MFJ-1740
INSTALLATION INSTRUCTIONS
The MFJ-1740 can be mounted
on
any 1" to 1-1/2" tubular mast. The
mast may be a conductive (metal) or a non-conductive (pvc)
material
.
.
WARNING: DO NOT MOUNT ANTENNA NEAR POWER LINES.
Death or serious injury can result.
For optimum performance the antenna should be mounted as high
as possible. However, if the mast itself is located on a high
elevation, such as a hill or mountain, the need for a tall mast will
not be as critical.
To mount the antenna on the mast, insert the mast into the
clamp as shown in figure-2. Confirm that the mast is mounting on
the front of the chassis, as shown in figure-2.
The coax from your radio may
now
be connected to the antenna.
The connector is an SO-239; so the connection should be fast and
easy.
TUNING INSTRUCTIONS
The antenna has been preset for low SWR through the 2 meter band.
However, SWR can change from place to place; so some adjustment might
be necessary.
After installing the antenna, check the SWR. For operation
.throughout the 2 meter band, the SWR should be lowest at 146 MHz.
If the antenna needs to be adjusted, loosen the radiator retaining
nu
t
(see figure-2). If the SWR is lowest on a frequency above the
desired operating frequency, lengthen the radiator. If the SWR is
lowest on a frequency below the desired operating frequency, shorten
the radiator.
Be careful when tightening the retaining nut on the radiator. If
the retaining nut is too tight the ceramic insulator may be damaged.
CONVERSION INSTRUCTIONS
READ ENTIRE INSTRUCTIONS BEFORE ATTEMPTING TO CONVERT YOUR ANTENNA
To convert the MFJ-1740 to a 1/4 wave antenna for 220 MHz, the
radiator should be trimmed to a length of 12 inches, and each radial
should be trimmed to a length of 12 3/4 inches.
To convert the MFJ-1740 to a 1/4 wave antenna for 440 MHz, the
radiator should be trimmed to a length of 6 3/16 inches, and each
radial should be trimmed to a length of 7 1/16 inches'.
IMPORTANT NOTE:
To find radiator length, measure from the tip of the radiator to
the top of the radiator retaining nut. Leave approximately one inch
of threaded radiator below the retaining nut.
Measure the radial length from the tip of the radial to the
center of its 6-32 screw.
Содержание MFJ-1740
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