Standard Radio Antenna; Antenna Tests; Mast-To-Ground; Tip Of Mast-To-Tip Of Conductor - Jeep 1987 Wrangler Workshop Manual

6^1
c
ACCESSORIES
STANDARD RADIO ANTENNA
GENERAL INFORMATION
AM and AM/FM radio antennas must have a
good ground to eliminate static. The antenna
mast is grounded through the radio. The
antenna base is grounded to the vehicle body.
The wire mesh coaxial shield surrounding the
center conductor wire of the antenna lead-in
cable is grounded to the radio and the antenna
base.
A1TENNA
TESTS
Antenna ground continuity is checked with an
ohmmeter. The following four tests are required:
• Mast-to-ground test 1
• Tip of mast-to-tip of conductor test 2
• Body ground-to-battery ground test 3
r Body ground-to-coaxial shield test 4
Test lead connections for the ohmmeter (OM)
are shown in the following schematic.
OM
i
OM
© o
1
OM
0=H
4
- 0 0 -
T
OM
85118
Mast-To-Ground Test 1
Test 1 determines if the antenna is making
electrical contact with the radio and if the
antenna mast is insulated from the base.
Procedure is as follows:
• Connect one ohmmeter (OM) lead to the tip of
the antenna mast and the other lead to the
antenna base.
• With the antenna connected to the radio, there
should be continuity (approximately 15
ohms).
• Disconnect the antenna from the radio and
check continuity again.
• Continuity should not exist with the antenna
disconnected from the radio.
Tip Of Mast-To-Tip Of Conductor Test 2
Test 2 checks the antenna for an open circuit as
follows:
• Disconnect the antenna cable from the radio.
• Connect one ohmmeter test lead to the tip of
the mast and the other lead to the tip of the
antenna cable lead-in (the part inserted into
the radio).
• Continuity should not exist (ohmmeter should
only register a fraction of an ohm).
M-3