MFJ-1792/1793 Instruction Manual
Vertical Antenna
3
2.) DO NOT LOCATE THE ANTENNA SUPPORT WHERE IT
CAN
CONTACT POWER LINES IN THE EVENT OF MECHANICAL
FAILURE OR ACCIDENT.
3.) FOLLOW THE GUIDELINES FOR ANTENNA
INSTALLATION
AS RECOMMENDED BY THE US
CONSUMER PRODUCT
SAFETY COMMISSION.
CHOOSING A LOCATION FOR THE ANTENNA
The ideal antenna mounting location is an open area more than 70 feet away from other
large conducting objects or antennas. If such a location is
not
available, the
least
obstructed
location should be selected.
This antenna should be mounted on a rigid support. The mounting U-Bolts are supplied
with this antenna. The antenna accepts masts between one and 1.5 inches outside
diameter. Additional holes in the base mount of this antenna will accept mast clamps up to
2" OD. Soft or thin wall masts should not be used to mount this antenna to any
supporting structure.
The MFJ-1792 / 1793 will perform quite well in ground mounted installations with a good
ground system of either welded mesh chicken wire or 8 or more 33 foot long radials. The
antenna can be mounted a few feet above level with its ground plane hanging down until it
reaches the ground then spreads out. If the antenna is ground mounted, it
MUST
be
surrounded with a protective non-metallic fencing. This will increase the safety and lessen
the likelihood of damage to the antenna.
GROUNDING
Unlike some other verticals, this antenna requires an RF ground system. However, it is a
good idea to have some sort of earth connection to avoid lightning damage to station
equipment and to improve operator safety. The feedline's shield should be grounded at the
entrance point of the building
before
it reaches the operating position. Failure to do so
can result in lightning damage to the equipment.
Grounds should consist of a solid copper rod driven into the soil (at least 6 feet deep).
Never use woven flexible braiding for ground connections unless
absolutely necessary
.
Braiding has a very high resistance to both RF and lightning. Copper flashing, wide
copper foil, or large gauge solid copper wires are the proper materials for use in RF and
lightning grounding applications.
The use of an in-line coaxial lightning arrestor will only offer a minimal improvement in
lightning protection. The best method of protecting the station equipment is to disconnect
the feedline outside the building or, at the minimum, use a switch to disconnect and
ground the feedline.
