17
VX-1400 O
PERATING
M
ANUAL
dipole at a height of 10 meters could, ionospheric propagation conditions permitting, be
expected to provide outstanding performance over the same 3000 km distance.
Excellent reference texts and computer software are available for the design and optimi-
zation of HF antennas. Your dealer or installer should be able to assist you with all aspects
of your antenna installation.
Use high-quality coaxial cable for the lead-in to your
VX-1400
transceiver. All efforts at
providing an efficient antenna system will be wasted if poor quality, lossy coaxial cable is
used. Losses in coaxial lines increase as the frequency increases, so a coaxial line with 0.5
dB of loss at 6 MHz may have 2 dB of loss at 26 MHz (1 dB is a just-perceptible decrease
in signal strength). As a general rule, smaller-diameter coaxial cables tend to have higher
losses than larger-diameter cables, although the precise differences depend critically on
the cable construction, materials, and the quality of the connectors used on the cable. See
the cable manufacturers’ specifications for details.
For reference, the chart below shows approximate loss figures for typically-available co-
axial cables frequently used in HF installations.
I
NSTALLATION
B
ASE
S
TATION
I
NSTALLATION
Loss in dB per 30 m
(
100 ft
)
for Selected 50 Ohms Coaxial Cables
(A
SSUMES
50 O
HMS
I
NPUT
/O
UTPUT
T
ERMINATIONS
)
Loss figures are approximate; consult cable manufactures’
catalog for complete specifications.
Loss figures can increase significantly if high SWR is present
on the transmission line.
C
ABLE
T
YPE
RG-58A
RG-58 Form
RG-8X
RG-8A, RG-213
RG-8 Form
Belden
®
9923
RG-17A
2 MHz
0.55
0.54
0.39
0.27
0.22
0.18
0.08
15 MHz
1.75
1.50
1.07
0.85
0.65
0.50
0.30
28 MHz
2.60
2.00
1.85
1.25
0.88
0.69
0.46
L
OSS
Summary of Contents for VX-1400
Page 39: ...37 VX 1400 OPERATING MANUAL SELCALL TELCALL OPERATION NOTE ...
Page 55: ......
