Realistic PRO-16A Mobile Antennas, Mobile Noise Suppression, Electrical System, Ignition System

Mobile Antennas

There are many possible mounting locations on a car. Three of the most popular locations for monitor antennas are shown below.

MOBILE NOISE SUPPRESSION

This rece iver is ve ry sens1t1ve, and will pick up signals that are extremely weak. With th is extreme sensitivity, you will fi nd that the receiver wi II amplify weak signals, along with any noise that may be present.

When operating a receive r in a vehicle, you will find that the vehicle generates noise, and this noise can become very objectionable. Mobile operation will not be as quiet as base station operation, but steps can be taken that wi II greatly improve the noise situation.

	ROOF MOUNT- The antenna is mounted in the center of the roof.
	This position is considered the best by many, because it generally
	results in better reception than the other locations. Radio Shack's
	Hi-VHF/UHFMobile Mount (Catalog Number) 20-177 comes
	complete, like all our monitor antennas, with low-loss coax cable.
	COWL MOUNT-Ifyou would rather not cut a hole in the center of
	your vehicle's roof, you may prefer this location . Ask about our
t	20-016 Cowl Mount antenna which is especially designed for Hi-Low
	VHF monitoring. For UHF, use 20-183.
	REAR DECK-Installationin this location, may result in less noise
	because it is further from the engine. Your Radio Shack salesman will
	help you select the antenna which is best for you.

Keep the following points in mind when installing your mobile antenna.

1.Mount the antenna as high as possible .

2.Mount it rigidly, so it will remain vertical while in motion.

3.Mount as far as possible from the engine compartment.

ELECTRICAL SYSTEM:

Generally speaking, noise can be generated by any device or connec- tion that carries electrical current. Any device that generates a spark should also be suspected. Bypass any suspected w ire to ground with a high quality 1 µF coaxial capacitor.

A very common source of noise is the generator or alternator. This type of noise will sound like a musical whine, and will also vary with speed of the engine. Generator and alternator noise can usually be reduced by connecting a coaxia l-type capacitor from the armature terminal to the metal case .

IGNITION SYSTEM:

The ignition system is the most common source of noise. This noise can be identified by the fact that its speed varies with the engine speed. Ignition noise will sound like a series of "popping " sounds, while the engine is idling, and will speed up to a buzzing sound as engine speed is increased .

There are a number of things that can be done for this type of no ise .

1.Use radio suppression-type ignition wire and resistor spark plugs.

2.Check high-voltage wiring for leakage, cracks, etc . Replace any old wiring.

3.In extreme cases, obtain an ignition noise suppression kit-itshould shield all ignition wiring. This will provide maximum noise suppression .

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