Vertex Standard VXD Series User manual

Professional Digital Two-Way Radio System
VXD Series
Installation Guide
Vertex Standard LMR, Inc

Page 1
Foreword
This manual is intended for use by experienced technicians familiar with similar types of equipment. Speci-
cally, it contains installation information required for the VXD Series Mobile Radios.
For information related to the service of the VXD Series Mobile Radios, refer to the list applicable manuals
available separately.
Product Safety and RF Exposure Compliance
See Installation Requirements for Compliance with Radio Frequency (RF) Energy Exposure Safety Stan-
dards on next page.
Manual Revisions
Changes which occur after this manual is printed are described in PMRs (Publication Manual Revisions).
These PMRs provide complete replacement pages for all added, changed, and deleted items.
To obtain PMRs, go to: http://www.vertexstandard.com/manuals/
Parts Ordering
See Appendix: Replacement Parts Ordering for information on how to obtain replacement parts. For part
numbers, refer to the VXD Series Mobile Radios Basic Service Manual.
Computer Software Copyrights
The Vertex Standard products described in this manual may include copyrighted Vertex Standard computer
programs stored in semiconductor memories or other media. Laws in the United States and other countries
preserve for Vertex Standard 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. According-
ly, any copyrighted Vertex Standard computer programs contained in the Vertex Standard products described
in this manual may not be copied, reproduced, modied, reverse-engineered, or distributed in any manner
without the express written permission of Vertex Standard. Furthermore, the purchase of Vertex Standard
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 Vertex Standard, except for the normal non-exclusive
license to use that arises by operation of law in the sale of a product.
Document Copyrights
No duplication or distribution of this document or any portion thereof shall take place without the express
written permission of Vertex Standard. No part of this manual may be reproduced, distributed, or transmitted
in any form or by any means, electronic or mechanical, for any purpose without the express written permis-
sion of Vertex Standard.
Disclaimer
The information in this document is carefully examined, and is believed to be entirely reliable. However, no
responsibility is assumed for inaccuracies. Furthermore, Vertex Standard reserves the right to make changes
to any products herein to improve readability, function, or design. Vertex Standard does not assume any li-
ability arising out of the applications or use of any product or circuit described herein; nor does it cover any
license under its patent rights nor the rights of others.
Trademarks
Vertex Standard, the Stylized VS logo are registered in the US Patent & Trademark Ofce. All other product
or service names are the property of their respective owners.
© 2013 by Vertex Standard LMR, Inc.
Foreword

Page 2
Table of Contents
Foreword ..............................................................................................................................1
Product Safety and RF Exposure Compliance ........................................................................................1
Manual Revisions .....................................................................................................................................1
Parts Ordering ..........................................................................................................................................1
Computer Software Copyrights ................................................................................................................1
Document Copyrights...............................................................................................................................1
Disclaimer ................................................................................................................................................1
Trademarks ..............................................................................................................................................1
Installation Requirements for Compliance with
Radio Frequency (RF) Energy Exposure Safety Standards ............................................4
Commercial Warranty .........................................................................................................5
Limited Warranty ......................................................................................................................................5
Chapter 1 Introduction ........................................................................................................7
1.1 Mobile Radio Description ...............................................................................................................7
1.1.1 Overview ..............................................................................................................................7
1.1.2 Dimensions ..........................................................................................................................7
1.1.3 Connections on the Back of the Radio ................................................................................8
1.2 Standard Congurations ................................................................................................................9
1.2.1 Dash Mount Conguration ...................................................................................................8
1.3 Base/Control Stations .................................................................................................................. 10
Chapter 2 Reducing Noise Interference .......................................................................... 11
2.1 Introduction .................................................................................................................................. 11
2.1.1 Noise Sources ................................................................................................................... 11
2.1.2 Radiated Noise .................................................................................................................. 11
2.1.3 Conducted Noise ............................................................................................................... 12
2.1.4 Induced Noise .................................................................................................................... 12
2.2 Operation of a Conventional Ignition System .............................................................................. 13
2.2.1 Introduction ........................................................................................................................ 13
2.2.2 Sources of Ignition Interference ........................................................................................13
2.3 Detection of Noise Sources ......................................................................................................... 14
2.3.1 Noise Detection Procedure ................................................................................................ 14
2.3.2 Sources of Noise ............................................................................................................... 14
2.4 Noise Reduction Techniques ....................................................................................................... 15
2.4.1 General ..............................................................................................................................15
2.4.2 Ignition System Interference .............................................................................................. 15
2.4.2.1 Engine Maintenance and Tune-Up ..................................................................... 15
2.4.2.2 Noise Reduction Kits .......................................................................................... 15
2.4.2.3 Ignition Coil Interference ....................................................................................15
2.4.2.4 Distributor Interference .......................................................................................16
2.4.2.5 Battery Connections ........................................................................................... 16
2.4.3 Alternator/Generator Whine ............................................................................................... 17
2.4.4 Voltage Regulator Noise ....................................................................................................18
2.4.5 Other Electrical Noises ......................................................................................................19
2.4.6 Ground Bonding .................................................................................................................19
Table of Contents

Page 3
Chapter 3 Installation Details for Standard Congurations ..........................................21
3.1 Planning the Installation ...............................................................................................................21
3.1.1 Tools Required for Installation ........................................................................................... 21
3.1.2 Installation Example...........................................................................................................21
3.1.3 Wiring Diagrams ................................................................................................................22
3.2 Radio Mounting ............................................................................................................................23
3.2.1 Dash Mount with Trunnion .................................................................................................24
3.2.2 Locking Kit (Optional) ........................................................................................................25
3.2.2.1 All Radios ...........................................................................................................25
3.2.3 DIN Mount ..........................................................................................................................25
3.2.3.1 To install the frame into the dashboard ..............................................................25
3.2.3.2 To Mount the radio in the frame .........................................................................26
3.2.3.3 To Remove the radio from the frame ..................................................................26
3.3 Power Cable .................................................................................................................................26
3.4 Ignition Sense Cable ....................................................................................................................27
3.5 Antenna Installation .....................................................................................................................28
3.5.1 Selecting an Antenna Site/Location on a Metal Body Vehicle ...........................................28
3.5.2 Antenna Installation Procedure .........................................................................................29
3.5.3 Antenna Connection ..........................................................................................................30
3.6 Microphone Hang-Up Clip ...........................................................................................................31
3.6.1 Standard Hang-Up Clip ..................................................................................................... 31
3.7 Completing the Installation ..........................................................................................................31
Chapter 4 Options and Accessories Installation ............................................................33
4.1 Accessory Installation ..................................................................................................................33
4.1.1 Horn and Lights (External Alarm) Relay ..............................................................................35
4.1.2 External Speaker .................................................................................................................36
Appendix ............................................................................................................................37
Replacement Parts Ordering ................................................................................................................. 37
Servicing Information .............................................................................................................................37
Index ...................................................................................................................................38
Table of Contents
Table of Contents

Page 4
Installation Requirements for Compliance with
Radio Frequency (RF) Energy Exposure Safety Standards
ATTENTION!
This radio is intended for use in occupational/controlled conditions, where users have full knowledge of their
exposure and can exercise control over their exposure to meet FCC limits. This radio device is NOT autho-
rized for general population, consumer, or any other use.
To ensure compliance to RF Energy Safety Standards:
• Install only Vertex Standard approved antennas and accessories.
• Be sure that antenna installation is per Antenna Installation on page 3-8 of this manual.
• Be sure that Product Safety and RF Energy Exposure chapter in the Operating Manual is available
to the end user upon completion of the installation of this radio.
Before using this product, the operator must be familiar with the RF energy awareness information and oper-
ating instructions in the Product Safety and RF Energy Exposure chapter in the Operating Manual to ensure
compliance with Radio Frequency (RF) energy exposure limits.
For radios installed in vehicles fuelled by liqueed petroleum gas, refer to the (U.S.) National
Fire Protection Association standard, NFPA58, for storage, handling, and/or container infor-
mation.
This radio has a transmitter Time-out Timer that disables the transmitter during a transmission after a pre-
dened time period, which by default is set to 60 seconds.
It is recommended NOT to change the default 60 seconds time period for the Time-out Timer
as the radio is intended for intermittent duty cycle operation.
Installation Requirements for Compliance with Radio Frequency (RF) Energy Exposure Safety Standards

Page 5
Commercial Warranty
Limited Warranty
Vertex Standard Communication Products
What This Warranty Covers and For How Long
Vertex Standard LMR, Inc. (“Vertex Standard”) warrants the Vertex Standard manufactured Communication
Products listed below (“Product”) against defects in material and workmanship under normal use and service
for a period of time from the date of purchase as scheduled below:
Vertex Standard, at its option, will at no charge either repair the Product (with new or reconditioned parts),
replace it (with a new or reconditioned Product), or refund the purchase price of the Product during the war-
ranty period provided it is returned in accordance with the terms of this warranty. Replaced parts or boards
are warranted for the balance of the original applicable warranty period. All replaced parts of Product shall
become the property of Vertex Standard.
This express limited warranty is extended by Vertex Standard to the original end user purchaser only and is
not assignable or transferable to any other party. This is the complete warranty for the Product manufactured
by Vertex Standard. Vertex Standard assumes no obligations or liability for additions or modications to this
warranty unless made in writing and signed by an ofcer of Vertex Standard.
Unless made in a separate agreement between Vertex Standard and the original end user purchaser, Vertex
Standard does not warrant the installation, maintenance or service of the Product.
Vertex Standard cannot be responsible in any way for any ancillary equipment not furnished by Vertex Stan-
dard which is attached to or used in connection with the Product, or for operation of the Product with any
ancillary equipment, and all such equipment is expressly excluded from this warranty. Because each system
which may use the Product is unique, Vertex Standard disclaims liability for range, coverage, or operation of
the system as a whole under this warranty.
Commercial Warranty

Page 6
Note
Note

Page 7
Chapter 1 Introduction
This manual covers the installation procedures for VXD Series Mobile Radios and accessories re-
quired to complete the radio system. The radio system consists of a control head, radio, antenna, mi-
crophone, speaker, cabling, and accessories.
1.1 Mobile Radio Description
1.1.1 Overview
VXD-7200: The Display model with 4 programmable buttons and a dot-matrix LCD.
1.1.2 Dimensions
Figure 1-1 and Figure 1-2 show the basic dimensions of the dash mount trunnion of the mobile radio.
When installing the radio, make sure to plan the installation carefully and leave additional room in the
rear of the radio for cabling and accessory connections; in the front of the radio for access, controls,
and cabling; and to the sides of the radio so that you may access and install the trunnion wing screws.
Chapter 1 Introduction
8.2”
6.8”
Figure 1-2 Side View of Dash Mount with Low Prole Trunnion
8.3”
7.9”
2“
2.4“
Figure 1-1 Front View of Dash Mount Trunnion
NOTE: The rear accessory connector adds 0.75 in. (1.91 cm) to the overall length.

Page 8
1.1.3 Connections on the Back of the Radio
Figure 1-3 shows the connections that are found on the back of the radio.
For complete pin conguration of the rear accessory connector, see Figure 4-2, on page 4-2.
Chapter 1 Introduction
#PVGPPC%QPPGEVQT $CVVGT[ $CVVGT[
4GCT#EEGUUQT[
%QPPGEVQT
Figure 1-3 Back View of the Mobile Radio

Page 9
Chapter 1 Introduction
1.2 Standard Congurations
Currently the mobile radio can only be dash-mounted.
1.2.1 Dash Mount Conguration
In the dash mount conguration of the mobile radio, the control head is mounted on the front of the
transceiver housing. Electrical connection between the two takes place within the radio via a exible
cable between the connectors on the front of the transceiver and at the back of the control head.
Figure 1-4 Dash Mount Conguration
For details on this conguration, see Section 3.2.1 on page 3-4.

Page 10
1.3 Base/Control Stations
If the mobile radio equipment is installed at a xed location and operated as a control station or as a
xed unit, the radio and antenna installation must comply with the following requirements in order to
ensure optimal performance and compliance with the Product Safety and RF Energy Exposure chapter
in the Operating Manual:
For outdoor antenna installations, proper site grounding and lightning protection are vitally
important.
Failure to provide proper lightning protection may result in permanent damage to the radio
equipment.
• The antenna should be mounted outside the building on the roof or a tower if at all possible and the
antenna cable should be earth grounded.
• The radio chassis must be earth grounded and a lightning surge protector should be used in line
with the radio connector and the outdoor antenna. The lightning surge protector should be earth
grounded and located at the point where the antenna cable enters the building.
• The line voltage power supply must have a proper ground connection.
• As with all xed site antenna installations, it is the responsibility of the licensee to manage the site
in accordance with applicable regulatory requirements. Also, additional compliance actions such as
site survey measurements, signage, and site access restrictions may be required in order to ensure
that exposure limits are not exceeded.
Figure 1-5 shows a typical setup of a Base/Control Station conguration.
Chapter 1 Introduction
Figure 1-5 Example of a Base/Control Station Conguration
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
C
CC
C
C
Speaker
Desk
Microphone
Power Supply
Wall-
outlet
Radio in
Desktop Tray
Line Cord
with Ground
Desktop
Power Cable
Antenna
Cable
Antenna Connector
Outdoor Antenna
Lightning Protector With
Quarter Wave Shorting Stub

Page 11
Chapter 2 Reducing Noise Interference
2.1 Introduction
Electrical noise generated by the electrical system of a vehicle, as well as local ambient noise, can
interfere with normal operation of mobile radios. Satisfactory operation of a mobile radio may require
slight or heavy noise reduction, depending upon the relative strength of the radio signal, and upon the
ability of the radio to reject undesired noise. These requirements vary from one vehicle to another, de-
pending upon the vehicle type and required coverage area. When operating in a strong signal area, a
certain amount of noise interference can be tolerated. In weak signal areas, however, noise reduction
becomes very important. As a rule of thumb, noise levels create greatest interference in the 25-50MHz
band and reduce with increasing frequency.
Before attempting any noise reduction procedures, determine the noise source(s). Then, follow a logi-
cal, systematic method of elimination until the interference is eliminated or reduced to an acceptable
level.
DO NOT add interference elimination equipment to vehicles equipped with electronic ignition
systems before obtaining advice from the vehicle manufacturer. Addition of some noise sup-
pression components may interfere with proper operation of electronic ignition systems and
could seriously damage them.
Care and patience must be exercised in locating and eliminating noise sources. There may be several
sources of noise, each slightly stronger or weaker than the other. Elimination of one source may seem
ineffective because another noise source remains active at a barely discernible difference in level.
Consult a service manual for the vehicle to determine what noise reduction provisions the manufactur-
er applies when AM, AM/FM, or CB radios are installed as original equipment. These radios are also
subject to electrical noise interference, and the manufacturer may install noise suppression compo-
nents only upon those vehicles which require radio equipment at the time of manufacture. These noise
suppression components should be added in any rst attempt to suppress noise.
2.1.1 Noise Sources
The three major noise sources affecting mobile radio systems are: (1) radiated noise, (2) conducted
noise, and (3) induced noise. (See Figure 2-1 for typical vehicular noise sources.)
2.1.2 Radiated Noise
Radiated noise enters the radio through the antenna along with the desired signal and can block or
degrade desired communication. It can be generated by power lines, uorescent lights, or by electrical
discharges from static build-up, ignition systems, or electrical motors. Radiated noise is the most com-
mon cause of mobile radio interference.
When a spark discharge or arc takes place through air, energy is radiated at frequencies from a few
kilohertz to hundreds of megahertz. This spurious radiation may have some energy radiated at a fre-
quency near or even identical to the desired radio signal. The standard receiver may be unable to dis-
tinguish between the two signals (desired and noise). Therefore they both enter the receiver, resulting
in degradation of the desired signal.
Chapter 2 Reducing Noise Interference

Page 12
It is impractical to prevent all arcing in the standard vehicle electrical system. In an 8-cylinder engine
running at 2,000 RPM, arcing occurs across the spark plugs at a rate of 8,000 sparks per minute or
133 sparks per second. Electrical motors and generators also produce arcs.
Chapter 2 Reducing Noise Interference
Figure 2-1 Noise Sources
2.1.3 Conducted Noise
Conducted noise enters the radio through the points where the radio is attached to the vehicle’s electri-
cal system such as battery cables, ignition switch, chassis ground etc. It can be generated by electrical
transients, electrical motors, poor grounding points, or inadequate electrical system ltering (from alter-
nators, generators, voltage regulators, or weak batteries). Conducted noise can degrade both transmit
and receive performance of a mobile radio.
2.1.4 Induced Noise
Induced noise enters the radio through the proximity of radio wiring to other wiring in the vehicle.
Electrical currents through the standard vehicular wiring can induce undesirable noise signals into
the radio cabling. Communication is degraded simply because the wiring provides a transformertype
coupling action without any actual physical connection. Induced noise can degrade both transmit and
receive performance of a mobile radio.
Electric Fuel Pump
Antenna Ground
or Location
Radiated Noise Pick-up
Inadequate Terminal
or Fuse Block Filtering
Windshield Wiper Motor
Heater Air Conditioner Blowe
Electric Windows Motors
Hood Static
Power Seat Motor
Spark Plugs
Idle Stop
Solenoid
Spark Plug
Wires
Alternator or
Generator
Voltage
Regulator
Distributor Ignition
Coil
(.1

Page 13
2.2 Operation of a Conventional Ignition System
2.2.1 Introduction
To effectively reduce ignition interference in a vehicle, it is well to understand the operation of an auto-
mobile ignition system.
Ignition is necessary in a gasoline engine to ignite the gasoline vapor and the air mixture in its cyl-
inders. The system is made up of the battery, distributor, breaker points, coil, condenser, and spark
plugs. The battery is the only electrical source of power in an automobile, so the lower battery voltage
must be stepped up to the high voltage necessary to arc across the spark plug electrodes.
This arc ignites the gas mixture.
2.2.2 Sources of Ignition Interference
In the conventional ignition system (Figure 2-2) a mechanical circuit breaker (the cam and points in the
distributor) opens the primary circuit of the ignition coil, and high voltage is developed at the second-
ary. This high voltage is synchronized and applied to each spark plug by the distributor.
Chapter 2 Reducing Noise Interference
The battery is connected to the primary winding of the coil through the ignition switch. The primary cir-
cuit is returned to the battery through the breaker points, which are bypassed by the condenser.
The points are normally closed. As the cam shaft is rotated by the engine, its lobes or corners open
and close the points in proper synchronization with the piston in each cylinder.
With the ignition switch on and the breaker points closed, coil primary current builds up at a rate eter-
mined by the coil inductance.
HV Lead
Distributor
Spark plug leads
Spark
Plugs
Ignition
Coil
Condenser
Cam
Breaker
Points
Ignition
Switch
$CVVGT[
Ignition
Coil
Condenser
Stray
Capacitance
Cam
Breaker
Points
Ignition
Switch
Battery
Rotor Gap
Lead Inductance
Spark Plug Gap
(.1
Figure 2-2 Typical Vehicular Ignition System, Simplied Schematic Diagram

Page 14
Chapter 2 Reducing Noise Interference
When the breaker points open, primary current decreases and, by self-induction, an electromotive
force is induced in the primary which is many times greater than the battery voltage. The high voltage
inducted in the coil secondary causes a spark across the distributor rotor-to-spark plug wire gap and
then across the spark plug gap for a short interval of time when the breaker points open. The condens-
er reduces arcing of the points.
The secondary circuit of the ignition coil, including the distributor rotor gap and the spark gap, is the
main source of ignition interference. The lead inductance and stray capacitance provide a tuned circuit.
Because the discharge of the circuit is through a low resistance (ionized spark gap), the circuit tends to
oscillate. The frequency and amplitude of oscillation vary as current changes in the spark gap.
2.3 Detection of Noise Sources
2.3.1 Noise Detection Procedure
Detection of offending noise sources is the heart of noise suppression because, after the noise source
is identied, the solution becomes obvious. A logical methodical procedure is basic to the effective
noise suppression.
Use your available equipment to best advantage. A pick-up loop, about one inch in diameter, can be
connected to a portable CB radio or a mobile radio being operated at a frequency similar to the in-
stalled radio frequency but from an isolated supply voltage. The pick-up loop can be moved throughout
the vehicle with the radio used as a radiated noise detector. Be sure the pick-up loop has sufcient in-
sulation to prevent the input of the radio from coming into direct contact with high voltage points in the
vehicle ignition system.
A non-polarized bypass capacitor, which has alligator clips rmly attached, can be used on a trialand-
error basis to locate wiring which needs additional ltering. Keep capacitor lead lengths short for best
suppression. Ceramic disc capacitors are not as suitable or effective as automotive coaxial capacitors.
2.3.2 Sources of Noise
Some interference is due to geographic location. This interference does not need to be eliminated
since it is possible for the vehicle to be moved away from the interfering noise source. Noise from
power lines, uorescent lights, and other vehicles (emitting high levels of radiated noise) are examples
of noise which depends upon location. Make certain that you are not attempting to suppress noise
in a vehicle while it is in a noisy location. If you suspect that your location is noisy, simply turn off ev-
erything in the vehicle except the radio and listen to the remaining ambient noise. If the noise level is
objectionable, you may have to noise suppress the vehicle during a less noisy time of day or in a differ-
ent, quieter location.
Check the installed radio for conducted and inducted noise by using an unmodulated signal generator
to supply a clean RF signal through a coaxial cable directly to the antenna connector on the radio set.
This should prevent radiated noise from entering the receiver and masking conducted and induced
noise. Ensure that the signal generator is not microphonic and is placed away from the noise of the en-
gine and exhaust.
Operate the controls for fans, blowers, power windows, headlamps, turn signals, windshield wipers,
and other electrical accessories. Listen for the presence of noise in the received radio signal. This will
allow the source of the interference to be determined. Some noise sources cannot be turned on and off
at will. These sources will need to be attacked piecemeal on a trial and error basis: alternator whine,
voltage regulators, electric fuel pump, and other possible sources. Remember that induced noise can
result from radio wiring being too close to other vehicle wiring. This problem is most easily solved by
proper cable routing at the time of installation.

Page 15
Chapter 2 Reducing Noise Interference
Radiated noise must be attacked after conducted and induced noise has been satisfactorily sup-
pressed. The vehicle ignition system is usually the primary source of this interference. Antenna place-
ment can be critical in some installations. Remember that static discharge generates static or radiated
noise and will probably be generated only when the vehicle is in motion. Since radiated noise interfer-
ence is most noticeable in weak signal areas, it is suggested that suppression be nalized while listen-
ing to a weak “on frequency” signal. (The squelch should be “open” so that even marginal signals can
be heard.)
2.4 Noise Reduction Techniques
2.4.1 General
There are three basic ways to suppress noise. The rst is the addition of resistance in circuits subject
to ringing. This method is used for the ignition coil HV cable, spark plug wires, and spark plugs. The
second is to lter noise from low voltage wiring using coaxial bypass capacitors. The third is to control
static charge build-up using wipers for movable parts such as automobile hoods and trunk lids, or ex-
ible bonding leads for xed members. Static in wheels may also be controlled using collector rings. Ap-
plications of each of these techniques are discussed below.
The vehicle manufacturer’s service manual also may provide noise suppression information which is
valuable in any rst attempt at noise suppression.
2.4.2 Ignition System Interference
2.4.2.1 Engine Maintenance and Tune-Up
The most important step in reducing ignition noise is insuring that the engine is in proper tune. Pay
particular attention to the following points if the noise interference from the ignition system is severe:
1. Be sure the spark plugs distributor points, and condenser are in good condition.
2. Be sure ignition timing is properly adjusted.
3. Be sure the distributor cap and rotor are in good condition. They should be replaced at least ev-
ery 30,000 miles.
4. Be sure that spark plug wires make good, solid contact at each end and are routed as far as
possible from low voltage leads.
5. Many late-model automobiles are equipped with a shield over the distributor points. Check to
see that this shield is properly positioned and securely attached.
2.4.2.2 Noise Reduction Kits
Most auto parts dealers can supply 0.05 μF bypass capacitors (condensers), resistive ignition wires,
and resistor spark plugs. The type of spark suppression used in noise reduction should always be in
accordance with the recommendations of the vehicle manufacturer, that is, if spark plugs are to be re-
placed with built-in suppressor types, they should be in the proper heat ranges and thread sizes for the
particular engine. In each ignition system, there is a maximum amount of resistance that may be con-
nected between the distributor and a spark plug. If resistance-type ignition wire is used, the length of
each wire must be limited so that its resistance does not exceed the allowable maximum.
2.4.2.3 Ignition Coil Interference
This type of interference is characterized by a popping sound which is most noticeable when the en-
gine is running slowly. To suppress the noise, connect a 0.1 μF coaxial capacitor from the battery side
of the ignition coil to vehicle ground (see Figure 2-3). This keeps the distributor noise from being con-
ducted through the battery lead into the electrical system of the vehicle. Note that some electronic igni-
tion systems do not route the battery lead to the ignition coil; proper operation of the ignition system
can be impaired if the”input” terminal is bypassed.

Page 16
2.4.2.4 Distributor Interference
This type of interference is characterized by popping sounds which are present at all engine speeds.
It is caused by sparking between the rotor and the distributor cap inserts as the rotor turns. To sup-
press this noise, use resistance ignition wire to connect the ignition coil to the distributor cap.
2.4.2.5 Battery Connections
The radio set power cable can pick up noise generated in the vehicle. This can be minimized by con-
necting the power cable directly to the battery instead of the fuse block. The battery acts like a large
capacitor (about one Farad for a 50 Amp/hour battery), which bypasses induced noise. The battery
ground lead should be securely bonded to the vehicle frame. Undesirable parallel ground currents can
be minimized by using the vehicle frame as a common ground point. If ignition switch control of the
radio is desired, the radio power leads may be connected to the battery through a relay which is con-
trolled by the ignition switch.
Step 3.
Connect wire lead to capacitor
using lockwasher and nut.
Step 1.
Mount Capacitor
(0.1µF Coaxial Type)
to vehicle chassis
using lockwasher
and self-tapping screw.
Step 2.
Disconnect wire (dashed)
from battery post and
connect to capacitor using
lockwasher and nut.
Step 4.
Connect capacitor
lead to battery post. From distributor
Distributor Post
Battery Post
(.1
Chapter 2 Reducing Noise Interference
Figure 2-3 Ignition Coil Nose Suppression

Page 17
Chapter 2 Reducing Noise Interference
2.4.3 Alternator/Generator Whine
This type of interference is characterized by a high-pitched whine which varies with engine speed. A 0.5
μF coaxial capacitor can be used to bypass the whine. For generators, the capacitors is connected in
the armature lead. Never use a capacitor in the eld lead. For alternators, the capacitor is connected in
the lead to the battery post (see Figure 2-4 and Figure 2-5).
Step 1.
Mount Capacitor
(0.5µF Coaxial Type)
under generator ground screw.
Step 3.
Connect wire lead to capacitor
using lockwasher and nut.
Step 4.
Connect capacitor
lead to armature post.
Caution:
Do not connect
capacitor to field teminal.
Step 2.
Disconnect wire (dashed)
from armature post and
connect to capacitor using
lockwasher and nut.
(.1
Figure 2-4 Generator Whine Suppression

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Chapter 2 Reducing Noise Interference
Figure 2-5 Alternator Whine Suppression
Step 1.
Mount Capacitor to
(0.5µF Coaxial Type)
under alternator
ground screw.
Step 2.
Disconnect wire from
battery post and connect
to capacitor using
lockwasher and nut.
Step 3.
Connect wire lead to capacitor
using lockwasher and nut.
Step 4.
Connect capacitor
lead to battery post.
Caution:
Do not connect
capacitor to field terminal.
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2.4.4 Voltage Regulator Noise
This type of interference is characterized by erratic popping noises which change only slightly with
changes in engine speed. The noise is generated by arcing in the vibrating breaker contacts of the
voltage regulator. It can be suppressed by connecting a 0.5 μF coaxial capacitor in the battery and ar-
mature leads of the voltage regulator (see Figure 2-6).
Disconnect the battery ground terminal before attempting to connect components to the volt-
age regulator.