Vertex Standard VX-1400 Spezifikationen PDF herunterladen (Seite 19)

17VX-1400 OPERATING MANUAL

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.

INSTALLATION

BASE STATION INSTALLATION

Loss in dB per 30 m

(

100 ft

)

for Selected 50 Ohms Coaxial Cables

(

ASSUMES 50 OHMS INPUT/OUTPUT TERMINA TIONS

)

 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.

CABLE TYPE

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

LOSS

1 2 ... 14 15 16 17 18 19 20 21 22 23 24 ... 55 56

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