MFJ MFJ-1779A User Manual
MFJ-1779A 160-Meter Dipole Instruction Manual
INTRODUCTION
The MFJ-1779A half-wavelength, single-band dipole is a center-fed antenna that
can be tuned for resonance anywhere in the 160 meter amateur band (1.8-2.0
MHz). It will handle full legal limit power. The dipole is made using number 14
stranded copper wire, a durable center insulator with a SO-239 coax connector,
and is terminated with ceramic insulators. The dipole should be shortened to the
required length, and enough wire is provided for resonance at 1.8 MHz..
CHOOSING A LOCATION
Choose a location as clear as possible from obstructions such as other antennas,
buildings, and power lines. Never place any antenna near power lines. Try to
keep the antenna away from metal structures, which will affect its performance.
The optimum height of any dipole is one-half wavelength of the operating
frequency above ground or higher. This can be calculated in feet by dividing 468
by the frequency in MHz. Optimum antenna height always varies due to
different ground conditions and nearby objects.
The antenna should be suspended using a weather resistant, non-metallic rope.
Always leave a few extra inches in the support rope to allow for wind movement
of the antenna, especially important when trees are used for supports. Dipoles
can be installed in three different ways
:
Horizontal: Requires two supports as far apart as the length of the antenna
(about 270 feet for 160 Meters). Because of its length (and consequent weight)
this antenna must also be supported in the middle.
Inverted “V”:
center insulator should be the highest point of the antenna; tie off the ends to any
convenient points and get the ends of the antenna as high as possible.
Sloped: One end of the antenna is supported as high as possible and the other
end tied off to a support at ground level.
A more likely installation for an antenna of this length. The
TOOLS AND ACCESSORIES FOR ASSEMBLY
• SWR analyzer (an MFJ-259) or SWR meter and HF radio
• Weather resistant, strong non-metallic rope
• Wire cutters (large enough to cut #14 wire)
• Coax
1
MFJ-1779A 160-Meter Dipole Instruction Manual
1. Attach a suitable length of strong nylon rope to the center insulator.
Remember to install enough rope to raise and lower the antenna for
tuning.
2. Attach a suitable length of 50-ohm coax to the antenna.
3. Install the insulators on each end of the antenna temporarily by placing
the wire through one end hole of the insulator and winding it back
around the dipole wire.
4. Attach rope to the center and end insulators.
5. Raise the antenna into position.
6. Check the resonant frequency of the antenna using an SWR analyzer or
a transmitter/SWR meter. The resonance point should be near or below
the bottom of the 160 meter band (1.8 MHz).
7. To raise the resonance point, remove equal lengths of wire from each
end of the antenna. Start by removing about two feet from each end and
re-check the resonance point.
8. When the desired resonant frequency is reached wrap the wire ends
securely to the end insulators
Always hang the antenna in the desired
operating position for tuning. Check the
resonant point of the antenna before
removing any wire.
WARNING: Never place any antenna where
contact with power lines is possible. You can
be electrocuted.
TECHNICAL ASSISTANCE
If you have any problem with this unit first check the appropriate section of this
manual. If the manual does not reference your problem or your problem is not
solved by reading the manual you may call MFJ Technical Service at 662-323-
0549 or the MFJ Factory at 662-323-5869. You will be best helped if you have
your unit, manual and all information on your station handy so you can answer
any questions the technicians may ask.
You can also send questions by mail to MFJ Enterprises, Inc., 300 Industrial
Park Road, Starkville, MS 39759; by Facsimile to 662-323-6551; or by email to
techinfo@mfjenterprises.com. Send a complete description of your problem, an
explanation of exactly how you are using your unit, and a complete description
of your station.
2
Loading...