1987 MITSUBISHI MONTERO radio antenna

INTRODUCTION - Precautions Before Service 13
IKITE ON INSTALLATION OF RADIO EQUIPMW&
The computers of the electronic control system has been
designed so that external radio waves will not interfere with
their operation.
However, if antenna or cable of amateur transceiver etc. is
routed near the computers, it may affect the operation of the
computers, even if the output of the transceiver is no more
than 25W.
To protect each of the computers from interference by
transmitter (hum, transceiver, etc.), the following should be
observed.
1. Install the antenna on the roof.
2. Because radio waves are emitted from the coaxial cable of
the antenna, keep it 200 mm (8 in.) away from the
computers and the wiring harness. If the cable must cross
the wiring harness, route it so that it runs at right angles to
the wiring harness.
3. The antenna and the cable should be well matched, and
the standing-wave ratio* should be kept low.
4. A transmitter having a large output should not be installed
in the vehicle.
5. After installation of transmitter, run the engine at idle, emit
radio waves from the transmitter and make sure that the
engine is not affected.
High-frequency power supply If an antenna and a cable having different impedances are
connected, the input impedance Zi will vary in accordance
with the length of the cable and the frequency of the
transmitter, and the voltage distribution will also vary in
accordance with the location.
The ratio between this maximum voltage and minimum
voltage is called the standing-wave ratio. It can also be
represented by the ratio between the impedances of the
antenna and the cable.
The amount of radio waves emitted from the cable increases
as the standing-wave ratio increases, and this increases the
possibility of the electronic components being adversely
affected.
_. r.
; ST6 Revision

8-192 AUDIO SYSTEM - Specifications
AUDIO SYSTEM I
/
SPECIFICATIONS
GENERAL SPECIFICATIONS NOENB-
Items
Radio
Model
Receiving band
Tape player
Model
Speaker
Instrument panel
Model
Rated input power
Center pillar trim
Model.
Reted input power
Antenna
Type Spe,cifications
AR-7 127PY AR-7 177PY
AM/ FM AMI FM
-
CX-25Y
-_-
-
SR-28A4-Y K-2
5W (Max. 7W)
SG-13SL4-G2 (GRAY) or SG-13SL4-G2 (GRAY) or
SG-13SL4-BE87 (BEIGE) SG-13SL4-BE87 (BEIGE)
15W (Max. 30W) 15W (Max. 3OW)
Pole antenna Pole antenna
TROUBLESHOOTING
Symptom
NOTE
Number in circle indicates inspection sequence
( STB Revision

8-196 AUDIO SYSTEM - Service Adjustment Procedures
SERVICE ADJUSTMENT PROCEDURES
ANTkNNA TRUMMER NOBNIAA
70R0351
1.
2.
3.
1.
2.
3.
4.
5. The antenna trimmer is essential for matching the antenna
with the radio in order to obtain the maximum sensitivity of
the radio.
It must be adjusted with the antenna actually mounted on
the vehicle. If the trimmer is not adjusted properly, the
radio suffers from not only low sensitivity but also noises,
su’ch as external noise and noise from passing vehicles.
In the following cases, therefore, adjust it as described
below.
(1) When radio is installed.
(2) If antenna is replaced.
(3) If radio has low sensitivity.
(4) If radio is noisy.
AkTENNA TRIMMER ADJUSTMENT
Mgke the following preparations for adjustment:
(1)’ Turn the ignition key to the “ACC” position.
(2) Extend the antenna all the way.
(3) Tune accurately to a station near 1,400 kHz in order to
receive a broadcast in as weak an electric field as can
be barely received. If there is no station near 1,400 kHz,
tune to any high-frequency station (above 1,000 kHz)
available. If there are two or more stations near 1,400
kHz, choose the louder one.
(4) Set the volume control to the proper volume.
(5) Set the tone ccontrol to treble position.
Be sure that preparations 1 through 5 have been correctly
made.
Insert a screwdriver into the trimmer adjusting hole.
Tumrn the screwdriver clockwise or counterclockwise for
maximum sensitivity (maximum broadcast wave sound).
If the optimum sensitivity point cannot be found, check for
an antenna malfunction or a broken wire.
NOTE
The antenna trimmer of an electronic tuning radio does not
require adjustment.
/ STB Revision

AUDIO SYSTEM - Radio and Tape Player e-197
RADIO AND TAPE PLAYER
REMOVAL AND INSTALLATION NOINJAF
16W1519
Post-installation Operation l Adjustment of Antenna Trimmer
(Refer to P.8-196.) Removal steps
1. Knob
2. Plug
3. Center console
4. Connection of center panel wiring har-
ness to front wiring harness connector 7. Radio
8. Tape player
9. Box (Vehicles without tape player)
5. Radio panel
6. Radio bracket NOTE
Reverse the removal procedures to reinstall. 1 STB Revision

8-200 AUDIO SYSTEM - Antenna/Noise Suppression
3. REMOVAL OF FRONT FENDER PANEL
Refer to GROUP 23 Body-Front Fender
SEFiVlCE ff OINTS OF INSTALLATION
3. IbSTALLATION OF FRONT FENDER PANEL
Refer to GROUP 23 Body-Front Fender.
NOISE SWPRESSION N08NOAA
I. Noise interfering with radio reception may be roughly
classified as follows:
(1) Noise produced by the vehicle itself
Noise from the ignition circuit, alternator circuit, etc
(2) Noise generated in the radio itself
Thermal noise from transistors, IC, resistor, etc.
(3) Atmospheric noise
Noise from other cars, neon signs, etc.
2. The radio has devices to suppress noise of the radio itsel f
3. and atmospheric noise, but it is difficult to eliminate them
completely. Noise produced by the vehicle includes whin-
ing from the alternator system, and a strong, impulsive,
fast popping noise from the ignition system.
Before performing any checking or adjustments, first
confirm the following points.
Adjust the antenna trimmer completely.
Set the push buttons (tuning) properly.
Extend the antenna all the way.
PREVENTION OF IGNITION CIRCUIT NOISE
A resistance-equipped cable is used for the high-tension cable
in order to prevent noise; however, if any noise from the
ignition circuit does occur, check the tightness and ground
connection of the positive (+) terminal of the noise filter, and,
if necessary, check the noise filter.
Caution
Be careful not to connect the noise filter to the hightension
cable; doing so could damage the noise filter.
PREVENTION OF OTHER CIRCUIT NOISE
1. For other noises, take necessary corrective actions in
accordance with the following items and the NOISE
SUPPRESSION CHART.
2. Polish the grounding cable terminal, and connect it proper-
ly.
3. Polish the pillar antenna ground terminal, and connect it
properly.
4. Ground electric parts completely.
5. Keep the antenna cable and speaker lead wire away from
other electric wiring.
STB Revision