Yaesu VR-5000, Руководство по эксплуатации

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VR-5000 O
PERATING
M
ANUAL
10
Installation
Antennas for Low- and Medium-Frequency Reception (below 2 MHz)
Good all-around reception will be obtained using a single long random length wire, con-
nected to the (red)
Hi-Z
terminal on the rear panel. The wire should be supported as high
above ground as possible by insulators at the end at possibly mid-span, depending on the
length of the wire. The longer the wire, the stronger will be the signals received.
Insulated wire is generally preferred, as it is less susceptible to corrosion. The wire should
be clear of nearby metallic objects to the greatest extent possible.
A good earth ground connection, as shown in the illustration, can be essential to good
performance of a random length antenna. It may be connected to the Black terminal just to
the left of the Red antenna terminal.
Antennas for Short-wave (HF)
Optimum performance on frequencies between 2 and 30 MHz will generally be obtained
through use of a resonant antenna with an impedance near 50 Ohms at the frequency of
interest. Broadband or multiband “Dipole” antennas, such as the Yaesu model YA-30, are
available from your dealer.
If a particular frequency in the HF range is of interest to you, a half-wavelength Dipole
antenna may easily be constructed from readily-available materials. A dipole consists of a
length of wire, cut according to the formulas below; the wire is broken in the middle, and
insulators are installed at each end and in the middle. A 50- or 75-Ohm coaxial cable is
then connected in the middle, with the center conductor of the coaxial cable going to one
side of the center insulator and the shield of the coaxial cable connecting to the other side
of the insulator.
Length (meters) = 142.5 ÷ Frequency (MHz), or
Length (feet) = 468 ÷ Frequency (MHz)
Better “balance” in the antenna’s reception pattern will be obtained if you make a coil of
coaxial cable, ten turns of about 10” (25 cm) in diameter, just below the center insulator of
the Dipole antenna. Tape the turns together securely to hold them in place.
The Dipole will work well near its design frequency. However, if you are interested in
reception on several frequency bands separated by a number of MHz (for example, the 7
MHz band and the 15 MHz band), you may wish to cut wires for each band of interest, and
solder the center ends of these different-length wires together on each side of the center
insulator. The outer ends may then be fanned out so that they are separated by a few feet.
Install a type “M” (“PL-259”) coaxial connector at the station-end of the coaxial cable, and
connect the coaxial cable to the coaxial jack (“
Antenna A ”) on the rear panel of the VR-
5000
.