MFJ MFJ-1779C Instruction Manual

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MFJ-1779C 20-6 Meter Dipole Antenna

INTRODUCTION

The MFJ-1779C one-half wavelength, single-band, dipole is a center-fed
antenna that can be tuned for operation on any frequency between 6 meters and
20 meters. (54-14 MHz) The antenna will handle full legal limit power. The
dipole is made using #14 copper wire, a durable center insulator enclosing an
SO-239 connector, and terminated with ceramic insulators. The ends of the
dipole are adjustable and should be cut to the desired length of operation. A
suitable length of wire comes with each antenna to achieve resonance at the low
end of each band.

WARNING: Never place the antenna in a location where contact

with power lines is possible. Death, serious injury, and
damage can occur.

CHOOSING A LOCATION

Choose a location clear from obstructions such as other antennas, buildings, and
power lines. Never place the antenna near power lines. Try to keep the
antenna away from metal buildings and other such structures, which will affect
the performance of the antenna. The optimum height of the antenna is 1/2
wavelength of the operating frequency above ground. This can be calculated by
dividing 468/ (frequency in MHz). Optimum antenna height will vary due to
different ground conditions and nearby objects.

The MFJ-1779C can be suspended from many different supports. The most
common being two trees. The antenna should be suspended using a weather
resistant, non-metallic, nylon rope. Always leave a few extra inches in the
support rope to allow for wind movement of the antenna. This is especially
important when trees are used for supports. If the rope is to tight the antenna
could be damaged.

The antenna can be installed in three different ways:

HORIZONTAL ANTENNA

This installation requires two supports with a minimum distance of the overall
length of the antenna. It is a good idea to also provide a support for the center
insulator of the antenna, which will relieve the stress on the center insulator.

MFJ-1779C ½ Wavelength Dipole Antenna Instruction Manual

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INVERTED ANTENNA

This installation only requires one tall and two short supports. The center
insulator of the antenna should be the highest point of the antenna.

SLOPED ANTENNA

This installation requires one tall and one short support.

TOOLS AND ACCESSORIES NEEDED FOR ASSEMBLY

• SWR Analyzer (MFJ-259) OR SWR Meter And HF Radio

• Weather Resistant Non-Metallic Nylon Rope

• Wire Cutters (large enough to cut #14 wire)

• Coax

FREQUENCY ADJUSTMENT

The MFJ-1779C dipole antenna can be tuned for use on any amateur band from

14.0 to 54 MHz. Refer to the tuning chart below for approximate lengths.
ALWAYS HANG THE ANTENNA IN THE DESIRED OPERATING
LOCATION FOR TUNING. CHECK THE RESONANCE POINT OF THE
ANTENNA BEFORE ANY WIRE IS REMOVED.

1. Remove the antenna and parts from the packaging.

2. Decide on the center frequency of operation. The table below has
approximate lengths for each band. Column A gives the approximate lengths
of the entire antenna. Column B gives the length of each side of the dipole.
The lengths can also be determined by using the following formula. This
formula will give the length of the ½ wavelength dipole. This must be
divided by two in order to get the length of each side of the dipole.

468/frequency (MHz)=1/2 wavelength

Band A B

20 424"(36ft) 211"(18ft)
17 312"(26 ft) 156 (13ft)
15 267"(23ft) 133" (12ft)
12 230"(20 ft) 115" (10ft)
10 198" (17ft) 99" (9ft)

6 112”(10ft) 56”(5ft)