MFJ MFJ-1756 User Manual
MFJ-1756 Instruction Manual 6 Meter Ground Plane Antenna
MFJ-1756 6 METER GROUND PLANE ANTENNA
INTRODUCTION
The MFJ-1756 Ground Plane Antenna features a DC grounded element and a ground
isolated radial system for improved performance.
The ground isolated radial system, unique to the MFJ-1756 antenna, reduces undesirable
feedline and supporting structure radiation by eliminating common mode current paths.
This unique system improves transmission by producing a much cleaner pattern with
more signal at desired angles, and also reduces conducted noise reaching the antenna over
the outside of the feedline or antenna support. It also insures that the length of the
feedline or support does not change the antenna's resonant frequency or SWR.
The MFJ-1756 is easily cut for the desired area of the six meter band. A rugged low
impedance air insulated matching stub provides convenient adjustment of base impedance
(a normal ground plane is much less than 50 ohms) allowing adjustment to a perfect 1:1
SWR. Power capability is 1000 watts RF continuous.
CHOOSING A LOCATION FOR THE ANTENNA
WARNING: Improper installation and assembly can be
hazardous! Read these instructions thoroughly
before attempting to assemble, install or operate
this product! Always mount this antenna so that
it is out of the reach of adults as well as
children. High power transmitting devices produce
voltages that can cause severe burns or other
injuries.
For the best performance on receiving and transmitting, mount this antenna in a clear
location at least a few feet above or 20 feet away from buildings, towers, feedlines, utility
wires, and other antennas. While your own ingenuity and particular circumstances will
determine the final mounting method, we will pass along some rules that can not be
neglected.
Never mount this antenna in a location that will permit unsuspecting people to come in
contact with the radials or any other part of the antenna.
Never mount this antenna where a mechanical failure might allow the antenna to contact
power lines or other utility wires.
Always ground the feed line at the point where it enters a building to a good earth ground
for lightning protection.
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MFJ-1756 Instruction Manual 6 Meter Ground Plane Antenna
This antenna should be mounted on a rigid support. The mounting clamp supplied with
this antenna accepts masts between one and 1.5 inches outside diameter.
Tools required for assembly are:
• Hacksaw or Tubing Cutter
• 1-Phillips screwdriver
• 3/8" open end wrench
• 7/16" open end wrench
PARTS LIST
Note: All screws and nuts are stainless steel.
As you unpack this antenna, you should find the following items. Before attempting to
install this antenna, check the parts bag to insure that all hardware is accounted for. In the
event anything is missing, please contact MFJ Enterprises, Inc. immediately.
1 MFJ-1756 Instruction Manual
1 Antenna Base assembly
Parts Bag:
2 10-32 x 1" Phillips head bolts
2 10-32 stainless nuts
4 10-32 lock washers
1 10-32 nut
1 4-40 Phillips head screw
1 4-40 kep nut
2 2 1/2" x 1 3/4" Stainless steel plates
2 2 1/2" x 1 1/4" Fiberglass plates
1 U bolt assembly (2 nuts and 2 washers included)
2 plastic bushings
1 1/4" endcap
Rod Pack:
4 59 5/8" radials
1 54 3/4" radiator
1 Matching hairpin stub
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MFJ-1756 Instruction Manual 6 Meter Ground Plane Antenna
ASSEMBLY PROCEDURE
Locate the base of the antenna (Figure 1) to begin the assembly.
Figure 1 Antenna base.
Step 1:
To attach the matching hairpin stub to the antenna base (Refer to Figure 2):
A. Place the longer end of the matching stub through the 10-32 screw that extends
through the ceramic insulating post on top of the antenna base. Thread the 10-32 nut
on the 10-32 screw and tighten with a 3/8" open end wrench. Do not over tighten..
B. Locate the hole on the top of the base and insert the 4-40 screw through the holes on
the short end of the matching stub and the antenna base. From the inside of the base,
thread the 4-40 kep nut on the screw and tighten. To tighten, hold the screw with the
1-Phillips screwdriver and hand tighten the nut.
.
Figure 2 Antenna base with Matching Stub attachment.
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