Reference; Antenna Installation - Kenwood TS-680S Instruction Manual

8. REFERENCE
8-1. ANTENNA INSTALLATION
8-1-1. Fixed Station
For HF fixed-station operation, an antenna
specifically designed for amateur operation is recom-
mended. Antenna types include wire antennas, ver-
ticals, rotary beams, and other antenna types. {Fig.
8-1) HF antennas are quite large and must be install-
ed to withstand strong wind, heavy rain, etc.
Any antenna used with the TS-140S should be of
50-ohm impedance and should be connected using
an appropriate coaxial cable such as 5D-2V.
Impedance matching is important. Impedance
mismatching will result in a high VSWR and power
loss, or can cause unwanted harmonic radiation and
interference {TVI, BCI).
The impedance match can be checked with an SWR
meter. Generally, satisfactory operation is assured
when the VSWR {Voltage Standing Wave Ratia) is
less than 1.5:1.
A rotary beam antenna is very effective for OX com-
munication in the 14,21 and 28 MHz bands. (Fig.
8-2) If open wire or balanced type transmission line
is used with the antenna, a suitable antenna tuner
with balun is recommended between the transceiver
and the feed line. Methods of canstructian and
operating such tuners are described in detail in the
ARRL Antenna Handbook, ar similar publications.
For operation on the 160,75 and 40 meter bands, a
simple dipole antenna, cut to resonance in the most
used portion of the band, will perform satisfactorily.
For operation on the 10,15 and 20 meter bands, the
efficiency of the station will be greatly increased if a
good directional rotary antenna is used. Remember
that even the most saphisticated transceiver is
useless without a good antenna.
Ground plane antenna
Dipole antenna
Fig. 8-1
40
Fig. 8-2
8-1-2. Mobile
(1) Antenna
Use a sturdy mount for the mobile antenna since HF
antennas are larger (and have more wind load) and
ase heavier than VHF antennas. A bumper mount is
recommended for general use. The ground side of
the mount must be well grounded to the car body,
since the body itself functions as the ground plane
for the mobile antenna. (Refer to Fig. 8-4)
Notes:
1.Some cars have plastic bumpers. For such cars,
ground the antenna mount to the body.
2. When tuning a newly installed antenna, use the
following procedure:
* Tum the CAR control fully counterclockwise
for minimum transmit power.
» With the transceiver in transmit mode. Raise
transmit power output slowly by rotaing the
CAR control clockwise. The antenna should be
adjusted with minimum power.
* Transmitting with full power is recommended
only after the antenna has been adjusted for a
VSWR below 1.5:1.
3. Antenna installation is critical for successful
Mobile operation. For further information refer to
THE RADIO AMATEUR'S HANDBOOK, RADIO
HANDBOOK, or other texts.
{2) Coaxial cable connection
When the antenna is mounted on the behicles
bumper, the coaxial cable from the antenna can be
routed through a drain hole in the trunk. When the
antenna is roof mounted pass the cable between the
body and door, Leave a driploop at the lowest point
in the cable before entry into the vechicle to prevent
water from entering the car.
(3) Adjustment
Some mobile antennas are not designed at 50-ohm
impedance. In this case, impedance matching be-
tween the antenna and the coaxial cable (50 0) is re-
quired. This can be achieved by using an antenna
matching device or coupler.