MFJ MFJ-6215, MFJ-6217, MFJ-6220, MFJ-6230, MFJ-6240 User Manual

MFJ-62xx Instruction Manual Two Element Colinear Array Antenna

INTRODUCTION

The MFJ version of the classic Collinear Array consisting of two ½ wave radiators in phase is an
antenna that exhibits some degree of gain (~1.6 -1.8 dB), and delivers better than average
transmitted signals even when installed at only ~¼ wavelength above ground, and is directly-fed
with any length of 50-Ohm coax.

A further consideration is that this antenna is also quiet, when compared to inverted “V’s” (and
verticals, especially). A reduction of 2 – 3 “S” units of noise may make the difference in that
DX contact you can now hear above the noise!
And, the modest gain the antenna exhibits might also make the difference in whether that station
also hears you. Only 1.5 dB of gain increases your effective radiated power by half-again as
much; from 100 watts to 150 watts, for example. Capture area is another factor in the good
performance of the array; the MFJ-62XX has twice the capture area of a doublet, or inverted
vee-type “droopy doublet.”

The added bonus: you can virtually “hang & play” this antenna as we construct them. No
tuning, trimming, etc. required. Just follow the easy installation instructions and suggestions, the
warnings, and you’ll be “up and running” in no time flat, and capturing DX, while receiving
signal reports as never before using lesser antennas.

Once connected, you’ll find the MFJ 62xx Collinear Array presents a low SWR across the entire
band. However, it is a “one-band antenna” depending on which band you chose to purchase.
Figure 1 is a generic illustration of the antenna with its shorted stub and coaxial connection.

• Always mount or install antennas beyond the reach of adults and
children. Make certain your antenna installation meets RF
exposure guidelines

• Contact with exposed parts of this antenna system can cause RF
burns and other injuries.

• Constructing or erecting antennas where they may contact
electrical power lines can result in injury or even death

Warnings

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MFJ-62xx Instruction Manual Two Element Colinear Array Antenna

SYSTEM DESCRIPTION

LL

F

Coax to
XCVR or
remote
switch

Figure 1 Two Element Colinear Array

SYSTEM DESCRIPTION

Dimension “L” represents a ½ wavelength, and “F” represents a ¼ wave, which, in this case is a
¼ wave stub, used for matching and phase-shifting. The MFJ 62xx Collinear Array is a
“broadside array,” and is bi-directional perpendicular to the run of the wire. A pair of these
antennas at right angles (NE/SW; NW/SE for example) can provide world-wide coverage. And,
when used with a suitable antenna switching system (Ameritron RCS-10), switching is
convenient and fast, with only a single-line feed into the shack. Or, you can run both coaxial
lines into the shack, and effect switching with a wall-mounted switching unit (MFJ 1700).

If height is a constraint, this antenna functions better than average at even a bit less than a ¼
wavelength above ground/structure. However, it really performs best if “hung” at ½ wave; up to
¾ wave. Higher than that provides diminishing return.

Especially important is keeping the symmetry of the antenna in reference to its ½ wave radiators.
They must not sag more than a foot, with pulled-tight being the best configuration. The
feedline/stub can be “bent” at the bottom, or pulled away at an angle, and some twisting is OK.
Practically, it is best to let it hang straight down and tie it off with rope to avoid lashing about in
windy conditions.

ASSEMBLY AND INSTALLATION

Warning: Never Install an antenna where contact with electrical power lines
is possible. Serious injury or Death may occur.

The MFJ 62xx Collinear Array ships assembled and ready to install. The lengths of the antenna
wires and stub are quite critical and should not be changed. Use Nylon ropes to support the ends
of the antenna from suitable structures or trees. If you are using trees for end supports, be sure to
allow enough slack, or use some type of pulley and counterweight system to prevent the antenna
or rope from breaking when trees sway. Suspend the antenna with at least a 50-pound working

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