MFJ MFJ-1768 User Manual
MFJ-1768 Dual Band Yagi Instruction Manual
MFJ-1768
Instruction Manual
Table of Contents
Introduction ..................................................................................................................... 2
Choosing a Location for the Antenna.............................................................................. 2
Tools and Time Requirements......................................................................................... 3
MFJ-1768 Parts List ........................................................................................................ 3
Safety Precautions ........................................................................................................... 3
Assembly and Installation ............................................................................................... 4
Tuning..............................................................................................................................7
Grounding Considerations............................................................................................... 7
Maintenance ....................................................................................................................8
Technical Assistance .......................................................................................................8
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MFJ-1768 Dual Band Yagi Instruction Manual
MFJ-1768
Instruction Manual
Introduction
The MFJ-1768 is a National Bureau of Standards (NBS) style yagi that provides optimum gain and
front to back ratio on both the 2 meter and the 70 centimeter bands. On the 2 meter band the MFJ-1768
is a 4 element antenna, on the 70 centimeter band the MFJ-1768 is a 7 element antenna. It is
constructed using lightweight and strong 6061-T6 aluminum material for both the elements and the
boom. The MFJ 1768 elements are insulated from the boom to eliminate the problem of poor electrical
contact to the boom. This antenna uses a dual balance driven element that provides a clean pattern with
minimal skewing. The antenna's 1/4" diameter driven elements provide wide bandwidth that covers
both bands with a low SWR. This antenna uses a single feedline with a ferrite decoupled current balun
for both bands. This technique eliminates the need for extra coax cables, and stops all the parallel RF
current on the coax shield. This prevents unwanted radiation.
The MFJ-1768 is an excellent antenna for use with dual band transceivers. Since the MFJ-1768 is a
dual band antenna there is no need to switch antennas when changing bands. With the use of a duplexer
(such as the MFJ-916) you can connect two different radios (two different bands) to the MFJ-1768 at
the same time.
Choosing a Location for the Antenna
The MFJ-1768 can be mounted on any 1" to 1 1/2" mast
supporting the weight of the antenna and the torque developed by the boom. The MFJ-1768 can be
mounted vertically (generally used for FM transmission), or horizontally (commonly used for SSB
transmission).
The best performance on receiving and transmitting will be obtained by mounting the antenna as high
as possible in a clear location above or away from buildings, feed lines, utility wires, and other
antennas. Your ingenuity and particular circumstances will determine the final mounting method.
The MFJ-1768 is a directional antenna with a major high gain forward lobe and fewer lower gain side
and back lobes. The operating frequency of this antenna is used only in line of site communication. For
that reason it is best to mount the MFJ-1768 on a rotor and be able to orient its major lobe toward the
desired location and obtain maximum performance. Also since the side and the back lobe exist but with
low gain, it is possible to use these lobes for local area communication without rotating the antenna.
(conductive or non-conductive)
capable of
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MFJ-1768 Dual Band Yagi Instruction Manual
Tools And Time Requirements
The estimated time of assembly for this antenna (including reading time) is 1 hour.
Tools required for this antenna are as follows:
- #1 Phillips screwdriver
- 1/4" nut driver
- 7/16" open end wrench
- Push nut assembly tool (supplied)
- Eye protection
- Temporary mast and a table, or flat ground
MFJ-1768 Parts List
The MFJ-1768 parts and hardware are stainless steel, aluminum, or non-corrosive material.
As you unpack your antenna you should find the following list:
[ ] One bundle of long elements for the two meter band
[ ] One bundle of short elements for the 440 MHz band
[ ] One bag containing the following hardware:
- Twenty 3/16" ID insulators
- 30 push nuts 3/16" ID
- Two 1 1/8" red end caps
- One U-bolt and saddle clamp assembly
- Push nut assembly tool
- Two capacitor thin plates for 2 m elements
- Two 4-40 x 1/2" SST screws
- Ten 4-40 SST nuts
[ ] One 1 1/8" diameter (6061-T6) aluminum tubing boom
Safety Precautions
WARNING
-
This antenna is an electrical conductor.
- Contact with power lines can result in death, or serious injuries.
- Do not install this antenna where there is any possibility of contact with power cables or
service drop to buildings.
- The antenna supporting mast and/or tower should not be close to any power lines during
installation or removal in the event the system should accidentally fall.
- Follow the guidelines for antenna installation recommended by the U.S. consumer
product safety commission.
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