Motorola Solutions 92FT4848 VRS 750- Vehicular Repeater System User Manual User and Service Manual

Motorola Solutions, Inc. VRS 750- Vehicular Repeater System User and Service Manual

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User and Service Manual

VRS 750

Vehicular Repeater System

Detailed Service Manual

Foreword

The information contained in this manual relates to the VRS750 Vehicular Repeater System, unless

otherwise speciﬁed. This manual provides sufﬁcient information to enable service shop personnel to

troubleshoot and repair the VRS750 to the component level.

Safety Information

Before operating the VRS750, please read the “User Safety, Training, and General Information” section in

the front of this manual.

Manual Revisions

Changes which occur after this manual is printed are described in “FMRs.” These FMRs provide complete

information on changes, including pertinent parts list data.

Computer Software Copyrights

The Motorola products described in this manual may include copyrighted Motorola computer programs

stored in semiconductor memories or other media. Laws in the United States and other countries preserve

for Motorola certain exclusive rights for copyrighted computer programs, including, but not limited to,

the exclusive right to copy or reproduce in any form the copyrighted computer program. Accordingly, any

copyrighted Motorola computer programs contained in the Motorola products described in this manual

may not be copied, reproduced, modiﬁed, reverse-engineered, or distributed in any manner without the

express written permission of Motorola. Furthermore, the purchase of Motorola products shall not be

deemed to grant either directly or by implication, estoppel, or otherwise, any license under the

copyrights, patents or patent applications of Motorola, except for the normal non-exclusive license to use

that arises by operation of law in the sale of a product.

Table of Contents

➠

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . inside front cover

User Safety, Training, and General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Safe Handling of CMOS Integrated-Circuit Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Model Chart for the VRS750 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii

VHF VRS750 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

UHF VRS750 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

Glossary of Terms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix

List of Abbreviations and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .x

1 - Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

VRS Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Mutually-Exclusive Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 - Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

VRS Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Installation of the Mounting Trunnion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

VRS Antenna Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

VRS750 Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

3 - VRS Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Control Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Vehicle Interface Ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

VRS Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

In-Car Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Mobile Audio Repeat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4 - Operation of VRS Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Base Repeater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Mobile Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

VRS Transmit PL Generator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

, Private Line, and Motorola are registered trademarks of Motorola Inc.

Systems 9000, ASTRO, Spectra, Call Alert, Private Conversation, Single Tone,

Digital Private-Line, and Slimnet are trademarks of Motorola Inc.

Torx is a trademark of Camcar Div. of Textron, Inc.

Commercial, Government and Industrial Solutions Sector

8000 W. Sunrise Blvd., Ft. Lauderdale, FL 33322

6881094C84

Detailed Service Manual

VRS Mode Steering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Time-Out Timer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

VRS Single Tone. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

VRS Mobile-TX Acknowledgment Tones (Conventional Only) . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Flashing Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Repeater PPI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Quick-Key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

5 - Detailed VRS Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Multi-VRS Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Rptr PPI—Portable Priority Interrupt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

TX PL Self-Clearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

ICM Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Acknowledgment Tones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Non-Priority VRS Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Emergency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

6 - Hardware Detailed Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Power Regulation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Bus Translation Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Audio Routing Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Single Tone Encoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Single Tone Decoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Boot Control Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Program Sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Mode Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

7 - Maintenance and Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Troubleshooting Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Disassembly and Reassembly Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

VRS Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

VRS Tuning and Alignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

8 - Troubleshooting Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

List of Troubleshooting Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

9 - Diagrams and Parts Lists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

List of Diagrams and Parts Lists. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

iii

User Safety, Training, and General Information

READ THIS IMPORTANT INFORMATION ON SAFE AND EFFICIENT OPERATION BEFORE INSTALL-

ING AND USING YOUR MOTOROLA MOBILE TWO-WAY RADIO IN A VEHICLE OR AS A CONTROL

STATION.

Compliance with RF Energy Exposure Standards

Your Motorola two-way radio is designed and tested to comply with a number of national and

international standards and guidelines (listed below) regarding human exposure to radio frequency

electromagnetic energy.

This radio complies with the IEEE (FCC) and ICNIRP exposure limits at duty

cycles of up to 50% talk-50% listen and should be used for occupational use only.

In terms of

measuring RF energy for compliance with the FCC exposure guidelines, your radio radiates measurable RF

energy only while it is transmitting (during talking), not when it is receiving (listening) or in standby

mode.

Your Motorola two-way radio complies with the following RF energy exposure standards and guidelines:

•

United States Federal Communications Commission, Code of Federal Regulations; 47CFR 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

•

International Commission on Non-Ionizing Radiation Protection (ICNIRP) 1998

•

Ministry of Health (Canada) Safety Code 6. Limits of Human Exposure to Radiofrequency

Electromagnetic Fields in the Frequency Range from 3 kHz to 300 GHz, 1999

•

Australian Communications Authority Radiocommunications (Electromagnetic Radiation - Human

Exposure) Standard 1999 (applicable to wireless phones only)

Operational Instructions and Training Guidelines

To ensure optimal performance and compliance with the RF energy exposure limits in the above

standards and guidelines, users should transmit no more than 50% of the time and always adhere

to the following procedures:

Transmit and Receive

•

To transmit (talk), push the Push-To-Talk (PTT) button; to receive, release the PTT button.

•

Transmit only when people outside the vehicle are at least the minimum lateral distance away,

as shown in Table 1, from a properly installed, externally-mounted antenna.

Table 1 lists the minimum lateral distance for bystanders in an uncontrolled environment from the

transmitting antenna at several different ranges of rated radio power for mobile radios installed in a

vehicle.

Mobile Antennas

•

Install antennas at the center of the roof or the center of the trunk deck. These mobile antenna

installation guidelines are limited to metal body vehicles.

•

The antenna installation must additionally be in accordance with:

a. The requirements of the antenna manufacturer/supplier

b. Instructions in the Radio Installation Manual

•

Use only Motorola approved supplied antenna or Motorola approved replacement antenna.

Unauthorized antennas, modiﬁcations, or attachments could damage the radio and may violate FCC

regulations.

Approved Accessories

For a list of Motorola approved antennas see the appendix of this user manual.

Fixed Site Antennas

If mobile radio equipment is installed at a ﬁxed location and operated as a control station or as a ﬁxed

unit, the antenna installation must comply with the following requirements in order to ensure optimal

performance and compliance with the RF energy exposure limits in the above standards and guidelines.

•

The antenna should be mounted outside the building on the roof or a tower if at all possible.

•

As with all ﬁxed site antenna installations, it is the responsibility of the licensee to manage the site in

accordance with applicable regulatory requirements and may require additional compliance actions

such as site survey measurements, signage, and site access restrictions in order to insure that

exposure limits are not exceeded.

Electromagnetic Interference/Compatibility

NOTE:

Nearly every electronic device is susceptible to electromagnetic interference (EMI) if

inadequately shielded, designed or otherwise conﬁgured for electromagnetic

compatibility. It may be necessary to conduct compatibility testing to determine if any

electronic equipment used in or around vehicles or near ﬁxed antenna sites is sensitive to

external RF energy and if any procedures need to be followed to eliminate or mitigate the

potential for interaction between the radio transmitter and the equipment or device.

Facilities

To avoid electromagnetic interference and/or compatibility conﬂicts,

turn off your radio in any facility

where posted notices instruct you to do so

Hospitals or health care facilities may be using equipment

that is sensitive to external RF energy.

Table 1. Rated Power and Lateral Distance

Rated Power of Vehicle-Installed

Mobile Two-Way Radio

Minimum Lateral Distance from

Transmitting Antenna

Less than 7 watts 8 inches (20 centimeters)

7 to 15 watts 1 foot (30 centimeters)

16 to 50 watts 2 feet (60 centimeters)

51 to 110 watts 3 feet (90 centimeters)

Vehicles

To avoid possible interaction between the radio transmitter and any vehicle electronic control modules,

for example, ABS, engine, or transmission controls, we recommend that the radio be installed by an

experienced installer and that the following precautions be used when installing the radio:

1. Refer to any manufacturers instructions or other technical bulletins or recommendations on radio

installation.

2. Before installing the radio, determine the location of the electronic control modules and their

harnesses in the vehicle.

3. Route all radio wiring, including the antenna transmission line, as far away as possible from the

electronic control units and associated wiring.

Driver Safety

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.

•

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 or mobile radio in the area over an air bag or in the air bag deployment area. Air

bags inﬂate with great force. If a radio is placed in the air bag deployment area and the air bag inﬂates,

the radio may 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. Sparks in a

potentially explosive atmosphere can cause an explosion or ﬁre resulting in bodily injury or even

death.

The areas with potentially explosive atmospheres referred to above include fueling areas such as below

decks on boats, fuel or chemical transfer or storage facilities, areas where the air contains chemicals or

particles, such as grain, dust or metal powders, and any other area where you would normally be advised

to turn off your vehicle engine. Areas with potentially explosive atmospheres are often but not always

posted.

Blasting Caps and Blasting Areas

To avoid possible interference with blasting operations, turn off your radio when you are near electrical

blasting caps, in a blasting area, or in areas posted: "Turn off two-way radio." Obey all signs and

instructions.

For radios installed in vehicles fuelled by liqueﬁed petroleum gas, refer to the (U.S.) National Fire

Protection Association standard, NFPA 58, for storage, handling, and/ or container information. For a

copy of the LP-gas standard, NFPA 58, contact the National Fire Protection Association, One Battery Park,

Quincy, MA.

Safe Handling of CMOS Integrated-Circuit Devices

Many of the integrated-circuit (IC) devices used in communications equipment are of the CMOS (Complementary

Metal Oxide Semiconductor) type. Because of their high open-circuit impedance, CMOS ICs are vulnerable to damage

from static charges. Everyone involved in handling, shipping, and servicing them must be extremely careful not to

expose them to such damage.

CMOS ICs do have internal protection, but it is effective only against overvoltages in the hundreds of volts, such as

those that could occur during normal operations. Overvoltages from static discharge can be in the thousands of volts.

When a CMOS IC is installed in a system, the circuit elements in the system distribute static charges and load the

CMOS circuits. This decreases the vulnerability of the ICs to static discharge, but improper handling will probably

cause static damage even when the ICs are so installed.

To avoid damaging CMOS ICs, take the following precautions when handling, shipping, and servicing them.

1. Before touching a circuit module, particularly after having moved around in the service area, touch both hands

to a bare-metal, earth-grounded surface. This discharges any static charge you may have accumulated.

NOTE:

Wear a conductive wrist strap (Motorola part number RSX-4015A) to minimize the buildup of

static charges on your person while you are servicing CMOS equipment.

When wearing a conductive wrist strap, be careful near sources of high voltage.

By grounding you thoroughly, the wrist strap also increases the danger of lethal

shock from accidental contact with such a source.

2. Whenever possible, avoid touching any electrically conductive parts of the circuit module with your hands.

3. Check the INSTALLATION and MAINTENANCE sections of this manual and the notes on the schematic to ﬁnd

out whether or not you can insert or remove circuit modules with power applied to the unit, and act

accordingly.

4. When servicing a circuit module, avoid carpeted areas, dry environments, and the wearing of static-generating

clothing.

5. Be sure that all electrically powered test equipment is grounded. Attach the ground lead from the test

equipment to the circuit module before connecting the test probe. Similarly, disconnect the test probe before

removing the ground lead.

6. When you remove a circuit module from the system, lay It on a sheet of aluminum foil or other conductive

surface connected to ground through 100,000 ohms of resistance.

If the aluminum foil is connected directly to ground, you may get a shock if you

touch it and another electrical circuit at the same time.

7. When soldering, be sure the soldering iron is grounded.

8. Before connecting jumpers, replacing circuit components, or touching CMOS pins (if this becomes necessary

during the replacement of an integrated-circuit device), be sure to discharge any static buildup on your person

(see step 1, above). Because you can have a voltage difference across your body, you should use only one hand if

you must touch the board wiring or any of the pins on the CMOS device.

9. When replacing a CMOS integrated-circuit device, leave the device in its metal rail container or conductive

foam until you are ready to insert it into the pronged circuit module.

10. Connect any low-impedance test equipment, such as a pulse generator, to CMOS device inputs after you have

applied power to the CMOS circuitry. Similarly, disconnect such low-impedance equipment before turning off

the power.

11. Wrap CMOS modules in conductive material when transporting them from one area to another, even within

the same room. Use wrapping material similar to that in which replacement modules are wrapped when they

arrive from the factory. (You can also use aluminum foil.) Never use nonconductive material for packaging these

modules.

vii

Model Chart for the VRS750

MODEL NUMBER DESCRIPTION

P2080 VRS750 VHF (136-174 MHz)

P2081 VRS750 UHF R1 (403-470 MHz)

P2082 VRS750 UHF R2 (450-512 MHz)

ITEM NUMBER DESCRIPTION

X X X

HHN4044* VRS750 Housing

X X X

HLN6855* VRS750 Mounting Assembly

X X X

PLN7780

†

VRS750 Controller Board

XX X

HLN6856* XCVR Hardware

PMLD4196 VHF Transceiver

PMLE4242 UHF R1 Transceiver

PMLE4243 UHF R2 Transceiver

XX X

HKN6153 Cable, Mobile-to-VRS

1 1 1

HKN6154 Cable, Siren-to-VRS

2 2 2

6881094C84 VRS750 Detailed Service Manual

XXX

2884606M01 Mini-UHF crimp connector

XXX

YLN4480 VRS Pushbutton

XXX

HBN5086 Packing Kit

3085031D02 Cable, VRS Programming (accessory)

NTN4056 Adapter, VRS Flash programming (accessory)

NKN6460 y-cable kit for dual controlhead w/vrs (accessory)

TLN5277 DC ﬁlter for excessive alternator whine (accessory)

RLN5394 VRS750 Test Box (accessory)

3080384N02 VRS750 ATE Cable (accessory)

= With option G334AC. Deletes HKN6153 cable.

= One item per 10 units.

*For piece part information, refer to the Exploded View section.

†

For piece part information, refer to the Electrical Parts List section.

viii

VHF Performance Speciﬁcations

UHF Performance Speciﬁcations

GENERAL TRANSMITTER RECEIVER

Model

P2080 (136-174 MHz)

†

Number of Channels:

1, T1 = R1

Frequency:

Programmable, Synthesized

Frequency Channel

Channel Spacing:

12.5/20/25 kHz

Operation Temp. Range:

-30°C to +60°C

Primary Power:

13.8 VDC ± 20%,

Negative Ground

DC Current Drain (max):

120 mA Receive

500 mA Transmit @ 275 mW

1.10 A Transmit @ 2 W

Squelch Operation:

Private-Line required for

repeater access

Duty Cycle:

Intermittent per EIA at 275 mW

PPI Sample Time:

16 ms Typical

Singletone Encoder/Decoder:

Nominal 847.5 Hz

FCC Identiﬁers:

AZ492FT3802 (P2080)

Industry Canada:

RF Power Out:

275 mW to 2 W tunable

Spurious and Harmonic Emissions:

-36 dBm < 1 GHz

-30 dBm > 1 GHz

Frequency Stability:

±2.5 ppm @ 25 kHz

±2.5 ppm @ 12.5 kHz

Modulation Limiting (Max):

±2.5 kHz @ 12.5 kHz

±4.0 kHz @ 20 kHz

±5.0 kHz @ 25 kHz

Audio Response:

(from 6 dB/octave

pre-emphasis, 300 to 3000 Hz)

+1, -3 dB

Audio Distortion:

3% Typical @ 1 kHz,

60% maximum deviation

FM Hum and Noise:

-40 dB

TX Attack Time:

32 ms Typical

Antenna Impedance:

50 ohms

Antenna Connector: mini-uhf

Intermodulation per EIA: 70 dB

Hum and Noise: -40dBm @ 25 kHz

-35dBm @ 12.5 kHz

Reference Sensitivity (typical):

0.28 µV (-118dBm) at 12 dB SINAD

Conducted Spurious Rejection: 70 dB

Adjacent Channel Selectivity:

60 dB @ 12.5 kHz

70 dB @ 25/30 kHz

Audio Response (0.3-3 kHz): +1 to -3 dB

Audio Distortion: 3% Typical @

Mobile Rated Audio*

Conducted Spurious Emissions:

-57 dBm <1 GHz

-47 dBm > 1 GHz

RX Attack Time: 60 ms Typical

*Typically 5 W in 8 ohms.

†Consult the product catalog sheets (ECAT Price Pages) for a list of disallowed frequencies.

GENERAL TRANSMITTER RECEIVER

Model P2081 (403-470 MHz)

P2082 (450-512 MHz)†

Number of Channels: 1, T1 = R1

Frequency: Programmable, Synthesized

Frequency Channel

Channel Spacing: 12.5/20/25 kHz

Operation Temp. Range: -30°C to +60°C

Primary Power: 13.8 VDC ± 20%,

Negative Ground

DC Current Drain (max): 120 mA Receive

700 mA Transmit @ 275 mW

1.20 A Transmit @ 2 W

Squelch Operation: Private-Line required for

repeater access

Duty Cycle: Intermittent per EIA at 275 mW

PPI Sample Time: 16 ms Typical

Singletone Encoder/Decoder:

Nominal 847.5 Hz

FCC Identiﬁers: AZ492FT4848 (P2081)

AZ492FT4849 (P2082)

Industry Canada:

RF Power Out: 275 mW to 2 W tunable

Spurious and Harmonic Emissions:

-36 dBm < 1 GHz

-30 dBm > 1 GHz

Frequency Stability:

±2.5 ppm @ 25 kHz

±2.5 ppm @ 12.5 kHz

Modulation Limiting (Max):

±2.5 kHz @ 12.5 kHz

±4.0 kHz @ 20 kHz

±5.0 kHz @ 25 kHz

Audio Response: (from 6 dB/octave

pre-emphasis, 300 to 3000 Hz)

+1, -3 dB

Audio Distortion: 3% Typical @ 1 kHz,

60% maximum deviation

FM Hum and Noise: -40 dB

TX Attack Time: 14 ms Typical

Antenna Impedance: 50 ohms

Antenna Connector: mini-uhf

Intermodulation per EIA: 70 dB

Hum and Noise: -40dBm @ 25 kHz

-35dBm @ 12.5 kHz

Reference Sensitivity (typical):

0.28 µV (-118 dBm) at 12 dB SINAD

Conducted Spurious Rejection: 70 dB

Adjacent Channel Selectivity:

60 dB @ 12.5 kHz

70 dB @ 25/30 kHz

Audio Response (0.3-3 kHz): +1 to -3 dB

Audio Distortion: 3% Typical @

Mobile Rated Audio*

Conducted Spurious Emissions:

-57 dBm <1 GHz

-47 dBm > 1 GHz

RX Attack Time: 60 ms Typical

*Typically 5 W in 8 ohms.

†Consult the product catalog sheets (ECAT Price Pages) for a list of disallowed frequencies.

Glossary of

Terms

The following glossary of terms and deﬁnitions help you to understand the

VRS theory of operation.

Countdown A term that describes the incremental step-down function of the counter in

the repeater. Approximately 500 milliseconds of time delay for conventional

modes and 1500 milliseconds for trunked modes separate each successive

delay state.

Delay State The speciﬁc condition of the counter. A series of eight delay states prioritize

the repeaters within a common geographical area. Delay state zero has the

least time delay (0 milliseconds); delay state seven has the greatest delay

(approximately 3.5 seconds for conventional modes, and 10.5 seconds for

trunked modes). A unit that is in delay state zero is the priority unit.

Disable The deactivation of the repeater. Press the VRS button on the control head or

switch the VIP input off.

Enable The activation of the repeater. Press the VRS button on the control head or

switch the VIP input on.

Inhibit A condition that occurs when the countdown sequence of the logic circuitry

of the repeater ends, or anytime the repeater stops transmitting.

Non-Priority

Repeater

A repeater in any delay state other than delay state zero. This unit is inactive

and does not repeat until the unit steps down to delay state zero.

PTT The Push-To-Talk button on a portable radio or mobile microphone.

Priority Repeater A repeater with its counter in delay state zero. This unit repeats any signal with

the proper carrier frequency and PL code.

Quick-Key A short press of the portable’s PTT—one that is long enough for the VRS to key

the mobile and access the trunking system, but less than 1 second in duration.

Single Tone Burst When a repeater enables, it transmits a 700-millisecond audible tone. This

tone burst increases the delay counter in all other repeaters within range of the

transmitting vehicle by one delay increment.

List of

Abbreviations

and Acronyms

B-P Base to Portable

CPS Customer Programming Software

DPL Digital Private Line

HUB Hang Up Box

ICM In Car Monitor

ms Millisecond

PAC Portable Area Coverage

PL Private Line

PPI Portable Priority Interrupt

P-B Portable to Base

RF Radio Frequency

RX Receive

SB Serial Bus

SBEP Serial Bus Expanded Protocol

TOT Time Out Timer

TX Transmit

VIP Vehicle Interface Port

VRS Vehicular Repeater System

VRS-EP Vehicular Repeater System—Expanded Protocol

VRS750 Vehicular Repeater System—Model 750

Introduction 1

Description The VRS750 Vehicular Repeater System is a mobile radio system

component that provides on-site repeater capability between a

portable radio and a base station (see Figure 1). The VRS gives the

portable user the equivalent range of a mobile radio with the ﬂexibility

of a portable. The VRS is not an ASTRO-capable radio; instead, it is

designed to interface with an ASTRO Spectra® mobile radio. It can only

transmit and receive clear analog transmissions.

The VRS receives transmissions on the portable radio’s transmit

frequency with the proper access PL, and passes these portable signals

to the mobile radio. The mobile radio re-transmits the signals to the

base station on the mobile radio’s transmit frequency.

NOTE: These transmissions have the mobile’s ID, not the

portable’s.

Similarly, base station signals received by the mobile radio are sent to

the VRS and re-transmitted to the portable radio. The VRS does not

provide local repeater capability (received portable signals are not

repeated on the portable receive frequency).

The VRS-to-portable and portable-to-VRS communications are limited

to clear analog only. This is a simplex-only interface; the VRS cannot

receive and transmit simultaneously. The base station-to-mobile and

mobile-to-base communications protocol is not limited to analog

only. Rather, this interface is limited by the features and functions of

the ASTRO Spectra and the base.

Figure 1. VRS750 Vehicular Repeater System

SPEAKER CONTROL HEAD

ASTRO MOBILE

VRS750

HKN6153A

MOBILE

MICROPHONE

Ordering

Information

The VRS is a crossband repeater that operates on either UHF or VHF

frequencies. The repeater cannot be operated with a mobile radio

operating in the same band as the VRS unit.

The VRS RF platform is based on a synthesized transceiver. The VRS

supports one channel whose frequency and channel spacing can be

programmed in the ﬁeld. The VRS remains a simplex repeater and as a

result, the transmit frequency must be set equal to the receive

frequency. The VRS receives its programming information from the

ASTRO Spectra mobile at power-up. The ASTRO Spectra mobile

supports the VRS programming ﬁelds via ASTRO Customer

Programming Software (CPS). For more information, refer to “VRS750

Programming,” in Chapter 2, “Installation.”

The VRS is not compatible with ASTRO Spectra mobiles with the

VSELP signaling type.

When integrating a VRS with an ASTRO mobile with a Siren/PA, an

alternate interface cable is needed (HKN6154A). This cable allows the

VRS to be connected to the Siren/PA. For more information, refer to

“Installation,” Chapter 2.

When integrating a VRS with an ASTRO mobile with Dual Control

heads, an alternate interface cable is needed (NKN6460A). This y-cable

allows the VRS to be connected to the ASTRO mobile with two control

heads.

A separate antenna (not included) is necessary for use with the

repeater. Typically, a one-quarter (1/4) wave length antenna

maximizes radiation efﬁciency when installed at the center of the

vehicle roof. If it is necessary to mount the antenna on the vehicle’s

trunk lid, an appropriate 3 dB gain antenna should be used. See “VRS

Antenna Installation,” in Chapter 2, for details.

A ﬁlter for the battery lines (TLN5277B)is available for use with ASTRO

Spectra mobiles. This ﬁlter can be used to prevent excessive alternator

whine noise from being heard on the mobile speaker during VRS

operation.

The VRS ships from the factory with the low output power setting at

275 mW and a high output power setting of 2 W. The low output

power setting is the default setting. We recommend the LOW Transmit

Power setting of 275 mW for optimal performance. This output power

provides the VRS with a similar range as the portable when attached

to a mobile antenna. Any deviation from this setting could result in a

loss of communication from the portable to the base.

The Global Tuning Tool (not included) can be used to tune the VRS

output power in the ﬁeld. For more information refer to “VRS750

Global Tuner,” in Chapter 2.

Contact Customer Resources for information on how to obtain this

Global Tuning Tool.

VRS Features The VRS operates with the ASTRO mobile radio and contains the

following integrated features:

•Automatic, multiple-unit, priority-resolution algorithm.

•Portable priority interrupt (PPI) function.

•Conventional/trunked operation.

•Remote switch enable/disable capability for control charger

interface.

•Remote activation of emergency alarm feature.

•In-car monitor operation.

•VRS mobile access tones.

•Mobile radio transmitter steering of up to eight modes via Private-

Line® (PL) code transmission from the portable radio.

•TX PL generator.

•Base repeater operation for two-frequency, simplex, ﬁxed-repeater

systems.

•Mobile audio repeat.

•Compatible with the VRS-EP.

All VRS features can be programmed in the ﬁeld using ASTRO Spectra

mobile CPS. For more information, refer to “VRS750 Programming,”

in Chapter 2.

IMPORTANT NOTE: All ASTRO Spectra VRS systems with the

same VRS RF transmit/receive frequency

need to be CPS programmed identically

to ensure proper operation. Failure to do

so could result in erratic system operation.

The VRS does not have to be installed in the system for

programming—only the mobile radio is programmed. If the VRS is not

connected after programming the mobile system, an error message

“ERR 12/10” will be displayed on the control head.

Mutually-Exclusive

Features

The VRS IS NOT compatible with the following mobile radio features:

•W3 Control Head is not supported with VRS

•Flush-mounted control heads

•VSELP signaling type

•Data—VRS and data are not compatible on the same channel and

cannot be used simultaneously. VRS should never be activated on

a channel that has packet data enabled, and VRS mode steering

channels should not have packet data enabled.

•Scan

•Over-the-Air Rekeying (OTAR) Rekey Request

•Message (from the Control Head)—Trunking or Conventional

•Status (from the Control Head)—Trunking or Conventional

•Emergency Call—Trunking or Conventional—Emergency Call

and VRS are mutually exclusive. Even if the mobile is

programmed for Alarm and Call, when the Alarm case is exited,

the mobile will not transition into Emergency Call while the VRS

is activated. Likewise, if the mobile is in Emergency Call, the VRS

cannot be activated.

NOTE: When an Emergency Alarm is received, the dispatcher

may elevate that talkgroup to Emergency status.

•Reprogram Request—Trunking

•Repeater Access Control—Conventional

•Mobile Single Tone—Conventional

•Seven-Tone Modat—Conventional

•Motorcycle

•Consolette (Digital Remote and Tone Remote)

The following mobile radio features may be received but may not be

initiated or responded to while VRS is enabled.

•Private Conversation™—Trunking

•Call Alert™—Trunking or Conventional

•Telephone Interconnect—Trunking or Conventional

•Voice Selective Call—Conventional

Installation 2

When selecting the location for the VRS, make certain that there is

sufﬁcient clearance for routing the antenna cable to the rear of the

unit.

VRS Installation The VRS750 is installed using the HKN6153A interface cable. The

molded DB-25 end connects to the ASTRO mobile front connector.

The DB-25 end with the plastic housing connects to the VRS (see

Figure 2).

If an external Siren/PA is to be used, the G334AC option must be

ordered which replaces the HKN6153A cable with a HKN6154A cable,

or a separate HKN6154A cable must be ordered. To install, plug the “T”

side of the HKN6154A cable to the Siren/PA. Replace the mounting

screw on the HKN4363B cable with the double length screw. Plug this

side into the “T” cable. Plug the DB-25 end of the HKN6154A into the

VRS (see Figure 3).

Figure 2. Installing the VRS to an ASTRO Mobile

Figure 3. Installing the VRS750 with an External Siren/PA

Control Head

ASTRO Mobile

VRS750

HKN6153A

Control Head

ASTRO Mobile

Siren/PA

VRS750

HKN4363B

HKN6154A

Installation of the

Mounting Trunnion,

HLN6855

1. Select the location to mount your VRS750. The VRS750 must be

mounted within six feet of the mobile radio. Allow sufﬁcient

space around the VRS750 for free air ﬂow for cooling.

2. Using the trunnion mounting bracket as a template, mark the

positions of the holes on the mounting surface.

3. Center-punch the spots you have marked and drill a 4 mm (0.16

inch) hole at each.

4. Secure the trunnion mounting bracket with the four screws

provided (see Figure 4).

5. Connect the VRS-to-Mobile cable to the 25 pin connector on the

bottom of the VRS750.

6. Position the VRS750 in the trunnion.

7. Secure the VRS750 with the two wing screws, and the split and

ﬂat washers provided.

Figure 4. Securing the Trunnion Mounting Bracket

VRS Antenna

Installation

Recommended mobile antenna installations are limited to metal body

vehicles at the center of the roof and center of the trunk deck

locations.

1. Mount the antenna using the instructions provided with the

antenna kit by the manufacturer (an antenna is not included with

the VRS models). Mount the antenna as far from the mobile radio

antenna as possible, never less than three feet. An ideal conﬁguration

would be a roof-mounted mobile radio antenna and a trunk-

mounted VRS antenna.

2. Run the coaxial cable to the VRS750 mounting location. If

necessary, cut off the excess cable and install the cable connector.

3. Connect the antenna cable mini-UHF connector to the antenna

jack on the rear of the VRS750 (see Figure 5). A mini-UHF crimp

connector is provided with each VRS750 unit for easier

installation with a pre-existing antenna. Ensure that the

antenna’s cable connector is fully tightened. An adapter should

NOT be used between the antenna cable mini-UHF connector and

the VRS750.

VRS750

Programming

The user selectable operating parameters for the VRS750 reside in the

ASTRO mobile EEPROM during normal operation. The EEPROM

located in the VRS750 holds the tuning parameters. The VRS750

programming windows reside in ASTRO Spectra CPS and are accessible

when the “VRS-EP Option” is enabled in CPS under the Radio

Conﬁguration --> Radio Wide --> Advanced Window (see Figure 6).

The VRS750 does not function without CPS programming and is not

pre-programmed at the factory. To ensure operational compatibility

from one unit to the next within the ﬂeet, all of the ASTRO Mobile and

VRS750/VRS-EP systems should be programmed the same way.

Figure 5. Connecting the Antenna Cable

Mini-UHF Connector to the Antenna Jack

ANTENNA

CONNECTOR

Special Programming

Notes

The VRS button can be located in any of the indicator button

positions normally used for option buttons.

The VRS750 option can be enabled/disabled by a vehicle interface port

(VIP). Use the VIP Control of VRS box in the Radio Conﬁguration

--> Radio Wide --> VRS window (see Figure 8) to enable VIP control

and to select whether the input control is active open or active closed.

Then use the Radio Conﬁguration --> Radio Wide --> Radio VIP

window (see Figure 7) to select the VIP to be used. However, the VRS

button must still be added to the control unit if it is desired to have

the indicator light when the VRS750 is enabled. See the ASTRO Spectra

CPS user’s manual for details concerning programming the VIP.

NOTE: The ASTRO Spectra CPS user’s manual does not

indicate that the VRS button is required in order to

have the indicator light when the VIP is enabled.

Figure 6. Advanced Window

(Radio Conﬁguration --> Radio Wide --> Advanced)

ASTRO VRS

Programming Windows

There are ﬁve windows for editing the VRS Option. Four of these

windows are in the Radio Wide section of Radio Conﬁguration while

the ﬁfth window is a table for the VRS mode steering PLs. The ﬁrst

window is the VRS subsection of the Radio Wide options (see Figure

8). In this window Base Repeater, Mobile Detector, Flashing Display,

VIP control of VRS, and Trunking Access Tones can be enabled or

disabled by clicking in the box to the left of the option. This window

is also where the ICM mode can be selected using a pull down menu.

Enabling Base Repeater will add 300 ms of delay to the prioritization

routine to account for ﬁxed repeater attack time.

The second window is the VRS Private Line subsection (see Figure 9).

This window allows the user to select a Mode Steering type, if one is

being used. If Mode Steering is set to Disabled, the Access PL Freq. and

Access PL Code ﬁelds will become user selectable. These ﬁelds specify

the one PL frequency transmitted by the portable that will be used to

access the VRS750. The VRS750 will treat that access PL in the same

manner as a “select mode” mode steering PL. To edit these ﬁelds click

in the Access PL Freq. or Access PL Code box and use the pull down

menu to select the desired frequency or code.

Also located on the second window is the VRS Tx Squelch Type. To edit

this ﬁeld click in the box to the right and use the pull down menu to

choose between TPL and CSQ. If TPL is selected, meaning that the VRS

should transmit to the portable with PL, the VRS Tx PL Freq. and VRS

Tx PL Code ﬁelds will become user selectable. To edit these ﬁelds, click

in the VRS Tx PL Freq. or VRS Tx PL Code box and use the pull down

menu to select the desired frequency or code.

Figure 7. Radio VIP Window

(Radio Conﬁguration --> Radio Wide --> Radio VIP)

Figure 8. VRS Window

(Radio Conﬁguration --> Radio Wide --> VRS)

Figure 9. VRS Private Line Window

(Radio Conﬁguration --> Radio Wide --> VRS Private Line)

The third window is the VRS Advanced subsection (see Figure 10).

This window is used to enable/disable the Access Acknowledgment

and Time-Out-Timer Tones and Repeater Portable Priority Interrupt

(PPI) as well as selecting the Time-Out-Timer duration. The Time-Out-

Timer duration may be set to 30, 60, or 120 seconds, or inﬁnite. The

inﬁnite setting should be used with caution, since damage to the

transmitter could result from any extremely extended transmission. It

should be noted that the Repeater PPI feature must be enabled to allow

the multi-unit priority algorithm to function correctly when there will

be multiple VRS units on scene. The time between interrupts may be

set to Fast (500 ms) or Slow (2 seconds) for conventional modes and

Fast (500 ms) or Slow (1 second) for trunked modes.

NOTE: When using Rptr PPI, the receiver squelch setting of

the portable must be programmed for CSQ (carrier

squelch).

The fourth window is the VRS Personality subsection (see Figure 11).

The VRS Personality sets the VRS Frequency Band, Simplex

Frequency, Channel Spacing, and TX Output Power for the VRS750.

The VRS750 can be programmed for 12.5, 20, or 25 kHz Channel

Spacing with a High or Low output power (factory power settings are

2 W for High and 275 mW for Low). Note that the VRS Personality

will allow the Frequency Band to be set to VHF, UHF R1, or UHF R2

regardless of which model VRS750 is being used, but upon power up

the error message “VRS 001” will be displayed if the frequency band is

incorrect.

Figure 10. VRS Advanced Window

(Radio Conﬁguration --> Radio Wide --> VRS Advanced)

NOTE: Older VRS units, such as the VRS-EP, do not support

any of the ﬁelds in the VRS Personality window.

However, these ﬁelds can be programmed without

having any effect on the VRS-EP, so that the VRS-EP

and VRS750 can be interchangeable without

reprogramming the mobile.

The VRS Personality can be programmed directly into the VRS750

EEPROM using Professional Radio CPS and a new dip switch

conﬁguration, Professional CPS Mode. All other operating parameters

will still be programmed using the ASTRO Spectra CPS. For more

information, refer to “Mode Conﬁguration,” Chapter 6.

The ﬁfth window, Radio Conﬁguration --> Radio Wide VRS-EP

Mode Steering --> VRS-EP Mode Steering List --> VRS-EP Mode

Steering - 1 (see Figure 12) is a table containing PL and mode steering

information that can be edited. Mode Steering must ﬁrst be enabled in

the VRS Private Line window before the mode steering PLs in the

table can be edited. To enter the PL codes used in mode steering and

their corresponding destinations, enter the desired PL code or

frequency by using the pull down menu in each PL Freq. or PL Code

box. Then select the corresponding Steering Destination in the same

manner.

If the VRS Tx Squelch Type was set to TPL in the VRS Private Line

window, none of the mode steering PLs may be the same as the VRS

Tx PL Frequency.

Figure 11. VRS Personality Window

(Radio Conﬁguration --> Radio Wide --> VRS Personality)

NOTE: The Receive PL ﬁlter internal to the VRS is a low pass

ﬁlter with a -3 dB point of approximately 170 Hz. As a

result, the PLs greater than 170 Hz will be attenuated

to allow for a decreased decode sensitivity. The higher

the PL frequency the greater the attenuation. The

Emergency, Message, and Status features of the VRS are

best suited for use with these higher PL frequencies.

Due to Host memory considerations, the maximum number of Zones

allowed to be accessed by the VRS Mode Steering window is 20. Any

Zone number greater than 20 will not be allowed in this window but

is allowed for normal radio operation.

VRS750 Global Tuner The Tuner for Professional Radios (Global Tuner) can be used to adjust

the VRS750’s Transmitter Output Power and Receiver Squelch Settings

while in Normal Mode (see Table 6 in Chapter 6). In order to program

the VRS750 using the Global Tuner it should be connected to the

mobile and to a PC via its COM port as indicated in Figure 13.

Figure 12. VRS-EP Mode Steering Window

Figure 13. VRS Connection to the PC

VRS750 SRIB

ASTRO MOBILE

VRS750 TO MOBILE CABLE CONNECT TO THE PCs

COM PORT

Once the setup is complete and the mobile is turned on the current

tuning parameters can be read from the VRS750 by selecting File -->

Read Radio Information and Softpots on the Global Tuner.

NOTE: Radio Serial Number and Radio Model Number shown

at the bottom of the screen will not match the model

number and serial number of its associating VRS.

Transmit Power Tuning The VRS750 supports 2 different power levels (High and Low). There

are separate alignments for High and Low power (see Tables 2 and 3).

We recommend setting and using a Low transmit power setting of

275 mW for optimal performance. This output power provides the

VRS750 with a similar range as the portable when attached to a mobile

antenna. Any deviation from this setting could result in a loss of

communication from the portable to the base.

NOTE: Please also note that some countries may have

different restrictions on the power level. If you are not

sure on the power to tune, please check with your

regulatory body. The maximum available power level

given in the table below must not be exceeded.

NOTE: When checking the RF power output of the VRS750,

always use an attenuator pad of at least 30 dB attached

to the radio end of the RF cable. This will avoid an RF

mismatch and ensure a stable RF reading that will not

change with varying lengths of connecting cable.

NOTE: The VRS750 will be programmed from the factory with

a high power setting of ~2 W and a low power setting

of ~275 mW.

To perform Transmit High Power Tuning, do the following:

1. Under the Tx Align menu, select Transmit Power, then select

High (see Figure 14).

2. Press PTT Toggle. This will key the radio up at F1.

3. Adjust the high power level by moving the slider/spin control or

keying in values in the edit control (press ENTER to conﬁrm

selection after typing in the softpot value).

4. Press PTT Toggle to dekey the radio, go to the next frequency

point by selecting the slider, typing in the edit control box (press

ENTER to conﬁrm selection after typing in the softpot value) or

toggling the softpot value using the spin control.

Table 2. Transmit High Power Level for VRS750s

RF Band (MHz) High Power (W)

VHF (136-174) 5.2-5.7

UHF Band 1 (403-470) 4.2-4.6

UHF Band 2 (450-527) 4.2-4.5

5. Press PTT Toggle again to key up the radio at the selected

frequency point.

6. Repeat steps 3-5 for (F2-F7).

7. Press Program to store the softpot values into the radio’s

codeplug.

8. Exit the Transmit High Power function. The mobile will reset

upon exiting

If low power channels are used, perform Transmit Low Power Tuning

as shown in Table 3.

To perform Transmit Low Power Tuning, do the following:

1. Under the Tx Align menu, select Transmit Power, then select

Low.

2. Press PTT Toggle. This will key the radio up at F1.

3. Adjust the power level by moving the slider/spin control or

keying in values in the edit control (press ENTER to conﬁrm

selection after typing in the softpot value).

Figure 14. Transmit High Power Window in the Global Tuner

Table 3. Transmit Low Power Level for VRS750s

RF Band (MHz) Low Power (mW)

VHF (136-174) 240-310

UHF Band 1 (403-470) 240-310

UHF Band 2 (450-527) 240-310

4. Press PTT Toggle to dekey the radio, go to the next frequency

point by selecting the slider, typing in the edit control box (press

ENTER to conﬁrm selection) or toggling the softpot value using

the spin control.

5. Press PTT Toggle again to key up the radio at the selected

frequency point.

6. Repeat steps 3-5 for (F2-F7).

7. Press Program to store the softpot values into the radio’s

codeplug.

8. Exit the Transmit Low Power function. The mobile will reset upon

exiting.

Squelch Tuning Under Rx Align, select Squelch Attn. Select either Squelch Attn. 12.5

kHz, Squelch Attn. 20 kHz, or Squelch Attn. 25 kHz Channel

Spacing variations (see Figure 15).

1. Apply an RF signal modulated with 1 kHz tone at 60% rated

deviation (see Table 10 in Chapter 7) for current frequency point

(F1 being the ﬁrst) of -110 dBm. Make sure that the mobile mic is

off HUB and the VRS is programmed for ICM BOTH mode so that

the audio will be routed to the mobile speaker.

NOTE: The -110 dBm squelch level was chosen so that each

VRS750 would have the same squelch performance as

other VRS750 units as well as VRS-EP units. This

prevents one unit from receiving a signal that the

other cannot.

2. Set softpot to its maximum value to mute the radio. If the VRS750

remains totally unmute at this setting, leave it at the maximum

setting and continue to step 4.

3. Adjust the softpot value by using the slider, keying in the edit box

(press ENTER to conﬁrm selection), or using the spin controls.

Figure 15. Squelch Attenuation Window in the Global Tuner

Do this until the radio is totally unmuted. Verify the squelch

closing by inputting a signal level of 4 dB lower (than that of the

-110 dBm level).

4. Repeat steps 1-3 for F2-F7.

5. Press Program to commit the softpot values into the codeplug.

6. Exit the Squelch Attn. function. The mobile will reset upon

exiting.

NOTE: The Auto Tuning feature does not work for the

VRS750.

Table 4 shows the softpot ranges to achieve approximately -110 dBm.

The actual value varies from radio to radio. The VRS transceiver ships

from the factory with the softpot set for -110 dBm. In the event that

this value needs to be re-set in the ﬁeld, it is recommended that a

communications analyzer or similar piece of test equipment be used to

verify these settings.

Other adjustments can be made using the Global Tuner in the event

that the transceiver is replaced. For more information, refer to

“Transceiver Board Tuning Procedure,” Chapter 7.

When all adjustments have been made, select File --> Program All.

This will program all off the softpot values into the VRS750’s EEPROM.

VRS750 Upgrade Kit The VRS750 ﬁrmware can be reprogrammed/reﬂashed using the

VRS750 Upgrade Kit. In order to use the VRS750 Upgrade Kit the

VRS750 should be connected to a desktop or laptop PC via a COM port

as indicated in Figure 13. The Flash adapter (NTN4056A) should be

placed between the VRS750 programming cable (3085031D02) and

the SRIB (see Figure 16). When connecting the VRS750 to the SRIB via

the Flash adapter, make sure that the switch on the adapter is in the

“B” position. With the ASTRO mobile powered on and “PROG VRS”

displayed on the control head, the upgrade can be started. Open the

VRS750 Upgrade Kit and click on the “PROGRAM” button. Follow the

instructions through to the completion of the Flash process. Upon

completion, place the switch on the Flash adapter back in the “B”

position and disconnect the VRS750 from the programming cable. For

more detailed information on the ﬂashing process, consult the “read

me” ﬁle for the Upgrade Kit.

Table 4. Softpot Ranges

Band Channel

Spacing (kHz)

Approximate Softpot

Range for -110 dBm

VHF 25 56-63

VHF 12.5 63

UHF R1 25 44-52

UHF R1 12.5 63

UHF R2 25 43-46

UHF R2 12.5 63

NOTE: The VRS750 Upgrade Kit will request which baud rate

to use when ﬂashing the ﬁrst radio. For the VRS750 the

baud rate should not exceed 38,400 bps.

Contact Customer Resources for information on how to obtain this

VRS750 Upgrade Kit.

Figure 16. Flashing Adapter

VRS Operation 3

General The VRS is a crossband repeater that repeats either UHF or VHF

portable transmissions though a VHF, UHF, or 800 MHz ASTRO

mobile. The repeater cannot be operated with a mobile radio operating

in the same band as the VRS unit. In multiple-VRS sites, the VRS uses

a priority algorithm to prevent other VRS units from repeating. In this

mode, only the highest priority VRS will serve multiple portable users.

This prevents interference problems associated with multiple VRS

units in proximity to one another.

Control Unit The VRS may be enabled/disabled from the ASTRO mobile radio’s

remote-mounted W4, W5, W7, or W9 control head (see Figure 17).

The VRS button may occupy any of the indicator button positions.

Field programming determines the exact position. The VRS requires an

ASTRO radio with a remote-mount control head.

When the VRS is turned on, the indicator illuminates and, after

transmitting the Single Tone burst, the words “VRS BOTH” (indicating

the In-Car Monitor mode) will be displayed momentarily. The

indicator remains on for as long as the VRS is on.

When the VRS unit is activated, it transmits Single Tone on the

portable frequency, and assumes the priority (active) repeater state.

The Single Tone frequency is ﬁxed at 847.5 Hz. For proper operation,

all VRS units to be used in the same system must be programmed with

Figure 17. Typical ASTRO Control Head with VRS

Dir MPL VRS Siren

XMIT BUSY

DIM

Wail Yelp

Hi-Lo

Mon

ExRad

Rcl Sql

Del

Pri

Non

Pri

Mode Vol Sel Home

123

456

789

*0#

MODE ROCKER HOME BUTTON

Astro

the same Single Tone frequency, as well as other VRS and ASTRO

mobile features.

Press the VRS button to disable the VRS option. When the system is

turned off and then back on from the control head, the VRS option

returns to the state it was in immediately before the control head was

turned off.

Vehicle Interface

Ports

Another method of enabling/disabling the VRS option is through the

use of a vehicle interface port (VIP). Using ASTRO CPS, the user can

select which VIP to use and whether the input control voltage is to be

high/ground or ground/high.

One use of VIP operation connects the VRS switch lead to a portable

radio vehicular control charger, such as the AVA, SVA, MVA, MTVA, or

ASTRO XTS. Remove the portable from its charger pocket to

automatically enable the VRS option. Replace the portable unit in its

charger to disable the VRS option. A toggle switch on the portable unit

charger allows the portable unit to be removed without enabling the

VRS option.

NOTE: This requires the VIP hardware interface kit,

0180757T61, which is not included with the VRS.

Turning the portable unit charger off, then on does not disable the VRS

option. The VIP setting controls the on/off state of the VRS option. If

the ﬁeld programmer chooses the VIP option, pressing the VRS button

on the control head will only cause the display to change momentarily

to the In Car Monitor Mode (“VRS BOTH”). It will not enable or

disable the VRS as previously described. It is still necessary, however,

to select in CPS an indicator button for the VRS if it is desired to have

the indicator light when the VRS is enabled.

VRS Access With the VRS on, press the portable radio’s PTT button to begin

transmissions. The VRS programming must include correct PL

frequencies to allow the portable unit to access the option. The VRS

option receives signals with the correct PL, then uses the mobile radio

to re-transmit the signals. The control head’s XMIT indicator lights

during the re-transmission.

The VRS re-transmits received mobile signals as explained in the

“Mobile Audio Repeat” paragraph on page 21. Note that the XMIT

indicator does not light when the VRS is transmitting to the portable.

To transmit directly to the other portable units, turn off the portable

transmit PL. This allows you to talk around the VRS without

transmitting on the mobile channels.

In-Car Monitor The “In-Car Monitor” (ICM) feature is for use in a two-man operation

where one user (user 1) is out of the vehicle while the other (user 2)

remains in the vehicle. This allows user 2 limited access to both mobile

and portable communications when the VRS is on, even when the

repeater is the priority unit. ICM operation is set to BOTH.

ICM Transmissions VRS BASE:

Press the mobile’s PTT to transmit on the frequency corresponding to

the mode shown on the control head’s display. If this mobile’s VRS is

the priority unit (in delay state zero), the VRS unit will then become

non-priority upon the mobile PTT. If you press the mobile’s PTT during

portable-to-base VRS activity, a talk-prohibit tone sounds and the mic

audio is disabled.

VRS BOTH:

Press the mobile’s PTT to transmit simultaneously on the frequency

corresponding to the mode shown on the control head’s display, and

the portable frequency. Use the ASTRO CPS to enable the VRS TX PL

generator option to transmit with the proper PL frequency. If you press

the mobile’s PTT during portable-to-base VRS activity, a momentary

talk-prohibit tone sounds and the microphone audio is disabled.

When using VRS BASE or VRS BOTH mode, all mobile transmissions

are on the mode that is shown on the control head’s display. If the VRS

is currently steering to another mode, that steered mode will be

displayed on the control head. Any mobile transmissions will be on

that new mode until the portable steers the VRS back or the mode

rocker switch is used to change modes. If the mode rocker switch is

used to change modes, the portable user will not be made aware of this

mode change. With Ack Tones are enabled, the portable user will hear

a “bad” tone if the mode is changed during the transmission.

VRS Reception The VRS option has no effect on mobile radio squelch control or

normal mobile radio reception. The VRS portable unit’s squelch

setting is not user adjustable. Portable audio is heard from the mobile

speaker of the priority VRS unit as shown in Table 5.

Repeated portable transmissions will always be heard from the mobile

speakers.

Portable transmissions without proper PL will only be heard from the

mobile speaker if the microphone is off HUB.

Mobile Audio

Repeat

The VRS transmits to the portable when audio unmutes the mobile

speaker. This allows the user to set the monitor button “on” to defeat

the coded squelch requirements of the mobile radio on a base-to-

portable transmission or “off” to prevent the VRS from repeating

base-to-portable (HUB will also disable this), unless the coded squelch

requirements of the mobile radio are met. Button presses (that is,

Volume, Mode, etc.) on the priority mobile unit will also be

transmitted by the VRS.

Table 5. Portable Audio Heard from Mobile Speaker

Mobile

Microphone

Portable Audio Heard

from Mobile Speaker

On HUB PL*

Off HUB CSQ

* = any valid repeater access PL

Notes

Operation of VRS

Options

The following sections describe the operation of CPS ﬁeld-

programmable options of the VRS. This includes information about

when to use an option and compatibility between options.

Base Repeater

For two-frequency simplex systems using a ﬁxed-site repeater, you can

enable the base repeater option. This adds 300 ms of delay to the

prioritization routine to account for the ﬁxed repeater attack time.

This allows non-priority mobiles to detect any priority mobile in the

system through the base repeater.

Mobile Detector

The Mobile Detector feature allows the user to operate VRS units with

two-frequency simplex dispatch systems without a base repeater. This

feature allows the automatic multi-unit priority resolution algorithm

to function in the above scenario. When this feature is activated by the

CPS, a non-priority VRS will send a message to the mobile to enable a

“Listen Around” feature when a proper portable PL is received.

“Listen Around” switches the mobile radio’s receive frequency to

match that of its transmit frequency of the steered mode. The non-

priority VRS will count down in priority if its corresponding mobile

does not detect the repeated transmission on the “Listen Around”

frequency. When the portable is dekeyed, the non-priority VRS will

send a second message to the mobile to disable “Listen Around” and

return to normal operation. This feature does not use any additional

user modes in the mobile.

NOTE:

The Mobile Detector feature only works on

conventional modes. Trunked modes will be

unaffected.

VRS Transmit PL

Generator

The transmit PL generator, when enabled, causes the VRS to transmit

(base-to-portable), with speciﬁc ﬁeld programmable PL tones. The

selected VRS transmit PL frequency cannot be the same as any of the

VRS receive PL frequencies that the portable uses to access the

vehicular repeater.

VRS Mode Steering

The VRS steering option gives the portable operator the ability to select

the current mobile radio mode via PL tones. The total number of

Mode-Steered modes can not exceed eight (including emergency,

message, and status). The operator may program as many as eight such

tones, along with corresponding mobile mode numbers, into the VRS.

The portable operator sets the channel or mode select switch to the

position corresponding to the desired mobile mode and keys up the

portable. The VRS unit decodes the PL tone and steers the mobile radio

to the desired mode. There are two types of steering supported:

Transmitter Steering/Receiver Latching, and Transmitter Steering/

Receiver Steering.

NOTE:

If mode steering is not selected during CPS

programming, the programmer will need to enter the

repeater access PL, which corresponds to a single access

PL with select mode steering.

Steering Types

•

<Transmitter Steering/Receiver Latching>—On portable-to-base

repeating, the mobile radio is steered to the proper mode as

determined by the received PL from the portable. When the

portable dekeys, the condition to repeat ceases, and the mobile

radio remains on this mode. Thus, all future base-to-portable

repeating is heard via the mobile mode last steered by the

portable.

The mobile control head will display the steered/latched mode. If,

sometime after this operation and while no repeat is occurring,

the ICM user keys the mobile with the microphone’s PTT button,

the mobile will now transmit on the latched mode that is

displayed on the control head. If, however, the in-car-monitor

(ICM) user changes the selected mode using the mobile’s mode

rocker switch before pressing the mic PTT, the mobile will now

transmit on the new selected mode.

NOTE:

For the above type of steering, the portable user will be

able to steer back to the selected user mode on the

control head by programming one PL destination for

Sel-Mode. However, the selected mode can be changed

by the rocker mode switch.

•

<Transmitter Steering/Receiver Steering>—On portable-to-base

repeating, the mobile radio is steered to the proper mode as

determined by the received PL from the portable. When the

portable dekeys, the condition to repeat ceases, and the mobile

radio remains on this mode for 6 seconds. During this 6 seconds,

the VRS waits for a repeatable base-to-portable transmission to be

received.

• If a base-to-portable transmission is not received, the mobile

will return to the last mode selected by the control head’s

rocker switch (current user-selected mode).

• If a base-to-portable transmission is received during the 6-

second timer, the timer will be reset back to 6 seconds and

start over at the end of the transmission.

• If the portable is keyed during the 6 seconds, the VRS will

handle the destination PL accordingly and reset the timer. If

the 6-second timer has not expired, no repeat is occurring,

and the ICM user keys the mobile with a microphone PTT, the

mobile will transmit on the steered mode and the 6-second

timer will start over at the end of the transmission.

Steering Destination

Types

There are ﬁve types of actions, or “steering destination types,” that the

VRS can be programmed to perform as a result of receiving a portable

transmission with the speciﬁed PL:

NOTE: Each receive PL can only be used once and can only be

programmed with one type of steering destination (for

example, a single PL cannot be programmed to both

change the mobile mode and send a message.)

Zone/Chan The VRS will command the ASTRO mobile to change to the mode

programmed by the CPS. Once the mobile has steered, it will follow

the conventions of the type of steering selected (for example,

Transmitter Steering/Receiver Latching).

Select Mode The VRS will command the ASTRO mobile to return to the last mode

selected by the rocker switch on the control head. If the portable user

has steered to another mode, and the selected mode is changed in the

car, the steering will be canceled until the VRS receives another mode

steering PL.

Emergency Alarm The VRS will initiate an Emergency Alarm through the ASTRO mobile,

if the mobile is programmed for this type of Emergency, in the same

manner as if the Emergency button on the control head were pressed.

The type of Emergency (trunked or conventional) depends on the

currently selected mobile mode, (trunked or conventional,

respectively).

The VRS will only generate an Emergency, not perform a portable-to-

base audio repeat, while the portable is transmitting on an

“Emergency request” channel. This feature is typically implemented

in the portable, using a one-touch button that has been programmed

for Emergency-revert to a channel with the proper PL.

Although the portable generates MDC tones, the VRS cannot decode

MDC. Instead it responds to the PL of the portable mode on which the

Emergency MDC tones are transmitted. All of this is transparent to the

user.

Message The VRS will command the ASTRO mobile to send out a CPS-

programmed message on the mode currently displayed on the control

head, in the same manner as if the request to send a message had been

generated using the control head. The VRS will send out only one

message per received portable signal. No mode steering will occur; the

currently steered/latched mode and the selected mobile mode will

remain as they were before the request to send a message was received.

If the message selected is valid, the VRS will transmit to the portable

the mobile tones indicating whether or not the valid message was

acknowledged. If the message selected is invalid, (either incorrectly

programmed in CPS or not a valid message for the currently displayed

mode), the VRS will send a low-pitched alarm tone to the portable.

To generate a message request, the portable user would:

•select the channel on the portable programmed for the message

request,

•momentarily press the PTT button,

•wait for the conﬁrmation tone, and

•return the channel selector to a voice channel.

The VRS will not perform a portable-to-base audio repeat while the

portable is transmitting on a “message request” channel.

NOTE: A message cannot be generated from the control head

while the VRS is activated.

Status The VRS will command the ASTRO mobile to send out a CPS-

programmed status on the mode currently displayed on the control

head, in the same manner as if the request to send status had been

generated using the control head. The VRS will send out only one

status per received portable signal. No mode steering will occur; the

currently steered/latched mode and the selected mobile mode will

remain as they were before the request to send a status was received.

If the status selected is valid, the VRS will transmit to the portable the

mobile tones indicating whether or not the valid status was

acknowledged. If the status selected is invalid, (either incorrectly

programmed in CPS or not a valid status for the currently displayed

mode), the VRS will send a low-pitched alarm tone to the portable.

To generate a status request, the portable user would:

•select the channel on the portable programmed for the status

request,

•momentarily press the PTT button,

•wait for the conﬁrmation tone, and

•return the channel selector to a voice channel.

The VRS will not perform a portable-to-base audio repeat while the

portable is transmitting on a “status request” channel.

NOTE: A status cannot be generated from the control head

while the VRS is activated.

Time-Out Timer The Time-out Timer (TOT) duration value sets the maximum allowable

time for a base-to-portable transmission. The VRS TOT may be set to

30, 60, 120 seconds, or disabled. When a unit times out, it counts up

to delay state one. This removes it as the priority unit.

VRS Single Tone When the VRS unit is enabled, it transmits an audible tone (Single

Tone) for 700 mS which is used by other VRS units for the automatic

prioritization routine. The Single Tone frequency is ﬁxed at 847.5 Hz.

VRS Mobile-TX

Acknowledgment

Tones

(Conventional Only)

When this option is enabled, the VRS transmits a 750 Hz feedback

tone after it has received a repeatable message on the portable

frequency. This signals the portable operator that the transmission was

received. If the repeated message was cut short due to the mobile TOT

being exceeded or the mobile channel being changed during the

repeat, a lower-pitched tone (304 Hz) sounds. If the portable user does

not hear a tone after completing a transmission, the portable is either

out of range of the repeater or there is no priority repeater in the area.

See “VRS Mobile Trunking Tones (Trunking Only)” on page 38 for a

description of trunking acknowledgment tones.

Flashing Display The Flashing Display feature causes the display on the control head to

alternate between the current mode and “VRS BOTH.” This feature is

used primarily when the VRS enable/disable button does not have an

indicator light or when VIP activation is used. This feature is normally

disabled in CPS. The length of time “VRS BOTH” is displayed every

6 seconds is determined by the “temporary message display timer”

value. This value (from 250 to 6250 ms [default = 1000 ms]) can

be programmed by the CPS. To conﬁgure, select Radio Conﬁguration

--> Display & Menu --> Advanced screen.

Repeater PPI The Repeater Portable Priority Interrupt (PPI), when enabled, causes a

base-to-portable transmission to be interrupted every 1 second in

trunked mode or 2 seconds in conventional mode so that the repeater

can search for a portable radio signal. (These times are programmable

and may be changed to 500 ms for trunked or 500 ms for conventional

modes). This interruption may be heard on the portable as a “clicking”

noise, but PPI is necessary to give the portable user priority over base-

to-portable transmissions, for the self-clearing function of the

automatic priority resolution feature, and to allow portable users in

trunked mode to break in during system hang time to prevent loss of

voice channel. This feature may be disabled through CPS.

Quick-Key This feature allows the portable user to determine the status of the

mobile trunking system. The feature is initiated by a short press of the

portable’s PTT that is long enough for the VRS to key the mobile and

access the trunking system, for less than 1 second in duration.

Notes

Detailed VRS Operation 5

Multi-VRS

Operation

The VRS is designed to accommodate multiple VRS units in the same

area. This is accomplished by each VRS maintaining a priority level or

delay state. During either portable-to-base or base-to-portable

transmissions, only the highest priority VRS will transmit or cause a

mobile PTT. The procedures for determining priority levels in multi-

VRS operation are discussed next.

Determining Priority

Levels

Whenever a VRS is enabled, it transmits a Single Tone burst (except if

portable activity is already present). The Single Tone burst frequency is

ﬁxed at 847.5 Hz. By default, when a VRS (VRS number 1) unit is

enabled, it becomes the priority unit with a delay state of zero. When

a second VRS unit (VRS number 2) is enabled in the area, it will

transmit a Single Tone burst as described. Upon receiving this signal,

VRS number 1 will know that another VRS is active and change its

priority to delay state one from delay state zero. If a third VRS were to

be enabled, VRS number 1 would change to delay state two and VRS

number 2 would change to delay state one. This process could

continue up until delay state seven is reached by VRS number 1,

meaning that eight VRS units have been enabled. After eight VRS units

are activated, they begin to stack up at delay state seven.

Portable-to-Base

Transmissions

If a portable begins to transmit, only the highest priority VRS will PTT

its corresponding mobile for transmission to the base. The other VRS

units, however, will be able to hear the portable transmission and

monitor for mobile channel activity. Channel activity is veriﬁed by a

squelch detect of the mobile. For non-priority units, the portable’s

audio will be sent to the mobile’s speaker (unmuted) from the VRS, not

from the mobile. This allows the mobile to monitor the correct

transmit frequency. If mode steering options are enabled then the

non-priority VRS units monitor their mobile’s channel activity on the

channel steered to by the portable’s PL and not on the mobile’s current

user selected channel.

The non-priority VRS units have a short delay in which they expect to

see the squelch detect message. Conventional system units will wait at

least 600 ms and trunking system units will wait at least 1500 ms. This

time period is referred to as one delay state. If in the appropriate time

frame a squelch detect message is not received, the priority VRS unit is

assumed to have been disabled and all other VRS units will increase

one priority level (for example, go from delay state 2 to delay state 1).

The VRS units will continue to count down until a squelch detect

message is received. In an extreme case, in which all but the lowest

priority VRS units are disabled, it is possible that the remaining VRS

unit which was the lowest priority (highest delay state) will have to

wait up to 7 delay states before transmitting. This can lead to a

transmission delay of up to 10.5 seconds for a trunking unit.

On conventional modes if the VRS <Base Repeater> option is enabled

via CPS, then an additional 300 ms time delay is added to the delay

states. This allows time for the mobile radios to transmit to and receive

from a repeater site.

Base-to-Portable

Transmissions

When a base transmits, only the priority VRS unit will transmit to the

portable. The other VRS units monitor activity on the portable

channel. Similar to the previous case, if portable activity is not

detected in the speciﬁed time frame after receiving mobile channel

activity, the non-priority VRS units will decrease one delay state, until

eventually one unit is in priority.

During base-to-portable transmissions, the delay state timing is

slightly different from that encountered during portable-to-base

transmissions. On conventional modes, the ﬁrst delay state is

1 second; on trunking modes, the ﬁrst delay state is 3.4 seconds. All

other delay states, on either trunking or conventional modes, are

400 mS. The worst-case delay for a unit to count into priority during a

base-to-portable transmission in a trunking system would, therefore,

be 5.8 seconds.

See the description of the Portable Priority Interrupt feature on

page 34 for information on the self-clearing feature used to re-

establish a single priority unit when multiple units are mistakenly in

priority. This condition may occur when a VRS unit is activated before

arriving on a scene, or in the unlikely case where several units stack up

at delay state seven and all higher priority units (those in delay states

one through six) leave the scene ﬁrst or are otherwise disabled.

Single Unit Operation Normal radio communication between a VRS-equipped vehicle (unit

A) and the base is via the mobile radio. When the operator decides to

leave the vehicle and use the VRS option, simply press the VRS button

or remove the portable from the charger if VIP operation is enabled to

turn on the vehicle’s repeater. The repeater transmits the Single Tone

burst on the associated portable radio frequency and sets the delay

state to zero. When the delay state is zero, this unit is the priority unit.

See Figure 18.

IMPORTANT NOTE: The VRS is designed to be a stationary

repeater system. The VRS unit should

always be disabled when the vehicle is

moving. FAILURE TO DO SO COULD

RESULT IN ERRATIC SYSTEM

OPERATION.

Two-Unit Operation The arrival of another VRS-equipped vehicle (unit B) into the coverage

area of unit A has no effect on unit A’s radio operation until unit B’s

VRS is enabled.

Unless there are portable transmissions occurring when unit B arrives,

unit B’s repeater transmits a Single Tone burst when its VRS option is

turned on. Unit B’s repeater priority counter initializes in delay state

zero, making unit B the priority unit. Unit A’s repeater/portable

receives unit B’s Single Tone transmission, which sets unit A’s repeater

to delay state one. See Figure 19. Transmissions from portable units in

the area now repeat through unit B. See Figure 20.

A portable radio’s transmissions (solid arrows in Figure 20) go to all

portable radios and VRSs in the area. Because unit B is the priority

repeater, it repeats the portable’s signal (open arrows in Figure 20) to

the base station and other mobile radios.

Unit A cannot countdown and repeat until the delay state one time

delay elapses. However, because unit A detects the mobile carrier of the

priority unit (open arrow in Figure 20) before the delay expires, the

priority counter does not begin the countdown. Unit A remains in

delay state one and does not repeat portable transmissions.

Figure 18. Single VRS Unit Operation

SINGLE TONE

BURST

UNIT A

“DELAY STATE ZERO”

PRIORITY UNIT

MAEPF-26079-O

Figure 19. Two-Unit VRS Operation

SINGLE TONE

BURST

UNIT A

“DELAY STATE ONE”

UNIT B

“DELAY STATE ZERO”

PRIORITY UNIT

MAEPF-26080-O

If unit B activates its VRS during portable transmissions, unit B does

NOT transmit Single Tone or enable in delay state zero. Unit B must

wait until it cannot detect the portable signal before transmitting

Singletone and taking over as the priority unit as described above.

Three-Unit Operation Should another VRS-equipped vehicle (unit C) come into the area, the

same sequence of events occurs as previously described in the “Two-

Unit Operation” section on page 31. Unit C’s arrival has no effect on

unit A’s or B’s radio operation until unit C’s VRS is enabled.

Unless there are portable transmissions occurring when unit C arrives,

unit C’s repeater transmits a Single Tone burst when its VRS option is

turned on. Unit C’s repeater priority counter initializes in delay state

zero, making unit C the priority unit. Unit A’s repeater/portable

receives unit C’s transmission which sets unit A’s repeater to delay state

two. Unit B’s repeater/portable receives unit C’s transmission which

sets unit B’s repeater to delay state one. Transmissions from portable

units in the area now repeat through unit C. All lower-priority units

will receive incoming portable transmissions, but will not key up their

mobiles because they are in a delay state. See Figure 21.

Figure 20. Two-Unit VRS Transmissions

UNIT A

“DELAY STATE ONE”

UNIT B

“DELAY STATE ZERO”

PRIORITY UNIT

MAEPF-26081-O

TRANSMITS TO

BASE STATION AND

MOBILE RADIOS

IN AREA

TRANSMITS TO

ALL REPEATERS AND

PORTABLE RADIOS

IN THE AREA

Departure of a VRS Unit The priority unit may change, depending upon the order in which

they leave, as vehicles leave the coverage area. For example, in Figure

21, when unit A turns the VRS option off, it has no effect on the

priority unit (unit C). Unit C continues to be the priority unit and

repeat transmissions.

When the priority unit (unit C) turns the VRS option off and

conditions for repeater transmissions occur, the unit in delay state one

(unit B in Figure 21) counts down to delay state zero and becomes the

priority unit. See Figure 22.

IMPORTANT NOTE: Non-priority units (those in delay state 1

or higher) will not count down into

priority if the portable user attempts to

send a status or message. If there is no

priority unit on scene, the request will be

ignored.

Figure 21. Three VRS Unit Transmission Sequence

UNIT B

“DELAY STATE ONE”

UNIT A

“DELAY STATE TWO”

UNIT C

“DELAY STATE ZERO”

PRIORITY UNIT

MAEPF-26082 -O

TRANSMITS TO

BASE STATION AND

MOBILE RADIOS

IN AREA

TRANSMITS TO

ALL REPEATERS AND

PORTABLE RADIOS

IN THE AREA

Rptr PPI—Portable

Priority Interrupt

NOTE: When using Rptr PPI, the receiver squelch setting of

the portable must be programmed for CSQ (carrier

squelch).

<Rptr PPI> is CPS programmable. The main function of <Rptr PPI> is

to allow the portable to interrupt base-to-portable transmissions.

During VRS to portable transmissions, an interrupt is sent to the

transmitter every 2 seconds on conventional modes and 1 second on

trunking modes. (These times are CPS programmable and may be

changed to 500 ms for trunked modes or 500 ms for conventional

modes.) There is also a random time factor added to the base interval

to prevent two VRS units from interrupting at the same time. This

interrupt allows the receiver to monitor portable or other VRS activity

for approximately 6 ms. See the timing chart in Figure 23.

Figure 22. Priority Unit Reassignment

MAEPF-26083-O

VRS REPEATER

TRANSMITTER

PORTABLE

TRANSMITTER

WITHOUT “PL”

PORTABLE

TRANSMITTER

WITH “PL”

MOBILE

TRANSMITTER

OFF

~ 2 sec ~ 6 msec

Figure 23. Portable Priority Interrupt

UNIT B

DELAY UNITS 1 0

MAEPF-26084-O

REPEATER WAITS ONE DELAY UNIT, COUNTS DOWN (1,0),

AND BECOMES PRIORITY UNIT.

THE PRIORITY STATE COUNTER IN OTHER REPEATERS

ALSO COUNTS DOWN BY ONE DELAY UNIT.

If a portable’s signal without PL tone is present when the repeater is

interrupted, the repeater transmitter remains inhibited for the

duration of the incoming signal. If the portable’s signal is modulated

with a PL signal, the priority unit repeats the message back to the base

station on top of the incoming signal.

In addition to giving the portable user priority over all incoming

signals, the Portable Priority Interrupt is used for three basic functions:

1. Self-Clearing—This is used when two or more priority VRS units

are on the same scene. On the ﬁrst base-to-portable transmission,

all priority VRS units will start to transmit. The ﬁrst one to have

an interrupt and detect carrier without proper portable PL

(meaning another VRS is transmitting) will count up to priority

state one, a condition which is referred to as self clearing. This

will continue to happen until only one priority VRS is on scene.

As an example, consider a case in which both units A and B are in

the priority state (delay state zero). When conditions for repeater

transmitting begin (i.e., the mobile receives a base signal), both

VRS units begin transmitting. Figure 24 shows the unit B

interrupt pulse occurring ﬁrst (due to the random time factor

added to the interrupt interval). When unit B is interrupted, it

detects another VRS unit transmitting and so unit B’s transmitter

remains inhibited. Unit B is set to delay state one and unit A

remains the priority unit since by the time unit A’s transmitter is

interrupted, unit B is no longer transmitting.

2. Repeater Hangtime—This allows the user to get back into a

conventional repeater or trunked system during hangtime. The

timing is faster for trunked systems due to the added feature of

talk permit tones being passed to the portable. If the portable keys

up with proper PL, then the VRS will key up the mobile. If proper

PL is not sent, the VRS will assume another VRS is in the area and

count itself out of priority.

Figure 24. Self-Clearing Timing Diagram

TWO UNITS IN PRIORITY STATE

MOBILE RADIOS A & B

RECEIVE MESSAGE

REPEATER A

TRANSMITS

REPEATER B

TRANSMITS

REPEATER A WAS NOT INTERRUPTED AND REMAINS

THE PRIORITY UNIT.

REPEATER B WAS INTERRUPTED BY ANOTHER REPEATER,

THEREFORE DELAY IS INCREMENTED BY ONE UNIT.

MAEPF-26085-O

INTERRUPT

PULSE DELAY STATE

DELAY STATE

0 0

0 1

NOTE: If Repeater PPI is disabled on an analog trunking

system with transmission trunking enabled, the Quick

Key feature becomes useless, since the user will be

unable to break-in during the repeater hangtime after

the channel is acquired. For this reason, repeater PPI

should always be ENABLED on an analog trunking

system.

3. Emergency—This allows the portable to have priority over

dispatch.

A drawback of portable priority interrupt is that during all base-

to-portable transmissions, the signal drops out for approximately

6-8 ms every: 2 seconds (conventional); or 1 second (trunking) if

the “slow” PPI option is chosen; or every 500 ms (either trunking

or conventional if the “fast” option is chosen in CPS).

The repeater PPI function may be used by the portable user in the

following manner:

During a base-to-portable transmission, the portable user wants to

interrupt and transmit to the base.

• Portable must transmit with the VRS correct access or steering

PL.

• When the VRS transmitter is interrupted, the VRS will detect

channel activity from the portable’s transmission and switch

to receive mode.

• The VRS will then transmit VRS TX Audio to the base.

• The VRS RX Audio is routed to the mobile speaker.

TX PL Self-Clearing As part of the multi-unit resolution prioritization algorithm, TX PL

Self-Clearing operates by adding the VRS transmit PL to the list of PLs

that the VRS monitors. If a VRS transmit PL is detected by a priority

VRS (delay state 0), it will indicate that another VRS is transmitting.

This feature will cause the original priority VRS to count up to delay

state 1, 2, or 3, and allow the transmitting VRS to remain in priority.

The delay state is randomized to prevent multiple units from stacking

up in delay state 1. In order to prevent ICM transmissions from other

VRS units affecting the priority states, the TX PL Self-Clearing feature

only works when detecting TX PL from a VRS that is repeating a Base-

To-Portable transmission. This function is not programmable, but has

no effect unless TX PL is used. This feature will not operate properly

unless all VRS units are programmed to transmit with the same

frequency PL, and the receiver squelch of the VRS750 units is set to

approximately -110 dBm.

NOTE: The VRS750 ships from the factory with a receiver

squelch setting of approximately -110 dBm. If the

VRS750 is not going to be programmed with a TX PL,

then the Global Tuner can be used to loosen the

receiver squelch for better radio performance.

ICM Functions The in-car-monitor (ICM) allows limited use of the mobile while the

VRS is enabled.

<ICM Base> Mode

In this mode pressing the mobile’s PTT will cause the mobile to

transmit on the mode shown on the control head display. The VRS will

not transmit the mic audio to the portable. During portable-to-base

repeat operations pressing the mobile’s PTT will result in the talk

prohibit tone sounding momentarily and the mic audio will not be

transmitted to the portable. When the mic is on HUB portable

transmissions will not be heard at the mobile’s speaker. When the mic

is off HUB only portable transmissions with the proper PL will unmute

the speaker. The following paragraphs detail how the VRS should

operate in <ICM Base> mode during different cases.

1. No VRS repeat operations in progress and the mobile user initiates

a PTT.

• The mobile will key up and transmit mic audio to the base.

• Mic-Hi line audio is not routed to the VRS transmitter.

2. During a portable-to-base repeat operation, the mobile user

initiates a mic PTT.

• A momentary talk prohibit tone will be heard and the mic

audio will be disabled.

3. During a base-to-portable repeat operation, the mobile user

initiates a mic PTT.

• The base-to-portable repeat operation will be interrupted.

• Mic-Hi line audio is not routed to the VRS transmitter.

• The mobile will key up and transmit mic audio to the base.

• When the mobile mic PTT is released, the base-to-portable

repeat will continue if the mobile is still receiving a base

transmission.

<ICM Both> Mode

In this mode pressing the mobile’s PTT will cause the mobile to

transmit on the mode shown on the control head display and cause

the VRS to transmit to the portable. If the portable is using a PL

frequency then the VRS can be programmed to transmit the proper PL.

During portable-to-base repeat operations pressing the mobile’s PTT

will result in the talk prohibit tone sounding momentarily and the mic

audio will not be transmitted to the portable. When the mic is off HUB

all portable transmissions are heard at the mobile’s speaker. When the

mic is on HUB only portable transmissions with the proper PL will

unmute the speaker. The following paragraphs detail how the VRS

should operate in <ICM Both> mode during different cases.

1. No VRS repeat operations in progress and the mobile user initiates

a PTT.

• Mic-Hi line audio is routed to the VRS and transmitted to the

portable.

• The mobile will key up and transmit mic audio to the base.

2. During a portable-to-base repeat operation, the mobile user

initiates a mic PTT.

• A momentary talk prohibit tone will be heard and the mic

audio will be disabled.

3. During a base-to-portable repeat operation, the mobile user

initiates a mic PTT.

• The base-to-portable repeat will be interrupted.

• Mic-Hi line audio is routed to the VRS and transmitted to the

portable.

• The mobile will key up and transmit mic audio to the base.

• When the mobile mic PTT is released, the base-to-portable

repeat will continue if the mobile is still receiving a base

transmission.

NOTE: If the VRS is in a non-priority state all portable

transmissions will be heard on the mobile’s speaker.

The above descriptions apply to a VRS unit in a priority

state.

Acknowledgment

Tones

VRS Mobile-TX

Acknowledgment Tones

(Conventional Only)

When this option is enabled, the VRS transmits a feedback tone after

it has received a repeatable message on the portable frequency. This

signals the portable operator that the transmission was received. If the

repeated message was cut short due to the mobile TOT being exceeded

or the mobile channel being changed during the repeat, a lower-

pitched tone sounds. If the portable user does not hear a tone after

completing a transmission, the portable is either out of range of the

repeater or there is no priority repeater in the area.

VRS Mobile Trunking

Tones (Trunking Only)

For trunked modes, the VRS regenerates the standard trunking access

tones and transmits them to the portable. These tones, which are

essentially the same as those heard at the mobile’s speaker, are accessed

with the “quick-key” feature. For this operation, the portable user

brieﬂy (less than one second) presses the PTT button, and then listens

for one of the following tones:

•The “talk permit” tone (three short beeps) indicates to the

portable user that the trunking system has granted a voice

channel to the mobile and that keying the portable during the

trunking system hangtime will result in acquiring this channel.

•The “system busy” tone (a telephone-like busy tone) indicates

that, at the time the portable user dekeyed, the trunking system

had no voice channel available. If the user does not key the

portable again after receiving a system busy signal, a “talk permit”

tone will be transmitted to the portable as soon as a voice channel

is available.

•The “talk prohibit” tone (a long, low tone) indicates to the

portable user that the mobile cannot access the trunking system.

For portable transmissions lasting longer than one second (as opposed

to a “quick-key,” which must be less than one second), the VRS will

respond with one of the following tones. If the “Trunking Access

Tones” option is disabled in the “VRS Options” screen of the ASTRO

mobile CPS, the “trunking access good tone” and the “trunking access

bad tone” will not be generated.

•The “trunking access good” tone (a single beep) indicates that a

portable-to-base transmission has occurred and the mobile

remained keyed for the entire transmission.

•The “trunking access bad” tone (a single, low-pitched tone)

indicates that all or part of the portable-to-base transmission was

not repeated or was interrupted during the portable’s valid PL

transmission. This would handle, for example, the case of the

mobile’s TOT expiring or the case where a “system busy” is

received ﬁrst, and then a “talk permit,” so that only part of the

transmission could be repeated. This tone can also indicate that

the VRS has counted down in priority from a delay state of 2 or

higher.

•The “talk prohibit” tone (a long, low tone) indicates to the

portable user that the mobile cannot access the trunking system.

•The “system busy” tone (a telephone-like busy tone) indicates

that, at the time the portable user dekeyed, the trunking system

had no voice channel available. If the user does not key the

portable again after receiving a system busy signal, a “talk permit”

tone will be transmitted to the portable as soon as a voice channel

is available.

Message/Status

Acknowledgment Tones

There are four different tones that the portable user can receive at the

end of a message/status attempt:

•Message/Status Acknowledged Good Tone—This tone is generated

by the mobile when the message/status has been acknowledged

by the base station. The VRS repeats the tone to the portable.

•Message/Status Not Acknowledged Bad Tone—This tone is

generated by the mobile when the message/status has been

transmitted but was not acknowledged by the base station. The

VRS repeats the tone to the portable.

•Message/Status Not Supported Conventional Bad Tone—This

tone is generated by the VRS when it receives a message from the

mobile indicating that the message/status number selected is not

a valid message or status while the mobile is on a conventional

channel.

•Message/Status Not Supported Trunking Bad Tone—This tone is

generated by the VRS when it receives a message from the mobile

indicating that the message/status number selected is not a valid

message or status while the mobile is on a trunking channel.

Non-Priority VRS

Rules

A priority VRS is placed into non-priority mode when one of the

following occurs:

1. It receives a Single Tone burst at the ﬁxed frequency of 847.5 Hz.

2. During a base-to-portable repeat, it receives a VRS/portable

frequency RF signal without proper PL during the PPI.

When a VRS goes from priority to non-priority, the internal delay state

changes from 0 to 1. Upon subsequent reception of Single Tone bursts

(that is, other VRS units activate in the same coverage area), the non-

priority unit will increase delay states up to a maximum of 7. While in

non-priority, the following occur:

Portable-to-Base Non-Priority Operation

1. Upon reception of a portable frequency RF signal with proper PL,

the VRS will determine if the mobile of another VRS system is

repeating the signal.

2. For the prioritization routine to function, all of the mobiles with

a VRS must be able to receive other mobile transmissions, either

directly (TX=RX), or on a trunked system (TX≠RX), or through a

base repeater (TX≠RX) in conventional modes with the <Base

Repeater> feature enabled. For conventional non-repeater

dispatch systems (TX≠RX), the Mobile Detector must be enabled

for the prioritization routine to function properly.

3. The VRS will determine if the mobile of another VRS system is

repeating the portable signal by steering the mobile to the mode

corresponding to the received PL. If, within one delay state

(at least 600 ms for conventional, at least 900 ms for <Base

Repeater>, and at least 1.5 seconds for trunking), the mobile in

the non-priority VRS system does not receive the repeated signal,

it will countdown from the current delay state.

4. Upon reaching delay state 0, the non-priority VRS will become

the priority VRS and start repeating. The maximum delay for a

non-priority VRS to countdown into priority is 4.2 seconds for

conventional, 6.3 seconds for <Base Repeater>, and 10.5 seconds

for trunking.

5. If the VRS does detect another VRS system repeating within the

delay state, it will stop the countdown process and stay non-

priority.

Base-to-Portable Non-Priority Operation

1. Upon reception of a repeatable base signal, the non-priority VRS

will monitor for a VRS-to-portable transmission from another VRS

system (that is, a signal on the portable frequency without proper

VRS access PL).

2. If, within one delay state, the VRS does not receive the repeated

signal, it will countdown from the current delay state.

3. Upon reaching delay state 0, the non-priority VRS will become

the priority VRS and start repeating. The maximum delay for a

non-priority VRS to countdown into priority is 3.4 seconds for

conventional and 5.8 seconds for trunking.

4. If the VRS does detect another VRS system repeating within the

delay state, it will stop the countdown process and stay non-

priority.

5. If the VRS detects a portable frequency signal with proper PL

while receiving a repeatable base signal, it will handle it according

to the portable-to-base case.

ICM Non-Priority Operation

The ICM feature will continue to operate as described in the “ICM

Functions” section except for the following:

1. While receiving a portable transmission with correct repeat

qualiﬁers, the unit will not repeat as long as the unit is non-

priority.

2. During a portable-to-base transmission with correct PL, the non-

priority VRS will steer the mobile to the mode programmed for

that PL frequency. This allows the mobile to monitor for priority

repeater trafﬁc.

Emergency

Emergency Feature

Summary

An emergency alarm is initiated when the VRS receives a portable

transmission which contains the Emergency Alarm PL, as

programmed in the mode-steering screen of CPS. Upon decoding the

Emergency Alarm PL, the VRS sends an “enter emergency” bus

message to the mobile radio. The mobile radio will respond as if the

Emer button had been pressed on the control head, and will proceed

with the Emergency operation which is programmed by the CPS.

In addition, an “emergency acknowledgment” tone is transmitted by

the priority VRS as part of the automatic multi-unit priority resolution

algorithm. The “Emergency ACK” tone generated by the VRS is a 1250

Hz tone lasting 500 ms in duration. Once in Emergency Alarm, the

VRS ignores subsequent portable transmissions with the Emergency

Alarm PL until the mobile exits Emergency. (The “Emergency ACK”

tone, however, will always be generated in response to each portable

transmission with the proper Emergency Alarm PL).

Emergency Call and VRS are mutually exclusive. Even if the mobile is

programmed for alarm and call, when the alarm case is exited, the

mobile will not transition into Emergency Call while the VRS is

activated. Likewise, if the mobile is in Emergency Call, the VRS cannot

be activated.

Emergency Feature

Operation

Whether the mobile is programmed for silent or non-silent alarm is

transparent to the VRS. However, the Emergency Alarm sequence

changes slightly between the silent and non-silent case. The main

differences are listed below:

1. The alarm exit sequence

For non-silent alarm, any of the following will cause the mobile

to exit Emergency:

• Extended keypress of the Emer button on the mobile’s

control head.

• Mobile microphone PTT or a portable-to-base repeat.

• Mobile exhausts its retries without receiving an “Emergency

ACK” from the base.

• The mobile receives an “Emergency ACK” from the base.

For silent Alarm, any of the following will cause the mobile to exit

Emergency:

• Extended keypress of the Emer button on the mobile’s

control head.

• Mobile mic PTT or a portable-to-base repeat.

2. The mobile will not unmute due to base trafﬁc during silent

alarm, and therefore the priority VRS will not attempt a base-to-

portable repeat. If there are other, non priority VRS units in the

area, they will perform the base-to-portable repeat without

counting into priority.

IMPORTANT NOTE: While in Emergency, attempts to send a

message or status from the portable will

be ignored and WILL NOT cause the

mobile to exit Emergency.

Hardware Detailed

Theory of Operation 6

The VRS750 contains two main modules: a transceiver and an

interface board.

Transceiver This module is an Analog synthesized FM device that contains the

receiver, transmitter, and controller section. A ﬂex cable connects the

transceiver’s two accessory connectors to a single connector, J30, on

the interface board. The RF jack is connected to W101 on the interface

board via the 50 ohm coaxial cable.

The VRS750 software is embedded in the digital portion of the

transceiver’s controller which consists of a microcontroller and

associated EEPROM, RAM, and ROM memories.

NOTE: This transceiver cannot be used as a stand-alone

portable.

Interface Board This board provide power regulation, bus translation circuitry, audio

routing circuitry, Single Tone Encoder and Decoder circuitry,

programming circuitry, and mode conﬁguration.

Power Regulation The VRS750 is powered by the mobile’s Radio_SWB+ (13.8 VDC) at the

connector P102-22. L101 and C137 are used to ﬁlter alternator whine

from this signal before providing it as SWB+ to the interface board. The

VRS750 utilizes the mobile’s analog (P102-2, 10, 11, 21) and digital

grounds (P102-18).

U111 regulates the SWB+ down to +5 VDC. This voltage provides

power for several switching transistors and voltage dividers on the

VRS750 board. U118 i a micropower low dropout regulator used to

provide +9.6 V for all of the analog audio circuitry. R162 and R164

form a divider network from this 9.6 V to produce the 4.8 V (VAG)

used to bias the audio circuits. Finally, U129 is a three-terminal

regulator used to provide the regulated 7.5V to the transceiver via

Q113 in the reset circuit. SW7.5 V is provided to the transceiver at pad

P31.

Bus Translation

Circuitry

The devices U100-2, U103, Q100, Q101, Q102, Q103, and Q104 are

used to separate messages from the bi-directional SB9600 serial bus

Bus+, Bus-, and Busy into and from the single direction RXD, TXD,

BUSY OUT, and BUSY IN signals at the transceiver.

The transceiver’s microcontroller can be reset by an external device by

generating an active high reset pulse at pin P102-19, RADIO_RESET.

This will cause Q109 to drive J30-5 low.

Audio Routing

Circuitry

There are four paths which are used to route audio between the mobile

and the transceiver: AUX_RX_AUD, TX_AUDIO, MOB_MIC_HI and

FIL_AUD. During the three types of communications of the VRS

(Portable-to-Base, Base-to-Portable, and In-Car-Monitor), the routing

is as follows:

Portable-to-Base On channel RF signals are received by the transceiver through the

connector, W101. The transceiver provides demodulated audio to the

interface board at EXT_SPKR+ (J30-17) and URX_SND (J30-11).

The receive audio at EXT_SPKR+ is volume controlled. The transceiver

monitors the mobile’s volume setting and then updates its volume

accordingly. The audio is ﬁltered by a 2-pole low pass ﬁlter, U107-1,

which has a corner frequency of 3.2 kHz. T1, a 600-ohm to 600-ohm

audio transformer, is used to isolate any ground noise such as

alternator whine from the receive audio before being routed to the

mobile at AUX_RX_AUD (P102-7). During portable-to-base

transmissions the mobile routes this audio to its speaker.

The receive audio at URX_SND is at a ﬁxed level of 260 mVrms. It is

attenuated through op amp circuit U104-3 to a level of 60 mVrms

which can be adjusted via potentiometer R146. T2, a 600-ohm to

600-ohm audio transformer, is used to isolate this audio from any

ground noise such as alternator whine before being routed to the

mobile at TX_AUDIO, P102-8. During portable-to-base transmissions,

the mobile routes TX_AUDIO to its transmitter.

Base to Portable The MIC_FIL_SEL (J30-15) and TONES-MOBILE_AUD (J30-8) control

signals are generated by the microcontroller and are used to control

audio routing circuits, U101-1 and U101-3, for “Base to portable”

activities.

FIL_AUD (P102-6)—This audio path contains receive audio from the

mobile during Base-to-portable transmissions. The receive audio

passes through op amp circuit U104-1 and can be level adjusted via

potentiometer R150. When a base-to-portable repeat occurs,

TONES_MOBILE_AUD is in a low state and MIC_FIL_SEL is in a high

state so that FIL_AUD is routed to the transmitter input (EXT_MIC,

J30-19).

In-Car-Monitor The MIC_FIL_SEL (J30-15) and TONES-MOBILE_AUD (J30-8) control

signals are generated by the microcontroller and are used to control

audio routing circuits, U101-1 and U101-3, for “In-Car-Monitor”

activities.

MOBILE_MIC_HI (P102-12)—This audio path contains microphone

audio from the mobile during In-Car-Monitor (ICM) transmissions.

The microphone audio passes through op amp circuit U104-4 and can

be level adjusted via potentiometer R148. During an ICM

transmission, both MIC_FIL_SEL line and TONES-MOBILE_AUD line

are set to a Low state to conﬁgure both mux U101-3 and mux U101-1

to route the mobile mic audio to the transmitter input (EXT_MIC,

J30-19).

Single Tone Encoder The VRS750 Single Tone Encoder (U100-1, U124-3, U124-2, and U124-

4) is used to produce a tone which is transmitted by the transceiver

when the VRS750 is activated. Other VRS750 repeaters that are on in

the operating area receive this Single Tone transmission. The other

repeaters will then increment their priority counters by one while the

transmitting VRS750 goes to delay state zero and becomes the priority

repeater.

When the VRS750 is in transmit mode for Single Tone, the

microcontroller generates a square wave at a set frequency of 847.5Hz

to the SNGL_TX_DATA (J30-6) pin. The control signal, TONES-

MOBILE_AUD, is set to a High state to allow the Single Tone signal to

be routed to the input of the Single Tone Filter. The Single Tone Filter

is a band pass ﬁlter that allows frequencies between 300Hz and 1.7

kHz. U124-4, R126 and R127 are for gain adjustment. The resulting

sine wave is then sent to the transceiver to be transmitted on EXT_MIC

(J30-19).

This circuit is also used when the transceiver generates various VRS750

acknowledgment tones.

Single Tone Decoder The VRS750 Single Tone Decoder (U100-1, U124-3, U124-2, and

U124-1) detects other Single Tone transmissions, then increments the

priority counter.

VRS_TX*_RX from the microprocessor is set to a High state when the

VRS750 is in the Single Tone Decode mode (receive mode). When this

signal is high, U101-2 allows receive audio (URX_SND, J30-11) to pass

to buffer U100-1. The output of the buffer drives the low-pass ﬁlter

that is also used in the encoder circuit. U124-1 and the associated

diodes, D100 and D101, produce a square wave which is divided down

to 3.3V by R172 and R173. This signal, SNGL_DET(J30-12), is then

sampled by the microprocessor to determine if Single Tone is present.

Boot Control

Circuitry

The ﬁrmware for the VRS750 is stored in the transceiver’s Flash

memory. This ﬁrmware can be programmed using the VRS750

Upgrade Tool (refer to “VRS750 Upgrade Kit,” Chapter 2). Prior to

programming the ﬁrmware, the microprocessor must be placed into

bootstrap mode.

To place the microprocessor into bootstrap mode, it must be reset

while the BOOT-CNTRL (J30-28) pin is grounded. This pin is grounded

when the programming cable is connected and the ﬂash adapter

switch is turned to the “A” position.

When the BOOT-CNTRL line is grounded, Q100 which controls U102

and U105, is opened and 9.6V passes through U102-2 to the base of

Q112. Q113 opens and disconnects SW7.5 V from 7.5 V. At this point

there is no supply voltage to the transceiver.

Meanwhile, 9.6V is also applied to the base of Q112 thus charging up

capacitor C182. After approximately 1.5 seconds, C182 is charged to a

voltage that saturates Q111, causing Q112 to open and Q113 to turn

On. SW7.5V is connected back to 7.5 V again. At this point the

microprocessor on the transceiver has been reset and is now in

bootstrap mode.

To prevent mobile bus messages from corrupting the ﬂash

programming of the transceiver, the control signals to U102-3, U105-2

and U105-3 are applied with 9.6V to disconnect the Bus+ (P102-5),

Bus- (P102-14) and Busy (P102-23)lines from the mobile when the

BOOT-CNTRL line is grounded.

Program Sense The PROG_SENSE signal(J30-10) is monitored by the VRS to detect

when the programming cable is connected at connector P101. This

line will be pulled to ground when the programming cable is

connected or will be 3.3VDC when the programming cable is not

connected.

The programming cable is used when adjusting the VRS using the

Tuning Tool (refer to “VRS750 Global Tuner,” Chapter 2) or when

updating the VRS ﬁrmware using the VRS750 Upgrade Kit (refer to

“VRS750 Upgrade Kit,” Chapter 2).

To prevent mobile bus messages from corrupting the codeplug

programming and/or tuning of the transceiver, the control signal to

U105-1 pin 10 is driven to ground.

Mode Conﬁguration There are various operating modes of the VRS750. The mode is selected

at power-up based on the settings of dipswitch S1 pins 1, 2 and 3. Pin

4 is unused. Table 6 shows the supported modes:

Normal mode is the default and standard conﬁguration for the

VRS750. The Test Mode conﬁguration is used when the transceiver

requires tuning. The VRS750 can be put into Test Mode by placing S1

Pins 1, 2, and 3 to the OFF position before system power-up. When this

setting is detected by the VRS µP at power up, the following will occur:

•VRS TEST is displayed momentarily on the control head.

•Portable Priority Interrupt is disabled.

•VRS TOT disabled.

•TX PL disabled.

Table 6. VRS750 Supported Modes

Operating Mode S1 Pin 1 S1 Pin 2 S1 Pin 3

Normal On On On

Test Mode Off Off Off

ATE Test Mode On Off Off

Professional CPS Mode Off On On

To exit Test Mode, power down the VRS750 and reconﬁgure S1 for

Normal mode.

The ATE Test Mode conﬁguration is used by Motorola for testing

purposes. Professional CPS Mode is available for when the user

requires the transmit and receive frequencies to differ. Operation

during this mode is not advised and if required please contact your

Motorola sales representative for details about this mode. All other

combinations of the dipswitch are not supported and will default to

the Normal mode.

Notes

Maintenance and

Troubleshooting 7

The following paragraphs contain information to help you maintain

and troubleshoot the VRS. A list of recommended test equipment is

found in the “Recommended Test Equipment, Service Aids, and Tools”

section of the ASTRO Spectra Basic Service Manual, Motorola

publication 68P81076C20.

Additional information may be found in the Troubleshooting Chart in

this manual.

Troubleshooting

Procedures

VRS Activation 1. Turn on the mobile radio control head. The radio should go

through self-check and then display the home mode of the

mobile radio.

2. Possible error messages on power up are:

• ERR 12/10—No VRS detected. See “Common Power-Up

Problems” section on page 50 for possible solutions.

• ERR 12/81—Flash EPROM failure. If re-ﬂashing the unit does

not ﬁx this problem the transceiver should be replaced.

• ERR 12/82—Codeplug checksum error. After verifying that

both mobile and VRS have the correct software version,

checking the mobile-to-VRS connection, and moving the

cable away from any interference, reprogram the VRS750’s

codeplug using the correct version of the CPS. If the codeplug

cannot be corrected using CPS then the unit will need to have

a new default codeplug written to the unit. Contact Customer

Service for the default codeplug that corresponds to your

model (see Table 7).

Table 7. Default Codeplugs

Band VRS750

Model No.

VRS750

Back Cover Kit No.

Internal

Codeplug No.

VHF P2080 PMLD4196 PMUD1479

UHF R1 P2081 PMLE4242 PMUE1433

UHF R2 P2082 PMLE4243 PMUE1476

• ERR 12/84—CONFIG register corruption. The unit should be

ﬂashed with the correct version software. If this fails to correct

the problem, the transceiver should be replaced.

• ERR 12/88—HC11 RAM failure. Replace the Transceiver.

• VRS 001—VRS Synthesizer out of lock error. See “Common

Power-Up Problems” section on page 50 for possible

solutions. If the solutions in the “Common Power-Up

Problems” section do not ﬁx the error then the transceiver

should be replaced.

• PROG VRS—The VRS750 is in programming conﬁguration.

This is only an error if the programming cable is not plugged

into the front connector of the VRS750. Reset the ASTRO

Mobile radio and if the problem is not corrected check P101

Pin 9 and the PROG_SENSE line for any shorts to ground.

3. Enable the VRS unit by pressing the VRS button on the mobile

control head.

•“VRS BOTH” must be displayed momentarily on the control

head and the indicator must light.

• Verify a short single tone burst is transmitted upon activation

at approximately 3 KHz deviation for a channel spacing of

25 kHz.

NOTE: Because of the short burst, it may be necessary to verify

the deviation on the modulation scope instead of the

usual deviation meter. Activation may be repeated by

pressing the VRS button once to disable the unit and

again to reactivate it.

Common Power-Up

Problems

1. “ERR 12/10” message is displayed on power-up.

• The VRS mobile interface cable is disconnected or bad.

• Verify the VRS Firmware is correct. Immediately after power

up press the HOME button on the control head ﬁve (5) times

and verify the correct ﬁrmware version is displayed.

• Check all regulators for proper voltages. The 9.6-volt regulator

is accessible at TP116.

CAUTION: Do not probe U118 pin1 when the unit is powered. U118

will shut down without any recovery if pins 1 and 2 are

accidentally shorted to each other.

2. “VRS BOTH” message does not display momentarily on control

head when VRS is enabled.

• VRS is receiving a VRS frequency signal. (VRS will not display

“VRS BOTH” or transmit Single Tone if there is RF activity on

the VRS frequency.)

• Check the VRS750’s squelch setting.

3. “VRS 001” message is displayed on power-up.

• VRS Frequency Band in the VRS Personality of the ASTRO

Mobile codeplug is incorrect.

• Check the VRS750’s codeplug for incorrect programming.

• Re-ﬂash the VRS750 with new ﬁrmware using the VRS750

Upgrade Kit.

Common Operational

Problems

1. Common Portable-to-Base Repeat Problems.

• Check portable for correct transmit frequency and PL.

• Check portable for low battery.

• Check VRS internal RF cable for loose connection.

2. Common Base-to-Portable Repeat Problems

• Check portable for correct receive frequency and PL.

• Check mobile for correct frequency.

• Check that portable is set for the bandwidth corresponding to

the VRS.

• Check VRS internal RF cable for loose connection.

Disassembly &

Reassembly

Procedures

The disassembly/reassembly procedure covers all VRS750 models.

CAUTION: Refer to the “Safe Handling of CMOS Integrated-Circuit

Devices” section at the beginning of this manual prior to

disassembling the radio.

Disassembly to Interface

Board Level

Remove Front Housing 1. Disconnect the Programming Connector Cover by squeezing the

top and bottom of the connector together, disengaging the

bottom snap then the top and pulling straight out.

2. Remove the gasket within the recessed area for the 18-pin

programming connector.

3. Insert a small ﬂat-blade screwdriver or like instrument in the side

groove at the interface between the remote front housing and the

main chassis (see Figure 25). Press while pulling the housing away

from the chassis until the snap releases. Repeat the operation on

the opposite side.

4. Pull front housing off the chassis.

5. Remove white retainer (p/n 4205395X01) from the header (or

front housing).

6. Remove the 18 pin connector (2805347X01) from the front of the

chassis.

7. Remove the front cover gasket.

Remove the Top Cover 1. Insert a wide ﬂat-blade screwdriver or like instrument in the

recess area on the side of the main chassis near the RF connector

end (see Figure 26).

2. Pry the cover off the chassis by pushing the handle of the

screwdriver in and toward the chassis. This will disengage the

snap between the cover and chassis.

3. Repeat Step 1 and Step 2 for the opposite side of the radio.

Remove the Interface

Board

1. Remove the antenna connector retaining clip by inserting a small

ﬂat-blade screwdriver or like instrument between the clip and the

top of the cavity wall as shown in Figure 27. Gently pry upwards.

2. Remove the board screws with a T-10 Torx Driver.

3. Carefully remove the interface board by rotating it out of the

chassis. Slowly lift the board on the front edge while pushing up

on the board through the accessory connector opening. Pull the

board forward out of the chassis (see Figure 28).

Figure 25. Removing the Front Housing

Depress Snap Here

See Detail "A"

Front Housing

Main Chassis

Detail "A"

Figure 26. Removing the Top Cover

Disengage Snap

here and on

other side

See Detail A

Disengage

Snap here

Detail “A”

4. Retain the heat conductive insulator from under the regulator.

Transceiver Disassembly 1. Detach the RF cable assembly from the right-angle SMB connector

on the interface board.

2. Turn over the interface board. Remove the ﬂex connector retainer,

4285168D01.

3. Gently lift the clasps of the 20-pin and 40-pin ﬂex connectors.

Remove the 20-pin and 40-pin ends of the ﬂex cable from the

transceiver leaving the 30-pin end attached to the interface board.

4. Loosen the screws for the two retainers holding the transceiver to

the interface board. Slide one of the retainers away from the edge

of the transceiver to free it.

5. Remove the transceiver from within the two retainers.

6. Detach the RF cable from the RF adapter plug. Unscrew the RF

adapter plug from the transceiver.

Figure 27. Removing the Antenna Connector Retaining Clip

Figure 28. Removing the Interface Board

Front

Pry Clip Off Here

2) Pull board

forward out

of chassis

1) Push up on board

through accessory

connector opening

VRS750 Reassembly NOTE: Replace all gaskets at each servicing to ensure proper

sealing of unit.

Transceiver Reassembly 1. Screw the RF adapter plug into the transceiver. Tighten until the

stop on the adapter is fully seated in the RF jack.

2. Connect the RF coax cable to the RF adapter.

3. Place the transceiver in between the two retainers, sliding one

sideways if needed.

4. Adjust the retainers so that they align with the groove between

the transceiver board and its chassis. Tighten the four screws of

the retainers. If needed, adjust the screws so that the transceiver

lays ﬂat against the interface board.

5. Connect the 20-pin and 40-pin ends of the ﬂex cable to the ﬂex

connector. Gently close the clasps on the connectors.

6. Reattach the ﬂex connector retainer, 4285168D01.

7. Turn over the board.

8. Connect the RF coax cable to the right-angle SMB connector on

the interface board.

Interface Board

Reassembly

1. Install a new gasket around the 25 pin connector and Antenna

connector located on the board.

2. Check that the foam seal is correctly positioned on the 25 pin

connector on the bottom side of the board.

3. Add the conductive insulator to the back of the regulator.

4. Insert the main board carefully at an appropriate angle

(approximately 30°) into the chassis. Start, but do not torque

down, screw number 6 per Figure 29 and Table 8.

5. Install the antenna retaining clip.

6. Attach the nylon washer to the regulator at screw hole number 4

as indicated in Figure 29.

7. Install the screws with 6-8 in-lbs of torque using a T-10 Torx driver

per sequence shown in Figure 29 and Table 8.

8. Place a new cover gasket around the chassis ensuring that it is

placed under the locking tabs and ledge at the front of the chassis

(see Figure 30). To ensure that the gasket remains seated along the

groove, twist the gasket between ﬁngers down and toward the

chassis on both sides of the chassis.

9. If chassis is being replaced, add the plastic insert and seal into the

area at the back of the main chassis opposite the antenna

connector.

10. Install the top cover by engaging the hooks on front of the chassis

and rotating the cover back. Ensure that the side snaps on the

cover are engaged.

11. Install the front cover gasket over the front of the chassis

ensuring that the rectangular hole in the chassis aligns with the

rectangular hole in the gasket. Press the gasket ﬂush against the

chassis to ensure proper sealing.

Assembly of Front Cover

to Main Chassis

Refer to exploded views on page 88 for parts referenced in this

procedure.

1. Install the 18 pin connector into the female connector (mounted

on the PC board) through the hole in the front of the chassis.

2. Place white remote retainer (4205395X01) over the 18 pin

connector.

Figure 29. VRS750 Torque Sequence

Table 8. VRS750 Torque Sequence

Step No. Screw P/N Bit Torque Notes

1 6 0310907A20 Torx T10 — Start Only

2 — — — Place Antenna Conn.

3 4-8 0310907A20 Torx T10 8 in-lb Number 6 Inclusive

4 1-3 0310907A20 Torx T10 8 in-lb

Figure 30. Cover Gasket Location

Cover gasket

Twist o-ring

3. Install the remote front housing over the 18 position connector

onto the front of the chassis ensuring that both snaps are

engaged.

4. Place the gasket within the recessed area for the 18-pin

programming connector.

5. Connect the Programming Connector Cover to the main chassis.

VRS Transceiver Field repair of the transceiver is not recommended. Contact your local

service representative for a replacement transceiver. If replacement of

the transceiver is necessary, refer to the Disassembly & Reassembly

section and the Tuning Procedure section.

VRS Tuning and

Alignment

The VRS is tuned at the factory and should not need to be realigned.

Refer to the proper manuals for programming and alignment for the

associated portable radio and mobile unit before attempting to

troubleshoot the VRS unit. If proper tuning of the associated radio fails

to correct a problem, the following procedure may be used to align the

VRS.

Setup

ASTRO Spectra Station

Cable Setup

Ensure that the ASTRO Spectra B+ cable is disconnected from the

power supply and the control head is off (WARNING: Never turn B+

power off with the control head still on.) Connect the VRS DB-25

cable (HKN6153A) into the accessory connector of the mobile.

Connect the other end of the VRS cable to the VRS. Set the test station

power supply to 13.8 Vdc and current limiter to 12 amps. Connect the

mobile’s B+ cable to the power supply (see Figure 31).

Tuning Procedure

Interface Board

Tuning Procedure

1. Place the VRS in the test mode:

a. Turn off the mobile radio control head.

b. Place the VRS into Test Mode by setting dipswitch S1 pins 1,

2, 3, and 4 to OFF.

c. Turn on the mobile control head and re-enable the VRS.

d. While in Test Mode, the VRS will not have portable priority

interrupt and will not transmit PL with VRS-to-portable

transmissions.

e. Figure 32 illustrates the relative placement of the tuning

potentiometers.

2. Adjust the VRS Deviation Level:

a. Set the Mobile Communications Analyzer RF output to

-50 dBm, with a standard test modulation (1 kHz tone, 3 kHz

deviation).

Figure 31. General Cabling Diagram

Figure 32. Tuning Potentiometers

Mobile

Communication

Analyzer DC Supply

ASTRO Spectra Mobile

W7 Control Head

Speaker

Mobile

Microphone

HKN6153A

VRS750

VRS

Communication

Analyzer

R150

R148 R146

b. Set the Mobile Communications Analyzer frequency to the

current mobile mode.

c. Switch on the Mobile Communications Analyzer RF.

d. Adjust R150 on the VRS board until 3.0 kHz deviation is

obtained on the VRS Communications Analyzer.

e. Switch off the Mobile Communications Analyzer RF.

3. Adjust the Mobile Microphone Deviation Level:

a. Inject a 1 kHz tone at 80 mVrms into the mobile microphone.

b. Key the mobile microphone. (Refer to the ASTRO Spectra

Mobile service manual for specialized equipment.)

c. Adjust the signal level of the 1 kHz tone until 3.0 kHz

deviation is obtained on the Mobile Communications

Analyzer.

d. Adjust R148 on the VRS board until 3.0 kHz deviation is

obtained on the VRS Communications Analyzer.

e. Dekey the mobile microphone.

4. Adjust the Mobile Deviation Level:

NOTE: Set the VRS Communications Analyzer RF output to

-50 dBm with a standard test modulation (1 kHz tone,

3 kHz deviation) and any receive PL for which the VRS

is programmed (750 Hz deviation). If the receive PL for

“select mode” is not used, the Mobile

Communications Analyzer frequency may need to be

adjusted.

a. Set the Mobile Communications Analyzer frequency to the

current mobile mode.

b. Switch on the VRS Communications Analyzer RF.

c. Adjust R146 on the VRS board until 3.00 kHz deviation is

obtained on the Mobile Communications Analyzer.

d. Switch off the VRS Communications Analyzer RF.

5. Check the VRS RF Sensitivity:

a. Set the VRS Communications Analyzer RF output to -115 dBm

with a standard test modulation (1 kHz tone, 3 kHz deviation)

and any receive PL for which the VRS is programmed (750 Hz

deviation).

NOTE: If the receive PL for “select mode” is not used, the

Mobile Communications Analyzer frequency may

need to be adjusted.

b. Switch on the VRS Communications Analyzer RF. The unit

should not retransmit this signal to the Mobile

Communications Analyzer.

c. Slowly increase the input signal. The unit should begin

repeating to the Mobile Communications Analyzer at no

more than -104 dBm.

d. Switch off the VRS Communications Analyzer RF.

6. Take the VRS out of test mode:

a. Turn off mobile control head and set the dipswitch S1 pins 1,

2, 3, and 4 to ON.

b. Turn on the mobile control head and re-enable the VRS.

7. Tuning is complete.

Transceiver Board Tuning

Procedure

The transceiver board can be tuned using the Global Tuner when the

VRS750 is in ATE Test Mode. Connect the VRS750 to the test box

(RLN6394A) instead of the ASTRO Spectra mobile using the VRS750

ATE Cable (3080384N02) as shown in Figure 33. Before applying

power, set dipswitch S1 pin 1 to ON and pins 2, 3, and 4 to OFF. This

conﬁgures the VRS750 for ATE Test Mode. Make the appropriate

connections to the VRS750 test box for power and audio. Once this is

complete the VRS750 can be tested and tuned using the Global Tuner.

Front End Filter Tuning NOTE: Tuning is normally not required for VHF radios. It

should only be performed if a radio has poor

sensitivity. VHF radios are only tuned at one softpot

frequency (F3: The values for the untuned frequencies

are determined by adding the offset, calculated by

subtracting the default softpot value for frequency F3

from the tuned softpot value for frequency F3. The

default softpot values are listed in Table 9.)

Figure 33. ATE Test Mode Conﬁguration

VRS750

TEST BOX

(RLN5394A)

VRS750

PROG. CABLE

RX AUDIO

AND EXT MIC

CONNECTORS

SRIB

DC SUPPLY

VRS750 ATE CABLE

(3080384N02)

CONNECT TO THE PCs

COM PORT

Under Rx Align, select the Front End Filter option.

1. Inject a -70 dBm RF Signal with Frequency F1 (for UHF)/F3 (for

VHF) modulated with 1 kHz tone at 60% rated deviation (see

Table 10) into the VRS750. A 1 kHz tone must be detected at the

RX Audio connector on the test box to verify that the radio is

receiving.

2. Measure the RSSI voltage with a DC voltmeter capable of 1 mV

resolution at test point 111 on the VRS750. It is recommended

that an RCA ﬁlter (1.5 K-47 uF) be added at the input of the

voltmeter to reduce RSSI noise.

3. Increment the softpot value by adjusting the slider, keying in the

softpot values in the edit box (press ENTER to conﬁrm selection)

or using the spin control until the maximum RSSI voltage has

been achieved.

4. For UHF and VHF radios:

a. UHF radios: Choose the next frequency and repeat steps 1 to

3 until all seven tuning points are done.

b. VHF radios: Calculate the softpot offset by subtracting the

default softpot value for F3 from the tuned softpot value for

F3. Add the calculated offset to all default values and enter the

results in the edit boxes for the appropriate softpot

frequencies.

5. Press Program to commit the softpot values into the codeplug.

Table 9. Default Softpot Values for VHF and UHF

Frequency Point

Softpot Value (Decimal)

VHF UHF

F1 36 38

F2 57 48

F3 84 79

F4 124 110

F5 166 135

F6 195 161

F7 225 186

Rated Volume Tuning Under Rx Align, select Rated Volume.

NOTE: The received audio output is taken from the positive

terminal of C189.

1. Inject a -47 dBm RF Signal modulated with 1 kHz tone at the 60%

rated deviation (see Table 10) into the VRS750.

2. Adjust the softpot value by using the slider, keying in the edit box

(press ENTER to conﬁrm selection/send a softpot value), or via

the spin controls. Repeat this until a 1.58 Vrms ±200 mVrms

signal can be obtained at the positive terminal of C189.

3. Press Program to commit the softpot value into the codeplug.

Reference Oscillator

Warp

NOTE: Perform this operation prior to all other transmit

tuning operations in order to minimize heating and

because of the impact of warp on signaling operations.

1. Under Tx Align menu, select Reference Oscillator Warp.

2. There is only 1 frequency point shown which is always the last

non 0 transmit frequency point, which will normally be F7.

3. Click on the slider thumb. Press PTT Toggle to key up the radio at

the corresponding frequency point.

4. Monitor the transmit frequency.

5. Adjust the slider, spin or edit control (press ENTER to conﬁrm

selection/send a softpot value) until the frequency is as close as

possible to the indicated transmit frequency (refer to Table 11).

6. Dekey the radio by pressing PTT Toggle.

Table 10. VRS750 Deviation Levels

Channel Spacing

(kHz)

Rated System

Deviation (kHz)

Signal Generator

Deviation (kHz)

12.5 2.5 1.5

20 4.0 2.4

20 5.0 3.0

25 5.0 3.0

30 5.0 3.0

Table 11. Frequency Error Speciﬁcations

RF Band Target (Hz)

VHF (136-174) ±200

UHF Band 1 (403-470) ±200

UHF Band 2 (450-527) ±200

7. Program the warp value into the radio by pressing the Program

button.

8. Exit the Reference Oscillator Warp function.

VCO Attenuation NOTE: The Transmit Deviation Limit softpot sets the

maximum deviation of the carrier. Tuning is

performed for 12.5 kHz, 20 kHz, and 25 kHz channel

spacing. Tuning for 25 kHz channel must be done ﬁrst

for all frequency points. Tuning for 12.5 kHz and 20

kHz channel spacing determines only the offset to the

previously tuned deviation for 25 kHz tuning channel

spacing. For (12.5, 20 kHz) channel spacing, only the

last non 0 transmit frequency point (normally F7) will

be used for tuning.

VCO Attn. 25 kHz 1. Under the Tx Align menu, select VCO Attn. 25 kHz.

2. Begin with the lowest frequency. Select the thumb of the slider at

the lowest frequency point and then press the PTT Toggle button

to key up the radio at the corresponding frequency point. The

spin control can also be toggled via its up/down arrow buttons.

The softpot value can also be typed into the edit control (press

ENTER to conﬁrm selection/send a softpot value).

3. Inject a 1 kHz at 80 mVrms signal into the external mic connector

on the test box (VRS750 input).

4. Note down the deviation obtained.

5. Adjust the slider, adjust the spin control or key in softpot values

(press ENTER to conﬁrm) for the frequency point until the

deviation is within range as deﬁned in Table 12.

6. Dekey radio (press the PTT Toggle button). Choose the next

frequency, key up and repeat steps 3 to 6 until all seven tuning

points are done.

7. Program the softpot value by pressing the Program button.

8. Exit the VCO Attn. 25 kHz function.

VCO Attn. 20 kHz NOTE: Tuning of Modulation Balance Attn. and VCO Attn. for

25 kHz channel spacing must be done ﬁrst.

1. Under the Tx Align menu, select VCO Attn. 20 kHz.

2. Press PTT Toggle to key up the radio at the last non 0 transmit

frequency point (normally F7).

3. Inject a 1 kHz at 80 mVrms signal into the external mic connector

on the test box (VRS750 input).

4. Note down the deviation obtained.

5. Adjust the slider, adjust the spin control or key in softpot values

(press ENTER to conﬁrm) for the frequency point until the

deviation is within range as deﬁned in Table 12.

6. Press PTT Toggle to dekey the radio.

7. Program the softpot value by pressing the Program button.

8. Exit the VCO Attn. 20 kHz function.

VCO Attn. 12.5 kHz NOTE: Tuning of VCO Attn. for 25 kHz channel spacing must

be done ﬁrst.

1. Under the Tx Align menu, select VCO Attn. 12.5 kHz.

2. Press PTT Toggle to key up the radio at the last non 0 transmit

frequency point (normally F7).

3. Inject a 1 kHz at 80 mVrms signal into the external mic connector

on the test box (VRS750 input).

4. Note down the deviation obtained.

5. Adjust the slider, adjust the spin control or key in softpot values

(press ENTER to conﬁrm) for the frequency point until the

deviation is within range as deﬁned in Table 12.

6. Press PTT Toggle to dekey the radio.

7. Program the softpot value by pressing the Program button.

8. Exit the VCO Attn. 12.5 kHz function.

PA Bias Tuning UHF/VHF

VRS750s (Procedure 1)

IMPORTANT NOTE: Tuning must be performed for both High

and Low power for UHF and VHF radios.

Take note that Procedure 1 IS NOT TO BE

PERFORMED for UHF low power level

tuning. Please refer to Procedure 2.

1. Ensure that the radio’s antenna output is terminated to a 50 Ohm

load. This is to prevent self destruction of the PA.

2. Under Tx Align, select PA Bias, select High Power.

3. Measure/read the dc current drawn from radio (speciﬁcations will

vary from radio to radio). Call this X. This value should typically

range from 70-100 mA or 0.07-0.1 A.

4. Press Toggle Voltage to enable the PA control voltage edit box/

spin control.

5. Increase the Voltage softpot value and measure/read from current

meter. Call the new value Y.

6. Increase Y until Y-X is within the range given for PA current in

Table 13.

7. Press Toggle Voltage again to disable the PA control voltage edit

box/spin control.

Table 12. Deviation Speciﬁcations for VRS750 UHF/VHF Radios

Band Channel Spacing (kHz) Deviation (kHz)

UHF/VHF 12.5 2.20-2.30

UHF/VHF 20 3.40-3.60

UHF/VHF 25 4.40-4.60

8. Press Toggle Bias 1 in order to enable the PA Bias softpot.

9. Increase the softpot value to obtain Z until Z-Y is within the

range for Bias Current as indicated in Table 13.

10. Press Toggle Bias 1 again to disable the PA Bias softpot.

11. Program the Bias softpot into the radio’s codeplug via pressing

Program.

12. Exit the PA Bias High Power function.

13. Under Tx Align, select PA Bias, Low Power. (If UHF, skip to step

15 and continue to Procedure 2.)

14. Repeat steps 3-11.

15. Exit the PA Bias Low Power function.

PA Bias Tuning for UHF

Low Power VRS750s

(Procedure 2)

NOTE: Failure in the instructions below means that you

cannot get a reading which is within the range of the

current window as speciﬁed in Table 14 for each

individual step.

Ensure that the radio’s antenna output is terminated to a 50 Ohm

load. This is to prevent self destruction of the PA.

STEP 1 1. Under Tx Align, select PA Bias, select Low Power.

2. Measure/read the dc current drawn from radio (speciﬁcations will

vary from radio to radio). Call this X. This value should typically

range from 70-100 mA or 0.07-0.1 A.

3. Press Toggle Voltage to enable the PA control voltage edit box/

spin control.

4. Increase the Voltage softpot value and measure/read from current

meter. Call the new value Y.

5. Increase Y until Y-X is within the range given for PA current in

Table 14 (STEP 1) below.

****** If a failure occurs, go to STEP 2 otherwise proceed

6. Press Toggle Voltage again to disable the PA control voltage edit

box/spin control.

7. Press Toggle Bias in order to enable the PA Bias softpot.

8. Increase the softpot value to obtain Z until Z-Y is within the

range for Bias Current as indicated in Table 14 (STEP 1).

Table 13. PA Bias High Power Speciﬁcations UHF/VHF VRS750s

RF Band PA Current (mA) Bias Current (mA)

VHF 90-110 90-110

UHF Band 1 30-45 600-700

UHF Band 2 30-55 400-480

****** If a failure occurs, go to STEP 3 otherwise proceed

9. Press Toggle Bias again to disable the PA Bias softpot.

10. Program the Bias softpot into the radio’s codeplug via pressing

Program.

11. Exit the PA Bias Low Power function.

STEP 2 1. Increase Y until Y-X is within the range given for PA current in

Table 14 (STEP 2).

2. Press Toggle Voltage again to disable the PA control voltage edit

box/spin control.

3. Press Toggle Bias in order to enable the PA Bias softpot.

4. Increase the softpot value to obtain Z until Z-Y is within the

range for Bias Current as indicated in Table 14 (STEP 2).

****** If a failure occurs, go to STEP 3 otherwise proceed

5. Press Toggle Bias again to disable the PA Bias softpot.

6. Program the Bias softpot into the radio’s codeplug via pressing

Program.

7. Exit the PA Bias Low Power function.

STEP 3 1. Press Toggle Bias twice to reset the softpot value.

2. Press Toggle Bias again to disable the PA Bias softpot.

3. Measure/read the dc current drawn from radio (speciﬁcations will

vary from radio to radio). Call this X. This value should typically

range from 70-100 mA or 0.07-0.1 A.

4. Press Toggle Voltage to enable the PA control voltage edit box/

spin control.

5. Increase the Voltage softpot value and measure/read from current

meter. Call the new value Y.

6. Increase Y until Y-X is within the range given for PA current in

Table 14 (STEP 3).

7. Press Toggle Voltage again to disable the PA control voltage edit

box/spin control.

8. Press Toggle Bias in order to enable the PA Bias softpot.

9. Increase the softpot value to obtain Z until Z-Y is within the

range for Bias Current as indicated in Table 14 (STEP 3).

Table 14. PA Bias Low Power Speciﬁcation for VRS750s (UHF Only)

Step PA Current (mA) Bias Current (mA)

STEP 1 20-30 630-750

STEP 2 30-45 750-900

STEP 3 40-55 600-750

10. Press Toggle Bias again to disable the PA Bias softpot.

11. Program the Bias softpot into the radio’s codeplug via pressing

Program.

12. Exit the PA Bias Low Power function.

NOTE: After tuning a transceiver, go back and tune the

interface board (details in this chapter) and then adjust

the output power and squelch settings (see Chapter 2).

Troubleshooting Charts 8

Introduction to this

Section

This section contains detailed troubleshooting ﬂowcharts. These

charts should be used as a guide in determining problem areas. They

are not a substitute for knowledge of circuit operation and astute

troubleshooting techniques. It is advisable to refer to the related circuit

descriptions in the “Hardware Detailed Theory of Operation,”

Chapter 6.

List of

Troubleshooting

Charts

Chart

Number Description

Page

Number

1 VRS Enable Failure 68

2 Error 12/10 69

3 Error 12/81 69

4 Error 12/82, Codeplug Checksum Error* 69

5 Error 12/84, Conﬁguration Register Corruption* 69

6 Error 12/88, HC11 RAM Failure 69

7 VRS 001, VRS Synthesizer Lock Failure 70

8 Single Tone Encode Failure 71

9 Single Tone Failure 72

10 Base-to-Portable Repeat Failure 73

11 Portable-to-Base Repeat Failure 74

12 VRS ICM Audio Failure 75

13 Serial Bus Failure 76

14 Portable Audio at Local Speaker Issue 77

15 Programming/Tuning Failure 78

*Older VRS-EP versions may show a 12/82 Error ﬂashing every 5 seconds for

Codeplug Checksum Error, and a 12/82 Error at power-up only for

Conﬁguration Register Corruption.

Chart 1—VRS Enable Feature

VRS ENABLE FAILURE

Ye s

START

Is VRS

button enabled in

the mobile

codeplug?

Is mobile

codeplug programmed

for VRS VIP?

Is the mobile

codeplug programmed

for VRS VIP?

Program mobile codeplug for

VRS button operation.

"VRS BOTH"

message displayed on

button press?

VRS is now enabled.

Reset system and start over.

If CSQ is being detected the

VRS will not enable.

the mobile

codeplug programmed for

VRS VIP active

state?

Program mobile codeplug for

VRS VIP.

Is switch in

correct VIP?

Program mobile codeplug for

proper VRS VIP active state.

Check VRS VIP switch

input.

Move switch or reprogram

mobile codeplug.

Chart 2—Error 12/10

Ye s

START

Is the VRS

mobile interface cable

connected?

Are the

regulated voltages

present?

Reconnect the

cable.

Is the

VRS750 firmware

correct?

Troubleshoot the

regulator circuit.

Check the

transceiver board.

Flash the VRS750

with the correct

firmware.

ERROR 12/10

Chart 3—Error

12/81

START

Reprogram the

Flash Memory.

ERROR 12/81

Chart4—Error

12/82, Codeplug

Checksum Error

START

Reprogram the

VRS750 Codeplug.

ERROR 12/82

Chart 5—Error 12/84, Conﬁguration

Ye s

START

Reflash the VRS750

with the correct

version firmware.

Reset the system.

Is the

12/84 error still

displayed?

Replace the

transceiver board.

Problem is

corrected.

ERROR 12/84

Chart 6—Error 12/88, HC11

RAM Failure

Replace

the transceiver.

Error

12/88

ERROR 12/88

Chart 7—VRS 001, VRS Synthesizer Lock Failure

VRS 001 FAILURE

Ye s

Does the

Freq. Band field in

ASTRO CPS match the freq. Band

of the VRS750 attached to

the mobile?

Replace the

transceiver board.

Correct the freq. band

field for the VRS750 in

the ASTRO mobile

codeplug.

START

Chart 8—Single Tone Encode Failure

Ye s

Is there

continuity between

J30-19 and J20-7 on the

flex cable?

Check and/or

replace C104.

Replace the

transceiver.

Replace the flex

cable.

Replace the

transceiver.

Replace the flex

cable.

START

SINGLE TONE ENCODE FAILURE

Ye s

3.3VDC square wave

at R114 during Single

Tone burst?

80mVpp sinewave

at TP104?

there continuity

between J30-6 and

J40-21 on the flex

cable?

Is the

sinewave present at

TP101?

Check and/or

replace U100,

U124.

the sinewave

present at the negative

terminal of C104?

Verify that pin 10 of U101 is

0VDC during the Single

Toneburst. Check U101 and

Q106.

Chart 9—Single Tone Failure

Ye s

START

Verify that the VRS750

dip switches are set to

normal operation.

Does

TP105 pulse ~5VDC

when the volume button

is pressed?

Does J30-21

pulse to ~0VDC when

the volume button is

pressed?

Check the mobile

to VRS cable.

Is there

continuity between

J30-21 and J20-9 on the

flex cable?

Check and/or

replace U103 and

Q103.

Check and/or

replace the

transceiver.

Replace the flex

cable.

Verify that J30-20

(boot control) is

~3.3VDC.

SINGLE TONE FAILURE

Chart 10—Base-to-Portable Repeat Failure

Ye s No

Ye s

Ye s No

Ye s

START

Verify that the VRS750

dip switches are set to

normal operation.

Activate the

VRS750.

Is "VRS

BOTH" displayed

briefly?

Provide an

on-channel RF

signal to the mobile.

The VRS750 is not

enabled and audio

will not be heard.

audio present at

C135?

Is audio

present @ U101 pin

Chekc mobile and

its connection to

the VRS.

Is audio

present @ U101 pin

Check U104.

Adjust R150 if

necessary.

audio present @

TP101?

Verify that the

local mic is not

pressed.

audio present

@ J30-19?

Is pin 10

of U101 HIGH

-9.6VDC?

there continuity

between J30-19 and

J20-7 of the flex

cable?

Replace the

transceiver. Replace U101.

there continuity

between J30-8 and

J40-23 on the flex

cable?

Is pin

9 of U101 low

(0VDC)?

Repair/replace

U101.

there continuity

between J30-15 and

J40-23 on the flex

cable?

Replace the

transceiver.

Replace the flex

cable.

Check and/or

replace Q106.

Replace the flex

cable.

Repair/replace

Q114.

Replace the flex

cable.

BASE TO PORT. AUDIO ISSUES

Chart 11—Portable-to-Base Repeat Failure

PORTABLE-TO-BASE AUDIO ISSUE

Ye s

NoNo

Verify dip switches

are set to normal

operation.

Is the

1kHz tone present @

J30-11?

Is the

1kHz tone present at

TP102?

Replace

transceiver.

audio present @

TP125?

Check U104 and

replace if

necessary.

Is mobile

transmit deviation

3kHz?

Check solder connextions

for C132, C133, and T2.

Replace if necessary.

Complete.

Adjust R146 to obtain

3kHz deviation from

mobile.

Activate the

VRS750.

Is "VRS

BOTH" displayed

briefly?

Provide an on channel RF

signal with an Access or

Mode Steering PL to the

VRS750.

The VRS750 is not

enabled and will

not repeat.

audio present @

TP128?

there continuity

between J30-11 and

J40-28 on the flex

cable?

Replace the

transceiver.

Replace the flex

cable.

Chart 12—VRS ICM Audio Failure

IN-CAR-MONITOR AUDIO ISSUES

Ye s

Ye s No

Verify that the VRS750

dip switches are set

for normal operation.

PTT the mobile's local

mic and talk into it.

audio present at

C134?

Refer to the

Base-to-Portable

troubleshooting chart.

Is audio

present @ pin 3 of

U101.?

Check the mobile

and its mic

connections.

Check U104 and

adjust R148 if

necessary.

Check and/or

replace U101.

Check and/or

replace Q114.

Activate the

VRS750.

Is "VRS

BOTH" displayed

briefly?

During

Base-to-Portable

communications, is audio heard

@ the portable?

Check C185 and C166 to

make sure they have not

been shorted to ground.

Verify that the

MOBILE_MIC_HI line in

the mobile to VRS is ok.

Is audio

present @ pin 1 of

U101?

Is audio

present @ pin 15 or

U101?

Is pin 9 of

U101 a logic HIGH -

9.6VDC.?

Is pin 10

of U101 a logic HIGH -

9.6VDC.?

Check and/or

replace U101.

Check and/or

replace Q106.

audio present @

J30-19?

there continuity

between J30-19 and

J20-7 of the flex

cable?

Check and/or

replace C104.

Replace the

transceiver.

Replace the flex

cable.

Chart 13—Serial Bus Failure

Ye s

START

Verify that the VRS750

dip switches are set to

normal operation.

Does

TP105 pulse ~5VDC

when the volume button

is pressed?

Does J30-21

pulse to ~0VDC when

the volume button is

pressed?

Check the mobile

to VRS cable.

Is there

continuity between

J30-21 and J20-9 on the

flex cable?

Check and/or

replace U103 and

Q103.

Check and/or

replace the

transceiver.

Replace the flex

cable.

Verify that J30-20

(boot control) is

~3.3VDC.

SERIAL BUS FAILURE

PORTABLE AUDIO AT LOCAL SPEAKER ISSUE

Ye s

audio present @

EXT_SPKR+ J30-17?

audio present at

C183?

there continuity

between J30-17 and

J20-4 on the flex

cable?

Verify that the VRS750

dip switch settings are

set to normal operation.

audio present at

TP108?

Repair and/or

replace U107.

Adjust mobile volume

on controlhead to level

Check solder

connections for C183,

C103, and T1.

Activate the

VRS750.

Is "VRS

BOTH" displayed

briefly?

Provide an on-channel RF

signal with the proper

Access or Mode Steering

PL to the VRS750.

The VRS750 is not

enabled and audio

will not be heard.

START

Replace the

transceiver.

Replace the flex

cable.

Chart 14—Portable Audio at Local Speaker Issue

Chart 15—Programming/Tuning Failure

ATE Test Normal

Ye s

Ye s No

Ye s

Start

the VRS750 in ATE

Test or Normal Mode?

Is 13.8V

supplied to the test

box?

Is the mobile radio

powered on?

Is the SRIB

connected to the computer

and powered on?

Plug the 25 pin connector

into the SRIB and the 18

pin connector into the

VRS750.

Is the

Flashing Adapter being

used?

Connect the SRIB to the

serial port of the

computer using a null

modem cable and make

sure it is turned on.

Verify that P101-7 is

connected to J30-24.

Is the SRIB

connected to the computer

and powered on?

Disconnect the

programming cable from

the VRS750.

Did

the mobile radio

reset?

Plug the

programming cable

back in to the

VRS750 and try

again.

Reset the mobile

radio.

Plug the programming

cable back in to the

VRS750.

Is "PROG

VRS" displayed on the mobile

control head?

Tr y

programming

again.

Connect the SRIB to the

serial port of the

computer using a null

modem cable and make

sure it is turned on.

Verify that the

mobile is

powered on. If

not, power the

mobile on and

start over.

the VRS750

programming cable

securely plugged into the

VRS750 and an

SRIB?

Supply 13.8V to the

VRS750 test box.

"PROG VRS"

displayed on the mobile

control head?

Power on the

mobile radio.

Is the

switch in the B

position?

Remove the flashing

adapter and cycle

power to the VRS750.

Place the switch in the B

position and cycle power to

the VRS750. The A position

is for flashing only.

Cycle power to the VRS750

and try again. If the problem

persists, try a different

programming cable.

PROGRAMMING AND

TUNING ISSUES

Chart 15—Programming/Tuning Failure (Cont.)

Ye s

the switch in the B

position?

Is there a 18 pin

extension in the connector,

2805347X01, on the front of the

VRS750?

Remove the Flashing

Adapter and reset the

mobile. The Flashing

adapter could be bad.

Place the switch in the B

position and reset the

mobile.

Is the

cathode of

VR121 grounded when

plugged into the

SRIB?

Replace the

header block.

Verify that P101-7 is

connected to J30-24.

Replace the

programming cable.

Is the

Flashing Adapter

being used?

PROGRAMMING AND

TUNING ISSUES (CONT.)

Notes

Diagrams and Parts Lists 9

Introduction to this

Section

This section contains schematics, a component layout diagram, an

exploded view, and electrical and exploded view parts lists.

List of Diagrams

and Parts Lists Description

Page

Number

Printed Circuit Board Electrical Parts List 83

Printed Circuit Board Component Location Diagram 84-85

Printed Circuit Board Schematic Diagram 86-87

Exploded View and Exploded View Parts List 88

VRS-to-Mobile Cable 89

VRS-to-Siren Cable 89

VRS750 Programming Cable 90

VRS750 Programming Cable Schematic Diagram 90

VRS750 Flashing Adapter Schematic Diagram 90

Notes

VRS750

epeater

ystem

Printed Circuit Board Electrical Parts List

(PLN7780A)

Notes:

1. For optimum performance, order replacement diodes, transistors,

and circuit modules by Motorola part number only.

2. When ordering crystals, specify carrier frequency, crystal frequency,

crystal type number, and Motorola part number.

3. Part value notations:

p=10

-12

µ=10

-6

k=10

n=10

-9

m=10

-3

M=10

ITEM MOTOROLA

PART NUMBER DESCRIPTION

CAPACITOR, Fixed; pF:

unless

otherwise stated

C100 2113740F59 220

C101 2113740F39 33

C102 2113740F59 220

C103, 104 2311049A08 Polar, 1 µF

C105 2113741B69 0.1 µF

C107 2113740F59 220

C108 2113741B69 0.1 µF

C109 2113740F59 220

C111, 112 2113740F59 220

C113 2113741F33 2200

C114 thru 116 2113741A45 .01 µF

C117 2113741A49 .015 µF

C118 2113740A79 1000

C119 2113743B21 0.22 µF

C120 2113741B69 0.1 µF

C121 2113740B49 100

C122 thru 131 2113740F59 220

C132, 133 2311049A08 Polar, 1 µF

C134, 135 2113743E20 0.1 µF

C136 2113740F59 220

C137 2380090M40 Polar, 2200 µF

C138, 139 2113740F59 220

C140 2113743E20 0.1 µF

C141 2113741A45 .01 µF

C142 2113740F59 220

C143 2113741B69 0.1 µF

C145 2113740A79 1000

C146, 147 2113740F59 220

C148 2311049A08 Polar, 1 µF

C149 2311049A19 Polar, 10 µF

C150 2113740F59 220

C151 2311049A19 Polar, 10 µF

C152 2113740F59 220

C153 2311049A19 Polar, 10 µF

C154 2113740F59 220

C155 2311049A19 Polar, 10 µF

C156 2380090M25 Polar, 100 µF

C157 thru 161 2113740F59 220

C162 2380090M25 Polar, 100 µF

C164 thru 167 2113740F59 220

C168 2113743E20 0.1 µF

C170 2113740F59 220

C171 2113743E20 0.1 µF

C172, 173 2113740F59 220

C175 2113740F59 220

C179 2113740F59 220

C180 2113740A79 1000

C182 2311049A19 Polar, 10 µF

C183 2311049A08 Polar, 1 µF

C184 2113740F59 220

C185 2113743A13 0.047 µF

C188 2113740F59 220

C189 2311049A08 Polar, 1 µF

C190 2113741F21 680

C191 2113740F59 220

C194 2113740A79 1000

C195 2113740F59 220

C196 2113743E20 0.1 µF

C197 2113740F59 220

C198 2113743E20 0.1 µF

C199 2113740F59 220

C200 2113743E20 0.1 µF

C201 thru 208 2113740F59 220

DIODE:

See Note 1

D100, 101 4813825A08 MBD701

D102 4813832C77 Transient supressor, 24 V

FUSE:

F100 6580542Z01 3 A

JACK:

J30 0985173D01 Connector, 30 pin ﬂex

COIL, RF:

L101 2505462S03 Inductor, 1000 µH

PLUG:

P101 0905904V02 Connector, J

P102 2805429W03 Connector, P

TRANSISTOR:

See Note 1

Q100, 101 4880141L02 NPN

Q102 4813824A17 PNP

Q103 4880141L02 NPN

Q104 4813824A17 PNP

Q106 4880141L02 NPN

Q109 thru 112 4880141L02 NPN

Q113 4813821A21 nchan_tmosfet_gsd

Q114, 115 4880141L02 NPN

RESISTOR: Ohms ±5%; 1/8 W

unless otherwise stated

R101 0662057A93 68 k

R102 0662057A73 10 k

R104, 105 0662057A25 100

R106 0662057A65 4.7 k

R107 0662057A69 6.8 k

R108 0662057A93 68 k

R109 0662057A97 100 k

R110 0662057A77 15 k

R111 0662057A83 27 k

R112, 113 0662057A97 100 k

R114 0662057B10 330 k

R115 0662057A94 75 k

R116 0662057A84 30 k

R117, 118 0662057A65 4.7 k

R119 0662057A69 6.8 k

R120, 121 0662057A73 10 k

R122, 123 0662057A83 27 k

R124 0662057A73 10 k

R125 0662057A91 56 k

R126 0662057A77 15 k

R127 0662057A73 10 k

R128 0662057P95 100 k, 1%

R129 0662057P27 27.4 k, 1%

R130 0662057P22 22.1 k, 1%

R131 0662057P95 100 k, 1%

R132, 133 0662057A65 4.7 k

R136, 137 0662057A73 10 k

R138 0662057A65 4.7 k

R139 0662057A49 1 k

R140, 141 0662057A65 4.7 k

R142 0662057A49 1 k

R143 0662057A65 4.7 k

R145 0662057A89 47 k

R146 1813905A11 Pot, 20 k

R147 0662057A65 4.7 k

R148 1813905A11 Pot, 20 k

R149 0662057A91 56 k

R150 1813905A11 Pot, 20 k

R151 0662057A97 100 k

R155 0662057A73 10 k

R156 0662057A49 1 k

R157 0662057A77 15 k

R158 0662057A38 360

R159 0662057A55 1.8 k

R160 0662057A77 15 k

R161 0662057A47 820

R162 thru 164 0662057A73 10 k

ITEM MOTOROLA

PART NUMBER DESCRIPTION

R165 0662057A56 2 k

R166 0662057A65 4.7 k

R171 0662057T64 47.5 k 1%

R172, 173 0662057A73 10 k

R174 0662057P27 27.4 k, 1%

R175 0662057A73 10 k

R180, 181 0662057A65 4.7 k

R182 0662057A49 1 k

R183 0662057A73 10 k

R184 0662057A65 4.7 k

R200 0662057A65 4.7 k

R210 0662057A49 1 k

R211, 212 0662057A73 10 k

R213' 0662057A65 4.7 k

R215 0662057A83 27 k

R216 0662057B26 1.5 M

R217 0662057A49 1 k

R220 0662057B47 0

R221 0662057A81 22 k

R224 0662057A97 100 k

R225 0662057A73 10 k

R226, 227 0662057A65 4.7 k

R228, 229 0662057A73 10 k

SWITCH:

S1 4080564C02 Dip

TRANSFORMER:

T1, T2 2584422T02 6-pin

INTEGRATED CIRCUIT MODULE:

See Note 1

U100 5113818A03 MC33072-1

U101, 102 5184704M60 MC14053B

U103 5113806A37 MC14106

U104 5113819A04 MC3303

U105 5184704M60 MC14053B

U107 5113818A03 MC33072-1

U111 5113816A03 MC78L05A

U118 5105109Z13 LT1129

U124 5113819A04 MC3303

U129 5105469E18 LM317T

DIODE:

See Note 1

VR102 thru 109 4805129M35 Zener, 13, 5.6 V

VR110 4813830A28 Zener, 13, 15 V

VR112, 113 4805129M35 Zener, 13, 5.6 V

VR115 4813830A28 Zener, 13, 15 V

VR118 4805129M35 Zener, 13, 5.6 V

VR121 4805129M35 Zener, 13, 5.6 V

VR123 4805129M35 Zener, 13, 5.6 V

CONNECTOR:

W101 0984345R02 SMB Jack Rt. Ang PCB

W102 0905901V10 J, Antenna Connector

MISCELLANEOUS:

8485176D01 Board, PC

0200835638 Nut

0300114832 Screw

ITEM MOTOROLA

PART NUMBER DESCRIPTION

VRS750 Vehicular Repeater System

Printed Circuit Board Electrical Parts List (PLN7780A)

C100

C101

C102

C104

C105

C107

C108

C109

C111

C112

C113

C114

C115

C116

C117

C118

C119

C120

C121

C122

C123

C124

C125

C126

C127

C128

C129 C130

C131

C134

C135

C136

C138

C139

C140

C141

C142

C143

C145

C146

C147

C148

C149 C150

C151

C152

C153

C154 C155

C158

C160

C161

C164C165

C166

C167

C168

C170

C171

C172

C173

C175

C179

C180

C182

C184

C185

C188

C189

C190

C191

C194

C197

C198

C199

C200

C201

C202

C203

C204

C205

C206

C207

C208

D100 D101

D102

F100

J30

Q100

Q101

Q102

Q103

Q104

Q106

Q109

Q110

Q111

Q112

Q113

Q114

Q115

R101

R102

R104

R105

R106

R107

R108

R109

R110

R111

R112

R113

R114

R115

R116

R117

R118

R119

R120

R121

R122

R123

R124

R125

R126 R127

R128

R129

R130 R131

R132

R133

R136

R137

R138

R139

R140

R141

R142

R143

R145

R146

R147

R148

R149

R150

R151

R155

R156

R157

R158

R159

R160

R161

R162

R163

R164

R165

R166

R171

R172

R173

R174

R175

R180

R181

R182

R183

R184

R200

R210

R211

R212

R213

R215

R216

R217

R220

R221

R224

R225

R226

R227

R228

R229

TP101

TP102

TP103

TP104

TP105

TP106

TP107

TP108

TP109

TP110

TP111

TP112

TP113

TP114

TP116

TP117

TP118

TP119

TP120

TP121

TP122

TP123

TP124

TP125

TP126

TP127

TP128

U100

U101

U102

U103

U104

U105

U107

U118

U124

U129

VR102

VR103

VR104

VR105

VR106

VR107

VR108

VR109

VR110

VR112

VR113

VR115

VR118

VR121

VR123

VRS750 Vehicular Repeater System

Printed Circuit Board Component Location Diagram (Sheet 1 of 2)

W102

8485176D01 REV A

C103

C132

C133

C137

C156

C157

C159

C162

C183

C195

C196

L101

P31

P32

P33

1810

P101

25 14

P102

U111

W101

VRS750 Vehicular Repeater System

Printed Circuit Board Component Location Diagram (Sheet 2 of 2)

(J20-16)

URX_SND

(J20-1)

(J20-15)

(J40-29)

(J40-24)

(J20-4)

(J20-12)

(J40-28)

(J40-20)

(J40-2)

EXT_MIC

(J40-22)

(J20-10)

(J20-13)

(J20-19)

(J20-20)

(J20-9)

(J20-14)

(J20-8)

(J40-21)

(J20-7)

(J40-1)

(J40-25)

(J20-11)

(J40-13)

(J40-23)

DNP

.015uF

C117

U124-1

MC3303

J30 20

9.6V

C104

1uF

27K

5.6V

VR112

R122

J30 5

C119

0.22uF

33pF

U100-1

MC33072

1000pF

C145

C101

220pF

C205

C204

220pF

C203

220pF

C202

220pF

C206

U124-2

MC3303

R217

J30 21

J30

4.7K

R166

10K

R102

220pF VR123

5.6V

P102-17

C207

P102-16

R118

4.7K

R171

J30 17

27K

R111

47.5K

P101-9

R114

330K

J30 1

J30 6

R175

VAG

10K

C188

220pF

TP112

R117

4.7K

R137

10K

J30

J30 4

5.6V

VR121

10K

R225

MMBT3904

Q103

5.6V

VR102

R220

1000pF

U124-3

MC3303

C118

MMBT3904

Q112

J30

TP110

J30

C146

220pF

Q111

MMBT3904

1000pF

C180

1uF

C189

TP111

C165

220pF

C111

220pF

C109

C113

R123

2200pF

27K

MC33072

U107-1

1R212

10K

J30 24

MMBT3904

Q110

TP113

220pF

C102

15K

R110

5.6V

VR113

R113

100K

22K

R221

10uF

C182

27K

R215

R107

6.8K

100K

R224

C114

.01uF

4.7K

R213

J30 7

Q113

R174

27.4K

VR118

5.6V

VAG

J30 22

J30 11

R172

10K

C100

220pF

100

22.1K

R130

220pF R104

R127

10K

C161

220pF

C112

R156

J30 10

R126

15K

C175

D100

220pF

R140

100K

4.7K

SW7.5V

R112

10K

R211

P101-1

R210

4.7K

R200

TP101

J30 3

C122

220pF

U103-5

MC14106

1110

1uF

C103

100K

R109

6.8K

P102-3

J30 26

R119

C116

.01uF

U107-2

MC33072

0.1uF

Q104

MMBT3906

10K

C105

C107

R173

220pF

9.6V

R216

C194

1.5MEG

MC14053B

U102-3

1000pF

MC14053B

U102-2

220pF

C191

7.5V

P102-1

0.1uF

C120

68K

P101-7

VR115

15V

R108

R105

R106

4.7K

U124-4

100

R139

MC3303

10K

68K

R124

R101

U101-2

MC14053B 11

J30 12

J30 30

9.6V

J30 8

J30 9

R128

100K

TP104

R120

10K

R116

30K

4.7K

R138

Q100

MMBT3904

R125

56K

J30 27

C164

220pF

SW7.5V

MC14106

U103-3

J30 29

R155

10K

R136

10K

J30 23

P101-3

J30 19

R121

Q101

MMBT3904

C179

P102-4

220pF

C121

100pF

D101

TP103

MC14106

U103-2

9.6V

.1uF

C108

100K

R131

75K

R115

TP123 TP124TP121 TP122

27.4K

R129

C125

220pF

C183

1uF

TP120

U100-2

MC33072

C190

680pF

TP102

.01uF

EXT_SPKR+

C115

TXD

SNGL_DET

TEST_MODE-IN

RSS TX_RX_AUDIO

PTT

VRS_TX*_RX

BUSYOUT

BOOT-CNTRL

RXD

SNGL_TX_DATA

TONES-MOBILE_AUD

RESET

BUSYIN

RX_FIL_AUD

PROG_SENSE

EXT_MIC

SNGL_OUT

VRS750 Vehicular Repeater System

Printed Circuit Board Schematic Diagram (Sheet 1 of 2)

MOB_ANA_GND

P102 IS 25 PIN DB25 CONNECTOR

(J40-30)

AUX_RX_AUD

MOB_ANA_GND

P101 IS 18 PIN PROGRAMMING CONNECTOR

FIL_AUD

CONNECTIONS

TO TRANSCEIVER

DGND

R226

4.7K

MC14106

U103-6

13 12

U107

SWB+

C150

220pF

C170

220pF

C139

220pF

W102 1

P102-5

7.5V

D102

4.7K

R132

220pF

C201

220pF

C200

0.1uF

C199

C197

220pF

C198

220pF

C127

9.6V

Q106

MMBT3904

220pF

C152

220pF

C167

10K

R163

U101-3

MC14053B

R229

10K

R228

10K

220pF

C208

9.6V

MMBT3904

Q115

R227

4.7K

F100

VAG

U103-1

MC14106

C195

0.1uF

C196

220pF

TP108

C124

220pF

U101-4

678

U104-3

MC3303

R180

4.7K

100uF

C156

C137

2200uF

TP114

5.6V

VR108

Q109

MMBT3904

1.8K

R159

P102-2

C126

220pF

C166

220pF

10K

R164

C132

1uF

P102-18

1000uH

L101

P102-10

4.7K

R133

MC14053B

U105-3

P102-23

P102-22

220pF

P102-12

C128

C157

220pF

360

R158

C155

10uF

R142

C151

10uF

OUT 1

SHDN*

TAB

U102-1

MC14053B

U118

LT1129CQ

ADJ 2

GND

SWB+

R141

4.7K

C173

4.7K

220pF

R147

VAG

1uF

C148

C133

C130

VAG

P102-8

1uF

220pF

U104-5

220pF

C160

C162

100uF

TP109

10uF

C153

TP116

C123

220pF

5.6V

U129

ADJ

IN OUT

P102-7

VR105

C136

220pF

W102 3

U124-5

15K

R157

U102-4

678

P102-21

C129

220pF

U104-4

MC3303

.1uF

C143

R160

15K

RADIO_SWB+

TP117

220pF

C147

R165

VAG

C158

220pF

C140

0.1uF

U104-1

MC3303

9.6V

SW7.5V

R161

220pF

C159

C149

10uF

820

220pF

.01uF

C131

C141

56K

R149

47K

R145

U100

POWER POWER POWER POWER

POWERPOWER

POWER

W101

P102-19

20K

R150

J30 13

P102-6

C142

5.6V

VR107

9.6V

220pF

TP119

220pF

9.6V

C138

VR104

5.6V

VR106

5.6V

220pF

C184

R183

10K

9.6V

R182

0.1uF

C135

9.6V

R146

20K

9.6V

P102-11

5.6V

VR103

C185

.047uF

100K

5.6V

VR109

R151

10K

R162

MC14053B

U101-1

0.1uF

C171

J30 15

TP106

9.6V

C172

220pF

R148

20K

U105-4

678

TP118

MMBT3906

Q102

VR110

15V

U103-7

P33

4.7K

R143

TP105

NC 4

NC1

8VIN VOUT 1

U111

GND 2

GND1 3

GND2

GND3

0.1uF

C134

P32

0.1uF

C168

TP127 TP128TP125 TP126

9.6V

220pF

C154

9.6V

MC14053B

U105-1

4.7K

R181

U105-2

MC14053B

R184

4.7K

W102 2

MMBT3904

Q114

P31

P102-14

TP107

RADIO_SWB+

SWB+

MIC_FIL_SEL

BUSY

RX_FIL_AUD

BUS+

BUS-

MOBILE_MIC_HI

RADIO_RESET

TX_AUDIO

SNGL_OUT

EXT_MIC

VRS_TX*_RX

LM317

VRS750 Vehicular Repeater System

Printed Circuit Board Schematic Diagram (Sheet 2 of 2)

VRS750 Vehicular Repeater System

Exploded View Parts List

ITEM

NO.

MOTOROLA

PART NUMBER DESCRIPTION

1 1505764X01 COVER ASSEMBLY, Midpwr Top

2 3205931V02 GASKET, Front Cover

3 1505905V02 HOUSING, Remote Front

4 2805347X01 CONNECTOR, 18 Position

5 4205395X01 RETAINER, Programming Connector

6 3205789X01 GASKET, Remote Cable

7 3385950D01 LABEL, Front

8 1505784W01 HOUSING, Programming Connector

9 1505791W01 HOUSING, Programming Connector Terminal

10 3285803D01 PLUG, Programming Connector

11 PLN7780A VRS750 Controller Board

12 0310907A20 SCREW, M3 x .5 x 10 (8 req’d)

13 320545Z03 GASKET, Antenna Connector

14 0410057A13 WASHER, Nylon (for Regulator)

15 1483820M02 INSULATOR, Nylon, Heat Conductive

(for Regulator)

16 TRANSCEIVER

PMLD4196A VHF Transceiver

PMLE4242A UHF R1 Transceiver

PMLE4243A UHF R2 Transceiver

17 2885170D01 PLUG, RF Phone to SMB

18 3085166D01 CABLE, RF Coax

19 4285033D01 RETAINER, Internal Radio (2 req’d)

20 0300139800 SCREW, 6-32 x .5

21 0200844628 NUT, 6-32

22 4285168D01 RETAINER, Flex Connector

23 1485171D01 INSULATOR, PC Board

24 8485177D01 CABLE, Flex

25 2785032D01 CHASSIS, Modiﬁed

26 3205934V01 GASKET, Casting

27 4205938V01 CLIP, Spring

28 3885558D01 PLUG, Plastic DC

29 3285169D01 SEAL, Power

30 0785588D01 BRACKET, Sp. Mounting

31 3205935V01 GASKET, 25-Pin Connector

32 0305760W02 SCREW, M5 x 0.8 x 12 (2 req’d)

33 0400135783 WASHER, Lk. Splt. (2 req’d)

34 0490440S01 WASHER, Flat (2 req’d)

35 0312002B14 SCREW, 10-16 x 1 (4 req’d)

VRS750 Vehicular Repeater System

Exploded View and Exploded View Parts List

VRS-to-Mobile Cable HKN6153A

Pin Number

Signal Name

VRS750

P102

ASTRO Spectra

Mobile DB25

Female

1 N/C

2 2 FIL_Audio_GND

3 N/C

4 N/C

5 5 Bus+

6 6 FLT_Audio

7 7 Rx_Audio

8 8 Tx_Audio

9 N/C

10 10 AGND

11 11 Mic_Lo

12 12 Mic_Hi

13 N/C

14 14 Bus-

15 N/C

16 N/C

17 N/C

18 18 DGND

19 19 Reset

20 N/C

21 21 Bus_GND

22 22 SWB+

23 23 Busy

24 N/C

25 N/C

VRS-to-Siren Cable HKN6154A

Pin Number

Signal Name

VRS750

P102

Siren

(HLN1439A)

39 pin J1

1 N/C

2 15 FIL_Audio_GND

3 N/C

4 N/C

5 17 Bus+

6 9 FLT_Audio

7 33 Rx_Audio

8 3 Tx_Audio

9 N/C

10 11 AGND

11 14 Mic_Lo

12 27 Mic_Hi

13 N/C

14 25 Bus-

15 N/C

16 N/C

17 N/C

18 19 DGND

19 4 Reset

20 N/C

21 18 Bus_GND

22 6 SWB+

23 5 Busy

24 N/C

25 N/C

VRS750 Programming Cable 3085031D01

Pin Number

Signal Name

VRS750

P101

SRIB DB25

Female

1 1 Ground

2 N/C

3 16 Boot_Cntl

4 N/C

5 N/C

6 N/C

7 15 TXD

8 N/C

9 2 Prog_Sense

10 N/C

11 N/C

12 N/C

13 N/C

14 N/C

15 N/C

16 N/C

17 N/C

18 N/C

VRS750 Programming Cable 3085031D01

Pin Number

Signal Name

VRS750

P101

SRIB DB25

Female

VRS750 Programming Cable 3085031D01

VRS750 Programming Cable Schematic (3085031D01)

VRS750 Flashing Adapter Schematic (NTN4056A)

REPLACEMENT PARTS ORDERING

ORDERING INFORMATION

MAIL ORDERS

Send written orders to the following addresses:

TELEPHONE ORDERS

United States and Canada Accessories and Aftermarket Division: Servicers Training (VHS Video Tapes):

Call: 1-800-422-4210 Call: 847-576-2828

1-800-826-1913 (For Federal Government Orders)

1-847-538-8023 (International Orders)

FAX ORDERS

United States and Canada Accessories and Aftermarket Division: Federal Government Orders:

FAX: 847-538-8198 (Domestic) FAX: 410-712-4991

847-576-3023 (International) International: 410-712-6200

Parts ID: 847-538-8194

PARTS CUSTOMER SERVICE PRODUCT CUSTOMER SERVICE

When ordering replacement parts or equipment

information, the complete identiﬁcation number

should be included. This applies to all components,

kits, and chassis. If the component part number is

not known, the order should include the number of

the chassis or kit of which it is a part, and sufﬁcient

description of the desired component to identify it.

Crystal and channel element orders should specify

the crystal type or channel element type number,

crystal and carrier frequency, and the model

number in which the part is used.

Replacement Parts/

Test Equipment/Manuals/

Crystal Service Items:

Motorola Inc.

United States and Canada

Accessories and Aftermarket

Division

Attention: Order Processing

1313 E. Algonquin Road

Schaumburg, IL 60196

Federal Government Orders:

Motorola Inc.

United States and Canada

Accessories and Aftermarket

Division

Attention: Order Processing

7230 Parkway Drive

Landover, MD 21076

International Orders:

Motorola Inc.

United States and Canada

Accessories and Aftermarket

Division

Attention: International Order

Processing

1313 E. Algonquin Road

Schaumburg, IL 60196

United States and Canada Accessories and

Aftermarket Division:

Call: 1-800-422-4210

Parts Identiﬁcation:

Call: 847-538-0021

Customer Resource Product Support

(Sales and Service Assistance):

Call: 1-800-927-2744

FAX: 1-954-723-4800

Motorola

8000 West Sunrise Boulevard

Fort Lauderdale, Florida 33322

6881094C84

Motorola Solutions 92FT4848 VRS 750- Vehicular Repeater System User Manual User and Service Manual

Motorola Solutions, Inc. VRS 750- Vehicular Repeater System User and Service Manual

Contents

User and Service Manual

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