Motorola GM1200E, Руководство по установке

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Noise Reduction Techniques
2-8 Reducing Noise Interference in Mobile Two-Way Radio Installations
5.2.3 Ignition Coil Interference
This type of interference is characterised by a popping sound which is most noticeable when the
engine is running slowly. To suppress the noise, connect a 0.1
µ
F coaxial capacitor (Motorola Part
No. 8C82571B02) from the battery side of the ignition coil to vehicle ground (see Figure 2-5). This
keeps the distributor noise from being conducted through the battery lead into the electrical system
of the vehicle. Note that some electronic ignition systems do not route the battery lead to the ignition
coil and can have proper operation impaired if the ”input” terminal is bypassed.
Figure 2-5 Ignition Coil Noise Suppression.
5.2.4 Distributor Interference
This type of interference is characterised 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
suppress this noise, use resistance ignition wire to connect the ignition coil to the distributor cap.
5.3 Battery Connections
The radio set power cable can pick up noise generated in the vehicle. This can be minimised by
connecting 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/hr. battery), which bypasses induced noise. The
battery ground lead should be securely bonded to the vehicle frame. Undesirable parallel ground
currents can be minimised 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 controlled by the ignition switch.
Step 1.
Step 2.
Step 3.
Step 4.
From distributor
Distributor Post
Battery Post
Connect capacitor
lead to battery post.
Connect wire lead to capacitor
using lockwasher and nut.
Disconnect wire (dashed)
from battery post and
connect to capacitor using
lockwasher and nut.
Mount Capacitor
(0.1
µ
F Coaxial Type)
to vehicle chassis
using lockwasher
and self-tapping screw.