MFJ-2990 43-Foot Self-Supporting Vertical Antenna

MFJ-2990 43-Foot Self-Supporting Vertical Antenna
MFJ-2990 43-Foot Vertical Antenna
MFJ-2990 43-Foot Self-Supporting Vertical Antenna
The MFJ-2990 is a 43-foot self-supporting vertical antenna that covers 160-6 meters with the use of
an wide range antenna tuner. Because the top 9-foot section of the antenna consists of a 1/8”
diameter stainless steel whip, the MFJ-2990 has the lowest wind-loading and has the least visual
impact of any 43-foot vertical antenna on the market.
The MFJ-2990 is built-to-last – using incredibly strong 6063 T-6 aircraft strength aluminum tubing for
the radiator and all stainless steel hose clamps and hardware. And it assembles in about an hour.
WARNING: Improper installation and assembly can be hazardous! Read these instructions
thoroughly before attempting to assemble, install or operate this product! High power
transmitting devices produce voltages that can cause severe burns or other injuries.
Electrical Specifications
Band Coverage:
Power Rating:
160-6 Meters with external antenna tuner
1500 watts CW/SSB
Mechanical Specifications
Antenna Diameter
Overall Length:
Wind Load:
2”OD bottom section, 1/8” stainless steel whip top section
43 feet
20 pounds
2 square feet
For best performance, mount the antenna in a clear location away from buildings, towers,
feedlines, utility wires, and other antennas.
Never mount this antenna in a location that will permit unsuspecting people to come in
contact with any part of the antenna.
Never mount this antenna where a mechanical failure might allow the antenna to contact
power lines or other utility wires.
Always ground the feedline to a good earth ground at the point where it enters a building for
lightning protection.
WARNING: Contact with the antenna during operation can result in severe RF burns.
MFJ-2990 43-Foot Vertical Antenna
Permanent Installation
The ideal installation location is a rigid pole set in concrete.
Portable Operation
The MFJ-2990 may be disassembled as necessary for transporting to a temporary location.
Even for temporary or portable operation, do not be casual about mounting integrity. If the
antenna falls, it will be damaged and may cause serious injury. Whatever type of installation
you choose, remember that the antenna should be installed where it cannot be contacted by
people or animals or come in contact with power lines.
As you unpack your antenna, verify that the following parts are supplied:
Item Part Description
2” OD x 0.12” x 6’ AL Slotted Tube
1.75”ODx0.058”x6’ AL Slotted Tube
1.625”ODx0.058”x6’ AL Slotted Tube
1.50”ODx0.058”x6’ AL Slotted Tube
1.375”ODx0.058”x6’ AL Slotted Tube
1.25”ODx0.058”x6’ AL Slotted Tube
1.125”ODx0.058”x6’ AL Slotted Tube
1.00”ODx0.058”x6’ AL Slotted Tube
Parts Pack
Stainless Steel Clamp 2-1/4
Stainless Steel Clamp 1-1/2
Stainless Steel Clamp 1-1/6
Hy-gain Base Mount Assembly Kit
Mast saddle
Insulator ABS
Split washer
5/16 Nut
Base Plate
4-40X3/8 Screw
4-40 kep nut
108-inch Stainless Steel Whip
Legal Limit 4:1 Balun
Part No.
Optional Items:
MFJ-915 RF Isolator
MFJ-272 Lightning Surge Protector
MFJ-2990 43-Foot Vertical Antenna
The estimated assembly time is about one hour. Antenna assembly requires the following hand
• ½” wrench, #2 Phillips screwdriver
• 5/16" nut driver for hose clamps.
• Safety glasses.
• Felt-tip permanent marker
• 4-6 foot step ladder
Additional Materials Needed
1) Mounting pipe: 4-foot long steel pipe 2.0″ OD/0.125″ wall thickness.
2) Quick-setting concrete – For installing the mounting pipe
3) High quality low-loss 50-Ohm coax terminated with PL-259 connectors from antenna to
transmitter. LMR-400 coax cable is recommended.
4) 3/8” lugs for attaching radials to the ATB-65 mounting plate.
5) 18-gauge or larger copper wire for radials, insulated or uninsulated.
WARNING! You can be killed if the antenna, feedline, or the equipment used to install the
antenna accidentally contacts any utility lines. Never install an antenna near power lines!
1. Be careful when carrying and installing the antenna. It is heavy enough to cause you to lose
your balance if it is handled too casually or if the antenna is snagged on anything.
2. Mount the antenna to minimize accessibility. The antenna can cause serious RF burns.
Refer to the figures in this manual during assembly. Assembly consists of installing a ground
mount, installing the base mount assembly to the ground mount, assembling the telescoped
antenna, installing the antenna to the base mount, installing the balun, radials and feedline, and
finally telescoping the antenna to its full height. .
WARNING: Wear safety glasses whenever working with any antenna.
Step-By-Step Procedure
Note: Select a mounting location clear of power lines, structures and other antennas. Consider
the proximity of overhead power lines, utility cables and wires. The vertical should be
MFJ-2990 43-Foot Vertical Antenna
mounted away from local noise sources or metallic objects which can re-radiate noise and affect
the radiation pattern.
Note: The use of radials is required with any vertical antenna for optimum performance. If
possible, a minimum of 16 radials should be used and the radials should be at least 43 feet long
(the length of the antenna). However, more short radials are better than fewer longer radials.
Increasing the number and length of the radials will improve performance. Radials should be
connected as close to the base of the antenna as possible. A good location for connecting radials
is the U-bolt mounting nuts on the ATB-65 base mounting assembly.
Mounting Pipe Installation:
The mounting pipe should consist of a 4-foot length of thick-walled (1/8” minimum) galvanized
steel pipe with an outside diameter of 2”. Do NOT use aluminum, as aluminum will corrode in
short order. Dig a 1-foot diameter hole deep enough to accommodate 2.5-feet of pipe and a few
inches of gravel at the bottom for drainage. 18” of pipe should extend above ground level.
These are minimum requirements in that a longer pipe, deeper mounting hole, and larger
diameter hole is better – especially if your ground soil is somewhat unstable (moves due to
freezing/thawing or moisture content). Set the pipe on the gravel and pour concrete around the
pipe until the concrete is level with the ground. Use a level to ensure that the pipe is straight.
Allow 8-10 hours for the concrete to set.
Alternative Mounting Pipe Installation
You may elect to support the antenna by bracketing it to your house, wood fence or other
structure. If you elect to do this, it is not necessary to pour concrete for the mounting pipe.
To bracket the antenna to a house, wood fence or other structure, place a piece of 2” PVC pipe
around the antenna and use a 2” galvanized fence post support bracket to affix the antenna to the
support structure. The fence post support bracket should go around the 2” PVC pipe as shown in
Figure 1 below. Add one or more 2x4” treated wood spacers as desired to space the antenna
away from the supporting structure as shown in Figure 1.
House eve or
wood fence
Lag bolts or
screws, 2 plcs
Treated 2x4” wood
spacer, painted
2” fence post
Short piece of 2” PVC
around antenna
Figure 1: Alternative House or Fence Support
Use a plumb to determine the proper location for the ATB-65 Base Mounting assembly and the
mounting pipe. Now simply bury 2-1/2 feet of the mounting pipe in the ground with drainage
gravel at the base, and tamp the fill soil snugly around the pipe. Use a level to ensure that the
mounting pipe is vertical.
MFJ-2990 43-Foot Vertical Antenna
ATB-65 Base Mounting Installation
Attach the ATB-65 Base Mounting assembly to the mounting pipe using two of the U-bolts, pipe
clamps and associated hardware supplied in the ATB-65 kit. The U-bolts should be placed in the
outer mounting holes and the mounting plate. Tighten the U-bolt nuts securely.
Alternative Construction Method
The MFJ-2990 can be assembled without the whip on top if desired. The whip on top of the
antenna reduces wind loading and visual impact of the antenna. If these are not a concern, the
bottom sections of the antenna can be overlapped 5 inches per section. This will create a more
uniform tapered look to the antenna and reduce some of the sway in the top section. After the
overlap is reduced, the very top section, which would normally contain the whip, should be
extended enough to make the overall length of the antenna 43 feet. The aluminum inserts that
hold the whip can be removed by unscrewing the Phillips head screws all the way out. Retain
the parts in case you want to change the assembly in the future.
MFJ-2990 Tubing Preparation:
1) Slide the stainless steel whip into the top 1” section of tubing by loosening the setscrews
on the top and bottom adapter. Insert the whip until it seats into the bottom adapter
completely. Adjust the nut until it is all the way back to the head of the screw. Tighten
the top and bottom screw until the whip is secure in the adapters. Tighten the nut against
the tube until it is snug.
2) Except for the 2”OD 6-foot aluminum tube and the 1”OD tube, measure four-feet from the
slotted end of each tube and clearly mark this position with a permanent felt marker. You
will use these marks when telescoping the antenna to its full length. Mark the 1”OD 6foot tube one foot from the end without the set screws.
3) Slide two tubing clamps over the 1.75”, 1.625”, 1.500”, 1.325”, 1.250”, and 1.125” OD
aluminum tubes. Use the appropriately-sized tubing clamps for the particular aluminum
tubes. Securely tighten one clamp just below the slot cut in the tubes, but leave the
second clamp loosely fitted over the tube slot. The tightened clamp will keep the tubes
from falling into each other when the antenna is vertically placed prior to telescoping the
individual sections. See Figure 3.
MFJ-2990 43-Foot Vertical Antenna
Leave loose until tubing
is extended
Tighten just below slot
Tubing Clamps
Figure 3: Tubing Clamp Positioning
4) Place a #28 (largest) tubing clamp over the bottom 2”OD tube, and tighten over the slot just
enough to keep the tubing clamp from falling.
5) Install the MFJ-1966 108” stainless steel whip into the 3/8x24 insert in the top section of the
antenna. Make sure to use a 3/8 stainless steel split lockwasher, and tighten securely in
6) Progressively telescope each of the aluminum tubing sections into each other, starting with
the top section with the 108” whip.
7) Install the antenna mount U-bolts and insulators on the ARB-65 Base Mount. Raise the
telescoped antenna into a vertical position and insert the lower end into the ARB-65
insulators and U-bolts. Tighten the U-bolt hardware securely.
Balun and Radial Installation
1) Unscrew the balun pipe clamp mounting screws such that the clamps can be fully opened.
Place the balun alongside the antenna mast with the balun pipe clamps located between the
antenna insulating tubing and the UHF connector oriented down. Close the pipe clamps
around the antenna and tighten the clamps securely. The balun pipe clamps provide the
antenna feed. Attach the balun ground wire with the 3/8” lug to a bottom 3/8” U-bolt. See
Figure 4 below.
Balun gnd
Balun clamps
Attach radials under
any/all U-bolt nuts
Gnd Mtg
Figure 4: Balun/Antenna Mounting Details
MFJ-2990 43-Foot Vertical Antenna
2) Attach radials to the ATB-65 using the 3/8” lugs under the U-bolt mounting hardware.
Multiple radials can be attached to each 3/8” lug. Use as many radials as possible –
preferably 16 or more - and make the radials as long as possible.
Final Assembly
1) Place a 4-6” high step ladder alongside the antenna and begin telescoping each section.
Begin with the top section, and telescope this section until you get to the 4-foot marker.
Securely tighten the tubing clamp over the slot in the lower tubing section.
2) Continue telescoping each additional tubing section to its 4-foot mark and securely tighten
each hosing clamp over the slots as you progress. When all sections have been extended,
the antenna has been lengthened to its final 43-foot height.
3) Attach a high quality coax feedline to the SO-239 connector on the UHF connector on the
4:1 balun.
The MFJ-2990 is normally considered to be self-supporting when installed as described in this
manual. And when bracketed to a house, this antenna is even more stable in adverse conditions.
However, if your antenna is located in a part if the country characterized by ice loading or
sustained high winds greater than about 40 mph, you should consider guying to ensure maximum
antenna life. If guying is employed, a 3-point guying system will provide the necessary stability.
The guys should be attached at the top of the 1.25” OD aluminum tube just above the hose
clamp. MFJ-19C100 polyester rope is an appropriate guy rope. Finally, the MFJ-2990 can be
easily telescoped down should very strong storms be forecasted for your area.
Like all 43-foot verticals, the is an MFJ-2990 untuned antenna that provides a compromise SWR
across the 160-6 Meter frequency range. While the untuned SWR may vary depending on your
ground system and mounting location, typically you can expect an untuned SWR of less than 4:1
at your transceiver from 60-6 meters when the antenna is fed with good quality, low loss coaxial
cable (the SWR will actually be lower when higher-loss cables are used). This is easily handled
by any external antenna tuner, and even by most transceiver internal antenna tuners (check your
transceiver’s owner manual to see what your transceiver’s antenna tuner matching range is).
Operation on 160- and 80-meters does require the use of an external wide-range antenna tuner
due to the much higher SWR of the 43-foot vertical on these bands.
For best low angle radiation (good DX performance), an antenna should be no more than 5/8wavelength long on your highest frequency. So the MFJ-2990 43-foot antenna length provides
an excellent low-angle radiation pattern from 160-20 meters. From 17-6 meters the angle of
radiation becomes higher, which reduces the antenna’s DX effectiveness on these higher
frequency bands. However, for optimum performance on the higher frequency bands, the MFJ2990 is easily telescoped down to a shorter length.
MFJ-2990 43-Foot Vertical Antenna
Safety grounding should always be provided to protect equipment, property and persons from the
hazards of lighting strikes and other weather related electrical discharges. Adequate protection
can be accomplished by grounding the shield of the coax to a good earth ground where it enters
the building, or directly burying the cable in the earth for several feet before it enters the
building. A better solution is to use a MFJ-272 Lightning Surge Protector at the entrance of your
home with a heavy duty ground wire to a suitable earth ground, as well as tying into your main
home electrical ground as required by NEC. For maximum lightning protection, the coaxial
cable should be disconnected from the station during threatening weather conditions.
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 balun/coax connection, especially in coastal areas where salty mist is
commonplace. GE makes a pure, silicone grease called "SILICONE DIALECTRIC
COMPOUND" that can be applied SPARINGLY to the threaded area of the female connector.
This compound, or even a clear silicone heatsink compound, will prevent moisture from entering
the connector through the threads and protect the connectors from corrosion. This is the same
type of sealer that commercial antenna installers and CATV companies use with great success.
Plast-DipTM and Liquid Electrical TapeTM, available at your local hardware store, also do an
excellent job of insulating/waterproofing connectors, and can be easily peeled off when desired.
A less desirable, but still adequate sealer is the automobile seam sealer commonly sold as "coax
seal". This is a semi-pliable black or white sealing compound. When installing any "coax seal",
NEVER completely cover the barrel of the coax connector. The sealer should ONLY be placed
near the junction of the threaded part of the chassis connector and the knurled area of the male
connector. This will leave the bottom of the male outer sleeve open and permit the connector to
"breathe" so it does NOT collect moisture!
MFJ-2990 43-Foot Vertical Antenna
MFJ-2990 43-Foot Vertical Antenna
MFJ warrants to the original owner of this product, if manufactured by MFJ and purchased from an
authorized dealer or directly from MFJ to be free from defects in material and workmanship for a period
of 12 months from date of purchase provided the following terms of this warranty are satisfied.
1) The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check, credit card or
money order receipt, etc.) describing the product to establish the validity of the warranty claim and
submit the original or machine reproduction of such proof of purchase to MFJ at the time of warranty
service. MFJ can deny warranty without dated proof-of-purchase. Any evidence of alteration,
erasure, of forgery shall be cause to void any and all warranty terms immediately.
2) MFJ agrees to repair or replace at MFJ 's option without charge to the original owner any defective
product provided the product is returned postage prepaid to MFJ with a personal check, cashiers
check, or money order for $12.00 covering postage and handling.
3) MFJ will supply replacement parts free of charge for any MFJ product under warranty upon request.
A dated proof of purchase and a $7.00 personal check, cashiers check, or money order must be
provided to cover postage and handling.
4) This warranty is NOT void for owners who attempt to repair defective units. Technical consultation
is available by calling (601) 323-9538.
5) Under no circumstances is MFJ liable for consequential damages to person or property by the use of
any MFJ.
6) Out-of-Warranty Service: MFJ will repair any out-of-warranty product provided the unit is shipped
prepaid. All repaired units will be shipped COD to the owner. Repair charges will be added to the
COD fee unless other arrangements are made.
7) This warranty is given in lieu of any other warranty expressed or implied.
8) MFJ reserves the right to make changes or improvements in design or manufacture without incurring
any obligation to install such changes upon any of the products previously manufactured.
9) All MFJ products to be serviced in-warranty or out-of-warranty should be addressed to MFJ, 300
Industrial Park Road, Starkville, Mississippi 39759, USA and must be accompanied by a letter
describing the problem in detail along with a copy of your dated proof-of-purchase.
10) This warranty gives you specific rights, and you may also have other rights, which vary from state to
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