Motorola GM Series Installation Manual - Page 29

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Detection of Noise Sources

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 the

installed 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

sufficient insulation 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 firmly attached, can be used on a trial-

and-error basis to locate wiring which needs additional filtering. Keep capacitor lead lengths short

for best suppression. Ceramic disc capacitors are not as suitable or effective as automotive coaxial

capacitors. (See Figure 2-3 TLN8845_ Noise Reduction Kit for Alternator-Equipped Vehicles and

Figure 2-4 TLN6252_ Noise Reduction Kit for Generator-Equipped Vehicles for part numbers.)

Ignition

Switch

Battery

Notes:

1. Noise reduction can only be achieved if components are grounded properly.

2. Items not supplied in kit. See auto parts dealer.

Reference

Number

Figure 2-3 TLN8845_ Noise Reduction Kit for Alternator-Equipped Vehicles

Ignition

Coil

Breaker

Points

Quantity

Motorola

Part Number

0100839913

0882571B02

3000502396

0180782A52

Resistive Wire

Distributor

Description

Lead & Lug Assembly

Capacitor, Coaxial (0.1µF, 100V)

Ignition Coil Suppressor Cable

Hood Wipers (2) and Mounting

Hardware Kit (not illustrated).

(Note 2)

Resistor

Spark Plugs

(Note 2)

FL0830262-O

2-5