (PCIC)............................................................................ 2-26

2.18 800 MHz Receiver ....................................................................................................... 2-27Figure 2-20:800MHz Receiver Block Diagram ............................................................... 2-272.18.1 Receiver Front-End............................................................................................................ 2-272.18.2 Receiver Back-End ............................................................................................................ 2-28

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2.18.3 Automatic Gain Control Circuit .......................................................................................... 2-282.18.4 Frequency Generation Circuit............................................................................................ 2-29Figure 2-21:800 MHz Frequency Generation Unit Block Diagram.................................. 2-29

2.19 Synthesizer .................................................................................................................. 2-30Figure 2-22:800 MHz Synthesizer Block Diagram .......................................................... 2-302.19.1 Voltage Control Oscillator (VCO)....................................................................................... 2-31Figure 2-23:800 MHz VCO Block Diagram ..................................................................... 2-31

2.20 Trunked Radio Systems ............................................................................................. 2-322.20.1 Privacy Plus Trunked Systems.......................................................................................... 2-322.20.2 LTR™ Trunked Systems ................................................................................................... 2-322.20.3 MPT Trunked Systems ...................................................................................................... 2-322.20.4 PassPort™ Trunked Systems ........................................................................................... 2-33

2.21 900 MHz Transmitter................................................................................................... 2-34Figure 2-24:Transmitter Block Diagram .......................................................................... 2-342.21.1 Power Amplifier ................................................................................................................. 2-352.21.2 Antenna Switch.................................................................................................................. 2-352.21.3 Harmonic Filter .................................................................................................................. 2-352.21.4 Power Control Integrated Circuit (PCIC) ........................................................................... 2-35

2.22 900 MHz Receiver........................................................................................................ 2-36Figure 2-25:900 MHz Receiver Block Diagram............................................................... 2-362.22.1 Receiver Front-End ........................................................................................................... 2-362.22.2 Receiver Back-End............................................................................................................ 2-372.22.3 Hear Clear IC..................................................................................................................... 2-372.22.4 Automatic Gain Control Circuit .......................................................................................... 2-38

2.23 Frequency Generation Circuitry ................................................................................ 2-39Figure 2-26:Frequency Generation Unit Block Diagram ................................................. 2-39

2.24 900 MHz Synthesizer .................................................................................................. 2-40Figure 2-27:Synthesizer Block Diagram.......................................................................... 2-40

2.25 900 MHz Voltage Control Oscillator (VCO) ............................................................... 2-41Figure 2-28:VCO Block Diagram..................................................................................... 2-41

Chapter 3 Maintenance

3.1 Introduction ................................................................................................................... 3-13.3 Inspection ...................................................................................................................... 3-1

3.3.1 Cleaning .............................................................................................................................. 3-13.4 Safe Handling of CMOS and LDMOS........................................................................... 3-23.5 General Repair Procedures and Techniques ............................................................. 3-23.6 Recommended Test Tools ........................................................................................... 3-43.7 Replacing the Circuit Board Fuse ............................................................................... 3-5

Figure 3-1:UHF/VHF/Low Band/800MHz/900MHz Circuit Board Fuse Locations ............ 3-63.2 Removing and Reinstalling the Circuit Board............................................................ 3-7

Figure 3-2:Circuit Board Removal and Reinstallation ....................................................... 3-73.3 Power Up Self-Test Error Codes.................................................................................. 3-73.4 UHF Troubleshooting Charts ....................................................................................... 3-9

Troubleshooting Flow Chart for Controller........................................................................................ 3-9Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 3-10Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 3-11Troubleshooting Flow Chart for Transmitter ................................................................................... 3-12Troubleshooting Flow Chart for Synthesizer .................................................................................. 3-13Troubleshooting Flow Chart for VCO ............................................................................................. 3-14

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3.5 VHF Troubleshooting Charts ..................................................................................... 3-15Troubleshooting Flow Chart for Controller ...................................................................................... 3-15Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 3-16Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 3-17Troubleshooting Flow Chart for Transmitter ................................................................................... 3-18Troubleshooting Flow Chart for Synthesizer................................................................................... 3-19Troubleshooting Flow Chart for VCO.............................................................................................. 3-20

3.6 Low Band Troubleshooting Charts ........................................................................... 3-21Troubleshooting Flow Chart for Controller ...................................................................................... 3-21Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 3-22Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 3-23Troubleshooting Flow Chart for Transmitter ................................................................................... 3-24Troubleshooting Flow Chart for Synthesizer................................................................................... 3-25Troubleshooting Flow Chart for VCO.............................................................................................. 3-26

3.7 800 MHz Troubleshooting Charts.............................................................................. 3-27Troubleshooting Flow Chart for Controller ...................................................................................... 3-27Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 3-28Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 3-29Troubleshooting Flow Chart for Transmitter ................................................................................... 3-30Troubleshooting Flow Chart for Synthesizer................................................................................... 3-31Troubleshooting Flow Chart for VCO.............................................................................................. 3-32

3.8 PassPort Trunking Troubleshooting Chart .............................................................. 3-333.9 Keypad Troubleshooting Chart ................................................................................. 3-343.10 900 MHz Troubleshooting Charts.............................................................................. 3-35

Troubleshooting Flow Chart for Controller (Sheet 1 of 2) ............................................................... 3-35Troubleshooting Flow Chart for Controller (Sheet 2 of 2) ............................................................... 3-36Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 3-37Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 3-38Troubleshooting Flow Chart for Transmitter ................................................................................... 3-39Troubleshooting Flow Chart for Synthesizer................................................................................... 3-40Troubleshooting Flow Chart for VCO.............................................................................................. 3-40

Chapter 4 Schematic Diagrams, Overlays, and Parts Lists

4.1 Introduction................................................................................................................... 4-14.1.1 Notes For All Schematics and Circuit Boards...................................................................... 4-1

4.2 Flex Layout .................................................................................................................... 4-2Figure 4-1:Keypad-Controller Interconnect Flex ............................................................... 4-24.2.1 Keypad-Controller Interconnect Flex Schematic ................................................................. 4-3Figure 4-2:Keypad-Controller Interconnect Flex Schematic Diagram............................... 4-34.2.2 Keypad-Controller Interconnect Flex Parts List ................................................................... 4-34.2.3 Universal Flex Connector ................................................................................................... 4-4Figure 4-3:Universal Flex Connector ................................................................................ 4-44.2.4 Universal Connector Flex Schematic................................................................................... 4-5Figure 4-4:Universal Flex Connector Schematic Diagram................................................ 4-54.2.5 Universal Flex Connector Parts List .................................................................................... 4-54.2.6 Keypad Top and Bottom Overlays....................................................................................... 4-6Figure 4-5:Keypad Top and Bottom Board Overlays ........................................................ 4-6Figure 4-6:Keypad Board (5000 and 7000 Series) Schematic Diagram.......................... 4-7Figure 4-7:9000 Series Keypad Top and Bottom Board Overlays................................... 4-9Figure 4-8:9000 Series Keypad Board Schematic Diagram ........................................... 4-10

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Figure 4-9:VHF/UHF Complete Controller Schematic Diagram...................................... 4-13Figure 4-10:VHF/UHF Controller ASFIC/ON_OFF Schematic Diagram ......................... 4-14Figure 4-11: VHF/UHF Controller ASFIC/ON_OFF Schematic Diagram ........................ 4-15Figure 4-12:VHF/UHF Controller Micro Processor Schematic Diagram ......................... 4-16Figure 4-13:VHF/UHF Controller Micro Processor Schematic Diagram ......................... 4-17Figure 4-14:Controller Memory Schematic Diagram....................................................... 4-18Figure 4-15:Controller Audio Power Amplifier Schematic Diagram ................................ 4-19Figure 4-16:Controller Interface Schematic Diagram...................................................... 4-20Figure 4-17:UHF (403-470MHz) 5000/7000 Series Main Board Top SidePCB 8480450Z03............................................................................................................ 4-21Figure 4-18:UHF (403-470MHz) 5000/7000 Series Main Board Bottom SidePCB 8480450Z03............................................................................................................ 4-22Figure 4-19:UHF (403-470MHz) 5000/7000 Series Main Board Top SidePCB 8480450Z13............................................................................................................ 4-23Figure 4-20:UHF (403-470MHz) 5000/7000 Series Main Board Bottom SidePCB 8480450Z13............................................................................................................ 4-24Figure 4-21:UHF (403-470MHz) Controls and Switches Schematic Diagram ................ 4-25Figure 4-22:UHF (403-470MHz) Receiver Front End Schematic Diagram ..................... 4-26Figure 4-23:UHF (403-470MHz) Receiver Back End Schematic Diagram ..................... 4-27Figure 4-24:UHF (403-470MHz) Synthesizer Schematic Diagram ................................. 4-28Figure 4-25:UHF (403-470MHz) Voltage Controlled Oscillator Schematic Diagram ...... 4-29Figure 4-26:UHF (403-470MHz) Transmitter Schematic Diagram.................................. 4-30Figure 4-27:UHF (403-470MHz) 9000 Series Main Board Top Side PCB ...................... 4-39Figure 4-28:UHF (403-470MHz) 9000 Series Main Board Bottom Side PCB................. 4-40Figure 4-29:UHF (403-470MHz) Controls and Switches Schematic Diagram ................ 4-41Figure 4-30:UHF (403-470MHz) Receiver Front End Schematic Diagram ..................... 4-42Figure 4-31:UHF (403-470MHz) Receiver Back End Schematic Diagram ..................... 4-43Figure 4-32:UHF (403-470MHz) Synthesizer Schematic Diagram ................................. 4-44Figure 4-33:UHF (403-470MHz) Voltage Controlled Oscillator Schematic Diagram ...... 4-45Figure 4-34:UHF (403-470MHz) Transmitter Schematic Diagram.................................. 4-46Figure 4-35:UHF (450-527MHz) 5000/7000 Series Main Board Top SidePCB 8485641Z02............................................................................................................ 4-51Figure 4-36:UHF (450-527MHz) 5000/7000 Series Main Board Bottom SidePCB 8485641Z02............................................................................................................ 4-52Figure 4-37:UHF (450-527MHz) 5000/7000 Series Main Board Top SidePCB 8485641Z06............................................................................................................ 4-53Figure 4-38:UHF (450-527MHz) 5000/7000 Series Main Board Bottom SidePCB 8485641Z06............................................................................................................ 4-54Figure 4-39:UHF (450-527MHz) Controls and Switches Schematic Diagram ................ 4-55Figure 4-40:UHF (450-527MHz) Receiver Front End Schematic Diagram ..................... 4-56Figure 4-41:UHF (450-527MHz) Receiver Back End Schematic Diagram ..................... 4-57Figure 4-42:UHF (450-527MHz) Synthesizer Schematic Diagram ................................. 4-58Figure 4-43:UHF (450-527MHz) Voltage Controlled Oscillator Schematic Diagram ...... 4-59Figure 4-44:UHF (450-527MHz) Transmitter Schematic Diagram.................................. 4-60Figure 4-45:UHF (450-527MHz) 9000 Series Main Board Top Side PCB ...................... 4-69Figure 4-46:UHF (450-527MHz) 9000 Series Main Board Bottom Side PCB................. 4-70Figure 4-47:UHF (450-527MHz) Controls and Switches Schematic Diagram ................ 4-71Figure 4-48:UHF (450-527MHz) Receiver Front End Schematic Diagram ..................... 4-72Figure 4-49:UHF (450-527MHz) Receiver Back End Schematic Diagram ..................... 4-73Figure 4-50:UHF (450-527MHz) Synthesizer Schematic Diagram ................................. 4-74

xii

Figure 4-51:UHF (450-527MHz) Voltage Controlled Oscillator Schematic Diagram ...... 4-75Figure 4-52:UHF (450-527MHz) Transmitter Schematic Diagram.................................. 4-76Figure 4-53:UHF (450-527MHz) Voice Storage Schematic Diagram ............................. 4-77Figure 4-54:VHF (136-174MHz) Main Board Top Side PCB 8486062B09..................... 4-83Figure 4-55:VHF (136-174MHz) Main Board Bottom Side PCB 8486062B09................ 4-84Figure 4-56:VHF (136-174MHz) Controls and Switches Schematic Diagram ............... 4-85Figure 4-57:VHF (136-174MHz)Receiver Front End Schematic Diagram ..................... 4-86Figure 4-58:VHF (136-174MHz)Receiver Back End Schematic Diagram ...................... 4-87Figure 4-59:VHF (136-174MHz)Synthesizer Schematic Diagram ................................. 4-88Figure 4-60:VHF (136-174MHz)Voltage Controlled Oscillator Schematic Diagram ....... 4-89Figure 4-61:VHF (136-174MHz)Transmitter Schematic Diagram................................... 4-90Figure 4-62:VHF (136-174MHz) 5000/7000 Series Main Board Top SidePCB 8486062B12 ........................................................................................................... 4-95Figure 4-63:VHF (136-174MHz) 5000/7000 Series Main Board Bottom SidePCB 8486062B12 ........................................................................................................... 4-96Figure 4-64:VHF (136-174MHz) 5000/7000 Series Main Board Top SidePCB 8486062B16 ........................................................................................................... 4-97Figure 4-65:VHF (136-174MHz) 5000/7000 Series Main Board Bottom SidePCB 8486062B16 ........................................................................................................... 4-98Figure 4-66:VHF (136-174MHz) Controls and Switches Schematic Diagram ................ 4-99Figure 4-67:VHF (136-174MHz) Receiver Front End Schematic Diagram ................... 4-100Figure 4-68:VHF (136-174MHz) Receiver Back End Schematic Diagram ................... 4-101Figure 4-69:VHF (136-174MHz) Synthesizer Schematic Diagram ............................... 4-102Figure 4-70:VHF (136-174MHz) Voltage Controlled Oscillator Schematic Diagram .... 4-103Figure 4-71:VHF (136-174MHz) Transmitter Schematic Diagram................................ 4-104Figure 4-72:VHF (136-174MHz) 9000 Series Main Board Top Side PCB .................... 4-113Figure 4-73:VHF (136-174MHz) 9000 Series Main Board Bottom Side PCB............... 4-114Figure 4-74:VHF (136-174MHz) Controls and Switches Schematic Diagram .............. 4-115Figure 4-75:VHF (136-174MHz) Receiver Front End Schematic Diagram ................... 4-116Figure 4-76:VHF (136-174MHz) Receiver Back End Schematic Diagram ................... 4-117Figure 4-77:VHF (136-174MHz) Synthesizer Schematic Diagram ............................... 4-118Figure 4-78:VHF (136-174MHz) Voltage Controlled Oscillator Schematic Diagram .... 4-119Figure 4-79:VHF (136-174MHz) Transmitter Schematic Diagram................................ 4-120Figure 4-80:Low Band (29.7-42/35-50MHz) Main Board Top Side PCB ...................... 4-125Figure 4-81:Low Band (29.7-42/35-50MHz) Main Board Bottom Side PCB................. 4-126Figure 4-82:Low Band (30-50MHz) Controls and Switches Diagram ........................... 4-127Figure 4-83:Low Band (29.7-42/35-50MHz) Controller OverallSchematic Diagram....................................................................................................... 4-128Figure 4-84:Low Band (29.7-42/35-50MHz) Controller MemorySchematic Diagram....................................................................................................... 4-129Figure 4-85:Low Band (29.7-42/35-50MHz) Controller AFSICSchematic Diagram....................................................................................................... 4-130Figure 4-86:Low Band (29.7-42/35-50MHz) Controller MicroprocessorSchematic Diagram....................................................................................................... 4-131Figure 4-87:Low Band (29.7-42/35-50MHz) Controller Audio PASchematic Diagram....................................................................................................... 4-132Figure 4-88:Low Band (29.7-42/35-50MHz) Receiver Front EndSchematic Diagram....................................................................................................... 4-133Figure 4-89:Low Band (29.7-42/35-50MHz) Receiver Back EndSchematic Diagram....................................................................................................... 4-134

xiii

Figure 4-90:Low Band (29.7-42/35-50MHz) Frequency GenerationUnit Synthesizer ............................................................................................................ 4-135Figure 4-91:Lowband (29.7-42/35-50MHz) Frequency Generation UnitVCO Diagram................................................................................................................ 4-136Figure 4-92:Lowband (29.7-42/35-50MHz) Transmitter Schematic Diagram ............... 4-137Figure 4-93:800MHz (806-870MHz) Main Board Top Side PCB 84860641Z02 ........... 4-141Figure 4-94:800MHz (806-870MHz) Main Board Bottom Side PCB 84860641Z02...... 4-142Figure 4-95: 800MHz Popular/Preferred (806-870MHz) Main Board Top SidePCB 8480641Z03 (Rev B) ............................................................................................ 4-143Figure 4-96:800MHz Popular/Preferred (806-870MHz) Main Board Bottom SidePCB 8480641Z03 (Rev B) ............................................................................................ 4-144Figure 4-97:800MHz Complete Controller .................................................................... 4-145Figure 4-98: 800MHz Controller ASFIC/ON_OFF......................................................... 4-146Figure 4-99: 800MHz Controller Micro Processor......................................................... 4-147Figure 4-100: 800MHz Controller Memory.................................................................... 4-148Figure 4-101: 800MHz Controller Audio Power Amplifier ............................................. 4-149Figure 4-102: 800MHz Controller Interface................................................................... 4-150Figure 4-103:800MHz Controls and Switches Schematic Diagram .............................. 4-151Figure 4-104:800MHz Receiver Front End Schematic Diagram................................... 4-152Figure 4-105:800MHz Receiver Back End Schematic Diagram ................................... 4-153Figure 4-106:800MHz Synthesizer Schematic Diagram............................................... 4-154Figure 4-107:800MHz Voltage Controlled Oscillator Schematic Diagram .................... 4-155Figure 4-108:800MHz Transmitter Schematic Diagram (Rev A) .................................. 4-156Figure 4-109:800MHz Transmitter Schematic Diagram (Rev B) .................................. 4-157Figure 4-110:PassPort Trunking Controller PCB Board Side 1 & 2.............................. 4-161Figure 4-111:PassPort Controller Schematic Diagram ................................................ 4-162Figure 4-112:900MHz (896-941MHz) Main Board Top Side PCB 8485910Z01........... 4-163Figure 4-113:900MHz (896-941MHz) Main Board Bottom Side PCB 8485910Z01...... 4-164Figure 4-114:900MHz Complete Controller .................................................................. 4-165Figure 4-115:900MHz Controller ASFIC/ON_OFF........................................................ 4-166Figure 4-116:900MHz Controller Microprocessor ......................................................... 4-167Figure 4-117:900MHz Controller Memory..................................................................... 4-168Figure 4-118:900MHz Controller Audio Power Amplifier .............................................. 4-169Figure 4-119:900MHz Controller Interface.................................................................... 4-170Figure 4-120:900MHz Controls and Switches Schematic Diagram .............................. 4-171Figure 4-121:900MHz Receiver Front End Schematic Diagram................................... 4-172Figure 4-122:900MHz Receiver Back End Schematic Diagram ................................... 4-173Figure 4-123:900MHz Synthesizer Schematic Diagram ............................................... 4-174Figure 4-124:900MHz Hear/Clear Schematic Diagram................................................. 4-175Figure 4-125:900MHz Voltage Controlled Oscillator Schematic Diagram .................... 4-176Figure 4-126:900MHz Transmitter Schematic Diagram................................................ 4-177

xiv

1-1

Chapter 1

Introduction

1.1 Scope of ManualThis manual is intended for use by service technicians familiar with similar types of equipment. Itcontains service information required for the equipment described and is current as of the printingdate. Changes that occur after the printing date are incorporated by a complete manual revision oralternatively, as additions.

1.2 Warranty and Service SupportMotorola offers long term support for its products. This support includes full exchange and/or repair ofthe product during the warranty period, and service/repair or spare parts support out of warranty. Any“return for exchange” or “return for repair” by an authorized Motorola dealer must be accompanied bya warranty claim form. Warranty claim forms are obtained by contacting customer service.

1.2.1 Warranty Period

The terms and conditions of warranty are defined fully in the Motorola dealer or distributor or resellercontract. These conditions may change from time to time and the following notes are for guidancepurposes only.

1.2.2 Return Instructions

In instances where the product is covered under a “return for replacement” or “return for repair”warranty, a check of the product should be performed prior to shipping the unit back to Motorola. Thisis to ensure that the product has been correctly programmed or has not been subjected to damageoutside the terms of the warranty.

Prior to shipping any radio back to a Motorola warranty depot, please contact the appropriatecustomer service for instructions. All returns must be accompanied by a warranty claim form,available from your customer services representative. Products should be shipped back in the originalpackaging, or correctly packaged to ensure no damage occurs in transit.

1.2.3 After Warranty Period

After the Warranty period, Motorola continues to support its products in two ways:

First, Motorola's Accessories and Aftermarket Division (ADD) offers a repair service to both end usersand dealers at competitive prices.

Second, Motorola’s service department supplies individual parts and modules that can be purchasedby dealers who are technically capable of performing fault analysis and repair.

NOTE Before operating or testing these units, please read the Safety Information Section in thefront of this manual.

1-2 Related Documents

1.3 Related DocumentsThe following documents are directly related to the use and maintainability of this product.

1.4 Technical SupportTechnical support is available to assist the dealer/distributor and self-maintained customers inresolving any malfunction which may be encountered. Initial contact should be by telephone tocustomer resources wherever possible. When contacting Motorola technical support, be prepared toprovide the product model number and the unit’s serial number. The contact locations and telephonenumbers are located in the Basic Service Manual listed under the Related Documents paragraph ofthis chapter.

1.4.1 Piece Parts Availability

Some replacement parts, spare parts, and/or product information can be ordered directly. If acomplete Motorola part number is assigned to the part, and it is not identified as “Depot ONLY”, thepart is available from Motorola Accessories and Aftermarket Division (AAD). If no part number isassigned, the part is not normally available from Motorola. If the part number is appended with anasterisk, the part is serviceable by a Motorola depot only. If a parts list is not included, this generallymeans that no user-serviceable parts are available for that kit or assembly.

Table 1-1

Title Part Number

Professional Radio Portable Level 1&2 BasicService Manual- EnglishProfessional Radio Portable Level 1&2 BasicService Manual- SpanishProfessional Radio Portable Level 1&2 BasicService Manual- PortugueseProfessional Radio Portable Service ManualLevel 3 -EnglishProfessional Radio Portable Service ManualLevel 3 -SpanishProfessional Radio Portable Service ManualLevel 3 -Portuguese

68P81088C45

68P81088C47

68P81088C49

68P81088C46

68P81088C48

68P81088C50

Radio Model Chart and Specifications 1-3

1.5 Radio Model Chart and SpecificationsThe radio model charts and specifications are located in the Basic Service Manual listed under theRelated Documents paragraph of this chapter.

1.6 Radio Model InformationThe model number and serial number are located on a label attached to the back of your radio. Youcan determine the RF output power, frequency band, protocols, and physical packages from thesenumbers. The example below shows one portable radio model number and its specific characteristics

Parts Order Entry7:00 A. M. to 7:00 P. M. (Central StandardTime)Monday through Friday (Chicago, U. S. A.)

To Order Parts in the United States of America:1-800-422-4210, or 847-538-80231-800-826-1913, or 410-712-6200 (U. S.Federal Government)TELEX: 280127FAX: 1-847-538-8198FAX: 1-410-712-4991 (U. S. FederalGovernment)(U. S. A.) after hours or weekends:1-800-925-4357

To Order Parts in Latin America and the Caribbean:1-847-538-8023

Motorola PartsAccessories and Aftermarket Division(United States and Canada)Attention: Order Processing1313 E. Algonquian RoadSchaumburg, IL 60196

Accessories and Aftermarket Division Attention: Latin America and Caribbean

Order Processing1313 E. Algonquian RoadSchaumburg, IL 60196

Parts Identification1-847-538-0021 (Voice)1-847-538-8194 (FAX)

1-4 Radio Model Information

.

Table 1-2 Radio Model Number

Example: AAH25KC9AA2 and LAH25KDC9AA3

Type of Unit

Model Series

Freq. Band

Power Level

Physical Packages

Channel Spacing

ProtocolFeature Level

ModelRevision

Model Package

AA orLA

H 25 KVHF(136-

174MHz)

C2.5W

CNo Display

9Program-

mable

AAConventional

22F for AA4F for LA

A N

RUHF1(403-

470MHz)

D4-5W

DKeypad

625 kHz

DULTR

316F

SUHF2(450-

527MHz)

E6W

H1-Line Dis-

play

CKMPT

5256F

LTR forAA only

BLow Band,R1 (29.7-42.0MHz)

N4-Line Dis-

play

GBPrivacy Plus

6128F256FLTR

CLow Band,R2 (35.0-50.0MHz)

GEPrivacy Plus

Roaming

8160F

U800MHz

(806-824)(851-

869MHz)

DPPassPort

FCSmart Zone

AA

or

LA

=M

otor

ola

Inte

rnal

Use

H=

Por

tabl

e

2-1

Chapter 2

Theory of Operation

2.1 IntroductionThis chapter provides a detailed theory of operation for the radio components. Schematic diagramsfor the circuits described in the following paragraphs are located in Figures 4-1 through 4-120.

2.2 Radio Power DistributionA block diagram of the DC power distribution throughout the radio board is shown in Figure 2-1. A7.5V battery supplies the basic radio power (UNSWB) directly to the electronic on/off control, audiopower amplifier, 3.5V regulator, power amplifier automatic level control (ALC), and low battery detectcircuit. When the radio on/off/volume control is turned on, the switched SWB+ is applied to the variousradio power regulators, antenna switch, accessories 20-pin connector, keypad/option board, andtransmit LED. The Vdda signal from the 3.3V Vdda regulator supplies the microprocessor withoperating power. The Vdd regulator scheme is listed by band in Table 2-1. Data is then sent to thecontroller ASFIC to turn on a DAC which takes over the momentary-on path within 12ms. The SWB+signal supplies power until the radio is turned off. Jumpers for configuring the Vdda and Vdddregulators are shown in Figure 2-1 and described in Table 2-2.

The radio turns off when either of the two following conditions occur:

• Radio on/off/volume control is turned off.• Low battery condition is detected.

If a low battery level is detected by the microprocessor through either of the above conditions, theradio personality data is stored to EEPROM prior to turning off.

Figure 2-1: DC Power Distribution Block Diagram

SWB+

Fuse

Low BatteryDetect

AntennaSwitch

PA, DriverPCIC(ALC)

LI Ion

3.5VReg.

AudioPower

Amplifier 4.0V/3.3V

ASFIC_CMP VCOBIC FRACTN LVZIF

LCDDriver

5V

MECH.SWB+

UNSWB+

Int/Ext Vdd

Vdda

Accessories20 pin Connector

Keypad/Option Board

Prime Expansion Board

SwitchingRegulator

Vdda

MCU, ROMand EEPROM

TxLed

Control

7.5VBattery

VdddRegulator

VddaRegulator

5VRegulator

On/OffSwitch

RF, AMP, IF AMPExt. RX.

Buffer (NU)

2-2

R = Regulator Jumper

2.3 KeypadThe keypad block diagram is shown in Figure 2-2. The comparator compares the voltage when anyone of the keypad row or keypad column keys is pressed. Pressing a key sends a message to themicroprocessor through the output (KEY_INT) line signifying that a key has been pressed. Themicroprocessor then samples the analog to digital voltages at the keypad row and keypad column,then makes a comparison with a map table to identify the key pressed. Once the key is identified, acorresponding message is displayed.

The LED_EN is set by the codeplug. When the value is set to low, the LED lights up during power up.A high codeplug setting disables this feature.

Figure 2-2: Keypad Block Diagram

Table 2-1 VDD Regulator Scheme by Band

BandVdd

Regulator Scheme

Low Band Dual

VHF Dual

UHF Dual

800 MHz Dual

900 MHz Dual

Table 2-2 Radio Jumpers

JumpersDual Vdd Regulator Scheme

Single Vdd Regulator Scheme

R401 Y Y

R402 N N

R403 N Y

R404 N N

R405 Y N

40 Pin Connector

ComparatorKeypadButtonLED

Display 18 PinConnector

Key_Int

Keypad Column

KeypadRow

Data

2-3

2.4 Controller BoardThe controller board is the central interface between the various radio functions. It is separated intoMCU digital and audio/signalling functions as shown in Figure 2-3.

Figure 2-3: Controller Block Diagram

2.4.1 MCU Digital

The digital portion of the controller consists of a microcontroller and associated EEPROM, RAM, andROM memories. Combinations of different size RAM and ROM are available to support variousapplication software. RAM supports 8KB and 32KB sizes. ROM supports 128KB, 256KB, and 512KBsizes. Table 2-3 lists the ROM, RAM and EEPROM requirements for different radios.

Table 2-3 Radio Memory Requirements

PROTOCOL FEATURE LEVEL ROM (KB)EXT RAM

(KB)EEPROM

(KB)

AA,DU 2 or 3 128 - 8

AA,DU 6 128 - 16

CK, GB, GE, FC - 512 32 16

ExternalMicrophone

InternalMicrophone

ExternalSpeaker

InternalSpeaker

SCI to SideConnector

Audio/Signalling

To SynthesizerMod Out

16.8 / 17.0 MHzReference Clockfrom Synthesizer

Recovered AudioSquelch

SPI

MCU Digital

RAM

EEPROM

ROM

Microcontroller

ASFIC

3.3VRegulator

(Vdda)

3.3VRegulator

(Vddd)

Audio PowerAmplifier/Filter

CLKTo RF Board

2-4

2.4.1 Real Time Clock

Radios with displays support a real time clock (RTC) module for purposes of message time stampingand time keeping. The RTC module resides in the microcontroller. The clock uses a back-up lithium-Ion battery for operating power when the primary battery is removed.

2.4.2 Circuit Description

The RTC module circuit, shown in Figure 2-4, is powered by the MODB/VSTBY pin and PI6/PI7 fromthe crystal oscillator circuit. A clock frequency of 38.4kHz from a crystal oscillator provides thereference signal which is divided down to 1Hz in the processor.

As the RTC module is powered separately from the processor Vdd, the RTC is kept active through theMODB/VSTBY pin which provides the lithium battery back-up power when the radio is switched off.

A MOSFET transistor (Q416) switches in the battery supply when Vdd is removed. Q416 alsoprovides isolation from BOOT_CTRL function. The 3.3V regulator charges the Lithium battery.

Figure 2-4: RTC Circuit

2.4.1 MODB/VSTBY Supply

The supply to the MODB/VSTBY pin varies depending on the conditions listed in Table 2-4.

Table 2-4 MODB/VSTBY Supply Modes

Condition Circuit Operation

Radio On Vddd supply voltage via CR411

Radio Off • Vddd turned off• Q416 gate pulled low by R462• Q416 switched on• U410 supplies 3.2V to MODB_VSTBY

Primary battery removed • Vddd turned off• Q416 gate pulled low by R462• Q416 switched on• Lithium battery provides 3.2V to MODB_VSTBY

TP405TEST_POINT

BOOT_CTRLR463

LI_ION

R462

R4193

4

2

1 5CR411

1

23

Q416

C434

U4103.3V

32

1

VIN VOUT

VS

S

UNSWB+

R460C435R461

Vddd

HC11FL0

MODAMODB

R420

R426

FL401 C436

C437

PI6

PI7

OUT

IN

GND

38.4kHz

2-5

2.4.1 Audio/Signaling

The audio/signalling/filter/companding IC (ASFIC) and the audio power amplifier (Figure 2-3) form themain components of the audio/signalling section of the controller board. Inputs include a 16.8 MHzclock from the synthesizer, recovered audio and squelch, MCU control signals, and external orinternal microphones. Outputs include a microprocessor clock (CLK), modulator output to thesynthesizer, and amplified audio signals to an internal or external speaker.

2.5 UHF TransmitterThe UHF transmitter consists of the following basic circuits as shown in Figure 2-5.

• Power amplifier (PA).• Antenna switch/harmonic filter.• Antenna matching network.• Power control integrated circuit (PCIC).

Figure 2-5: UHF Transmitter Block Diagram

2.5.1 Power Amplifier (PA)

The PA consists of two LDMOS devices:

• 9Z67 LDMOS driver IC (U101)• PRF1507 LDMOS PA (Q110)

The 9Z67 LDMOS driver (U101) provides 2-stage amplification using a supply voltage of 7.3V. Theamplifier is capable of supplying an output power of 0.3W (U101pins 6 & 7) with an input signal of2mW(3dBm) at U101 (pin 16). The current drain is typically 160mA while operating in the frequencyrange of 403-470MHz.

The LDMOS PA is capable of supplying an output power of 7W with an input signal of 0.3W. Thecurrent drain is typically 1300mA while operating in the frequency range of 403-470MHz. The poweroutput can be varied by changing the bias voltage.

PCIC

PADriver

Antenna Switch/Harmonic Filter

PA FinalStage

Vcontrol Vcontrol

AntennaMatchingNetwork

From VCO

Power Amplifier (PA)

2-6

2.5.2 Antenna Switch

The antenna switch circuit consists of two pin diodes (CR101 and CR102), a pi network (C107, L104and C106), and two current limiting resistors (R101 and R170). In the transmit mode, B+ at PCIC(U102 pin 23) goes low turning on Q111, which applies a B+ bias to the antenna switch circuit to biasthe diodes “on”. The shunt diode (CR102) shorts out the receiver port and the pi network. Thisoperates as a quarter wave transmission line to transform the low impedance of the shunt diode to ahigh impedance at the input of the harmonic filter. In the receive mode, the diodes are both off,creating a low attenuation path between the antenna and receiver ports.

2.5.3 Harmonic Filter

The harmonic filter consists of components C104, L102, C103, L101 and C102. The harmonic filterfor UHF is a modified Zolotarev design optimized for efficiency of the power module. This type of filterhas the advantage that it can give a greater attenuation in the stop-band for a given ripple level. Theharmonic filter insertion loss is typically less than 1.2dB.

2.5.4 Antenna Matching Network

The antenna matching network, which is made up of L116, matches the antenna's impedance with theharmonic filter to optimize the performance of the transmitter and receiver.

2.5.5 Power Control Integrated Circuit (PCIC)

The transmitter uses the PCIC (U102) to regulate the power output of the radio. To accomplish this,the current to the final stage of the power module, supplied through R101, provides a voltageproportional to the current drain. This voltage is then fed back to the automatic level control (ALC)within the PCIC to regulate the output power of the transmitter.

The PCIC contains internal digital to analog converters (DACs) that provide a programmable controlloop reference voltage.

The PCIC internal resistors, integrators, and external capacitors (C133, C134 and C135) control thetransmitter rise and fall times to reduce the power splatter into adjacent channels.

2.5.6 Temperature Cut Back Circuit

Diode CR105 and associated components are part of a temperature cutback circuit. This circuitsenses the printed circuit board temperature around the transmitter circuits and outputs a DC voltageto the PCIC. If the DC voltage produced exceeds the set threshold of the PCIC, the transmitter outputpower decreases to reduce the transmitter temperature.

2.6 UHF ReceiverThe UHF receiver consists of a front end, back end, and automatic gain control circuits. A blockdiagram of the receiver is shown in Figure 2-6. Detailed descriptions of these stages are contained inthe paragraphs that follow.

2-7

Figure 2-6: UHF Receiver Block Diagram

2.6.1 Receiver Front-End

The RF signal received by the antenna is applied to a low-pass filter. For UHF, the filter consists ofcomponents L101, L102, C102, C103, and C104. The filtered RF signal is passed through theantenna switch circuit consisting of two pin diodes (CR101 and CR102) and a pi network (C106,L104, and C107). The signal is then applied to a varactor tuned filter bandpass.

The UHF bandpass filter consists of components L301, L302, C302, C303, C304, CR301, andCR302. The filter is electronically tuned by DACRx from the ASFIC (U404) which supplies a controlvoltage to the varactor diodes (CR301 and CR302) in the filter as determined by the microprocessordepending on the carrier frequency. Wideband operation of the filter is achieved by shifting thebandpass filter across the band.

The output of the bandpass filter is coupled to the RF amplifier transistor Q301 via C307. After beingamplified by the RF amplifier, the RF signal is further filtered by a second varactor tuned bandpassfilter, consisting of L306, L307, C313, C317, CR304, and CR305.

Both the pre and post-RF amplifier varactor tuned filters have similar responses. The 3 dB bandwidthof the filter is approximately 50 MHz. This enables the filters to be electronically controlled by using asingle control voltage from DACRx.

The output of the post-RF amplifier filter is connected to the passive double balanced mixer consistingof components T301, T302, and CR306. Matching of the filter to the mixer is provided by C381. Aftermixing with the first local oscillator (LO) signal from the voltage controlled oscillator (VCO) using lowside injection, the RF signal is down-converted to a 45.1 MHz IF signal.

Demodulator

Synthesizer

CrystalFilter Mixer

RFAmp

IFAmp

VaractorTuned Filter

VaractorTuned Filter

Antenna

AGC

Control Voltagefrom ASFIC

First LOfrom FGU

Recovered Audio

Squelch

RSSIIF IC

SPI Bus

16.8 MHzReference Clock

SecondLO VCO

RFJack

Pin DiodeAntennaSwitch

AGCProcessing

2-8

The IF signal coming out of the mixer is transferred to the crystal filter (FL301) through a resistor padand a diplexer (C322 and L310). Matching to the input of the crystal filter is provided by C324 andL311. The crystal filter provides the necessary selectivity and intermodulation protection.

2.6.2 Receiver Back-End

The output of crystal filter FL301 is coupled via R351 and C325 to the input of IF amplifier transistorQ302. Voltage supply to the IF amplifier is taken from the receiver 5 volts (R5). The IF amplifierprovides a gain of about 7dB. The amplified IF signal is then coupled into U301(pin 3) via C330, C338and L330 which provides a high-pass T-match for the IF amplifier and U301.

The IF signal applied to U301 (pin 3) is amplified, down-converted, filtered, and demodulated, toproduce recovered audio at U301(pin 27). This IF IC (U301) is electronically programmable, and theamount of filtering, which is dependent on the radio channel spacing, is controlled by themicroprocessor. Additional filtering, once externally provided by the conventional ceramic filters, isreplaced by internal filters in IF IC (U301).

The IF IC uses a type of direct conversion process, whereby the externally generated second LOfrequency is divided by two in U301 so that it is very close to the first IF frequency. The IF ICsynthesizes the second LO and phase-locks the VCO to track the first IF frequency. The second LO isdesigned to oscillate at twice the first IF frequency because of the divide-by-two function in the IF IC.

In the absence of an IF signal, the VCO searches for a frequency, or its frequency will vary close totwice the IF frequency. When an IF signal is received, the VCO locks onto the IF signal. The secondLO/VCO is a Colpitts oscillator built around transistor Q320. The VCO has a varactor diode, CR310,to adjust the VCO frequency. The control signal for the varactor is derived from a loop filter consistingof components C362, C363, C364, R320, and R321.

The IF IC also performs several other functions. It provides a received signal-strength indicator(RSSI) and a squelch output. The RSSI is a dc voltage monitored by the microprocessor, and used asa peak indicator during the bench tuning of the receiver front-end varactor filter. The RSSI voltage isalso used to control the automatic gain control (AGC) circuit at the front-end.

The demodulated signal on U301(pin 27) is also used for squelch control. The signal is routed toU404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audiosignal is also routed to U404 for processing before being supplied to the audio amplifier.

2.6.3 Automatic Gain Control (AGC)

The front end automatic gain control circuit provides automatic reduction of gain for the front end RFamplifier via feedback. This prevents overloading of backend circuits by drawing some of the outputpower from the RF amplifier output. At high radio frequencies, capacitor C331 provides a lowimpedance path to ground for this purpose. CR308 is a pin diode used for switching the path on or off.A certain amount of forward biasing current is needed to turn the pin diode on. Transistor Q315provides this current where, upon saturation, current will flow via R347, PIN Diode, collector andemitter of Q315 and R319 before going to ground. Q315 is an NPN transistor used for switching here.Maximum current flowing through the PIN is mainly limited by the resistor R319.

The Radio Signal Strength Indicator, RSSI, a voltage signal, is used to drive Q315 into saturation,hence turning it on. RSSI is produced by U301 and is proportional to the gain of the amplifier and theinput RF signal power to the radio.

The resistor network at the input to the base of the Q315 is scaled to turn on Q315, hence activatingthe AGC at certain RSSI levels. In order to turn on Q315, the voltage across the transistors base toground must be greater or equal to the voltage across R319, plus the base-emitter voltage (Vbe)present at Q315. The resistor network with thermistor RT300 is capable of providing temperaturecompensation to the AGC circuit, as RSSI generated by U301 is lower at cold temperatures

2-9

compared to normal operation at room temperature. Resistor R300 and Capacitor C397 form an R-Cnetwork used to dampen any transient instability while the AGC is turning on.

2.6.4 Frequency Generation Circuit

The frequency generation circuit, shown in Figure 2-7, is composed of Fractional-N synthesizer U201and VCO/Buffer IC U241. Designed in conjunction to maximize compatibility, the two ICs providemany of the functions that normally require additional circuitry. The synthesizer block diagramillustrates the interconnect and support circuitry used in the region. Refer to the schematic to locatereference designators.

The synthesizer is powered by regulated 5V and 3.3V, which are provided by ICs U247 and U248respectively. The 5V signal goes to U201(pins 13 and 30) while the 3.3V signal goes to U201(pins 5,20, 34 and 36). The synthesizer in turn generates a superfiltered (4.5V) signal to power U241.

In addition to the VCO, the synthesizer also interfaces with the logic and ASFIC circuits. Programmingfor the synthesizer is accomplished through the microprocessor data, clock, and chip select linesU409 (pins 7, 8 and 9) respectively. A 3.3V dc signal from U201(pin 4) indicates to the microprocessorthat the synthesizer is locked.

Transmit modulation from the ASFIC is supplied to U201 (pin 10). Internally the audio is digitized bythe Fractional-N and applied to the loop divider to provide the low-port modulation. The audio runsthrough an internal attenuator for modulation balancing purposes before going to the VCO (U241 pin41).

Figure 2-7: UHF Frequency Generation Unit Block Diagram

2.7 SynthesizerThe Fractional-N synthesizer, shown in Figure 2-8, uses a 16.8MHz crystal (FL201) to provide areference for the system. The LVFractN IC (U201) further divides this to 2.1MHz, 2.225MHz, and2.4MHz for use as reference frequencies. Together with C206, C207, C208, R204 and CR203, theybuild up the reference oscillator which is capable of 2.5ppm stability over temperatures of -30 to 85°C.It also provides 16.8MHz at U201 (pin 19) for use by the ASFIC and LVZIF.

The loop filter consists of components C231, C232, C233, R231, R232, and R233. This filter providesthe necessary dc steering voltage for the VCO and determines the amount of noise and spurs passingthrough.

SynthesizerU201

VCOBICU241

Low PassFilter

VoltageMultiplier Dual

Transistor

LoopFilter

MatchingNetwork

Attenuator

To Mixer

To PA Driver

VCP

Vmult1

Vmult2

Aux3

Aux4

MOD Out

ModulatingSignal

Rx VCOCircuit

Tx VCOCircuit

TRB

16.8 MHzRef. Osc.

RxOut

TxOut

2-10

To achieve fast locking for the synthesizer, an internal adapt charge pump provides higher current atU201 (pin 45) to put the synthesizer within lock range. The required frequency is then locked bynormal mode charge pump at U201 (pin 47).

Both the normal and adapt charge pumps get their supply from the capacitive voltage multiplier madeup of C258, C259, C228, triple diode CR201, and level shifters U210 and U211. Two 3.3V squarewaves, 180 degrees out of phase, are first shifted to 5V, then along with regulated 5V, put througharrays of diodes and capacitors to build up 13.3V at U201 (pin 47).

Figure 2-8: UHF Synthesizer Block Diagram

2.8 Voltage Control Oscillator (VCO)The VCOB IC (U241), shown in Figure 2-9, in conjunction with the Fractional-N synthesizer (U201)generates RF in both the receive and the transmit modes of operation. The TRB line (U241 pin 19)determines which oscillator and buffer are enabled. A sample of the RF signal from the enabledoscillator is routed from U241 (pin 12), through a low pass filter, to the prescaler input (U201 pin 32).After frequency comparison in the synthesizer, a resultant DC control voltage is received at the VCO.When the PLL is locked on frequency, this voltage can vary between 3.5V and 9.5V.

The VCOB IC is operated at 4.54V (VSF) and Fractional-N synthesizer (U201) at 3.3V. This differencein operating voltage requires a level shifter consisting of Q260 and Q261 on the TRB line. The levelshifter logic is shown in Table 2-5.

In the receive mode, U241 (pin 19) is low or grounded. This activates the receive VCO by enablingthe receive oscillator and the receive buffer of U241. The RF signal at U241 (pin 8) is run through amatching network. The resulting LO RF INJECTION signal is applied to the mixer at T302.

When PTT is pressed during the transmit condition, five volts is applied to U241 (pin 19). Thisactivates the transmit VCO by enabling the U241 transmit oscillator and buffer. The TX RFINJECTION signal at U241 (pin 10) is injected into the input of the PA module (U101 pin 16). Also in

DATA

CLK

CEX

MODIN

VCC, DC5V

XTAL1

XTAL2

WARP

PREIN

VCP

ReferenceOscillator

VoltageMultiplier

VoltageControlledOscillator

2-PoleLoop Filter

DATA (U409 Pin 100)

CLOCK (U409 Pin 1)

CSX (U409 Pin 2)

MOD IN (U404 Pin 40)

+5V (U247 Pin 4)

7

8

9

10

13,30

23

24

25

32

47

VMULT2 VMULT1

BIAS1

SFOUT

AUX3

AUX4

IADAPT

IOUT

GND

FREFOUT

LOCK4

19

6,22,23,24

43

45

3

2

28

14 15

40

Filtered 5V

SteeringLine

LOCK (U409 Pin 56)

Prescaler In

LO RFInjection

TX RFInjection

(First Stage of PA)

FREF (U201 Pin 21 & U404 Pin 34)

39BIAS2

41

DualTransistors

48

5VR405

(U248 Pin 5)

AUX1

VDD, 3.3V MODOUTU201

Low VoltageFractional-NSynthesizer

5,20,34,36

DualTransistors

2-11

transmit mode, the audio signal to be frequency modulated onto the carrier is received through U201(pin 41).

When a high impedance is applied to U241 (pin 19), the VCO operates in BATTERY SAVER mode. Inthis mode, both the receive and transmit oscillators as well as the receive transmit and prescalerbuffer are turned off.

Figure 2-9: UHF VCO Block Diagram

Table 2-5 Level Shifter Logic

Desired Mode AUX 4 AUX 3 TRB

Tx Low High (@3.2V) High (@4.8V)

Rx High Low Low

Battery Saver Low Low Hi-Z/Float (@2.5V)

Presc

RX

TX

MatchingNetwork

Low PassFilter

Attenuator

Pin 8

Pin 14

Pin 10

5V

(U201 Pin 28)VCC Buffers

TX RF Injection

U201 Pin 32

AUX4 (U201 Pin 3)

AUX3 (U201 Pin 2)

Prescaler OutPin 12

Pin 19Pin 20

TX/RX/BSSwitching Network

U241VCOBIC

Rx ActiveBias

Tx ActiveBias

Pin 2Rx-I adjust

Pin 1Tx-I adjust

Pins 9,11,17Pin 18

VsensCircuit

Pin 15

Pin 16TX VCOCircuit

TXTank

RX VCOCircuit

RXTank

Pin 7

Vcc-Superfilter

Collector/RF inPin 4

Pin 5

Pin 6

RX

TX

(U201 Pin 28)

Rx-SW

Tx-SW

Vcc-Logic

(U201 Pin 28)

Steer LineVoltage

(VCTRL)

Pin 13

Pin 3

TRB_IN

LO RF INJECTION

Level ShifterNetwork

2-12

2.9 VHF TransmitterThe VHF transmitter consists of the following basic circuits as shown in Figure 2-10.

• Power amplifier• Antenna switch/harmonic filter• Antenna matching network• Power control integrated circuit (PCIC)

Figure 2-10: VHF Transmitter Block Diagram

2.9.1 Power Amplifier

The power amplifier consists of two devices:

• 9Z67 LDMOS driver IC (U3501)• PRF1507 LDMOS PA (Q3501)

The 9Z67 LDMOS driver IC contains a 2-stage amplifier using a supply voltage of 7.3V.

This RF power amplifier is capable of supplying an output power of 0.3W (pin 6 and 7) with an inputsignal of 2mW (3dBm) (pin16). The current drain is typically around 130mA while operating in thefrequency range of 136-174MHz.

The PRF1507 LDMOS PA is capable of supplying an output power of 7W with an input signal of 0.3W.The current drain is typically around 1800mA while operating in the frequency range of 136-174MHz.The power output is varied by changing the bias voltage.

2.9.2 Antenna Switch

The antenna switch circuit consists of two pin diodes (D3521 and D3551), a pi network (C3531,L3551, and C3550), and two current limiting resistors (R3572 and R3573). In the transmit mode, B+at PCIC (U3502), pin 23 goes low to turn on Q3561 applying a B+ bias to the antenna switch circuit tobias the diodes “on”. The shunt diode (D3551) shorts out the receiver port, and the pi network, whichoperates as a quarter wave transmission line, transforms the low impedance of the shunt diode to ahigh impedance at the input of the harmonic filter. In the receive mode, the diodes are both off,creating a low attenuation path between the antenna and receiver ports.

PCIC

PADriver

Antenna Switch/Harmonic Filter

PA FinalStage

Vcontrol Vcontrol

AntennaMatchingNetwork

From VCO

Power Amplifier (PA)

2-13

2.9.3 Harmonic Filter

The harmonic filter consists of components C3532 to C3536, L3531, and L3532. This network forms alow-pass filter to attenuate harmonic energy of the transmitter to specifications level. The harmonicfilter insertion loss is typically less than 1.2dB.

2.9.4 Antenna Matching Network

A matching network, made up of L3538 and C3537, is used to match the antenna impedance to theharmonic filter. This optimizes the performance of the transmitter and receiver into an antenna.

2.9.5 Power Control Integrated Circuit (PCIC)

The transmitter uses PCIC, U3502 to control the power output of the radio by maintaining the radiocurrent drain. The current to the final stage of the power module is supplied through R3519 (0.1ohms), which provides a voltage proportional to the current drain. The voltage is then fed back to theautomatic level control (ALC) within the PCIC to provide loop stability.

The PCIC also contains internal digital-to-analog converters (DACs) that provide the referencevoltage for the control loop. The voltage level is controlled by the microprocessor through the data lineof the PCIC.

The resistors and integrators within the PCIC, and external capacitors (C3562, C3563, and C3565)control the transmitter rise and fall times. These are necessary to reduce the power splatter intoadjacent channels.

U3503 and its associated components act as a temperature cut back circuit. This provides thenecessary voltage to the PCIC to cut the transmitter power if the radio temperature gets too high.

2.10 VHF ReceiverThe VHF receiver consists of a front end, back end, and automatic gain control circuits. A blockdiagram of the VHF receiver is shown in Figure 2-11. Detailed descriptions of these features arecontained in the paragraphs that follow.

2-14

Figure 2-11: VHF Receiver Block Diagram

2.10.1 Receiver Front-End

The RF signal is received by the antenna and applied to a low-pass filter consisting of L3531, L3532,C3532 to C3563. The filtered RF signal is passed through the antenna switch. The antenna switchcircuit consists of two pin diodes (D3521 and D3551) and a pi network (C3531, L3551, and C3550).The RF signal is then applied to a varactor tuned bandpass filter which consists of L3301, L3303,C3301 to C3304, and D3301. The filter is tuned by applying a control voltage to the varactor diode(D3301) in the filter.

The bandpass filter is electronically tuned by the DACRx from IC 404 which is controlled by themicroprocessor. Depending on the carrier frequency, the DACRx supplies the tuning voltage to thevaractor diodes in the filter. Wideband operation of the filter is achieved by shifting the bandpass filteracross the band.

The output of the bandpass filter is coupled to the RF amplifier transistor Q3302 via C3306. Afterbeing amplified by the RF amplifier, the RF signal is further filtered by a second varactor tunedbandpass filter, consisting of L3305, L3306, C3311 to C3314, and D3302.

Both the pre and post-RF amplifier varactor tuned filters have similar responses. The 3dB bandwidthof the filter is about 12MHz. This enables the filters to be electronically controlled by using a singlecontrol voltage which is DACRx.

The output of the post-RF amplifier filter is connected to the passive double balanced mixer whichconsists of T3301, T3302, and CR3301. Matching of the filter to the mixer is provided by C3317,C3318, and L3308. After mixing with the first LO signal from the voltage controlled oscillator (VCO)using high side injection, the RF signal is down-converted to the 45.1MHz IF signal.

Demodulator

Synthesizer

CrystalFilter Mixer

RFAmp

VaractorTuned Filter

VaractorTuned Filter

Antenna

AGC

Control Voltagefrom ASFIC

First LOfrom FGU

Recovered Audio

Squelch

RSSIIF IC

SPI Bus

16.8 MHzReference Clock

SecondLO VCO

RFJack

Pin DiodeAntennaSwitch

2-15

The IF signal coming out of the mixer is transferred to the crystal filter (Y3200) through a resistor pad(R3321 - R3323) and a diplexer (C3320 and L3309). Matching to the input of the crystal filter isprovided by C3200 and L3200. The crystal filter provides the necessary selectivity andintermodulation protection.

2.10.2 Receiver Back-End

The output of crystal filter Y3200 is coupled to the input of IF amplifier transistor Q3200 by capacitorC3203. Voltage supply to the IF amplifier is taken from the receiver 5 volts (R5). The controlled gain IFamplifier provides a maximum gain of about 10dB. The amplified IF signal is then coupled into U3220,pin 3 via L3202, C3207, and C3230 which provides impedance matching for the IF amplifier andU3220.

The IF signal applied to U3220, pin 3 is amplified, down-converted, filtered, then demodulated toproduce the recovered audio at U3220, pin 27. This IF IC is electronically programmable, and theamount of filtering, which is dependent on the radio channel spacing, is controlled by themicroprocessor. Additional filtering, once externally provided by the conventional ceramic filters, isreplaced by internal filters in the IF IC (U3220).

The IF IC uses a type of direct conversion process, whereby the externally generated second LOfrequency is divided by two in U3220 so that it is very close to the first IF frequency. The IF IC (U3220)synthesizes the second LO and phase-locks the VCO to track the first IF frequency. The second LO isdesigned to oscillate at twice the first IF frequency because of the divide-by-two function in the IF IC.

In the absence of an IF signal, the VCO searches for a frequency, or its frequency will vary close totwice the IF frequency. When an IF signal is received, the VCO locks onto the IF signal. The secondLO/VCO is a Colpitts oscillator built around transistor Q3270. The VCO has a varactor diode (D3270)to adjust the VCO frequency. The control signal for the varactor is derived from a loop filter consistingof C3278 to C3280, R3274, and R3275.

The IF IC (U3220) also provides a received signal-strength indicator (RSSI) and a squelch output.The RSSI is a dc voltage monitored by the microprocessor and is used as a peak indicator during thebench tuning of the receiver front-end varactor filter. The RSSI voltage is also used to control theautomatic gain control (AGC) circuit in the front-end.

The demodulated signal on U3220, pin 27 is also used for squelch control. The signal is routed toU404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audiosignal is also routed to U404 for processing before going to the audio amplifier for amplification.

2.10.3 Automatic Gain Control (AGC)

The front end automatic gain control circuit provides automatic reduction of gain of the front end RFamplifier via feedback. This prevents overloading of backend circuits and is achieved by drawingsome of the output power from the RF amplifier output. At high radio frequencies, capacitor C3327provides the low impedance path to ground for this purpose. Pin diode CR3302 switches the path onor off. A certain amount of forward biasing current is needed to turn the pin diode on. TransistorQ3301 provides this current.

Radio signal strength indicator, RSSI, a voltage signal, drives Q3301 to saturation i.e. turned on.RSSI is produced by U3220 and is proportional to the gain of the RF amplifier and the input power tothe radio.

Resistors R3304 and R3305 make up a voltage divider designed to turn on Q3301 at certain RSSIlevels. To turn on Q3301, the voltage across R3305 must be greater or equal to the voltage acrossR3324 plus the emitter-base voltage (Vbe) present at Q3301. Capacitor C3209 dampens anyinstability while the AGC is turning on. The current flowing into the collector of Q3301, a high currentgain NPN transistor, is drawn through the pin diode to turn it on. Maximum current flowing through the

2-16

pin is limited by resistors R3316, R3313, R3306, and R3324. Feedback capacitor C3326 providessome stability to this high gain stage.

An additional gain control circuit is formed by Q3201 and associated components. Resistors R3206and R3207 are voltage dividers designed to turn on Q3201 at a significantly higher RSSI level thanthe level required to turn on pin diode control transistor Q3301. In order to turn on Q3201, the voltageacross R3207 must be greater or equal to the voltage across R3208 plus the emitter-base voltage(Vbe) present at Q3201. As current starts flowing into the collector of Q3201, it reduces the biasvoltage at the base of IF amplifier transistor Q3200 and in turn, the gain of the IF amplifier. The gain isthen controlled in a range of -30dB to +10dB.

2.10.4 Frequency Generation Circuit

The frequency generation circuit, shown in Figure 2-12, is composed of two main ICs, the FRACNsynthesizer (U3701), and the VCO/Buffer IC (U3801). Designed in conjunction to maximizecompatibility, the two ICs provide many of the functions that normally would require additional circuits.The synthesizer block diagram illustrates the interconnect and support circuit used in the region.Refer to the schematic for the reference designator.

Figure 2-12: VHF Frequency Generation Unit Block Diagram

The synthesizer is powered by regulated 5V and 3.3V which is provided from ICs U3711 and U3201respectively. The 5V signal is supplied to pins 13 and 30 and the 3.3V signal is applied to pins 5, 20,34 and 36 of U3701. The synthesizer in turn generates a superfiltered (4.5V) which powers U3801.

In addition to the VCO, the synthesizer must interface with the logic and ASFIC circuitry.Programming for the synthesizer is accomplished through the data, clock and chip select lines (pins7, 8 and 9) from the microprocessor, U409. A 3.3V dc signal from the synthesizer lock detect line (pin4) indicates to the microprocessor that the synthesizer is locked.

Transmit modulation from the ASFIC is supplied to U3701, pin 10. Internally the audio is digitized bythe FRACN and applied to the loop divider to provide low-port modulation. The audio runs through aninternal attenuator for modulation balancing purposes before going out at pin 41 to the VCO.

2.11 SynthesizerThe FRACN Synthesizer, shown in Figure 2-13, uses a 16.8MHz crystal (Y3761) to provide areference for the system. The LVFRACTN IC (U3701) further divides this to 2.1MHz, 2.225MHz, and2.4MHz as reference frequencies. Together with C3761, C3762, C3763, R3761, and D3761, theybuild up the reference oscillator that is capable of 2.5 ppm stability over a temperature range of -30 to85°C. A 16.8MHz signal at U3701, pin 19 is also provided for use by ASFIC and LVZIF.

SynthesizerU3701

VCOBICU3801

VoltageMultiplier Dual

Transistor

LoopFilter

To Mixer

To PA Driver

VCP

Vmult1

Vmult2

Aux3

MOD Out

ModulatingSignal

Rx VCOCircuit

Tx VCOCircuit

TRB

16.8 MHzRef. Osc.

Rx Out

Tx Out

2-17

The loop filter, which consist of C3721, C3722, R3721, R3722, and R3723, provides the necessary dcsteering voltage for the VCO and determines the amount of noise and spur passing through.

In achieving fast locking for the synthesizer, an internal adapt charge pump provides higher current atU3701, pin 45 to put the synthesizer within lock range. The required frequency is then locked bynormal mode charge pump at pin 43.

Both the normal and adapt charge pumps get their supply from the capacitive voltage multiplier madeup of C3701 to C3704 and triple diodes D3701 and D3702. Two 3.3V square waves (180 degrees outof phase) are first multiplied by four and then shifted, along with regulated 5V, to build up 13.5V atU3701, pin 47.

Figure 2-13: VHF Synthesizer Block Diagram

2.12 Voltage Control Oscillator (VCO)The VCOB IC (U3801), shown in Figure 2-14, in conjunction with the FRACTN synthesizer (U3701)generates RF in both the receive and transmit modes of operation. The TRB line (U3801, pin 19)determines which oscillator and buffer are enabled. A sample of the RF signal from the enabledoscillator is routed from U3801, pin 12, through a low pass filter, to the prescaler input (U3701, pin32). After frequency comparison in the synthesizer, a resultant control voltage is received at the VCO.This voltage is a DC voltage typically between 3.5V and 9.5V when the PLL is locked on frequency.

The RF section of the VCOB IC (U3801) is operated at 4.54 V (VSF), while the control section of theVCOBIC and FRACN synthesizer (U3701) is operated at 3.3V. The operation logic is shown in Table2-6.

In the receive mode, U3801, pin 19 is low or grounded. This activates the receive VCO by enablingthe receive oscillator and the receive buffer of U3801. The RF signal at U3801, pin 8 is routed througha matching network. The resulting LO RF INJECTION signal is applied to the mixer at T3302.

DATA

CLK

CEX

MODIN

VCC, DC5V

XTAL1

XTAL2

WARP

PREIN

VCP

ReferenceOscillator

VoltageMultiplier

VoltageControlledOscillator

2-PoleLoop Filter

DATA (U409 Pin 100)

CLOCK (U409 Pin 1)

CSX (U409 Pin 2)

MOD IN (U404 Pin 40)

+5V (U3711 Pin 4)

7

8

9

10

13,30

23

24

25

32

47

VMULT2 VMULT1

BIAS1

SFOUT

AUX3

AUX4

IADAPT

IOUT

GND

FREFOUT

LOCK4

19

6,22,23,24

43

45

3

2

28

14 15

40

Filtered 5V

SteeringLine

LOCK (U409 Pin 56)

Prescaler In

LO RFInjection

TX RFInjection

(First Stage of PA)

FREF (U3220 Pin 21 & U404 Pin 34)

39BIAS2

41

48

5VR405

(U3201 Pin 5)

AUX1

VDD, 3.3V MODOUTU3701

Low VoltageFractional-NSynthesizer

5,20,34,36

DualTransistors

2-18

During the transmit condition, when PTT is pressed, 3.2 volts is applied to U3801, pin 19. Thisactivates the transmit VCO by enabling the transmit oscillator and the transmit buffer of U3801. TheRF signal at U3801, pin 10 is injected into the input of the PA module (U3501, pin16). This RF signalis the TX RF INJECTION. Also in transmit mode, the audio signal to be frequency modulated onto thecarrier is received through U3701, pin 41.

When a high impedance is applied to U3801, pin19, the VCO is operating in battery saver mode. Inthis case, both the receive and transmit oscillators as well as the receive transmit and prescaler bufferare turned off.

Figure 2-14: VHF VCO Block Diagram

Table 2-6 VCO Control Logic

Desired Mode AUX 4 AUX 3 TRB

Tx Not Used High (@3.2V) High (@3.2V)

Rx Not Used Low Low

Battery Saver Not Used Hi-Z/Float(@1.6V)

Hi-Z/Float (@1.6V)

Presc

RX

TX

MatchingNetwork

Low PassFilter

Attenuator

Pin 8

Pin 14

Pin 10

(U3701 Pin 28)VCC Buffers

TX RF Injection

U3701 Pin 32

AUX3 (U3701 Pin 2)

Prescaler OutPin 12

Pin 19Pin 20

TX/RX/BSSwitching Network

U3801VCOBIC

Rx ActiveBias

Tx ActiveBias

Pin 2Rx-I adjust

Pin 1Tx-I adjust

Pins 9,11,17Pin 18

VsensCircuit

Pin 15

Pin 16TX VCOCircuit

TXTank

RX VCOCircuit

RXTank

Pin 7

Vcc-Superfilter

Collector/RF inPin 4

Pin 5

Pin 6

RX

TX

(U3701 Pin 28)

Rx-SW

Tx-SW

Vcc-Logic

(U3701 Pin 28)

Steer LineVoltage

(VCTRL)

Pin 13

Pin 3

TRB_IN

LO RF INJECTION

2-19

2.13 Low Band TransmitterThe low band transmitter consists of the following basic circuits as shown in Figure 2-15.

• Power amplifier (PA).• Antenna switch/harmonic filter.• Antenna matching network.• Power control integrated circuit (PCIC).

Figure 2-15: Low Band Transmitter Block Diagram

2.13.1 Power Amplifier (PA)

The PA consists of two LDMOS devices:

• PA driver, U101.• PA final stage, Q100.

The LDMOS driver (U101) provides 2-stage amplification using a supply voltage of 7.3V. Theamplifier is capable of supplying an output power of 0.3W (pins 6 and 7) with an input signal of 2mWat (pin16). The current drain is typically 120mA while operating in the frequency range of 29.7 - 50MHz. The power output of this stage is varied by the power control loop which controls the voltage onpin 1.

The LDMOS PA is capable of supplying an output power of 8W with an input signal of 0.3W. Thecurrent drain is typically 2000 mA while operating in the frequency range of 29.7 - 50 MHz. The finalstage gate is bias by a voltage from PCIC, pin 24. This voltage is the output of a programmable DACinside the PCIC and the output is adjustable with the radio tuner.

2.13.2 Antenna Switch

The antenna switch circuit consists of two pin diodes (D100 and D101), a RF network (C147 andL103), and a DC feed network (L104, C144, and current limiting resistor R101). In the transmit mode,PCIC (U102) pin 32 goes high supplying current via the feed network to bias the diodes “on”. Theshunt diode (D101) shorts out the receiver port and L103 is connected from the RF path to ground.L103 and the input capacitance of the lowpass filter form a parallel resonant circuit, effectivelydisconnecting the receiver port from the antenna while not loading the transmit path. In the receivemode, pin 32 goes low and the diodes are off. D100 looks like a high impedance effectively

PCIC

PADriver

Antenna Switch/Harmonic Filter

PA FinalStage

Vcontrol

SPI Bus

Gate Bias

Antenna Switch Bias

AntennaMatchingNetwork

From VCO

Power Amplifier (PA)

2-20

disconnecting the transmitter from the antenna while L103 and C147 form a series resonant circuiteffectively connect the receiver to the antenna.

2.13.3 Harmonic Filter

The harmonic filter consists of components C103, C106, C103, C107,C110, C111, C114, C115 andinductors L100, L101, and L102 which are a part of the SH100 assembly. The harmonic filter forlowband is pole zero design. This feature gives greater attenuation in low frequencies where theharmonic energy of the transmitter is the greatest and less attenuation in high frequencies wherethere is less harmonic energy. The harmonic filter insertion loss is typically less than 0.8 dB.

2.13.4 Antenna Matching Transformer

The antenna matching transformer (T100) matches the antenna impedance with the harmonic filter tooptimize the performance of the transmitter and receiver.

2.13.5 Power Control Integrated Circuit (PCIC)

The transmitter uses the PCIC (U102) to regulate the power output of the radio. To accomplish this,the voltage across R102 is sensed. This voltage drop is directly proportional to the current drawn inthe final stage of the transmitter. This voltage is compared to a programmable reference inside thePCIC and the voltage on PCIC pin 4 adjusted. Pin 4 connects to the PA driver IC (U101) pin 1 viaresistor R100 and varies RF output power of the driver. This controls the current drain of the finalstage and sets the output power.

2.13.6 Temperature Cut Back Circuit

Temperature sensor VR101 and associated components are part of a temperature cut back circuit.This circuit senses the printed circuit board temperature around the transmitter circuits and outputs aDC voltage to the PCIC. If the DC voltage produced exceeds the set threshold of the PCIC, thetransmitter output power decreases to reduce the transmitter temperature.

2.13.7 Electrostatic Discharge (ESD) Protection Circuit

The LDMOS PA device (Q100) is very sensitive to static discharge. To protect the device from ESD, aprotection circuit consisting of single high-speed Schottky Diode (D104) is connected from theAntenna Nut (J102) to ground. This diode effectively shorts ESD energy to ground, but looks like anopen circuit to normal RF energy. The diode turns on when the voltage at the antenna nut exceeds150V.

2.14 Low Band ReceiverThe low band receiver consists of a front end, back end, and automatic gain control circuits. A blockdiagram of the receiver is shown in Figure 2-16. Detailed descriptions of these stages are containedin the paragraphs that follow.

2-21

Figure 2-16: Low Band Receiver Block Diagram

2.14.1 Receiver Front-End

The RF signal received by the antenna is routed through the transmitter lowpass filter and antennaswitch. These circuits are described in the transmitter section.The signal next passes through ahighpass filter consisting of L501, L502, C538, C533 and C504. This filter serves to reject below bandsignals and has a 3 dB corner frequency of 27 MHz.

The output of the highpass filter is connected to an RF amp consisting of Q509 and associatedbiasing components. This is a BJT amplifier powered off 5 volts and has 13 dB of gain. The amplifierdrives a lowpass filter consisting of L503, L504 L507, C534, C535, C536, C537 and C515. This filteris a pole zero design that filters off harmonic components from the RF amp. The 3 dB corner of thisfilter is at 56 MHz.

The output of the lowpass filter is connected to the passive double balanced mixer consisting ofcomponents T501, T502, and D501. After mixing with the first local oscillator up-converted to a109.65 MHz IF signal.

The IF signal coming out of the mixer is transferred to the crystal filter (FL301) through a resistor pad(R507, R508 and R509) and a diplexer (C516 and L508). Matching to the input of the crystal filter isprovided by L301, L302, C301 and C302. The 3 pole crystal filter provides the necessary selectivityand intermodulation protection.

Demodulator

Synthesizer

CrystalFilter Mixer

RFAmp

IFAmp

HighpassFilter

LowpassFilter

Antenna

First LOfrom FGU

Recovered Audio

Squelch

RSSI

SPI Bus

17.0 MHzReference Clock

SecondLO VCO

RFJackLowpass

FilterAntennaSwitch

AGCProcessing

IF IC U303

2-22

2.14.2 Receiver Back-End

The output of crystal filter FL301 is connected to the input of IF amplifier transistor U301. ComponentsL303 and C348 and R301 form the termination for the crystal filter and the signal is coupled to onegate of U301 by C303. The IF amplifier is a dual gate MOSFET powered off of the 5 volt supply. Thefirst gate receives the IF signal as indicated previously. The second gate receives a DC voltage fromU302 which serves as an AGC control signal. This signal reduces the gain of the IF amplifier toprevent overload of the IF IC, U303. The gain can be varied from a maximum of 13 dB to anattenuation of 55 dB. The output IF signal from U301 is coupled into U303 (pin 3) via C306, R304 andL304 which provides matching for the IF amplifier and U303.

The IF signal applied to pin 3 of U303 is amplified, down-converted, filtered, and demodulated, toproduce recovered audio at pin 27 of U303. This IF IC is electronically programmable, and theamount of filtering, which is dependent on the radio channel spacing, is controlled by themicroprocessor. Additional filtering, once externally provided by the conventional ceramic filters, isreplaced by internal filters in IF IC U303.

The IF IC uses a type of direct conversion process, whereby the externally generated second LOfrequency is divided by two in U303 so that it is very close to the first IF frequency. The IF IC (U303)synthesizes the second LO and phase-locks the VCO to track the first IF frequency. The second LO isdesigned to oscillate at twice the first IF frequency because of the divide-by-two function in the IF IC.

In the absence of an IF signal, the VCO searches for a frequency, or its frequency will vary close totwice the IF frequency. When an IF signal is received, the VCO locks onto the IF signal. The secondLO/VCO is a Colpitts oscillator built around transistor Q301. The VCO has a varactor diode, CR301,to adjust the VCO frequency. The control signal for the varactor is derived from a loop filter consistingof components C308, C309, and R310.

The IF IC (U303) also performs several other functions. It provides a received signal-strengthindicator (RSSI) and a squelch output. The RSSI voltage is also used to control the automatic gaincontrol (AGC) circuit at the back end.

The demodulated signal on pin 27 of U303 is also used for squelch control. The signal is routed toU404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audiosignal is also routed to U404 for processing before going to the audio amplifier for amplification.

2.14.3 Automatic Gain Control (AGC)

The automatic gain control circuit provides automatic reduction of gain to prevent overloading ofbackend circuits. This is achieved by lowering the voltage on one gate of U301 which will reduce thedrain current in that part and lower its gain.

The Radio Signal Strength Indicator (RSS I) voltage signal for the IF IC (U303) is used to drive theAGC processing circuitry consisting of R306, R307, R308, R309 C307 and U302. As the receivedsignal gets stronger, the RSSI line will rise. When the RSSI line passes a certain threshold, thevoltage at the output of U302 will begin to drop. This voltage is connected to one gate of IF amplifierU301 through resistor R305. As this voltage decreases, it will lower the drain current in U301 andreduce the gain of the stage. This will limit the power incident on the IF IC, U303.

2.14.4 Frequency Generation Circuit

The frequency generation circuit, shown in Figure 2-17, is composed of Low Voltage Fractional-Nsynthesizer U205 and discrete RX VCO, TX VCO.and buffers as well other supporting circuitry. Thesynthesizer block diagram illustrates the interconnect and support circuitry used in the region. Referto the schematic for the reference designators.

The synthesizer is powered by regulated 5V and 3.3V. The 5 volt signal to the synthesizer as well asthe rest of the radio is provided by U204. The 3.3 v signal is provided by U200 in the controller. The

2-23

5V signal goes to pins 13 and 30 while the 3.3V signal goes to pins 5, 20, 34 and 36 of U201. Thesynthesizer in turn generates a superfiltered 4.3V which powers the VCOs and buffers.

In addition to the VCO, the synthesizer also interfaces with the logic and ASFIC circuitry.Programming for the synthesizer is accomplished through the data, clock and chip select lines (pins7, 8 and 9) from the microprocessor, U409. A 3.3V dc signal from pin 4 indicates to themicroprocessor that the synthesizer is locked.

Transmit modulation from the ASFIC is supplied to pin10 of U205. Internally the audio is digitized bythe Fractional-N and applied to the loop divider to provide the low-port modulation. The audio runsthrough an internal attenuator for modulation balancing purposes before going out at pin 41 to theVCO.

Figure 2-17: Low Band Frequency Generation Unit Block Diagram

2.15 SynthesizerThe Fractional-N synthesizer, shown in Figure 2-18, uses a 17.0 MHz crystal (Y201) to provide areference for the system. Along with being used in the LVFracN, the 17.0 MHz signal is provided atpin 19 of U205 for use by the ASFIC and LVZIF.

The LVFractN IC (U205) further divides this by 8 internally to give 2.125 MHz to be used as thereference frequency in the frequency synthesis. While UHF and VHF can use other references,(divide by 7 or divide by 7/8), only the divide by 8 function is valid for lowband.

The internal oscillator device in the LVFracN together with C236, C237, C242, R219, CR211and Y201comprise the reference oscillator. This oscillator is temperature compensated is capable of 2.5 ppmstability over temperatures of -30 to 85°C. There is temperature compensation information that isunique to each crystal contained on Y201 that is programmed into the radio when built.

The loop filter consists of components C256, C257, C259, R224, R225 and R228. This circuitprovides the necessary dc steering voltage for the VCO and determines the amount of noise and spurpassing through.

To achieve fast locking for the synthesizer, an internal adapt charge pump provides higher current atpin 45 of U205 to put the synthesizer within lock range. The required frequency is then locked bynormal mode charge pump at pin 43.

Both the normal and adapt charge pumps get their supply from the capacitive voltage multiplier madeup of C247, C283, C284, C285, C286, and triple diodes D210 and D211. This circuit provides 13.3Vat U205, pin 47.

SynthesizerU205

VoltageMultiplier Switching

Network

LoopFilter

To Mixer

To PA Driver

VCPVSF

Vmult2

Vmult1

Aux2

Prescaler Input

ModulatingSignal

Rx VCOCircuit

Tx VCOCircuit

17.0 MHzRef. Osc.

Buffer

Amplifier

Aux3

MOD Out

2-24

Figure 2-18: Low Band Synthesizer Block Diagram

2.16 Voltage Control Oscillators (VCO)

2.16.1 Receive VCO

The receive VCO is a Colpitts type design and using two active devices in parallel, Q202 and Q204.The oscillator is powered off of the 4.3 volt super filter supply when the AUX3 line goes low. Theoscillator operates from 139 to 152 MHz for range 1 and 145 to 160 MHz for range 2. The frequencyis tuned by varactor diodes CR201 and CR202.

2.16.2 Transmit VCO

The transmit VCO is a Hartley type design with active devices Q203. The oscillator is powered off ofthe 4.3 volt super filter supply when the AUX2 line goes low. The oscillator operates from 29.7 to 42MHz for Range 1 and 35 to 50 MHz for Range 2. The frequency is tuned by varactor diodes in U203.Note that the values of the inductive tap, L208 and L209, and the capacitor C215 which couples thevaractor to the oscillator tank vary between the ranges.

2.16.3 Buffer

Both the receive and transmit VCO are fed to a buffer amplifier Q201. This is a BJT amplifier thatboosts the signal levels to +4 dBm and provides reverse isolation to the oscillators. The amplifier ispowered off the 4.3 volt super filter supply and the feed network is combined with the transmit filter.

2.16.4 Diplexer/Output Filters

The output of the buffer drives a pair of parallel filters forming a diplexer. One filter is a lowpass filter inthe TX pass that passes 29.7 - 50 MHz signals for the transmitter into the power amplifier while

DATA

CLK

CEX

MODIN

VCC, DC5V

XTAL1

XTAL2

WARP

PREIN

VCP

ReferenceOscillator

VoltageMultiplier

VoltageControlledOscillators

SwitchingNetwork

2-PoleLoop Filter

DATA (U409 Pin 100)

CLOCK (U409 Pin 1)

CSX (U409 Pin 2)

MOD IN (U404 Pin 40)

+5V (U204 Pin 4)

7

8

9

10

13,30

23

24

25

32

47

VMULT2 VMULT1

BIAS1

SFOUT

AUX3

AUX2

IADAPT

IOUT

GND

FREFOUT

LOCK4

19

6,17,22,29,31,33,44

43

45

1

2

28

14 15

40

Filtered 4.3V

SteeringLine

LOCK (U409 Pin 56)

Prescaler In

LO RFInjection

TX RFInjection

(First Stage of PA)

FREF (U303 Pin 21 & U404 Pin 34)

39BIAS2

41(U400 Pin 1) VDD, 3.3V MODOUT

U205Low VoltageFractional-NSynthesizer

5,20,34,36

2-25

rejecting the receive LO injection signals at 139 - 160 MHz. This filter is comprised of L204, L211,L212, C230 and C231.

The other filter is a highpass filter which passes 139 - 160 MHz signals for the receive LO into themixer while rejecting the transmit injection signals at 29.7 -50 MHz. This filter is comprised of C228,C229, C235 and L215.

2.16.5 Prescalar Feedback

The prescalar input signal for receive and transmit is tapped off of the outputs of each filter byresistors R234 and R238. This signal is routed to the buffer amplifier consisting of components C287,Q288, R287, R288, and R289. The output of this buffer feeds U205, pin 32. After frequencycomparison in the synthesizer, current is transferred in the loop filter and a control voltage isgenerated at the output of the loop filter to adjust the frequency of the VCO. This voltage is a DCvoltage between 3.5V and 9.5V when the PLL is locked on frequency.

2.17 800 MHz TransmitterThe 800MHz transmitter contains four basic circuits as shown in Figure 2-19:

• Power Amplifier (PA)• Antenna Switch• Harmonic Filter• Power Control Integrated Circuit (PCIC).

Figure 2-19: 800 MHz Transmitter Block Diagram

2.17.1 Power Amplifier

The power amplifier consists of two devices:

• 63J66 driver IC (U101) and• 85Y73 LDMOS PA (Q101).

The 63J66 driver IC contains a 2 stage amplification with a supply voltage of 7.5V.

PCIC

PADriver

Antenna Switch/Harmonic Filter

PA FinalStage

Vcontrol VcontrolAntenna

Jack

From VCO

Power Amplifier (PA)

2-26

This RF driver IC is capable of supplying an output power of 0.3W (pin 13 and 14) with an input signalof 2.5mW (4dBm) (pin16). The current drain would typically be 200mA while operating in thefrequency range of 806-870MHz.

The 85Y73 LDMOS PA is capable of supplying an output power of 4.5W with an input signal of 0.3W.The current drain would typically be 1100mA while operating in the frequency range of 806-870MHz.The power out can be varied by changing the biasing voltage and the drive level from the driver IC.

2.17.2 Antenna Switch

The antenna switch circuit consists of two PIN diodes (CR101 and CR102), a pi network (C109, L103and C110), and three current limiting resistors (R101, R102, R103). In the transmit mode, B+ at PCIC(U102) pin32 will go high, applying a B+ bias to the antenna switch circuit to bias the diodes “on”. Theshunt diode (CR102) shorts out the receiver port, and the pi network, which operates as a quarterwave transmission line, transforms the low impedance of the shunt diode to a high impedance at theinput of the harmonic filter. In the receive mode, the diodes are both off, and hence, there exists a lowattenuation path between the antenna and receiver ports.

2.17.3 Harmonic Filter

The harmonic filter consists of C104, L102, C105, C106,C107, L101 and C109. It has been optimizedfor efficiency of the power amplifier. This type of filter has the advantage that it can give a greaterattenuation in the stop-band for a given ripple level. The harmonic filter insertion loss is typically lessthan 1.2dB.

2.17.4 Power Control Integrated Circuit (PCIC)

The transmitter uses the Power Control IC (PCIC), U102 to regulate the power output of the radio.The current to the final stage of the power module is supplied through R104, which provides a voltageproportional to the current drain. This voltage is then fed back to the Automatic Level Control (ALC)within the PCIC to regulate the output power of the transmitter.

The PCIC has internal digital to analog converters (DACs) which provide the reference voltage of thecontrol loop. The reference voltage level is programmable through the SPI line of the PCIC.

There are resistors and integrators within the PCIC, and external capacitors (C126, C130 and C132)in controlling the transmitter rising and falling time. These are necessary in reducing the powersplatter into adjacent channels.

U103 and its associated components are part of the temperature cut back circuitry. It senses theprinted circuit board temperature around the transmitter circuits and provides a DC voltage to thePCIC. If the DC voltage produced exceeds the set threshold in the PCIC, the transmitter output powerwill be reduced so as to reduce the transmitter temperature.

2-27

2.18 800 MHz ReceiverThe receiver functions are shown in Figure 2-20 and are described in the paragraphs that follow.

Figure 2-20: 800MHz Receiver Block Diagram

2.18.1 Receiver Front-End

The RF signal is received by the antenna and applied to a low-pass filter. For 800MHz, the filterconsists of L101, L102, C104, C105, C106, C107, C109. The filtered RF signal is passed through theantenna switch. The antenna switch circuit consists of two PIN diodes(CR101 and CR102) and a pinetwork (C109, L103 and C110).The signal is then applied to a fixed tuned ceramic bandpass filter,FL300.

The output of the bandpass filter is coupled to the RF amplifier transistor Q302 via C300. The RFamplifier provides a gain of approximately 12 dB. After being amplified by the RF amplifier, the RFsignal is further filtered by a second fixed tuned ceramic bandpass filter, FL301.

Both the pre and post-RF amplifier ceramic filters have similar responses. The insertion loss of eachfilter across the 851-870MHz band is typically 1.8dB.

The output of the post-RF amplifier filter is connected to the passive double balanced mixer, U301.After mixing with the first LO signal from the voltage controlled oscillator (VCO) using low sideinjection, the RF signal is down-converted to the 109.65MHz IF signal.

The IF signal coming out of the mixer is transferred to the crystal filter (FL350) through a resistive padand a diplexer (C312 and L306). Matching to the input of the crystal filter is provided by L353,L354,C377, and C378. The crystal filter provides the necessary selectivity and intermodulation protection.

Demodulator

Synthesizer

CrystalFilter Mixer

RFAmp

IFAmp

3-PoleCeramic

Block Filter

3-PoleCeramic

Block Filter

Antenna

First LOfrom FGU

Recovered Audio

Squelch

RSSIIF IC

SPI Bus

16.8 MHzReference Clock

SecondLO VCO

RFJack

Pin DiodeAntennaSwitch

AGCProcessing

U351

2-28

2.18.2 Receiver Back-End

The output of crystal filter FL350 is matched to the input of the dual gate MOSFET IF amplifiertransistor U352 by components L355, R359 and C376. Voltage supply to the IF amplifier is taken fromthe receive 5 volts (R5). AGC voltage is applied to the second gate of U352. The IF amplifier providesa gain of about 11dB. The amplified IF signal is then coupled into U351(pin 3) via L352, R356 andC365 which provides the matching for the IF amplifier and U351.

The IF signal applied to pin 3 of U351 is amplified, down-converted, filtered, and demodulated, toproduce the recovered audio at pin 27 of U351. This IF IC is electronically programmable, and theamount of filtering (which is dependent on the radio channel spacing) is controlled by themicroprocessor. Additional filtering, once externally provided by the conventional ceramic filters, isreplaced by internal filters in the IF module (U351).

The IF IC uses a type of direct conversion process, whereby the externally generated second LOfrequency is divided by two in U351 so that it is very close to the first IF frequency. The IF IC (U351)synthesizes the second LO and phase-locks the VCO to track the first IF frequency. The second LO isdesigned to oscillate at twice the first IF frequency because of the divide-by-two function in the IF IC.

In the absence of an IF signal, the VCO will “search” for a frequency, or its frequency will vary close totwice the IF frequency. When an IF signal is received, the VCO will lock onto the IF signal. Thesecond LO/VCO is a Colpitts oscillator built around transistor Q350. The VCO has a varactor diode,CR350, to adjust the VCO frequency. The control signal for the varactor is derived from a loop filterconsisting of R365, C391, and C392.

The IF IC (U351) also performs several other functions. It provides a received signal-strengthindicator (RSSI) and a squelch output. The RSSI is a dc voltage monitored by the microprocessor,and used to control the automatic gain control (AGC) circuit in both the front-end and the IF.

The demodulated signal on pin 27 of U351 is also used for squelch control. The signal is routed toU404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audiosignal is also routed to U404 for processing before going to the audio amplifier for amplification.

2.18.3 Automatic Gain Control Circuit

The automatic gain control circuit provides automatic gain reduction of both the low noise amplifier inthe receiver front end and the IF amplifier in the receiver backend. This action is necessary to preventoverloading of the backend IF IC.

The IF automatic gain control circuit provides approximately 50 dB of attenuation range. The signalstrength indicator (RSSI) output of the IF IC produces a voltage that is proportional to the RF level atthe IF input to the IF IC. This voltage is inverted by U350, R351, R353, R352, R354 and C355 and itdetermines the RF level at which the backend end AGC is activated as well as the slope of thevoltage at the output of U350 vs. the strength of the incoming RF at the antenna. The inverted outputof U350 is applied to the second gate of the IF amplifier U352 via R355. As the RF signal into the IFIC increases the following occurs:

• the RSSI voltage increases,• the output of inverter U350 decreases, and• the voltage applied to the second gate of the FET is reduced thus reducing the gain of the IF

amplifier.

The output of inverter U350 is also used to control the receiver front end AGC.

The receiver front end automatic gain control circuit provides and additional 20 dB of gain reduction.The output of the receiver backend inverter U350 is fed into the receiver front end AGC inverter U302.The components R317, R314, and C318 determine:

• the RF level at which the front end AGC is activated, and

2-29

• the slope of the voltage at the output of U302 vs. the strength of the incoming RF at the antenna.

As the RF into the antenna increases the following occurs:

• The output voltage of the receiver backend inverter U350 decreases.• The voltage at the output of the front end inverter U302 increases.• The result is the forward biasing of pin diode CR301.

As the diode becomes more and more forward biased the following occurs:

• C310 loads the output of the low noise amplifier Q302 thus reducing the gain of the low noiseamplifier.

• R315 and R318 provide a DC path for CR301 and also limit the current through CR301.

The blocking capacitor C317 prevents DC from the AGC stage from appearing at the input of the filterFL301.

2.18.4 Frequency Generation Circuit

The frequency generation circuit is shown in Figure 2-21. The circuit is composed of the two main ICs:

• Fractional-N synthesizer, U201• VCO/Buffer IC, U250

Figure 2-21: 800 MHz Frequency Generation Unit Block Diagram

Designed in conjunction to maximize compatibility, the two ICs provide many of the functions thatnormally would require additional circuitry. The synthesizer block diagram illustrates the interconnectand support circuitry used in the region. Refer to the relevant schematics for the referencedesignators.

The synthesizer is powered by regulated 5V and 3.3V which come from U247 and U248 respectively.The synthesizer in turn generates a superfiltered 4.5V which powers U250.

In addition to the VCO, the synthesizer must interface with the logic and ASFIC circuitry.Programming for the synthesizer is accomplished through the data, clock and chip select lines fromthe microprocessor. A 3.3V dc signal from synthesizer lock detect line indicates to the microprocessorthat the synthesizer is locked.

SynthesizerU201

VCOBICU250

VoltageMultiplier Dual

Transistor

LoopFilter

InjectionAmplifier

BufferAmplifier

To Mixer

To PA Driver

VCP

Vmult1

Vmult2

Aux3

Aux4

MOD Out

ModulatingSignal

Rx VCOCircuit

Tx VCOCircuit

TRB

16.8 MHzRef. Osc.

RxOut

TxOut

2-30

Transmit modulation from the ASFIC is supplied to pin10 of U201. Internally the audio is digitized bythe Fractional-N and applied to the loop divider to provide the low-port modulation. The audio runsthrough an internal attenuator for modulation balancing purposes before going out to the VCO.

2.19 SynthesizerThe Fractional-N Synthesizer uses a 16.8MHz crystal (FL201) to provide a reference for the system.The LVFractN IC (U201) further divides this to 2.1MHz, 2.225MHz, and 2.4MHz as referencefrequencies. Together with C235, C236, C237, R211 and CR203, they comprise the referenceoscillator which is capable of 2.5ppm stability over temperatures of -30 to 85°C. It also provides16.8MHz at pin 19 of U201 to be used by ASFIC and LVZIF.

Some models are equipped with a packaged 1.5ppm reference oscillator, Y200. On these modelscomponents C235, C236, C237, CR203, FL201, and R211 are not placed. Components C238, C239,C241, R212, R213, R214 and Y200 are placed instead.

The loop filter which consists of C220, C225, C226, R204, R209 and R210 provides the necessary dcsteering voltage for the VCO and provides filtering of noise and spurs from U201.

In achieving fast locking for the synthesizer, an internal adapt charge pump provides higher current atpin 45 of U201 to put the synthesizer within the lock range. The required frequency is then locked bythe normal mode charge pump at pin 43.

Both the normal and adapt charge pumps get their supply from the capacitive multiplier which is madeup of D201, D202, C244, C245, C246, C247, R200, R218, C208, C243, R219, and R220. Two 3.3 Vsquare waves (180 degrees out of phase) are applied to R219 and R220. These square waves switchalternate sets of diodes from D201 and D202, which in turn charge C244, C245, C246, and C247 in abucket brigade fashion. The resulting output voltage that is applied to pin 47 of U201 is typically 12.8Vand allows the steering line voltage (VCO control voltage) to reach 11V.

Figure 2-22: 800 MHz Synthesizer Block Diagram

DATA

CLK

CEX

MODIN

VCC, DC5V

XTAL1

XTAL2

WARP

PREIN

VCP

ReferenceOscillator

VoltageMultiplier

VoltageControlledOscillator

2-PoleLoop Filter

DATA (U409 Pin 100)

CLOCK (U409 Pin 1)

CSX (U409 Pin 2)

MOD IN (U404 Pin 40)

+5V (U247 Pin 4)

7

8

9

10

13,30

23

24

25

32

47

VMULT2 VMULT1

BIAS1

SFOUT

AUX3

AUX4

IADAPT

IOUT

GND

FREFOUT

LOCK4

19

6,22,23,24

43

45

3

2

28

14 15

40

Filtered 5V

12.8V

3.3Vp-p

3.3Vp-p

SteeringLine

11.0V

LOCK (U409 Pin 56)

Prescaler In

LO RFInjection

TX RFInjection

(First Stage of PA)

FREF (U201 Pin 21 & U404 Pin 34)

39BIAS2

41

DualTransistors

48

5VR405

(U248 Pin 5)

AUX1

VDD, 3.3V MODOUTU251

Low VoltageFractional-NSynthesizer

5,20,34,36

DualTransistors

2-31

2.19.1 Voltage Control Oscillator (VCO)

The voltage controlled oscillator block diagram is shown in Figure 2-23.

Figure 2-23: 800 MHz VCO Block Diagram

The VCOBIC (U250) in conjunction with the Fractional-N synthesizer (U201) generates RF in boththe receive and the transmit modes of operation. The TRB line (U250 pin 19) determines whichoscillator and buffer will be enabled. A sample of the RF signal from the enabled oscillator is routedfrom U250 pin 12, through a low pass filter, to the prescaler input (U201 pin 32). After frequencycomparison in the synthesizer, a resultant CONTROL VOLTAGE is received at the VCO. This voltageis a DC voltage between 2.0V (low frequency) and 11.0V (high frequency) when the PLL is locked onfrequency.

The VCOBIC(U250) is operated at 4.54 V (VSF) and Fractional-N synthesizer (U201) at 3.3V. Thisdifference in operating voltage requires a level shifter consisting of Q200 and Q252 on the TRB line.

Presc

RX

TX

InjectionAmplifier

BufferAmplifier

Pin 8

Pin 14

Pin 10

5V

(U201 Pin 28)VCC Buffers

TX RF Injection

U201 Pin 32

AUX4 (U201 Pin 3)

AUX3 (U201 Pin 2)

Prescaler OutPin 12

Pin 19Pin 20

TX/RX/BSSwitching Network

U250VCOBIC

Rx ActiveBias

Tx ActiveBias

Pin 2Rx-I adjust

Pin 1Tx-I adjust

Pins 9,11,17Pin 18

VsensCircuit

Pin 15

Pin 16TX VCOCircuit

TXTank

RX VCOCircuit

RXTank

Pin 7

Vcc-Superfilter

Collector/RF inPin 4

Pin 5

Pin 6

RX

TX

(U201 Pin 28)

Rx-SW

Tx-SW

Vcc-Logic

(U201 Pin 28)

Steer LineVoltage

(VCTRL)

Pin 13

Pin 3

TRB_IN

LO RF INJECTION

Level ShifterNetwork

VSF

VSF

VSF

2-32

The operation logic is shown in Table 2-7.

In the receive mode, U250 pin 19 is low or grounded. This activates the receive VCO by enabling thereceive oscillator and the receive buffer of U250. The RF signal at U250 pin 8 is run through aninjection amplifier, Q304. The resulting RF signal is the LO RF INJECTION and it is applied to themixer at U301 (refer to Figure 4-88: 800MHz Receiver Front End Schematic Diagram).

During the transmit condition, when PTT is depressed, five volts is applied to U250 pin 19. Thisactivates the transmit VCO by enabling the transmit oscillator and the transmit buffer of U250. The RFsignal at U250 pin 10 is amplified by Q251 and injected into the input of the PA module (U101 pin1).This RF signal is the TX RF INJECTION. Also in transmit mode, the audio signal to be frequencymodulated onto the carrier is received through the U201 pin 41.

When a high impedance is applied to U250 pin19, the VCO is operating in BATTERY SAVER mode.In this case, both the receive and transmit oscillators as well as the receive transmit and prescalerbuffer are turned off.

2.20 Trunked Radio SystemsTrunked systems allow a large number of users to share a relatively small number of frequencies orrepeaters without interfering with each other. The airtime of all the repeaters in a trunked system ispooled, which maximizes the amount of airtime available to any one radio and minimizes channelcongestion. A benefit of trunking is that the user is not required to monitor the system beforetransmitting.

2.20.1 Privacy Plus Trunked Systems

Privacy Plus is a proprietary trunking protocol developed by Motorola which allows a large number ofusers to share small amounts of frequencies without interfering with each other. The Privacy Plusconfiguration consists of shared multiple channel repeaters. The Privacy Plus Trunked systemincludes a Central Controller, which directs the users to the open channels. This kind of Trunkedsystem requires no monitoring of the channel as in conventional systems. The Central Controllerplaces the user in a queue to wait for a free channel. The Central Controller does the monitoring andchannels selection for the user.

2.20.2 LTR™ Trunked Systems

LTR is a transmission based trunking protocol developed by the E. F. Johnson Company for primarilysingle site trunking applications. In transmission trunking, a repeater is used for only the duration of asingle transmission. Once a transmission is completed, that repeater becomes available to otherusers.

2.20.3 MPT Trunked Systems

MPT (Ministry of Post and Telecommunications) developed a signalling standard (MPT1327) fortrunked private land mobile radio systems. This standard defines the protocol rules for communicationbetween a trunking system controller (TSC) and user’s radio units. The protocol offers a broad rangeof options which can be implemented in subsets according to user requirements. Also, there is scope

Table 2-7 Level Shifter Logic

Desired Mode AUX 4 AUX 3 TRB

Tx Low High (@3.2V) High (@4.8V)

Rx High Low Low

Battery Saver Low Low Hi-Z/Float (@2.5V)

2-33

for customization for special requirements, and provision made to further standardized features to beadded to the protocol in the future. The standard defines only the over-air signalling and imposes onlyminimum constraints on system design.

2.20.4 PassPort™ Trunked Systems

PassPort is an enhanced trunking protocol developed by Trident Microsystems that supports widearea dispatch networking. A network is formed by linking several trunked sites together to form asingle system. This offers users an extended communication coverage area. Additionally, users withPassPort can seamlessly roam among all sites within the network. Seamless roaming means that theradio user does not have to manually change the position on the radio when roaming from site-to-site.

For models which feature PassPort Trunking operation, the standard keypad board is replaced withthe PassPort Trunking Controller Board (PTCB). This board also provides advanced voice storagefeatures. Refer to Figure 2-2 for connector and signal routing from, to and through the Radio, PTCBand Liquid Crystal Display (LCD) sub-systems.

2.20.4.1 Power Supplies

The radio supplies regulated Vdd of 3.3 VDC. This is used to power the Low Speed Data Filter andVoice Storage circuits. The radio also supplies Switched Battery Voltage (SWB+). U612 regulates theSWB+ to 3.3V which is applied to the PTCB microcontroller U601. A filtered voltage (Vdda) of _ Vddis developed by U603-4 and is used to supply a clean reference bias for the Low Speed Data filterand Voice Storage circuits. The circuit of Q607 which can limit the voltage applied to the VoiceStorage chip is not used in portable applications and is disabled by 0 Ohm resistor R614.

2.20.4.2 Microcontroller (MCU)

PassPort Trunking operation is managed by the reprogrammable FLASH ROM based microcontroller(U601). The MCU clock oscillator uses 8MHz crystal Y601 as a stable resonator. The PTCBcommunicates with the main radio microcontroller by attaching to the same Serial Peripheral (SPI)bus that passes though the PTCB to the LCD on the CLK, DATA, RDY, and MISO lines. The OPT_ENline is strobed low only for communications with U601.

The MCU includes an on-chip Analog to Digital Converter (ADC). The received and filtered sub-audible low speed trunking data waveform is applied to one of the ADC inputs. The software in theMCU decodes and acts upon the trunking data.

The MCU includes a Digital to Analog Converter (DAC). As required, the MCU software generatesappropriate PassPort Low Speed Trunking Data waveforms. These are applied to the Low SpeedData Filter and then to the radio transmitter modulation point. The amplitude of this waveform and theresulting transmitted deviation is controlled by software.

2.20.4.3 Low Speed Data Filter

This analog circuitry is a 4 pole, 150 Hz cutoff low pass filter comprised of U603-1, U603-2 andassociated passive components. In receive mode, it removes noise and voice band signals leavingonly the low speed data waveform which is applied to the ADC input of the MCU. U608-4 isolates thereceive signal from the filter in transmit mode. When the radio is transmitting PassPort data, the MCUDAC low speed data waveform is applied to the input of the filter which removes harmonics that wouldinterfere with voice and applies the resulting sub-audible data to the radio transmitter modulationpoint.

2.20.4.4 Keyboard Circuit

The keyboard consists of a matrix of key switches and resistors as described in section 2.3. U605-2monitors the column voltage and applies an interrupt signal to the radio microcontroller when any keyis pressed.

2-34

2.20.4.5 BackLight Driver and LED's

The logic level signal from the radio microcontroller is translated via Q611 and applied to Q610 whichuses Switched Battery Voltage (SWB+) to operate the keypad backlight LED’s.

2.20.4.6 Voice Storage

The Voice Storage (VS) can be used to store audio signals coming from the receiver or from themicrophone. Any stored audio signal can be played back over the radio’s speaker or sent out via theradio’s transmitter.

The PTCB hosts the Voice Storage circuitry. Voice Storage IC U611 provides all the requiredfunctionality and is powered from the regulated 5 volts. The mP controls U611 via SPI bus lines CLK(U611-8), DATA (U611-10) and MISO (U611-11). To transfer data, the mP first selects the U611 vialine VS CS and U611 pin 9. Then the mP sends data through line DATA and receives data throughline MISO. Pin 2 (RAC) of U611 indicates the end of a message row by a low state for 12.5 ms andconnects to mP pin 65. A low at pin 5 (INT), which is connected to mP pin 55, indicates that the VoiceStorage IC requires service from the mP.

Audio, either from the radio’s receiver or from one of the microphone inputs, emerges from the ASFICCMP (U404) at pin 43, through switch U608-1 that is selected by the mP via ASFIC CMP pin 5(DACR) and then enters the voice storage IC U611 at pin 25. During playback, the stored audioemerges from U611 at pin 20. To transmit the audio signal, it is fed through resistive divider R657 /R658, through switch U608-3 and through line EXT MIC. When this path is selected, the audio signalenters the ASFIC CMP at pin 48 and is processed like normal transmit audio. To play the stored audioover the radio’s speaker, the audio from U611 pin 20 is buffered by op-amp U605-1, through switchU608-2 and fed via line FLAT RX SND to ASFIC CMP pin 10 (UIO). In this case, this ASFIC CMP pinis programmed as input and feeds the audio signal through the normal receiver audio path to thespeaker or handset. Switches U608-2 and U608-3 are controlled by the mP via ASFIC CMP pin 6(DACG) and feed the stored audio only to the ASFIC CMP port UIO when it is programmed as input.

2.21 900 MHz Transmitter

Figure 2-24: Transmitter Block Diagram

PCIC

PADriver

Antenna Switch/Harmonic Filter

PA FinalStage

Vcontrol VcontrolAntenna

Jack

From VCO

Power Amplifier (PA)

2-35

The 900 MHz transmitter contains the following basic circuits:

• power amplifier• antenna switch• harmonic filter• power control integrated circuit (PCIC).

2.21.1 Power Amplifier

The power amplifier consists of two devices:

• 5185130C65 driver IC (U101) and• 4813828A09 LDMOS PA (Q101).

The 30C65 driver IC contains a 2 stage amplification with a supply voltage of 7.5V.

This RF driver IC is capable of supplying an output power of 0.3W (pin 6 and 7) with an input signal of2.5mW (4dBm) (pin16). The current drain would typically be 200mA while operating in the frequencyrange of 896-941 MHz.

The 28A09 LDMOS PA is capable of supplying an output power of 4.5W with an input signal of 0.3W.The current drain would typically be 1100mA while operating in the frequency range of 896-941 MHz.The power out can be varied by changing the biasing voltage and the drive level from the driver IC.

2.21.2 Antenna Switch

The antenna switch circuit consists of two PIN diodes (CR101 and CR102), a pi network (C115, L109and C138), and three current limiting resistors (R102, R103, R106). In the transmit mode, B+ at PCIC(U102) pin32 will go high, applying a B+ bias to the antenna switch circuit to bias the diodes “on”. Theshunt diode (CR102) shorts out the receiver port, and the pi network, which operates as a quarterwave transmission line, transforms the low impedance of the shunt diode to a high impedance at theinput of the harmonic filter. In the receive mode, the diodes are both off, and hence, there exists a lowattenuation path between the antenna and receiver ports.

2.21.3 Harmonic Filter

The harmonic filter consists of L104, L105, C114, C115, C124,C125, and C126. It has been optimizedfor efficiency of the power amplifier. This type of filter has the advantage that it can give a greaterattenuation in the stop-band for a given ripple level. The harmonic filter insertion loss is typically0.9 dB, and less than 1.2dB.

2.21.4 Power Control Integrated Circuit (PCIC)

The transmitter uses the Power Control IC (PCIC), U102 to regulate the power output of the radio.The current to the final stage of the power module is supplied through R101, which provides a voltageproportional to the current drain. This voltage is then fed back to the Automatic Level Control (ALC)within the PCIC to regulate the output power of the transmitter.

The PCIC has internal digital to analog converters (DACs) which provide the reference voltage of thecontrol loop. The reference voltage level is programmable through the SPI line of the PCIC.

There are resistors and integrators within the PCIC, and external capacitors (C156, C157, and C158)in controlling the transmitter rising and falling time. These are necessary in reducing the powersplatter into adjacent channels.

U103 and its associated components are part of the temperature cut back circuitry. It senses theprinted circuit board temperature around the transmitter circuits and output a DC voltage to the PCIC.If the DC voltage produced exceeds the set threshold in the PCIC, the transmitter output power will bereduced so as to reduce the transmitter temperature.

2-36

2.22 900 MHz Receiver

Figure 2-25: 900 MHz Receiver Block Diagram

2.22.1 Receiver Front-End

The RF signal is received by the antenna and applied to a low-pass filter. For 900 MHz, the filterconsists of L104, L105, C114, C115, C124, C125, and C126. The filtered RF signal is passed throughthe antenna switch. The antenna switch circuit consists of two PIN diodes(CR101, and CR102) and api network (C115, L109, and C138). The signal is then applied to a fixed tuned ceramic bandpassfilter, FL300.

The output of the bandpass filter is coupled to the RF amplifier transistor Q302 via C300. The RFamplifier provides a gain of approximately 14 dB. After being amplified by the RF amplifier, the RFsignal is further filtered by a second fixed tuned ceramic bandpass filter, FL301.

Both the pre and post-RF amplifier ceramic filters have similar responses. The insertion loss of eachfilter across the 935-941 MHz band is less than 2 dB.

The output of the post-RF amplifier filter is connected to the passive double balanced mixer, U301,through matching components C321, and L311. After mixing with the first LO signal from the voltagecontrolled oscillator (VCO) using low side injection, the RF signal is down-converted to the109.65MHz IF signal.

The IF signal coming out of the mixer is transferred to the crystal filter (FL350) through a resistor padand a diplexer (C312, and L306). Matching to the input of the crystal filter is provided by L353,L354,C377, and C378. The crystal filter provides some of the necessary selectivity, and intermodulationprotection.

Demodulator

Synthesizer

CrystalFilter Mixer

RFAmp

IFAmp

3-PoleCeramic

Block Filter

3-PoleCeramic

Block Filter

Antenna

First LOfrom FGU

Recovered Audio

Squelch

RSSIIF IC

SPI Bus

16.8 MHzReference Clock

SecondLO VCO

RFJack

Pin DiodeAntennaSwitch

AGCProcessing

U351

2-37

2.22.2 Receiver Back-End

The output of crystal filter FL350 is matched to the input of the dual gate MOSFET IF amplifiertransistor U352 by components L355, R359, and C376. Voltage supply to the IF amplifier is takenfrom the receive 5 volts (R5). AGC voltage is applied to the second gate of U352. The IF amplifierprovides a gain of about 11dB. The amplified IF signal is then coupled into U351(pin 3) via L352,R356 and C365 which provides the matching for the IF amplifier and U351.

The IF signal applied to pin 3 of U351 is amplified, down-converted, filtered, and demodulated, toproduce the recovered audio at pin 27 of U351. This IF IC is electronically programmable, and theamount of filtering (which is dependent on the radio channel spacing) is controlled by themicroprocessor. Additional filtering, once externally provided by the conventional ceramic filters, isreplaced by internal filters in the IF module (U351).

The IF IC uses a type of direct conversion process, whereby the externally generated second LOfrequency is divided by two in U351 so that it is very close to the first IF frequency. The IF IC (U351)synthesizes the second LO and phase-locks the VCO to track the first IF frequency. The second LO isdesigned to oscillate at twice the first IF frequency because of the divide-by-two function in the IF IC.

In the absence of an IF signal, the VCO will “search” for a frequency, or its frequency will vary close totwice the IF frequency. When an IF signal is received, the VCO will lock onto the IF signal. Thesecond LO/VCO is a Colpitts oscillator built around transistor Q350. The VCO has a varactor diode,CR350, to adjust the VCO frequency. The control signal for the varactor is derived from a loop filterconsisting of R365, C391, and C392.

The IF IC (U351) also performs several other functions. It provides a received signal-strengthindicator (RSSI) and a squelch output. The RSSI is a dc voltage monitored by the microprocessor,and used to control the automatic gain control (AGC) circuit in both the front-end and the IF.

The demodulated signal on pin 27 of U351 is also used for squelch control. The signal is routed toU851 where a “flutter fighter” process is implemented. The signal leaves U851 via pin F4 and is thenrouted to U404 (ASFIC) where squelch signal shaping and detection takes place. The demodulatedaudio signal is also routed to U404 for processing before going to the audio amplifier for amplification.

2.22.3 Hear Clear IC

Hear Clear (HC) IC is typically used for 900MHz radios. The HC IC comprises three main internalcircuit blocks:

• Compressor,• Flutter Fighter, and• Expander Circuits.

Only the Flutter Fighter section of this IC is used by this radio. The Compressor and the Expander areincluded in the ASFIC. There are six enable/control lines on the Hear Clear IC which determine theICs mode of operation. The Flutter Fighter Enable line (U851-E3) is controlled by ASFIC DACRX line(U404-4). The logic control and the IC status is summarized in Table 2-8.

Table 2-8 Hear Clear Logic and IC Status

Name Ref. Des Set By RX1* RX2**

IC Enable U851-C4 SWB+ 1 1

Flutter FighterEnable

U851-E3 DACRX 1 0

LO Clamp Disable U851-A5 SWB+ 1 1

2-38

*RX1:receive voice with carrier squelch, PL or DPL (Flutter Fighter can be on or off).**RX2:refers to receive mode with all other data HST/MDC/DTMF (Flutter Fighter must be off).

2.22.3.1 Receive Path for Radios with Hear Clear

The audio signal enters Hear Clear controller from DEMOD_OUT signal on DISC. The detected audio“DISC” enters the Hear Clear Flutter Fighter through C857 and C859. C857 connects the signal to FFIN (U851-E4). C859 is a beginning of a noise sampling circuit consisting of components – C859,R853, C860, R854, C861, R855 and C862; and Hear Clear Ports Ref, Noise Filter In, and Noise FilterOut, Noise Hold.

After exiting Hear Clear at the “FF OUT” (U851-F4), the signal enters ASFIC at DISC (U404-2). Withinthe ASFIC, the signal passes through a low pass filter and high pass filter limiting the audio bandwidthto 300Hz-3KHz. It then goes through de-emphasis and exits the ASFIC at AUDIO (U404-41). Theaudio is then routed to the Audio PA in the same manner as the standard receive audio.

The purpose of the Flutter Fighter is to sample the amount of Noise in the receive audio between 10-20KHz using the Noise Filter (U851-B5), Noise Filter Out (U851-C6), and Noise Hold (U851-D5). Inaddition, it monitors the rate of change of RSSI (Receive Signal Strength In) (U303-1). The detectedaudio DISC enters into the Hear Clear IC at “FF IN” (U851-E4). The circuit then reduces the amountof popping Noise associated with fading. The improved audio exits the IC at “FF OUT” (U851-F4).

2.22.3.2 Hear Clear Routing of Data/Signaling

While receiving, sub-audible signals PL/DPL go through the Flutter Fighter along with the audio, andis unaffected by the Flutter Fighter operation. On entering the ASFIC, the sub-audible signaling isseparated from the voice and decoded.

While receiving other signals HST/MDC (not sub-audible), the Flutter Fighter is set to the “passthrough mode”. In this mode, the Flutter Fighter is routed from ”FF IN” to “FF OUT” without anyprocessing.

2.22.4 Automatic Gain Control Circuit

The automatic gain control circuit provides automatic gain reduction of both the low noise amplifier inthe receiver front end and the IF amplifier in the receiver backend. This action is necessary to preventoverloading of the backend IF IC.

The IF automatic gain control circuit provides approximately 50 dB of attenuation range. The signalstrength indicator (RSSI) output of the IF IC produces a voltage that is proportional to the RF level atthe IF input to the IF IC. This voltage is inverted by U350, R351, R353, R352, R354 and C355 and itdetermines the RF level at which the backend end AGC is activated as well as the slope of thevoltage at the output of U350 vs. the strength of the incoming RF at the antenna. The inverted outputof U350 is applied to the second gate of the IF amplifier U352 via R355. As the RF signal into the IFIC increases the following occurs:

• the RSSI voltage increases,• the output of inverter U350 decreases, and• the voltage applied to the second gate of the FET is reduced thus reducing the gain of the IF

amplifier.

LO Clamp Disable U851-C2 GND 0 0

HCI Disable U851-B6 SWB+ 1 1

LO Clamp Disable U851-D1 GND 0 0

Table 2-8 Hear Clear Logic and IC Status

2-39

The output of inverter U350 is also used to control the receiver front end AGC.

The receiver front end automatic gain control circuit provides and additional 20 dB of gain reduction.The output of the receiver back end inverter U350 is fed into the receiver front end AGC inverterU302. The components R317, R314, and C318 determine:

• the RF level at which the front end AGC is activated, and• the slope of the voltage at the output of U302 vs. the strength of the incoming RF at the antenna.

As the RF into the antenna increases the following occurs:

• The output voltage of the receiver back end inverter U350 decreases.• The voltage at the output of the front end inverter U302 increases.• The result is the forward biasing of pin diode CR301.

As the diode becomes more and more forward biased the following occurs:

• C310 loads the output of the low noise amplifier Q302 thus reducing the gain of the low noiseamplifier.

• R315 and R318 provide a DC path for CR301 and also limit the current through CR301.

The blocking capacitor C317 prevents DC from the AGC stage from appearing at the input of the filterFL301.

2.23 Frequency Generation Circuitry

Figure 2-26: Frequency Generation Unit Block Diagram

The Frequency Generation Circuitry is comprised of two main ICs, the Fractional-N synthesizer(U201), and the VCO/Buffer IC (U250). Designed in conjunction to maximize compatibility, the two ICsprovide many of the functions that normally would require additional circuitry. The synthesizer blockdiagram illustrates the interconnect and support circuitry used in the region. Refer to the relevantschematics for the reference designators.

The synthesizer is powered by regulated 5V and 3.3V which come from U247 and U248 respectively.The synthesizer in turn generates a superfiltered 4.5V which powers U250.

In addition to the VCO, the synthesizer must interface with the logic and ASFIC circuitry.Programming for the synthesizer is accomplished through the data, clock and chip select lines from

SynthesizerU201

VCOBICU250

VoltageMultiplier Dual

Transistor

LoopFilter

InjectionAmplifier

BufferAmplifier

To Mixer

To PA Driver

VCP

Vmult1

Vmult2

Aux3

Aux4

MOD Out

ModulatingSignal

Rx VCOCircuit

Tx VCOCircuit

TRB

16.8 MHzRef. Osc.

RxOut

TxOut

2-40

the microprocessor. A 3.3V dc signal from synthesizer lock detect line indicates to the microprocessorthat the synthesizer is locked.

Transmit modulation from the ASFIC is supplied to pin10 of U201. Internally the audio is digitized bythe Fractional-N and applied to the loop divider to provide the low-port modulation. The audio runsthrough an internal attenuator for modulation balancing purposes before going out to the VCO.

2.24 900 MHz SynthesizerThe Fractional-N Synthesizer uses a 16.8 MHz packaged 1.5 ppm reference oscillator (Y200) toprovide a reference for the system. The LV FractN IC (U201) further divides the 16.8 MHz to 2.1MHz,2.225 MHz, and 2.4 MHz. Y200, together with C238, C239, C241, R212, R213, and R214 comprisethe reference oscillator which is capable of 1.5 ppm stability over temperatures of -30 to 85°C. It alsoprovides 16.8 MHz at pin 19 of U201 to be used by ASFIC and LVZIF.

The loop filter which consists of C801, C802, C803, C804, C805, C225, C226, R204, R209, and R210provides the necessary dc steering voltage for the VCO and provides filtering of noise and spurs fromU201.

In achieving fast locking for the synthesizer, an internal adapt charge pump provides higher current atpin 45 of U201 to put the synthesizer within the lock range. The required frequency is then locked bythe normal mode charge pump at pin 43.

Both the normal and adapt charge pumps get their supply from the capacitive multiplier which is madeup of CR201, CR202, C244, C245, C246, C247, R200, R218, C208, C243, R219, and R220. Two 3.3V square waves (180 degrees out of phase) are applied to R219 and R220. These square wavesswitch alternate sets of diodes from CR201 and CR202, which in turn charge C244, C245, C246, andC247 in a bucket brigade fashion. The resulting output voltage that is applied to pin 47 of U201 istypically 12.8V and allows the steering line voltage (VCO control voltage) to reach 11V.

Figure 2-27: Synthesizer Block Diagram

DATA

CLK

CEX

MODIN

VCC, DC5V

XTAL1

XTAL2

WARP

PREIN

VCP

ReferenceOscillator

VoltageMultiplier

VoltageControlledOscillator

2-PoleLoop Filter

DATA (U409 Pin 100)

CLOCK (U409 Pin 1)

CSX (U409 Pin 2)

MOD IN (U404 Pin 40)

+5V (U247 Pin 4)

7

8

9

10

13,30

23

24

25

32

47

VMULT2 VMULT1

BIAS1

SFOUT

AUX3

AUX4

IADAPT

IOUT

GND

FREFOUT

LOCK4

19

6,22,23,24

43

45

3

2

28

14 15

40

Filtered 5V

12.8V

3.3Vp-p

3.3Vp-p

SteeringLine

11.0V

LOCK (U409 Pin 56)

Prescaler In

LO RFInjection

TX RFInjection

(First Stage of PA)

FREF (U201 Pin 21 & U404 Pin 34)

39BIAS2

41

DualTransistors

48

5VR405

(U248 Pin 5)

AUX1

VDD, 3.3V MODOUTU251

Low VoltageFractional-NSynthesizer

5,20,34,36

DualTransistors

2-41

2.25 900 MHz Voltage Control Oscillator (VCO)

Figure 2-28: VCO Block Diagram

The VCOBIC (U250) in conjunction with the Fractional-N synthesizer (U201) generates RF in both thereceive and the transmit modes of operation. The TRB line (U250 pin 19) determines which oscillatorand buffer will be enabled. A sample of the RF signal from the enabled oscillator is routed from U250pin 12, through a low pass filter, to the prescaler input (U201 pin 32). After frequency comparison inthe synthesizer, a resultant CONTROL VOLTAGE is received at the VCO. This voltage is a DCvoltage between 2.0V (low frequency) and 11.0V (high frequency) when the PLL is locked onfrequency.

The VCOBIC(U250) is operated at 4.54 V (VSF) and Fractional-N synthesizer (U201) at 3.3V. Thisdifference in operating voltage requires a level shifter consisting of Q200 and Q252 on the TRB line.

Presc

RX

TX

InjectionAmplifier

BufferAmplifier

Pin 8

Pin 14

Pin 10

5V

(U201 Pin 28)VCC Buffers

TX RF Injection

U201 Pin 32

AUX4 (U201 Pin 3)

AUX3 (U201 Pin 2)

Prescaler OutPin 12

Pin 19Pin 20

TX/RX/BSSwitching Network

U250VCOBIC

Rx ActiveBias

Tx ActiveBias

Pin 2Rx-I adjust

Pin 1Tx-I adjust

Pins 9,11,17Pin 18

VsensCircuit

Pin 15

Pin 16TX VCOCircuit

TXTank

RX VCOCircuit

RXTank

Pin 7

Vcc-Superfilter

Collector/RF inPin 4

Pin 5

Pin 6

RX

TX

(U201 Pin 28)

Rx-SW

Tx-SW

Vcc-Logic

(U201 Pin 28)

Steer LineVoltage

(VCTRL)

Pin 13

Pin 3

TRB_IN

LO RF INJECTION

Level ShifterNetwork

VSF

VSF

VSF

2-42

The operation logic is shown in Table 2-9.

In the receive mode, U250 pin 19 is low or grounded. This activates the receive VCO by enabling thereceive oscillator and the receive buffer of U250. The RF signal at U250 pin 8 is run through aninjection amplifier, Q304. The resulting RF signal is the LO RF INJECTION and it is applied to themixer at U301.

During the transmit condition, when PTT is depressed, five volts is applied to U250 pin 19. Thisactivates the transmit VCO by enabling the transmit oscillator and the transmit buffer of U250. The RFsignal at U250 pin 10 is amplified by Q251 and injected into the input of the PA module (U101 pin1).This RF signal is the TX RF INJECTION. Also in transmit mode, the audio signal to be frequencymodulated onto the carrier is received through the U201 pin 41.

When a high impedance is applied to U250 pin19, the VCO is operating in BATTERY SAVER mode.In this case, both the receive and transmit oscillators as well as the receive transmit and prescalerbuffer are turned off.

Table 2-9 Level Shifter Logic

Desired Mode AUX 4 AUX 3 TRB

Tx Low High (@3.2V) High (@4.8V)

Rx High Low Low

Battery Saver Low Low Hi-Z/Float (@2.5V)

3-1

Chapter 3

Maintenance

3.1 IntroductionThis chapter of the manual describes:

• Preventive maintenance• Safe handling of CMOS devices• Repair procedures and techniques

3.2 Preventive MaintenanceThe radios do not require a scheduled preventive maintenance program; however, periodic visualinspection and cleaning is recommended.

3.3 InspectionCheck that the external surfaces of the radio are clean, and that all external controls and switches arefunctional. It is not recommended to inspect the interior electronic circuitry.

3.3.1 Cleaning

The following procedures describe the recommended cleaning agents and the methods to be usedwhen cleaning the external and internal surfaces of the radio. External surfaces include the frontcover, housing assembly, and battery case. These surfaces should be cleaned whenever a periodicvisual inspection reveals the presence of smudges, grease, and/or grime.

The only recommended agent for cleaning the external radio surfaces is a 0.5% solution of a milddishwashing detergent in water. The only factory recommended liquid for cleaning the printed circuitboards and their components is isopropyl alcohol (70% by volume).

1. Cleaning External Plastic SurfacesThe detergent-water solution should be applied sparingly with a stiff, non-metallic, short-bristledbrush to work all loose dirt away from the radio. A soft, absorbent, lintless cloth or tissue shouldbe used to remove the solution and dry the radio. Make sure that no water remains entrappednear the connectors, cracks, or crevices.

2. Cleaning Internal Circuit Boards and ComponentsIsopropyl alcohol may be applied with a stiff, non-metallic, short-bristled brush to dislodge embed-ded or caked materials located in hard-to-reach areas. The brush stroke should direct the dis-lodged material out and away from the inside of the radio. Make sure that controls or tunablecomponents are not soaked with alcohol. Do not use high-pressure air to hasten the drying pro-cess since this could cause the liquid to collect in unwanted places. Upon completion of thecleaning process, use a soft, absorbent, lintless cloth to dry the area. Do not brush or apply any

NOTE Internal surfaces should be cleaned only when the radio is disassembled for servicing orrepair.

CAUTION: The effects of certain chemicals and their vapors can have harmful results on certain plastics. Aerosol sprays, tuner cleaners, and other chemicals should be avoided.!

3-2 Safe Handling of CMOS and LDMOS

isopropyl alcohol to the frame, front cover, or back cover.

3.4 Safe Handling of CMOS and LDMOSComplementary metal-oxide semiconductor (CMOS) and lateral diffusion metal oxide semiconductor(LDMOS) devices are used in this family of radios. Their characteristics make them susceptible todamage by electrostatic or high voltage charges. Damage can be latent, resulting in failures occurringweeks or months later. Therefore, special precautions must be taken to prevent device damageduring disassembly, troubleshooting, and repair.

Handling precautions are mandatory for the circuits and are especially important in low humidityconditions. DO NOT attempt to disassemble the radio without first referring to the CMOS CAUTIONparagraph in the Disassembly and Reassembly section of the basic manual (See Chapter 3).

3.5 General Repair Procedures and Techniques• Parts Replacement and Substitution

When damaged parts are replaced, identical parts should be used. If the identical replacementcomponent is not locally available, check the parts list for the proper Motorola part number andorder the component from the nearest Motorola Communications parts center listed in the “PieceParts” section of this manual (See Chapter 1).

• Rigid Circuit BoardsThe family of radios uses bonded, multi-layer, printed circuit boards. Since the inner layers are notaccessible, some special considerations are required when soldering and unsolderingcomponents. The printed-through holes may interconnect multiple layers of the printed circuit.Therefore, care should be exercised to avoid pulling the plated circuit out of the hole.

When soldering near the 20-pin and 40-pin connectors:

• avoid accidentally getting solder in the connector.• be careful not to form solder bridges between the connector pins.• closely examine your work for shorts due to solder bridges.

• Flexible CircuitsThe flexible circuits are made from a different material than the rigid boards and differenttechniques must be used when soldering. Excessive prolonged heat on the flexible circuit candamage the material. Avoid excessive heat and excessive bending.

For parts replacement, use the ST-1087 Temperature-Controlled Solder Station with a 600-700degree tip, and use small diameter solder such as ST-633. The smaller size solder will meltfaster and require less heat to be applied to the circuit.

To replace a component on a flexible circuit:

• grasp the edge of the flexible circuit with seizers (hemostats) near the part to be removed.• pull gently.• apply the tip of the soldering iron to the component connections while pulling with the

seizers.

Do not attempt to puddle out components. Prolonged application of heat may damage theflexible circuit.

NOTE Always use a fresh supply of alcohol and a clean container to prevent contamination bydissolved material (from previous usage).

General Repair Procedures and Techniques 3-3

• Chip ComponentsUse either the RLN-4062 Hot-Air Repair Station or the Motorola 0180381B45 Repair Station forchip component replacement. When using the 0180381B45 Repair Station, select the TJ-65 mini-thermojet hand piece. On either unit, adjust the temperature control to 700 degrees F. (370degrees C), and adjust the airflow to a minimum setting. Airflow can vary due to componentdensity.

• To remove a chip component:

• Use a hot-air hand piece and position the nozzle of the hand piece approximately 1/8” (0.3cm) above the component to be removed.

• Begin applying the hot air. Once the solder reflows, remove the component using a pair oftweezers.

• Using a solder wick and a soldering iron or a power desoldering station, remove the excesssolder from the pads.

• To replace a chip component using a soldering iron:

• Select the appropriate micro-tipped soldering iron and apply fresh solder to one of the sol-der pads.

• Using a pair of tweezers, position the new chip component in place while heating the freshsolder.

• Once solder wicks onto the new component, remove the heat from the solder.

• Heat the remaining pad with the soldering iron and apply solder until it wicks to the compo-nent. If necessary, touch up the first side. All solder joints should be smooth and shiny.

• To replace a chip component using hot air:

• Use the hot-air hand piece and reflow the solder on the solder pads to smooth it.

• Apply a drop of solder paste flux to each pad.

• Using a pair of tweezers, position the new component in place.

• Position the hot-air hand piece approximately 1/8” (0.3 cm) above the component andbegin applying heat.

• Once the solder wicks to the component, remove the heat and inspect the repair. All jointsshould be smooth and shiny.

• ShieldsRemoving and replacing shields will be done with the R-1070 station with the temperature controlset to approximately 415°F (215°C) [445°F (230°C) maximum].

• To remove the shield:

• Place the circuit board in the R-1070’s holder.

• Select the proper heat focus head and attach it to the heater chimney.

• Add solder paste flux around the base of the shield.

• Position the shield under the heat-focus head.

• Lower the vacuum tip and attach it to the shield by turning on the vacuum pump.

• Lower the focus head until it is approximately 1/8” (0.3 cm) above the shield.

• Turn on the heater and wait until the shield lifts off the circuit board.

• Once the shield is off, turn off the heat, grab the part with a pair of tweezers, and turn off thevacuum pump.

• Remove the circuit board from the R-1070’s circuit board holder.• To replace the shield:

• Add solder to the shield if necessary, using a micro-tipped soldering iron.

3-4 Recommended Test Tools

• Next, rub the soldering iron tip along the edge of the shield to smooth out any excess sol-der. Use solder wick and a soldering iron to remove excess solder from the solder pads onthe circuit board.

• Place the circuit board back in the R1070’s circuit board holder.

• Place the shield on the circuit board using a pair of tweezers.

• Position the heat-focus head over the shield and lower it to approximately 1/8” (0.3 cm)above the shield.

• Turn on the heater and wait for the solder to reflow.

• Once complete, turn off the heat, raise the heat-focus head and wait approximately oneminute for the part to cool.

• Remove the circuit board and inspect the repair. No cleaning should be necessary.

3.6 Recommended Test ToolsTable Table 3-1 lists the recommended tools used for maintaining this family of radios. These tools arealso available from Motorola.

Table 3-1 Recommended Test Tools

Motorola Part Number Description Application

RSX4043 Torx Driver Tighten and remove chassis screws.

6680387A70 T-6 Torx Bit Removable Torx driver bit.

R1453A Digital readout solder station Digitally controlled soldering iron.

0180386A78 Illuminated magnifying glasswith lens attachment.

0180386A826684253C726680384A981010041A86

1080303E45

Anti-static grounding kitStraight proberBrushSolder (RMA type),63/37, 0.5mm diameter1 lb. spoolSMD tool kit (included withR1319A)

Used during all radio assembly and disassembly pro-cedures.

R1319A (110V)

or R1321A(220V)

ChipMaster Surface Mount

Rework Station

Removal and assembly of surface-mounted inte-grated circuits and shields includes 5 nozzels.

R1364A Digital Heated Tweezer Sys-tem

Chip component removal.

R1427A Board Preheater Reduces heatsink on multi level boards.

8880309B53 Rework Equipment Catalog Contains application notes, procedures and technicalrework equipment.

Replacing the Circuit Board Fuse 3-5

3.7 Replacing the Circuit Board FuseIn cases where the radio fails to turn on when power is applied, the circuit board fuse should alwaysbe checked as a probable cause of the failure. The locations of the fuse for both the UHF and VHFboards are shown in Figure 3-1. The radio must be disassembled to replace the fuses as describedinthe Basic Service Manual (see Chapter 1 - Related Documents), then the circuit board separatedfrom the radio chassis as described in the paragraphs that follow.

3-6 Replacing the Circuit Board Fuse

Figure 3-1:UHF/VHF/Low Band/800MHz/900MHz Circuit Board Fuse Locations

C108J101

43

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310

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C355

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C363

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C369

C370

C372

C373

C374

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381C

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R211

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R216

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R221

R222

R223

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R261

R262

R263

R264

R269

R271

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R351

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VR506

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C125

C126

C127

C128

C129

C131

C132

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C137

C138

C139

C140

C141

C142

C143

C146

C204

C205

C214

C215

C216

C221 C222

C225C226

C227

C230

C231

C236

C242

C255

C256

C257

C258

C259

C261

C280

C281

C297

C298

C299

C307

C319

C320

C321

C323

C324

C325

C326

C327

C328

C330

C331

C332

C333

C334

C335

C336

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C340

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C342

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C412

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L204

L207

L208L209

L211

L212

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L225

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L307

L410

L411

L501

L502

M100

M101

M202

M300

M301

M400

M401

Q203

4 3Q410

Q416

Q509

R101

R102

R103

R107

R108

R109

R110

R111

R113

R114

R115

R116

R117

R118 R119

R204

R206

R219

R222

R223

R224

R225

R228

R231

R232

R234

R236

R238R239

R306

R307

R308

R309

R318

R400

R409

R411

R413

R414R415

R419

R420

R423 R424

R425 R426

R431

R432

R434 R445

R449

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R460

R461

R462

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R472

R473

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R504

R505

R512

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U410

11

1 20

10

U420

VR101

VR

200V

R201

VR202

VR

203

VR432VR433

VR

445

VR

446

VR

448

FL0830475O

Low Band Board800 MHz Board

123 B501

C101

C102

C103

C104

C105

C106

C107

C108

C110

C122

C123

C124

C125

C126

C133

C136

C137

C143

C144

C150

C154

C155

C156

C157

C158

C159

C160

C165

C201

C202

C203

C204 C

205

C208

C209

C210

C211

C212

C214

C216

C217

C218

C219

C221 C

222

C223

C225C226

C230

C231

C234

C240

C242

C243

C244

C245

C246

C247

C250

C251

C252

C253

C254

C255

C256

C257

C259

C260

C261

C262

C263

C264

C265

C266

C267

C268

C274 C280

C284

C286

C287

C290

C291

C292

C293

C300

C301

C302

C303

C305

C306

C308

C310

C317

C318

C350

C352

C353

C354

C355

C356

C357

C358

C359

C360

C363

C364

C366

C367

C369

C370

C372

C373

C374

C379

C380 C

381C

383C

394

C405

C407

C408

C409

C410

C411

C412

C414

C415

C416

C419

C420

C421

C422

C430

C431

C433C

434

C435

C436

C437

C439

C442

C445

C447C448

C449

C450

C451

C452 C453

C456

C458

C459

C463

C466

C475

C476

C479

C481

C492

C503

C522

C524

C525

C528

C801

C802

C803

C804

C805

C851

C852

C853

C856

C857

C859 C860C

861

C862CR201

CR202

CR300

CR

301

CR411

CR

501

E101

E400

E401E402

E403

E404 E405

E406

F501

2

FL301

3FL401

J101

L202L204

L250

L252

L253

L254

L256

L259 L260

L265

L301

L302 L303

L304

L350

L351

L410

L411

L505L851

M101

Q251

43

Q252

Q302

4 3Q410

Q416

R101

R102

R103

R108

R110

R117

R118

R121

R200

R202

R203

R204

R209

R210

R218

R219

R220

R250

R251

R253

R254

R255

R257R

261R

262

R263

R264

R271

R273

R274

R275

R280

R281

R282

R306

R307

R309R310

R312

R314

R315

R317

R318

R329

R330

R331

R332

R333

R334

R335 R336

R350

R351

R352

R353

R354

R400

R409

R411

R413

R414R415

R419

R420

R423 R424

R425 R426

R431

R432

R434

R438

R439

R445R449

R457

R460

R461

R462

R463

R471

R472

R473

R475

R851 R852

R853

R854

R855

R856

2 C 8

C4

S501

453 2

S502

SH102

SH201

SH250

SH301

SH353

SH402

SH403

1

179

25

U102

U103

U202

U203

11

120

10

U250

U302

U303

U350

137

2513

U351

1 372513

U404

176

5126

U409

U410

11

1 20

10

U420

E6

F5F2

E1 B1A2

B6A5

U851

VR101

VR432VR433

VR445

VR446

VR448

VR502

VR503

VR505

VR507

VIEWED

FRO

M SID

E 1

FL0830703O

900 MHZ Board

Removing and Reinstalling the Circuit Board 3-7

3.2 Removing and Reinstalling the Circuit Board Both the UHF and VHF circuit boards are removed from the radio chassis in the following manner:

1. Refer to the Basic Service Manual (see Chapter 1 - Related Documents) for radio disassembly,then use a Torx driver and a T-6 bit to remove the four Torx screws shown in Figure 3-2.

2. Lift the circuit board out of the radio chassis, then remove and discard the thermal pad locatedbetween the circuit board and chassis.

3. After repairs, replace the thermal pad (Motorola P/N 7580556Z01) then reinstall the circuit boardinto the radio chassis.

4. Reinstall and tighten the four Torx screws to secure the circuit board to the chassis.

5. Refer to the Basic Service Manual to reassemble the radio.

Figure 3-2:Circuit Board Removal and Reinstallation

3.3 Power Up Self-Test Error CodesTurning on the radio starts a self-test routine that checks the RAM, ROM checksum, EEPROMhardware and EEPROM checksum. If these checks are successful, the radio generates two high-pitched self-test pass tones. If the self-test is not successful, one low-pitched tone is heard. Radioswith displays are able to display the error codes. The displayed error codes and related correctionsare as follows:

If the error code displayed is ...

Then, there is a ...

To correct the problem ...

“RAM TST ERROR” RAM test failure. retest the radio by turning it off and turning it on again. Ifmessage reoccurs, replace RAM (U405).

“ROM CS ERROR” wrong ROMchecksum.

replace ROM (U406).

“EEPRM HW ERROR” codeplug structuremismatch or nonexistence ofcodeplug.

reprogram codeplug with correct version and retestradio. If message reoccurs, replace EEPROM (U407).

“EEPRM CS ERROR” wrong codeplugchecksum.

reprogram codeplug.

L400R

421

TP405

VR

434VR450 C

R41

3

Q41

7

34

TP406

J403

20

22

C441

C491

C492

C490

C493

C494

C495

C496

C497

R477

R45

0

21

1

C471C472

C473

L401

TP410

VR

447

VR

449

C443

40

R435

TP401

TP402 C427

C444

C428

RT400

85 4

1U

407

J400

C42

3 E407

E40

8E409

R41

8

R437

R410SH400

8 21

U405

17 22

C426 C425

C429

C424R408

R49

2

R42

9

R478

R428

116

U40

6

1732

PB503

3

FL201B

503

C43

2

SH201

TP201

C220

C22

9

C21

7

C22

8 L201

L203

C260

C29

4

C23

5

C29

1L2

02

U247

C203

Q210

34

R256

R255

C21

0

C211C21

2

C213

C21

4

C23

0

C292

C23

3

C238

C29

7

L232Q26

0 34

C257

CR

201

C251

C28

9

C253

Q261

34

R26

0

SH241 C247

C28

5

C248

C28

6

L282

Q241

R24

3

R248

R25

3

C273

3

L243

C37

0

C27

6

C27

1

C27

2

L273

3

L253 L271

C37

4

C38

6

L321

R33

3

R33

9

C12

2

C12

5

C16

5

C161

C12

9

C16

9 L114

L115

L113

R16

1

9 16

C109C11

0

C11

4

C166

C111

C112

C11

3

C131L106

L107

3

2

Q110C119

C171

L108

R103

R10

4

R12

0

R17

1

R173

U10181

C11

8

C121

C160

C115

C117

C116

C12

0

C127

L109

L160

R10

6

R10

7

R108

SH101

TP202

TP302

C37

5

C32

0

C31

9

L309

R348T302

346

C38

1

C32

2

L310

R30

9

R308

R310SH303

T301

3 46

C32

4

C32

3

L311

C325FL301

R35

1

R352SH323

B50

4 C397

PB504

R300

VR

444

C328

C39

1

R32

6

R314

R31

6

R325

R33

4

R335

R338

RT301

VR

300

Q315

Q316

R318

R31

9

R32

7

RT

300

C33

1

C396

C333

CR

308

R317

R336

R34

2

C10

4

C10

3

C106

C107

CR

102

L102

L104

SH100

C10

1

C102

CR101

L101

L105

C140

C141

L116

C520

PB

505

VR443

C30

2

C301

CR

301

L301

C30

8

C30

3

C304

C30

5

CR

302L302

R301

R302

SH301

C512

C384

C385C36

4

C351

C349C350

C352C353

C35

4

L325

Q320

R355

R32

2

R34

5

R32

0

R32

4

R34

6

C362 C363

CR310

L332

R321SH321

C521

PB501

VR440

C50

5

C50

2

R50

7

VR501

Q505

R506

C513 Q502

R505

C51

1

C51

4 CR503

2

3 4

R50

2

R501

PB502

TP415

C40

1

C40

0

CR412 Q40

0

R401

R40

2

R40

3

R405

R40

6R407

R427

R476U400

85

C402

C467

C403

CR

440

Q405

34

R41

6 R481 R44

6

4

C48

2

C48

0

Q403

R44

7

R44

8

SH401

T-6 Torx screw locations

Radiochassis

3-8 Power Up Self-Test Error Codes

For LTR Models:

No Display improperly connecteddisplay module ordamaged displaymodule.

check connection between main board and displaymodule or replace with new display module.

If the error code displayed is ...

Then, there is a ...

To correct the problem ...

ESN BAD defective PTCB return to factory for PTCB replacement.

AppCode Fail defective PTCBfirmware

reflash PTCB firmware.

EER: Watchdog firmware failure restart radio

Unprogrammed programming error use CPS to properly program radio and PTCB.

ERROR: NO PTG no primary talk group use CPS to program zone with a Primary Talk Group.

Backdoor --- turn radio off and restart.

If the error code displayed is ...

Then, there is a ...

To correct the problem ...

UHF Troubleshooting Charts 3-9

3.4 UHF Troubleshooting ChartsMCU Check

Power UpAlert Tone

OK?

SpeakerOK?

U409 EXTAL=7.3728 MHz?

U201 Pin 1916.8 MHz

5V at U247?3.3V at U248?

U409 Reset Pin94 High?

MCU is OK

Not able to pro-gram RF Board

ICs

Before replacingMCU, check SPIclock, SPI data,and RF IC select

ReplaceSpeaker

Read RadioOK?

CheckSetup

Reprogram thecorrect data.

See FGUTroubleshooting

7.5V atPin 3/5 U247?4/3.3V at Pin 1

U248

CheckQ400

ReplaceU247/U248

Check any shortto SWB+,

Vdda or Vddd

Press PTT. RedLED does not

light up

PTT U409Pin 53low?

Press PTTQ502-2High?

CheckPB504

CheckQ502-2voltage

LEDQ502,R501

OK?

ReplaceFaulty

Component

CheckAccessories

J403OPT_SEL_1 &OPT_SEL_2

Pin 8 & 9low?

Radio couldnot PTT

externally

U409Pin 52, 6

low?

See FGUTroubleshoot-

ing chart

LED shouldlight up

CheckMCU

PTT

NO

YES

YES

No

No

NO

YES YES

NO

YES

YES

NO

NO

YES

YES

NO

NO

YES

NO

YES

NO

YES

YES

NO

NO

YES

EXTSPKR

EXTPTT

INTAUDIO

J403 Pin 9 low?Pin 8 high?

ASFIC U404Pin 14 & 15

high?

CheckAccessories

CheckU404

CheckU420 Audio PA

NO

NO

YES

YES

J403 Audioat Pin 2 &

Pin 3

Check Spk.Flex Connec-

Audio atAudioPA(U420)input

Audio from Pin 41ASFIC, U404?

CheckASFIC U404

CheckAudio PA(U420)

CheckU301LV ZIF

Audio atPin 2

U404?

NO

NO

NO

YES

YES

NO

YES

Troubleshooting Flow Chart for Controller

3-10 UHF Troubleshooting Charts

Bad SINADBad 20dB QuietingNo Recovered Audio

START

Audio at pin27 of U301? Check Controller

Yes

No

Induce or inject 1st IF intoXTAL FilterIF Freq: 45.1MHz

Audio heard?BYes

No

Check 2nd LO ControlVoltage at C363

VCO locked?BYes

16.8 MHzcheck at pin22 U301?

Activity onU301 sel pin?

Check FGU

No

No

A

A

Yes

Check Q320 biascircuitry for faults

Rotate Freq. Knob

Check controller

Before replacing U301, check 2ndVCO Q320. Check VCO O/P level,C351, C352

Yes

No

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

UHF Troubleshooting Charts 3-11

IF Signalat L311?

No

RF Signal atT301?

RF Signal atC310?

No

RF Signal atC307?

No

RF Signal atC301?

No or

Check harmonic filter L101 & L102 andantenna switch CR101, CR102, L104

Check filter betweenC301 & C307; programfilter to schematic testfreq and check varactorvoltages

Inject RF into J101

Are varactorvoltages OK?

No

Yes

Check RF amp (Q301)Stage

Check filter betweenC310 & T301

Yes

Check T301, T302,CR306, R308, R309,R310

Yes

1st LO O/POK?Locked?

Yes

Check FGU

Yes

Trace IF signalfrom L311 toQ302. Check forbad XTAL filter

No

Yes Q302 collec-tor OK?IF signalpresent?

Before replacingU301, checkU301 voltages;trace IF signalpath

Yes

Check for 2.6VDC

Is R5present?

Check Q210, U201(pin 48) voltages andU247

No

No

No

Check U404 voltage.U404 can be selected byMCU before replacingU404

Check varactor filter

No

Yes

Yes

Yes

A

A

B

weak RF

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

3-12 UHF Troubleshooting Charts

START

No Power

Is There B+Bias for Antswitch

Check Q111

Is CurrentOK?

Is Control Volt-age High or Low

Check PCIC

1. Check Pin Diodes2. Check Harmonic Filter

Inspect/Repair Tx.Output Network

Is PowerOK?

Done

Check Drive toModule

Is DriveOK? Troubleshoot

VCO

Inspect PA Network/Check Power Out ofU101 at Cap C160

Is PowerOK?

Replace U101

Is PowerOK?

Replace Q101

Done

Done

No

Yes

Yes No

No

Yes

Low

High

No

Yes

Yes

No

Yes

No

Troubleshooting Flow Chart for Transmitter

UHF Troubleshooting Charts 3-13

5Vat pin 6 ofCR201

Is informationfrom mP U409

correct?

Is U201 Pin18

Is U201 Pin47

Is U241 Pin 19<0.7 VDC in RX &>4.3 VDC in TX?

Start

Visualcheck of theBoard OK?

CorrectProblem

Check 5VRegulator

+5V at U201Pin’s

13 & 30?

Is 16.8MHzSignal at

U201 Pin 19?

Check FL201, C206,C207, C208, CR203

& R204

Are signalsat Pin’s 14 &15 of U201?

CheckL202 Check Q260,

Q261 & R260

U201 pin 2 at>3V in Tx and<0.7V in Rx

Replace U201

RemoveShorts

Is there a shortbetween Pin 47 and

Pins 14 & 15 ofU201?

Replace orresolder

necessarycomponents

Is RF level atU201 Pin 32>-30 dBm?

Are R231,R232,R233,C231,C232,

& C233 OK?

Replace U201

If L261, C263 & C264are OK, then see VCOtroubleshooting chart

Are Waveformsat Pins 14 & 15

triangular?

Do Pins 7,8 & 9of U201 toggle

when channel ischanged?

Check programminglines between U409

and U201 Pins 7,8 & 9

Replace U201

Check uP U409Troubleshooting

Chart

NO

YES

NO

YES

NO

YES

NO

YES

NO

NO

NO

YES

YES

NO

YES

YES

NO

YES

YES

YESNO

NO

NO

NO

YES

NO

YES

YES

Check CR201,U210, U211, C258,

C259 & C228

3.3V at U201pins 5, 20, 34

& 36

Check U248,L201 & L202

Is16.8MHzsignal atU201 pin

23?

ReplaceU201

YES

NO

NO

YES

NO

YES

Troubleshooting Flow Chart for Synthesizer

3-14 UHF Troubleshooting Charts

START

No LO?

Tx Carrier?

VCO OK

CheckR260

TRB = 5V?Pin 10>1V?

L253 O/C? ChangeL253

ChangeU241

AUX 3High?

Check U201Pin 2 for 3.2V

Pin 19=0V

AUX 4High?

ChangeQ261

V ctrl 0Vor 13V?

L243 OpenCircuit?

ChangeU241

ChangeL243

ChangeU201

Check for faulty parts or dryjoints of L271, L273, C370,C386, R339 & L320

A

A

No

No

Yes

Yes

Yes

No

No

Yes

Yes

Yes

No

Yes

No

No

Yes

Yes

No

No

Check R245 for dryjoint or faulty

No

Troubleshooting Flow Chart for VCO

VHF Troubleshooting Charts 3-15

3.5 VHF Troubleshooting ChartsMCU Check

Power UpAlert Tone

OK?

SpeakerOK?

U409 EXTAL=7.3728 MHz?

U3701 Pin 1916.8 MHz

5V at U3711?3.3V at U3201?

U409 Reset Pin94 High?

MCU is OK

Not able to pro-gram RF Board

ICs

Before replacingMCU, check SPIclock, SPI data,and RF IC select

ReplaceSpeaker

Read RadioOK?

CheckSetup

Reprogram thecorrect data.

See FGUTroubleshooting

7.5V atPin 3/5 U3711?7.5V at Pin 1

U3201

CheckQ400

ReplaceU3711/U3201

Check any shortto SWB+,

Vdda or Vddd

Press PTT. RedLED does not

light up

PTT U409Pin 53low?

Press PTTQ502-2High?

CheckPB504

CheckQ502-2voltage

LEDQ502,R501

OK?

ReplaceFaulty

Component

CheckAccessories

J403OPT_SEL_1 &OPT_SEL_2

Pin 8 & 9low?

Radio couldnot PTT

externally

U409Pin 52, 6

low?

See FGUTroubleshoot-

ing chart

LED shouldlight up

CheckMCU

PTT

NO

YES

YES

No

No

NO

YES YES

NO

YES

YES

NO

NO

YES

YES

NO

NO

YES

NO

YES

NO

YES

YES

NO

NO

YES

EXTSPKR

EXTPTT

INTAUDIO

J403 Pin 9 low?Pin 8 high?

ASFIC U404Pin 14 & 15

high?

CheckAccessories

CheckU404

CheckU420 Audio PA

NO

NO

YES

YES

J403 Audioat Pin 2 &

Pin 3

Check Spk.Flex Connec-

Audio atAudioPA(U420)input

Audio from Pin 41ASFIC, U404?

CheckASFIC U404

CheckAudio PA(U420)

CheckU3220LV ZIF

Audio atPin 2

U404?

NO

NO

NO

YES

YES

NO

YES

Troubleshooting Flow Chart for Controller

3-16 VHF Troubleshooting Charts

Bad SINADBad 20dB QuietingNo Recovered Audio

START

Audio at pin27 of U3220? Check Controller

Yes

No

Induce or inject 1st IF intoXTAL FilterIF Freq: 45.1MHz

Audio heard?BYes

No

Check 2nd LO ControlVoltage at C3279

VCO locked?BYes

16.8 MHzcheck at pin21 U3220?

Activity onU3220 selpin?

Check FGU

No

No

A

A

Yes

Check Q3270 biascircuitry for faults.

Rotate Freq. Knob

Check controller.

Before replacing U3220, check 2ndVCO Q3270. Check VCO O/P level,C3272, C3273.

Yes

No

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

VHF Troubleshooting Charts 3-17

IF Signal atC3200?

No

RF Signal atT3301?

RF Signal atR3313?

No

RF Signal atC3306?

No

RF Signal atC3302?

No or

Check harmonic filter L3531 & L3532,C3532 and ant. switches D3521, D3551,L3551, R3551, C3551, C3552, L3552

Check filter betweenC3302 & C3306; pro-gram filter to schematictest freq and check var-actor voltages

Inject RF into J3501

Are varactorvoltages OK?

No

Yes

Check RF amp (Q3302)Stage.

Check filter betweenC3313 & T3301

Yes

Check T3301, T3302,CR3301, R3321, R3322,R3323

Yes

1st LO O/POK?Locked?

Yes

Check FGU

Yes

Trace IF signalfrom C3200 toQ3200. Check forbad XTAL filter.

No

Yes Q3200 collec-tor OK?IF signalpresent?

Before replacingU3220, checkU3220 volt-ages; trace IFsignal path

Yes

Check for 2.9VDC

Is R5present?

Check Q3721,U3701 (pin 48) volt-ages and U247

No

No

No

Check varactor filter

No

Yes

Yes

Yes

A

A

B

weak RF

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

Check U404 voltage and ifU404 can be selected byMCU before replacing U404

3-18 VHF Troubleshooting Charts

START

No Power

Is There B+Bias for Antswitch

CheckQ3561

Is CurrentOK?

Is Control Volt-age High or Low

Check PCIC

1. Check Pin Diodes2. Check Harmonic Filter

Inspect/Repair Tx.Output Network

Is PowerOK?

Done

Check Drive toModule

Is DriveOK? Troubleshoot

VCO

Inspect PA Network/Check Power Out ofU3501 at Cap C3512

Is PowerOK?

Replace U3501

Is PowerOK?

Replace Q3501

Done

Done

No

Yes

Yes No

No

Yes

Low

High

No

Yes

Yes

No

Yes

No

Troubleshooting Flow Chart for Transmitter

VHF Troubleshooting Charts 3-19

5Vat pin 6 of

D3701

Is informationfrom mP U409

correct?

Is U3701Pin 18 AT4.54 VDC?

Is U3701 Pin 47AT = 13 VDC

Is U3701 Pin 19<0.7 VDC in RX &>4.3 VDC in TX?

Start

Visualcheck of theBoard OK?

CorrectProblem

Check 5VRegulator

+5V atU3701Pin’s

13 & 30?

Is 16.8MHzSignal at

U3701 Pin

Check Y3761,C3761, C3762,

C3763, D3761 &R3761

Are signalsat Pin’s 14 &15 of U3701?

CheckL3701,R3701

Check Q260,Q261 & R260

U3701 pin 2 at>3V in Tx and<0.7V in Rx

RemoveShorts

Is there a shortbetween Pin 47 and

Pins 14 & 15 ofU3701?

Replace orresolder

necessarycomponents

Is RF level atU3701 Pin 32

>-30 dBm?

Are C3721,C3722,C3723,R3721, R3722,

R3723 OK?

ReplaceU3701

If R3727, C3726 & C3727are OK, then see VCOtroubleshooting chart

Are Waveformsat Pins 14 & 15

triangular?

Do Pins 7,8 & 9of U3701 togglewhen channel is

changed?

Check programminglines between U409

and U3701 Pins 7,8 & 9

ReplaceU3701

Check uP U409Troubleshooting

Chart

NO

YES

NO

YES

NO

YES

NO

YES

NO

NO

NO

YES

YES

NO

YES

YES

NO

YES

YES

YESNO

NO

NO

NO

YES

NO

YES

YES

Check D3701,D3702, U3701,C3701 - C3707

3.3V at U3701pins 5, 20, 34

& 36

Check U3201,L3731

Is16.8MHzsignal at

U3701 pin23?

ReplaceU3701

YES

NO

NO

YES

NO

YES

Troubleshooting Flow Chart for Synthesizer

ReplaceU3701

3-20 VHF Troubleshooting Charts

START

No LO?

Tx Carrier?

VCO OK

CheckR3829

TRB = 3.2V?Pin 10>1V?

L3831,L3832,L3833 O/C?

ChangeL3831, L3832

ChangeU3801

AUX 3High?

Check U3701Pin 2 for 3.2V

Pin 19=0V

AUX 3Low?

ChangeU3801

V ctrl 0Vor 13V? L3821,

L3822,L3823 OpenCircuit?

ChangeU3801

ChangeL3821,L3822,L3823,L243

ChangeU3701

Check for faulty parts or dryjoints of L3812 C3806,R3806, R3802 & L3801

A

A

No

No

Yes

Yes

Yes

No

No

Yes

Yes

Yes

No

Yes

No

No

Yes

Yes

No

No

Check R3811,L3811 for dry jointor faulty

No

Troubleshooting Flow Chart for VCO

Yes

Low Band Troubleshooting Charts 3-21

3.6 Low Band Troubleshooting Charts

MCU Check

Power UpAlert Tone

OK?

SpeakerOK?

U409 EXTAL=7.3728 MHz?

U205 Pin 1917.0MHz

5V at U204?3.3V at U400?

U409 Reset Pin94 High?

MCU is OK

Not able to pro-gram RF Board

ICs

Before replacingMCU, check SPIclock, SPI data,and RF IC select

ReplaceSpeaker

Read RadioOK?

CheckSetup

Reprogram thecorrect data.

See FGUTroubleshooting

7.5V atPin 5 U204?7.5V at Pin 8

U400

CheckQ400

ReplaceU204/U400

Check any shortto SWB+,

Vdda or Vddd

Press PTT. RedLED does not

light up

PTT U409Pin 53low?

Press PTTCR502-2

High?

CheckPB504

CheckCR502-2voltage

LED,CR502,R501

OK?

ReplaceFaulty

Component

CheckAccessories

J403OPT_SEL_1 &OPT_SEL_2

Pin 8 & 9low?

Radio couldnot PTT

externally

U409Pin 52, 6

low?

See FGUTroubleshoot-

ing chart

LED shouldlight up

CheckMCU

PTT

NO

YES

YES

No

No

NO

YES YES

NO

YES

YES

NO

NO

YES

YES

NO

NO

YES

NO

YES

NO

YES

YES

NO

NO

YES

EXTSPKR

EXTPTT

INTAUDIO

J403 Pin 9 low?Pin 8 high?

ASFIC U404Pin 14 & 15

high?

CheckAccessories

CheckU404

CheckU420 Audio PA

NO

NO

YES

YES

J403 Audioat Pin 2 &

Pin 3

Check Spk.Flex Connec-

Audio atAudioPA(U420)input

Audio from Pin 41ASFIC, U404?

CheckASFIC U404

CheckAudio PA(U420)

CheckU303LV ZIF

Audio atPin 2

U404?

NO

NO

NO

YES

YES

NO

YES

Troubleshooting Flow Chart for Controller

3-22 Low Band Troubleshooting Charts

Activity onU303 sel pin?

Bad SINADBad 20dB QuietingNo Recovered Audio

START

Audio at pin27 of U303?

Check ControllerYes

No

Spray of inject 1st IF intoXTAL FilterIF Freq: 109.65 MHz

Audio heard?BYes

No

Check 2nd LO ControlVoltage at C308

VCO locked?BYes

17.0 MHzcheck at pin22 U303?

Check FGU

No

No

A

A

Yes

Check Q301 biascircuitry for faults.

Rotate Freq. Knob

Check controller.

Before replacing U303, check 2ndVCO Q301. Check VCO O/P level,C315, C316

Yes

No

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

Low Band Troubleshooting Charts 3-23

IF Signal atL301?

No

RF Signal atT501?

RF Signalat collectorQ509?

No

RF Signal atC504?

No

RF Signal atC147?

No or

Check transmit harmonic filter, antennaswitch and J101

Check filter betweenC147 & C504

Inject RF into J101

No

Yes

Check RF amp (Q509)Stage

Check filter betweenQ509& T301

Yes

Check T501, T502,D501, R507, R508,R509,C516,L508

Yes

1st LO O/P310OK?Locked?

Yes

Check FGU

Yes

Trace IF signalfrom L301 toU301. Check forbad XTAL filter

No

Yes U301 drainOK?IF signalpresent?

Before replacingU303, checkU303 voltages;trace IF signalpath

Yes

Biaising onU301 OK?

Troubleshootbiasing, AGCcircuits and U301

No

No

YesA

B

weak RF

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

3-24 Low Band Troubleshooting Charts

START

No Power

Is Current~ 2 A?

Is control voltageat U101 Pin 1 > 5 Check PCIC

1. Check Pin Diodes2. Check Harmonic Filter3. Check PA Bias

Inspect/Repair Tx.Output Network

Is PowerOK?

Done

Check input toU101, Pin 16

Is voltage> 1 Vpp?

TroubleshootVCO

Check levelU101, Pin 6

Is level>5 Vpp?

Is PowerOK?

ReplaceQ101

Yes No

No

Yes

No

Yes

No

Yes

Yes

No

Yes

No

Troubleshooting Flow Chart for Transmitter

Check componentsaround U101

Is PowerOK?

Done

ReplaceU101

NoCheck componentsaround Q100

Yes

Done

Low Band Troubleshooting Charts 3-25

Is U205, pin18 at 4.54

VDC?

Signalsat Pin 14 and15 of U205?

Is informationfrom mP U409

correct?

Is U205 Pin47 > 12V

In receive, isPin 1 < .7 V and Pin 2 >

3 Vplus in transmit isPin 1 > 3 V and Pin 2 <

.7 V?

Start

Visualcheck of theBoard OK?

CorrectProblem

Check 5VRegulator

+5V at U205Pin’s

13 & 30?

Is 17.0 MHzSignal at

U205 Pin 19?

Check Y201,CR211,C236,C237,C242,

R219

Replace U205

Replace orresolder

necessarycomponents

Is RF level atU205 Pin 32>-30 dBm?

Are loop filter partsR224,R225,R227,R228,R229,C256,C257,C259 and C260

OK?

Replace U201

If R234, R238 & C297are OK, then see VCOtroubleshooting chart

Do Pins 7,8 & 9of U205 toggle

when channel ischanged?

Check programminglines between U409

and U205 Pins 7,8 & 9

Replace U205

Check uP U409Troubleshooting

Chart

NO

YES

NO

YES

NO

NO

YES

NO

YES

YES

NO

YES

YES

YESNO

NO

NO

NO

YES

NO

YES

YES

Check C247, C249,C283, C284, C285,C286, D210, D211,

R285, and R286

3.3V at U205pins 5, 20, 34

& 36

Check U200and L225

Is17.0MHzsignal atU201 pin

23?

ReplaceU205

YES

NO

NO

YES

Troubleshooting Flow Chart for Synthesizer

3-26 Low Band Troubleshooting Charts

Level >+2 dBm

Check signal atcollector of Q201

No

YesCheck L204, L211, L212,L215, C221, C228, C229,C230,C231, C235,C297,R204, R234, R238

Troubleshooting Flow Chart for VCO

Check signal atcollector of Q201

No RX LO or Nosignal at U205 Pin32 in RX

No TX LO or Nosignal at U205 Pin32 in TX

Level >+10 dBm?

Check signal atdrain of Q203

Level >-3 dBm?

Check signal atdrain of Q202and Q204

Level >+7 dBm?

No

Yes

Replace Q201Yes Yes

Done

Check DC volt-age across R203

Problemfixed?

Replace Q203

Check C215, C216,L207, L208, L209,U203

Level >500 mV ?

Check C200, C202, C203,C222, C223, L201, L203,TR201, CR202

Replace Q202and Q204

YesYes

No No

NoNo

800 MHz Troubleshooting Charts 3-27

3.7 800 MHz Troubleshooting Charts

MCU Check

Power UpAlert Tone

OK?

SpeakerOK?

U409 EXTAL=7.3728 MHz?

U201 Pin 1916.8 MHz

5V at U247?3.3V at U248?

U409 ResetPin 94 High?

MCU is OK

Not able to pro-gram RF Board

ICs

Before replacing MCU,check SPI clock, SPI

data, and RF IC select

Replace Speaker

Read Radio OK?Check Setup

Reprogram thecorrect data.

See FGUTroubleshooting

7.5V atPin 3/5 U247?4/3.3V at Pin 1

U248

Check Q400

ReplaceU247/U248

Check any short toSWB+,

Vdda or Vddd

Press PTT. RedLED does not light

up

PTT U409 Pin53

low?

Press PTTQ502-2 High?

CheckPB504

CheckQ502-2 volt-

age

LEDQ502,R501

OK?

Replace FaultyComponent

CheckAccessories

J403 OPT_SEL_1 &OPT_SEL_2

Pin 8 & 9low?

Radio couldnot PTT

externally

U409Pin 52, 6 low?

See FGUTroubleshooting

chart

LED shouldlight up

Check MCU

PTT

NO

YES

YES

No

No

NO

YES YES

NO

YES

YES

NO

NO

YES

YES

NO

NO

YES

NO

YES

NO

YES

YES

NO

NO

YES

EXTSPKR

EXTPTT

INTAUDIO

J403 Pin 9 low? Pin8 high?

ASFIC U404 Pin 14& 15 high?

CheckAccessories

CheckU404

CheckU420 Audio PA

NO

NO

YES

YES

J403 Audio atPin 2 & Pin 3

Check Spk. FlexConnection

Audio atAudio PA (U420)

input(U447)

Audio from Pin 41ASFIC, U404?

Check ASFICU404

CheckAudio PA(U420)

Check U351LV ZIF

Audio atPin 2

U404?

NO

NO

NO

YES

YES

NO

YES

Troubleshooting Flow Chart for Controller

3-28 800 MHz Troubleshooting Charts

Bad SINADBad 20dB Quieting

No Recovered Audio

START

Audio atpin 27 ofU351?

Check ControllerYes

No

Spray or inject 1st IF into XTALFilter

IF Freq: 109.65 MHz

Audio heard?BYes

No

Check 2nd LO ControlVoltage at R365

VCO locked?BYes

16.8 MHzcheck at pin21 of U351?

Activityon U351pin 19?

Check FGU

No

No

A

A

Yes

Check Q350 bias cir-cuitry for faults

Rotate Freq. Knob

Check controller

Before replacing U351, check2nd VCO Q350. Check VCO O/P

level, C385, C387

Yes

No

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

800 MHz Troubleshooting Charts 3-29

RF Signal atthe input of

FL300?

IF Signal atL353?

No

RF Signal atpin 8 of U301?

RF Signal atCR300?

No

No or

Check harmonic filter L101 &L102 CR101, CR102, and

CR300

Inject RF into J101

No

Yes

Check RF amp(Q302) Stage.

Replace filterFL301

Yes

Check U301, R320,R321, R322

Yes

1st LO O/POK?

Locked?

Yes

Check FGU

Yes

Trace IF signal fromL353 to U352.

Check for bad XTALfilter.

No

YesIs the level of theIF signal of the

output of U352 asindicated?

Before replacingU351, check U351voltages; trace IF

signal path.

Yes

Is the biasing ofU352 OK?

Is R5 present?

Check Q210, U201(pin 48) voltages

and U247

No

No

No

Yes

Yes

A

B

weak RF

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

RF Signal atC317?

No

ReplaceU352.

Are the AGCvoltages

without RFas indi-cated?

Yes

Check U302,U350, and CR301 Replace

FL300.

No orweak RF

3-30 800 MHz Troubleshooting Charts

Is the fuseF501 OK?

Is there ashort circuitafter C113?

Is overall radiocurrent between

0.8 and 1.3 Awhen transmit-

ting?

Is the voltageat pin 4 of

U102between 2Vand 5.6V?

Is the voltageat pin 32 of

U102 between6V and 9V?

START

No Power out or LowPower

Yes

Troubleshooting Flow Chart for Transmitter

Yes

Check L101, L102, C101,CR101 for open circuit

Find and removeshort circuit fromantenna switch or

harmonic filter

Low Power

Yes

Replace F501

Yes

Yes

Yes

ReplaceU102

No

No

No

Is the voltageat R105 and

C116 between1.8V and

2.2V?

Is the voltage atpins 6, 5, 8, 9 ofU101 between5.5V and 7.5V?

Yes

Troubleshoot VCO

ReplaceU101

ReplaceQ101

No

No

No Power

No

No

Yes

No

Is the voltageat pin 24 of

U102 between2V and 5V for

High Power, 0Vfor Low Power?

800 MHz Troubleshooting Charts 3-31

5Vat pin 6 of

D201

Is informationfrom µP U409

correct?

Is U201 Pin 28at 4.6 VDC?

Is U201 Pin 47AT = 13 VDC

Start

Visualcheck of theBoard OK?

CorrectProblem

Check 5VRegulator

+5V at U201Pin’s

13 & 30?

Is 16.8MHzSignal at

U201 Pin 19?

Check FL201, C235,C237, C236, CR203

& R211.Are the

waveformsat Pin’s 14

&15 of U201rectangular?

CheckL200

Replace U201

RemoveShorts

Is there a shortbetween Pin 47 and

Pins 14 & 15 ofU201?

Replace orresolderdefective

components

Is RF level atU201 Pin 32as indicated?

Are C226, R209,R210, L204, C231,C220, C225, C218,

R216, and R217 OK?

Replace U201

If L203, C227 & C228are OK, then see VCOtroubleshooting chart

Are Waveformsat Pins 14 & 15

triangular?

Do Pins 7,8 & 9of U201 toggle

when channel ischanged?

Check programminglines between U409

and U201 Pins 7,8 & 9

Replace U201

Check uP U409Troubleshooting

Chart

NO

YES

NO

YES

NO

YES

NO

NO

YES

YES

NO

YES

YES

NO

YES

YES

YESNO

NO

NO

NO

YES

NO

YES

Check D201, D202,C244, C245, C246 &

C247.

3.3V at U201pins 5, 20, 34

& 36

Check U248& L202

Is16.8MHzsignal atU201 pin

23?

ReplaceU201

YES

NO

NO

YES

NO

YES

Troubleshooting Flow Chart for Synthesizer

3-32 800 MHz Troubleshooting Charts

Is the Tx RFlevel at C254about 0dBm?

Are the biasvoltages of

Q251 as indi-cated?

Is the 1.9Vpresent at

R266 as indi-cated?

START

Is LO signalpresent at the

mixer IC U301?

Check the 4.6Vbiasing circuitry

and pin 28 of U201.

Yes

Is resonator ICU205 soldered

OK?

Is TRB pin 19of U250 low?

Is the 1.9Vpresent at

R265 as indi-cated?

Is the steeringline voltage

VCTRL 0V or13V?

Is the LO RFlevel at C253about 0dBm?

Are the biasvoltages of

Q304 as indi-cated?

No

Yes

Yes

Is the PRESCRF level at

C227 as indi-cated?

No

No

No

Troubleshoot theSynthesizer.

Check Q252 andQ200.

Yes

NoYesIs Tx signalpresent at the PAdriver IC, U101?

Is resonatorIC U206 sol-dered OK?

Is TRB pin 19of U250 high?

Is the steeringline voltage

VCTRL 0V or13V?

No

Yes

Yes

VCO is OK.

Is the 4.6VVSF voltage

present at pins3, 18, & 14 of

U250?Is the 4.6VVSF voltage

present at pins3, 18, & 14 of

U250?

Is pin 2(AUX3) of

U201 high?

No

Troubleshoot theSynthesizer.

Check Q252 andQ200.

Yes

Check the 4.6Vbiasing circuitry

and pin 28 of U201.

No

Replace U250.

Yes

Replace U250.No

Replace U250.No

YesIs the PRESCRF level at

C227 as indi-cated?

No

Replace U250.

Yes

Replace U250.

Tx VCO OK.

No

Yes

Yes

NoCheck Q251 and its

bias circuitry.

Check Q304 and itsbias circuitry.

No

Yes

Yes

Yes

Replace U250.

Rx VCO OK.

No

Yes

Resolder orreplace U206.

Resolder orreplace U205.

Yes

No

No

No

Yes

Yes

No

No

Is pin 3(AUX4) ofU250 low?

Troubleshooting Flow Chart for VCO

PassPort Trunking Troubleshooting Chart 3-33

3.8 PassPort Trunking Troubleshooting Chart

Start

Check Radio Operation on aNon PassPort Zone with a

Conventional Personality withoutthe Option Board Enabled

OK?

Check Radio PassPort

Programming using CPS

Check Switched Batteryand Vdd from Radio on PTCB

OK?

Check Radio PassPort

Programming using CPS

Rx Demod

J601-6?on

Tx Modon

J601-10?

Install and Reprogram anew PassPort TrunkingController Board

Repair RadioNo Yes

Yes

No

Yes

Yes

Yes

No

No

3-34 Keypad Troubleshooting Chart

3.9 Keypad Troubleshooting Chart

Display

KeypadLED

EndDisconnect andreconnect 18-pinflex

Disconnect andreconnect 40-pinflex

ON

OFF

OFF

ON

IF STILLOFFSTART

900 MHz Troubleshooting Charts 3-35

3.10 900 MHz Troubleshooting Charts

Audio atPin E4U851?

Press PTT. RedLED does not light

up.

PTT U409 Pin53

low?

Press PTTQ502-2 High?

CheckPB504.

CheckQ502-2voltage.

LEDQ502,R501

OK?

Replace FaultyComponent.

CheckAccessories.

J403OPT_SEL_1 &OPT_SEL_2

Pin 8 & 9low?

Radio couldnot PTT

externally.

U409Pin 52, 6 low?

See FGUTroubleshooting

chart.

LED shouldlight up.

Check MCU.

PTT

NO

YES

YES

No

No

NO

YES YES

NO

YES

EXTSPKR

EXTPTT

INTAUDIO

J403 Pin 9 low?Pin 8 high?

ASFIC U404 Pin14 & 15 high?

CheckAccessories

CheckU404.

CheckU420 Audio PA.

NO

NO

YES

YES

J403 Audio atPin 2 & Pin 3.

Check Spk. FlexConnection.

Audio atAudio PA (U420)

input(C447).

Audio from Pin 41ASFIC, U404?

Check ASFICU404.

CheckAudio PA(U420).

Check U351LV ZIF.

Audio atPin 2

U404?

NO

NO

YES

YES

YES

NO

YES

Troubleshooting Flow Chart for Controller (Sheet 1 of 2)

Audio from Pin F4,HC, U851?

Check HCU851.

YES

NO

NO

YES

3-36 900 MHz Troubleshooting Charts

7.5V atPin 3/5 U202?4/3.3V at Pin 1

U203.

5V at U202?3.3V at U203?

MCU Check.

Power UpAlert Tone

OK?

SpeakerOK?

U409 EXTAL=7.3728 MHz?

U201 Pin 1916.8 MHz.

U409 ResetPin 94 High?

MCU is OK.

Not able to pro-gram RF Board

ICs.

Before replacing MCU,check SPI clock, SPI

data, and RF ICselect.

Replace Speaker.

Read Radio OK?CheckSetup.

Reprogram thecorrect data.

See FGUTroubleshooting.

Check Q400.

ReplaceU202/U203.

Check any short toSWB+,

Vdda or Vddd.

YES

NO

NO

YES

YES

NO

NO

YES

NO

YES

NO

YES

YES

NO

NO

YES

Troubleshooting Flow Chart for Controller (Sheet 2 of 2)

900 MHz Troubleshooting Charts 3-37

Bad SINAD.Bad 20dB Quieting.

No Recovered Audio.

START

Audio atpin 27 ofU351?

Check Controller.Yes

No

Spray or inject 1st IF into XTALFilter.

IF Freq: 109.65 MHz

Audio heard?BYes

No

Check 2nd LO ControlVoltage at R365

VCO locked?BYes

16.8 MHzcheck at pin21 of U351?

Activityon U351pin 19?

Check FGU

No

No

A

A

Yes

Check Q350 bias cir-cuitry for faults

Rotate Freq. Knob

Check controller

Before replacing U351, check2nd VCO Q350. Check VCO O/P

level, C385, C387.

Yes

No

Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)

3-38 900 MHz Troubleshooting Charts

RF Signal atthe input of

FL300?

IF Signal atL353?

No

RF Signal atpin 8 of U301?

RF Signal atCR300?

No

No or

Check harmonic filter L101 &L102 CR101, CR102, and

CR300

Inject RF into J101.

No

Yes

Check RF amp(Q302) Stage.

Replace filterFL301

Yes

Check U301, R320,R321, R322.

Yes

1st LO O/POK?

Locked?

Yes

Check FGU

Yes

Trace IF signal fromL353 to U352.

Check for bad XTALfilter

No

YesIs the level of theIF signal of the

output of U352 asindicated?

Before replacingU351, check U351voltages; trace IF

signal path

Yes

Is the biasing ofU352 OK?

Is R5 present?

Check Q210, U201(pin 48) voltages

and U247

No

No

No

Yes

Yes

A

B

weak RF

Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)

RF Signal atC317?

No

ReplaceU352

Are the AGCvoltages

without RFas indi-cated?

Yes

Check U302,U350, and CR301 Replace

FL300

No orweak RF

900 MHz Troubleshooting Charts 3-39

Check C163,C127, and

C142 for opencircuit.

Is the fuseF501 OK?

Is there ashort circuitafter C113?

Is overall radiocurrent between

0.8 and 1.3 Awhen transmit-

ting?

Is the voltageat pin 4 of

U102between 2Vand 5.6V?

Is the voltageat pin 32 of

U102 between6V and 9V?

START

No Power out or LowPower.

Yes

Troubleshooting Flow Chart for Transmitter

Yes

Check L104, L105, C120,CR101 for open circuit.

Find and removeshort circuit fromantenna switch or

harmonic filter.

Low Power

Yes

ReplaceF501.

Yes

Yes

Yes

ReplaceU102.

No

No

No

Is the voltageat R105 and

C116 between1.8V and

2.2V?

Is the voltage atpins 6, 5, 8, 9 ofU101 between5.5V and 7.5V?

Yes

Troubleshoot VCO

ReplaceU101.

ReplaceQ101

No

No

No Power

No

No

Yes

No

Is the voltageat pin 24 of

U102 between2V and 5V for

High Power, 0Vfor Low Power?

Replaceparts.

No

Yes

3-40 900 MHz Troubleshooting Charts

5Vat pin 6 of

D201.

Is informationfrom µP U409

correct?

Is U201 Pin 28at 4.6 VDC?

Is U201 Pin 47AT = 13 VDC

Start

Visualcheck of theBoard OK?

CorrectProblem.

Check 5VRegulator.

+5V at U201Pin’s

13 & 30?

Is 16.8MHzSignal at

U201 Pin 19?

Check Y201, C235,C237, C236, CR203

& R211.Are the

waveformsat Pin’s 14

&15 of U201rectangular?

CheckL200.

Replace U201.

RemoveShorts.

Is there a shortbetween Pin 47 and

Pins 14 & 15 ofU201?

Replace orresolderdefective

components.

Is RF level atU201 Pin 32as indicated?

Are C226, R209,R210, L204, C231,C801, C802, C803,C804, C805, C225,C218, R216, and

R217 OK?

Replace U201.

If L203, C227 & C228are OK, then see VCOtroubleshooting chart.

Are Waveformsat Pins 14 & 15

triangular?

Do Pins 7,8 & 9of U201 toggle

when channel ischanged?

Check programminglines between U409

and U201 Pins 7,8 & 9.

Replace U201

Check uP U409Troubleshooting

Chart.

NO

YES

NO

YES

NO

YES

NO

NO

YES

YES

NO

YES

YES

NO

YES

YES

YESNO

NO

NO

NO

YES

NO

YES

Check D201, D202,C244, C245, C246 &

C247.

3.3V at U201pins 5, 20, 34

& 36.

Check U248& L202.

Is16.8MHzsignal atU201 pin

23?

ReplaceU201.

YES

NO

NO

YES

NO

YES

Troubleshooting Flow Chart for Synthesizer

Is resonatorFL202

solderedOK?

Is the Tx RFlevel at C254about 0dBm?

Are the biasvoltages of

Q251 as indi-cated?

Is the 1.9Vpresent at

R266 as indi-cated?

START

Is LO signalpresent at the

mixer IC U301?

Check the 4.6Vbiasing circuitry

and pin 28 of U201.

Yes

Troubleshooting Flow Chart for VCO

Is resonatorFL201 soldered

OK?

Is TRB pin 19of U250 low?

Is the 1.9Vpresent at

R265as indi-cated?

Is the steeringline voltage

VCTRL 0V or13V?

Is the LO RFlevel at C253about 0dBm?

Are the biasvoltages of

Q304 as indi-cated?

No

Yes

Yes

Is the PRESCRF level at

C227 as indi-cated?

No

No

No

Troubleshoot theSynthesizer.

Check Q252 andQ200.

Yes

NoYesIs Tx signalpresent at the PAdriver IC, U101?

Is TRB pin 19of U250 high?

Is the steeringline voltage

VCTRL 0V or13V?

No

Yes

Yes

VCO is OK.

Is the 4.6VVSF voltage

present at pins3, 18, & 14 of

U250?Is the 4.6VVSF voltage

present at pins3, 18, & 14 of

U250?

Is pin 2(AUX3) of

U201 high?

No

Troubleshoot theSynthesizer.

Check Q252 andQ200.

Yes

Check the 4.6Vbiasing circuitry

and pin 28 of U201.

No

Replace U250.

Yes

Replace U250.No

Replace U250.No

YesIs the PRESCRF level at

C227 as indi-cated?

No

Replace U250.

Yes

Replace U250.

Tx VCO OK.

No

Yes

Yes

NoCheck Q251 and its

bias circuitry.

Check Q304 and itsbias circuitry.

No

Yes

Yes

Yes

Replace U250.

Rx VCO OK.

No

Yes

Resolder orreplace U206.

Resolder orreplace U205.

Yes

No

No

No

Yes

Yes

No

No

Is pin 3(AUX4) ofU250 low?

4-1

Chapter 4

Schematic Diagrams, Overlays, and Parts Lists

4.1 IntroductionThis chapter provides schematic diagrams, overlays, and parts lists for the radio circuit boards andinterface connections.

4.1.1 Notes For All Schematics and Circuit Boards

* Component is frequency sensitive. Refer to the Electrical Parts List for value and usage.

1. Unless otherwise stated, resistances are in Ohms (k = 1000), and capacitances are in picofarads(pF) or microfarads (µF).

2. DC voltages are measured from point indicated to chassis ground using a Motorola DC multime-ter or equivalent. Transmitter measurements should be made with a 1.2 µH choke in series withthe voltage probe to prevent circuit loading.

3. Reference Designators are assigned in the following manner:

100 Series = Transmitter

200 Series = Frequency Generation

300 Series = Receiver

400/500 Series = Controller and Low-Band Receiver Front End

600 Series = Keypad Board

4. Interconnect Tie Point Legend:

UNSWB+ = Unswitched Battery Voltage (7.5V)

SWB+ = Switched Battery Voltage (7.5V)

R5 = Receiver Five Volts

CLK = Clock

Vdda = Regulated 3.3 Volts (for analog)

Vddd = Regulated 3.3 Volts (for digital)

CSX = Chip Select Line (not for LVZIF)

SYN = Synthesizer

DACRX = Digital to Analog Voltage (For Receiver Front End Filter)

VSF = Voltage Super Filtered (5 volts)

VR = Voltage Regulator

4-2

4.2 Flex Layout

Figure 4-1: Keypad-Controller Interconnect Flex

LAYER 1 (L1)

LAYER 2 (L2)LAYER 3 (L3)LAYER 4 (L4)

LAYER 5 (L5)LAYER 6 (L6)

INNER LAYERS

SIDE 1

SIDE 2

6-LAYER CIRCUIT

COPPER STEPS IN PROPERLAYER SEQUENCE

BOARD DETAIL VIEWING

98C

J200

40

J100

40 <- TO KP

8480475Z02 REV A TO CTRL ->

Front MetalView from Top side

4-3

4.2.1 Keypad-Controller Interconnect Flex Schematic

Figure 4-2: Keypad-Controller Interconnect Flex Schematic Diagram

4.2.2 Keypad-Controller Interconnect Flex Parts List

Reference Symbol

Motorola Part No.

Description

J100 0980521Z01 Connector, 40 pinJ200 0905505Y04 Speaker, 20 ohm

KEYPADJ100

EXT_MIC

VS_CS

SW_B+

Vddd

VS_AUDSEL

Det_Aud_Snd

Rx_Aud_Rtn

Tx_Aud_Snd

Tx_Aud_Rtn

Flat_Tx_Rtn

Opt_Bd_En

Rdy/Req

Rx_Aud_Snd

ON

INT_EXT_Vdd

Key_Row

Key_Col

PTT

KEY_INT

VS_INT

RESET

LED_EN

OFF_BATT_DATA_OUT

VS_GAINSEL

SrD_Rtn (MISO)

SrD_Snd (DATA)

R_W

LCD_SEL

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

A0

SCK_Snd (CLK)

VS_RAC

Gnd

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

CONTROLLERJ200

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

EXT_MIC

VS_CS

SW_B+

Vddd

VS_AUDSEL

Det_Aud_Snd

Rx_Aud_Rtn

Tx_Aud_Snd

Tx_Aud_Rtn

Flat_Tx_Rtn

Opt_Bd_En

Rdy/Req

Rx_Aud_Snd

ON

INT_EXT_Vdd

Key_Row

Key_Col

PTT

KEY_INT

VS_INT

RESET

LED_EN

OFF_BATT_DATA_OUT

VS_GAINSEL

SrD_Rtn (MISO)

SrD_Snd (DATA)

R_W

LCD_SEL

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7

A0

SCK_Snd (CLK)

VS_RAC

Gnd

FL0830765O

4-4

4.2.3 Universal Flex Connector

Figure 4-3:Universal Flex Connector

Front MetalView From Top Side

20J403

J404J405

J406J407

J408J409J410

J411J412

J413J414

J415J416M

40

1

FL

08

30

76

7O

VIE

WE

D F

RO

M S

IDE

1

Back MetalView From Top Side

c

98

8480549Z03 rev B

C4

02

M4

00

FL0830768O

4-5

4.2.4 Universal Connector Flex Schematic

Figure 4-4: Universal Flex Connector Schematic Diagram

4.2.5 Universal Flex Connector Parts List

Reference Symbol

Motorola Part No. Description

C402 2113740A55 Cap, 100pFM400 5085962A02 Speaker, 20 ohmM401 5013920A04 Microphone for 5000 and 7000 SeriesM401 5005227J08 Microphone for 9000 Series

8480549Z01 Flex, Speaker Microphone

13 PIN UNIVERSAL CONN

EXT_SPKR+

EXT_SPK-

OPT_B+

EXT_MIC

OPT_SEL_2

OPT_SEL_1

GND

RX_DATA

TX_DATA

J404

J405

J406

J407

J408

J409

J410

J411

J412

SPKR_20

SPKR_20

OPT_B+30

RSSI

RX_AUDIO/TX_AUDIO

BOOT_CTRL

NC

J413

J414

J415

J416

1

2

C402100pF

M401

GND

INT_SPK+

INT_SPK-

EXT_SPKR+

EXT_SPK-

DPT_B+

EXT_MIC

OPT_SEL_2

OPT_SEL_1

GND

RX_DATA

TX_DATA

GND

RSSI

RX_AUDIO/TX_AUDIO

BOOT_CTRL

NC

MIC

GND

GND

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

J40320 PIN CONN

M400SPKR_20

SPKR_20

4-6

4.2.6 Keypad Top and Bottom Overlays

Figure 4-5: Keypad Top and Bottom Board Overlays

Top View

Bottom View

D601

D602

D603

D604

D605

D606

M60

4M

605

M60

6

M60

7M

608

M60

9

M61

0M

611

M61

2

M61

3M

614

M61

5

M61

6M

617

M61

8

VIEW

ED F

ROM

SID

E 1

M61

9M

620

M62

1

FL08

3071

9O

C612

C613

2J6

0140 39

C610

R637

R632

C611

C615

R622

R633

R646

U602

C609

R611

R612

R613

R625R630

R628

R639R641R643R645

R638R640

R642R644

R601

R631

R618

R649J6

02

18

C614

R626

R602

R603

R604

R605

R607

R608R609

R610

R620

R614R615

R616

R617

R627

R629

R634

C616

Q601

Q602Q6

03 R619

R648

R647

R606

R621

VIEW

ED F

ROM

SID

E 2

FL08

3072

0O

MANUAL REVISION

4-2-02

®

© 2002 by Motorola, Inc.Commercial, Government and Industrial Solutions Sector8000 W. Sunrise Blvd., Ft. Lauderdale, FL 33322Printed in U. S. A. 4/02. All Rights Reserved.

This revision outlines changes that have occurred since the printing of your manual. Use this information to supplement your manual.

REVISION CHANGE:

On page 4-6, the bottom view of Figure 4-5 (in Section 4.2.6, Keypad Top and Bottom Overlays) should appear as shown below:

C61

2C

613

2J6

0140

39

C610

R637

R63

2

C61

1

C615

R62

2

R633

R646

U602

C609

R611

R612

R613

R625R630

R628

R639R641R643R645

R638R640

R642R644

R601

R631

R618

R649

J602

18

C614

R62

6

R602

R603

R604

R605

R607

R608R609

R610

R62

0

R614R615

R616

R617

R62

7

R62

9

R634

C616

Q60

1Q

602

Q60

3

R619

R648

R647

R60

6

R621

VIE

WE

D F

RO

M S

IDE

2

*FMR-2016A-1*FMR-2016A-1

Professional Radio™6881088C46-D

PRO SeriesDetailed Service Manual

Bottom View

Figure 4-5: Keypad Top and Bottom Board Overlays