Kenwood TS-780 Instruction Manual page 11

~ @ Adjustment (SWR)
Your antenna must be connected to a 50 ohms coaxial
cable, since the antenna impedance of the TS-780 is
50 ohms. Also, the antenna must be adjusted to
50 ohms impedance. This adjustment is called im-
pedance matching.
Proper impedance matching is accomplished by check-
ing SWR (VSWR: Voltage Standing Wave Ratio) using a
SWR meter. Ideal SWR is 1:1.
The SWR meter should be connected between the
antenna feeder and the antenna terminal at the rear of
the transceiver, whichever is more convenient. Note
that the reading of SWR meter varies somewhat depen-
ding on the location of connection because of the loss in
the antenna cable. This is particularly noticeable when
the antenna cable is more than 10 m long.
An antenna system which shows a standing wave ratio
of less than 1.5 will insure satisfactory transceive
operation.
4-2. COAXIAL CABLE
For satisfactory transceive operation, coaxial cable
must be used. When the transceiver is used for fixed sta-
tion service, the coaxial cable becomes relatively long, so
low loss (large sized) coaxial cable of the shortest possible
length should be used, as the loss of coaxial cable cannot
be neglected when operating in high frequency bands, par-
ticularly in 144 MHz or higher bands.
When the coaxial cable needs to be extended more than
10 m, use one of larger size such as RG8/U or UR67.
Antenna
Antenna-
feeder
Xp
KOLO
0x
Z N
<i
Coaxial cable
When SWR meter is connected as shown above, the actual
SWR at the antenna feeder is higher than 1.5 because of the
loss of the coaxial cable
Fig. 7 Adjustment of Antenna System
Antenna feeder
ANT terminal {/
Fig. 8
B. Antenna installation
1 Ground plane
antenna
Antenna feeder
SWR' at antenna feeder should
be less than 1.5: 1 Antenna
feeder should be waterproofed.
= 2
4-row horizontal
stack (4 parallel
elements)
Ideal type of antenna
Coaxial cable
10