INTRODUCTION: The MFJ-1754 is designed for use on the 2 meter and the 70 centimeter bands. On the 2 meter band the MFJ-1754
behaves as a vertical 1/4 wave antenna, however on 70 centimeter band the MFJ-1754 is a gain antenna. It is
constructed of a 1/2 wave over a 1/4 wave antennas, which gives it a higher gain for extra long range. The MFJ-1754
uses a sloped ground plane to ensure a low SWR across both bands and, to minimize the feed line radiation which
can result in pattern distortion and skewing.
CHOOSING A LOCATION FOR THE ANTENNA
The MFJ-1754 can be mounted on any 1" to 1 1/2" mast (conductive or non conductive.)
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. While your ingenuity and
particular circumstances will determine the final mounting method.
MFJ-1754 PARTS LIST
The MFJ-1754 is shipped partially assembled. The following parts should be in the package:
ITEM QUANTITY DESCRIPTION
A 3 Radials
B 1 Chassis
C 3 6-32 X 1/2 Screws, & nuts
D 1 U-Clamp Assembly
[ ] - 7/16" Open End Wrench
[ ] - #1 Screwdriver
[ ] - 5/64" Allen Wrench (Provided)
- Always mount this antenna so that it is out of reach of adults as well as children. The radiator and the
ground plane can cause injury and or severe RF burns.
- Always wear eye protection when working with antenna
- You can be killed if the antenna, feed line, or the equipment used to install the antenna accidentally
contact any utility lines. Never install an antenna near power lines.
ASSEMBLY AND INSTALLATION PROCEDURE
MFJ-1754 Dual Band Antenna Instructions
During assembly of this antenna refer to the figures in this manual and the picture on page 1.
After the antenna is assembled it must be checked and adjusted for resonant frequency and SWR.
NOTE: Wear safety glasses whenever working near or on this antenna
STEP BY STEP PROCEDURE
1- Insert a 6-32 x 1/2" screws through hole #1 with thread toward the inside of the chassis. Start a 3/8" nut on the tip
of this screw (see Figure 1).
2- Install the remaining two 6-32 x 1/2" screws and 3/8" nuts into hole #2 and hole #3 as was done in step 1
3- Insert a radial into hole A, straight end first (see figure 2). Sandwich the hooked end of radial between the chassis
and the 3/8" nut of the screw in hole #1. Secure the radial by tightening the 6-32 screw .
4- Install the remaining radials in the same manner. One radial should be inserted through hole B and secured with
screw in hole #2, the other through hole C and secured with screw in hole #3.
5- Assemble the U-Clamp in the chassis as shown in figure 2.
6- The antenna assembly is completed now. Antenna can be tested for frequency and SWR using an analyzer or a
transceiver on low power, then fine tuned before mounting it on a permanent location.
TUNING THE ANTENNA
The antenna is pre-tuned for low SWR on both the 2 meter and the 440 MHz bands. However, the SWR can change
from location to an other. In this case some minor adjustment is perhaps necessary.
Adjustment on this antenna in done by losing the set screw (see figure 1) and increase or decrease the length of the
radiator element to lower or increase the frequency respectively.
If a high frequency is desired and can not be obtained at the minimum setting of radiator length. Approximately 1/4
inch off the radiator bottom end can be cut to increase the frequency resonance of the antenna.
If the SWR of the antenna can not be adjusted using the radiator, it is possible to slightly bend the radials (only a few
degrees) up or down, one at a time to achieve a minimum SWR.
MFJ-1754 is constructed of heavy duty non corrosive materials (aluminum and stainless steel hardware) and should
withstand normal climates for many years. The use of some type of coaxial connector moister protections
recommended at the coax connection, especially in coastal areas where salty mist is common.
GE makes "SILICON DIELECTRIC COMPOUND" which are good material for this application.