MFJ-1768 Dual Band Yagi Instruction Manual
2
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
(conductive or non-conductive)
capable of
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.
