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MFJ-1792/1793 Instruction Manual
Vertical Antenna
MFJ-1792/1793 Vertical Antenna
Table of Contents:
Introduction ................................................................................................................ 1
Description.................................................................................................................. 1
Bandwidth, SWR, and Power Handling ....................................................................... 2
Choosing a Location for the Antenna........................................................................... 3
Grounding ................................................................................................................... 3
Maintenance ................................................................................................................ 4
Tools and Time Required for Assembly ....................................................................... 4
MFJ-1792 Parts List.................................................................................................... 5
Assembly and Installation Procedure............................................................................ 6
Raising the Antenna..................................................................................................... 11
Tuning the Antenna ..................................................................................................... 12
Technical Assistance.................................................................................................... 13
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Table of Contents
Related Manuals for Tarheel Antennas MFJ-1792
Summary of Contents for Tarheel Antennas MFJ-1792
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Page 1: Table Of Contents
Choosing a Location for the Antenna................3 Grounding ........................3 Maintenance ........................ 4 Tools and Time Required for Assembly ............... 4 MFJ-1792 Parts List....................5 Assembly and Installation Procedure................6 Raising the Antenna..................... 11 Tuning the Antenna ..................... 12 Technical Assistance....................13... -
Page 2: Introduction
80 meter band. DESCRIPTION The MFJ-1792 / 1793 operates as a full quarter wave on 40 and 20 meters, and a top loaded antenna on 80 meters. Over a good ground system the MFJ-1792 / 1793 has excellent efficiency on 40 and 20 meters, because no loading coils are used on these bands. -
Page 3: Bandwidth, Swr, And Power Handling
MFJ-1792/1793 Instruction Manual Vertical Antenna The radiating element on the 80 meter band is 33 feet tall, constructed with large diameter aluminum tubing. The smallest diameter used is 1 1/8 inches. The antenna has a swivel base to allow easy mounting and access to the top for tuning the 80 meter band. The swivel base is constructed with heavy duty thick aluminum, and a large diameter, super strong, solid fiberglass insulator rod. -
Page 4: Choosing A Location For The Antenna
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. -
Page 5: Maintenance
MFJ-1792/1793 Instruction Manual Vertical Antenna MAINTENANCE Your antenna is constructed of heavy duty non-corrosive materials and should withstand normal climates for many years. The use of some type of coaxial connector moisture protection is recommended at the bottom coax connection and also around the matching network feed point, especially in coastal areas where salty mist is commonplace. -
Page 6: Mfj-1792 Parts List
MFJ-1792/1793 Instruction Manual Vertical Antenna SAFETY PRECAUTIONS!! 1.) THIS ANTENNA IS AN ELECTRICAL CONDUCTOR. 2.) ANY CONTACT BETWEEN THE ANTENNA, FEEDLINE OR SUPPORTING STRUCTURE AND POWER LINES WILL RESULT IN DEATH OR SERIOUS INJURY. FOR SAFETY PLEASE: 1.) DO NOT INSTALL THIS ANTENNA WHERE THERE IS ANY POSSIBILITY OF CONTACT WITH UTILITY LINES. -
Page 7: Assembly And Installation Procedure
MFJ-1792/1793 Instruction Manual Vertical Antenna [ ] One 10-32 Nut [ ] One 1/4" Id Spacer [ ] Nine 1/4-20 Nuts [ ] Nine 1/4" Split Washers [ ] Two 6-32 Nuts HARDWARE BAG #3 (20 METER KIT - for 1793 only) [ ] Two 3/16"... - Page 8 MFJ-1792/1793 Instruction Manual Vertical Antenna NOTE: This antenna can be mounted on ground or roof level mounts only! 1- Prepare a ground-level mounting mast that will permit easy initial testing and adjustment. Set up stable supports (table, saw horses etc.). Also a flat ground can be used.
- Page 9 MFJ-1792/1793 Instruction Manual Vertical Antenna 8- Insert End B of Tube 4 into End A of Coupler 2. Line up holes. Bolt tube and coupler together with a 1/4 - 20 x 1 3/4" bolt, 1/4 - 20 nut and split washer. Place and secure a hose clamp over the slit. See Figure 2.
- Page 10 MFJ-1792/1793 Instruction Manual Vertical Antenna 16- Screw a #10 nut over the threaded rod. Slide the threaded end of the 55" rod through the triangular support bracket with the angle pointing down. Thread another #10 nut over the rod to sandwich the bracket between the two nuts.
- Page 11 MFJ-1792/1793 Instruction Manual Vertical Antenna 23- Attach the 20 meter element to the antenna using hose clamps over the L- brackets. Secure hose clamps. figure inside front cover and figure 3. 24- Place guy wires on guy wire mounts. Make sure the guys are non-...
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Page 12: Raising The Antenna
MFJ-1792/1793 Instruction Manual Vertical Antenna 26- Assemble the Loading coil assembly by placing six of the 27" long spokes into the ring assembly. Tighten the 6-32 x 1/4" screws until the spokes are snug. See Figure 9. 27- With the help of another person, move the antenna to the location of the ground pole. -
Page 13: Tuning The Antenna
TUNING THE ANTENNA Measure and record the frequency on which the lowest SWR occurs for the 80, 40 and 20 meter bands. The MFJ-1792 is tuned for lowest SWR either at the lower frequency of each band or slightly below. -
Page 14: Technical Assistance
MFJ-1792/1793 Instruction Manual Vertical Antenna 80 m: 1" trimmed off a spoke equals approximately 10 KHz WARNING: Shortening the spokes from the looped end will affect the performance of the antenna and degrade its power handling capabilities. If the resonant frequency on 80 meter is lower than your equipment can detect, take one spoke off the capacitance hat to raise the resonant frequency. - Page 15 MFJ-1792/1793 Instruction Manual Vertical Antenna...
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