Motorola Gm300 Installation Manual

Accessory Connections1-13
6.0 Accessory Connections
6.1 Accessory Connector Pin Functions
This section gives a description of the accessory connector pin functions.
CAUTION: The accessory connections shown are not compatible to some other models of
Motorola radios. Check the appropriate accessory or technical manual for further
information.
Ta b l e 1 - 4Connector Pin Functions
Pin Function Description
1External
Speaker -Speaker - and Speaker + (Pin 16) are used to connect an external speaker.
The audio...

1-14INSTALLATION
11Receiver Audio
(NPD Data In)There are two possible outputs: (1) Discriminator Audio; and (2) Continuous
filtered RX audio. The nominal output level for Discriminator Audio is
330m Vrms at 60% deviation and for Filtered Audio 600m Vrms at 60%
deviation at 1kHz. Function depends on dealer programming. For NPD calls,
this uses discriminator audio and cannot be configured by the CPS.
12 Digital In/Out 7
(CTS)This digital input/output function depends on dealer programming.
13Switched...

Accessory Connections1-15
6.2 Accessory Connection Plan
CAUTION: The accessory connections shown are not compatible to some other models of
Motorola radios. Check the appropriate accessory or technical manual for further
information. Ensure correct position of the accessory connector.
CAUTION: DO NOT short pin 16 or 1 on the accessory connector to ground; this may
damage the radio.
!
18 16 14 12 10
17 15 13 11 9 7 5 3
1198 6 4 2 20
86
8587
30
+12V
Ext. Alarm  4
86
8587
30
+12V
Ext. Alarm  4
+12V
+12V...

1-16INSTALLATION 

Chapter 2
REDUCING NOISE INTERFERENCE
1.0 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, depending upon the vehicle type and required...

2-2REDUCING NOISE 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
frequency near or even identical to the desired radio signal. The standard receiver may be unable to
distinguish between the two signals (desired and noise). Therefore they both enter the receiver,
resulting in degradation of the desired signal.
It is impractical to prevent all...

Operation of a Conventional Ignition System2-3
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 transformer-
type coupling action without any actual physical connection. Induced noise can degrade both
transmit and receive performance of a mobile radio.
2.0...

2-4REDUCING NOISE INTERFERENCE
The battery is connected to the primary winding of the coil through the ignition switch. The primary
circuit 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...

Detection of Noise Sources2-5
3.0 Detection of Noise Sources
3.1 Noise Detection Procedure
Detection of offending noise sources is the heart of noise suppression because, after the noise
source is identified, 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...

2-6REDUCING NOISE INTERFERENCE
Figure 2-4TLN6252_ Noise Reduction Kit for Generator-Equipped Vehicles
GeneratorIgnition
Switch
BatteryIgnition
Coil
Distributor
Breaker
PointsResistive Wire
(Note 2)
Resistor
Spark Plugs
(Note 2)
Armature
Field
Common GroundTo
Battery
To
Generator
FieldVoltage Regulator
ARMFLD
BAT
Notes:
1. Noise reduction can only be achieved if components are grounded properly.
Be sure that all the capacitors and the generator filed suppressor assembly are
grounded properly. This may...