DX Engineering DXE-SWA-148 User manual

Linear-Loaded 160m Dipole
Patent Pending
DXE-SWA-148 Rev 1
©DX Engineering 2006
P.O. Box 1491 · Akron, OH 44309-1491
Phone: [phone] ·Tech Support and International: [phone]
Fax: [phone] · E-mail: [e-mail]

Table of Contents
Introduction
Features 2
Mounting Considerations 2
Installation
Feedline 3
Feedline Length Calculator 4
Assembly
Cenetr T Support 5
Support Line 5
Antenna Conenctions 6
Wire Element Connections 6
End-Insulator Connections 7
Tuner Connections 7
Tuning Addendum 7
Optional Accessories 9-10
Technical Support and Warranty 11
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Introduction
The DX Engineering DXE-SWA-148 Linear-Loaded Multi-Band Dipole (Patent Pending) is
a 148 ft, lightweight yet rugged design that is usable with a tuner from 1.8 to 30 MHz. It’s
ideal for portable or tactical use and can be easily installed in attics, small lots or Covenant
Condition Restricted locations.
Features
•Linear-loaded elements for the lower bands reduce wingspan over a dipole
•High efficiency design gives dipole-like performance
•No traps or coils
•1.8 to 30 MHz continuous coverage, 1500W PEP Maximum (375W AM)
•Correct design makes it easily tuned
•Well-designed feedline reduces noise pickup over Windom types.
•Insulated Elements and stainless hardware
•Unique support line combats heavy ice loading
•Black UV color ideal for concealment
The Linear-Loaded Multi-Band Dipole kit includes multi-wire elements which are covered with
a flat-black, lightweight UV-resistant material, custom molded high impact center-T support and
end-insulators, 65 feet of premium ladder feedline and 200 feet of double-braided UV-resistant
Dacron mounting rope. Stainless steel hardware is used for all connections.
The DX Engineering Linear-Loaded Multi-Band Dipole can be used successfully with the balun
incorporated in most high quality antenna tuners to obtain a low SWR across the entire
frequency range. Using an external current balun may provide better performance and permits
converting to coax prior to entering the operating position which will reduce RFI.
Mounting Considerations
When planning the location of your antenna, consideration should be given to the height,
location of suitable support structures and feedline positioning and length.
Generally speaking, these antennas should be mounted as high as possible for best performance.
Antenna height will affect the exact resonance point, radiation pattern, and takeoff angle. The
higher the antenna, the lower the takeoff angle to the horizon, which increases the effective range
of the antenna.
For DX, the minimum height above ground should be 1/2- to 1 wavelength at the lowest
operating frequency. On the low bands, this height becomes impractical for most hams. For
example, a 160m dipole at 70 feet is about 1/8-wavelength above the ground. This antenna
would be good for local and short distance communications, but not optimal for DX, due to the
high takeoff angle and ground absorption. A 40m dipole at 70 feet is approximately
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1/2-wavelength high and is likely to be good for DX and less optimal for local or short range
communications. For more information on antenna design, feedline and radiation angles, consult
a reliable text such as the ARRL Antenna Book.

The antenna, including the 300 Ωfeedline, should also be mounted as far from other structures
as possible. This includes the ends of the wire elements, which are actually the most sensitive
part of the antenna. Any objects, metal in particular, within the near-field radiation pattern can
affect the impedance and radiation pattern of the antenna. The feedline should also come away
from the antenna at right angles for best performance.
Most installations involve compromises due to local terrain, available supporting structures, or
other restrictions. Do the best you can with what you have.
Installation
You should have two rolls of element wire, one 65 foot roll of ladder feedline, and a hardware
packet. Unroll the 2 wire elements and feedline using a hand-over-hand technique. This will
prevent kinks and allow the wires to lay flat.
Feedline
The SWA-148 dipole includes 65 feet of high quality 300 Ωladder line used for the feedline.
This length is the minimum for this antenna and should not be shortened. If your installation
results in excess feedline, it can be zigzagged while suspended in air, but it can't be closer than a
few conductor widths to metallic objects and should not be coiled. If it is necessary to pass close
to a metallic object, twist the line to partially balance the effect on both sides of the feedline.
If you need additional feedline length, the feedline must be in odd multiple lengths of 1/8-
wavelength on the lowest operating frequency, in this case 1.8 MHz, to optimize the impedance
presented to the balun over the frequency range of the antenna. This length can be calculated
using the following formula or use Table 1. The DX Engineering 300 Ωladder line has a VF of
0.88. Note: It might be more convenient to use an external 1:1 balun and convert to coax rather
than add additional 300Ωladder line.
Calculate the Proper Feedline Length
Formula:
123 / Freq (MHz) x VF: Multiply the result times the ODD multiple (1, 3, 5, 7, etc) to get
the correct length closest to your required feedline length.
Where:
123 = 1/8-Wavelength Factor
Freq = Frequency in MHz
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VF = Velocity Factor of Feedline

Lowest Frequency on which the
Antenna Will be Used (MHz)
Make Feedline an ODD Multiple of This Length in
Feet (1, 3, 5, 7, etc.)
VF is 0.88 (DX Engineering 300 Ωladder)
1.8 60.1
3.5 30.9
7 15.4
10.1 10.7
14 7.7
18 6.0
24.9 4.3
28 3.9
Table 1: 1/8-Wavelength Feedline Calculator
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Example: To use this antenna from 160m to 10m, the feedline should be in odd 1/8-wavelength
multiples on 160m. The 160m band starts at 1.8 MHz. Therefore, 123/1.8 = 68.3. Our feedline
VF = 0.88, so 68.3 x 0.88 = 60.1 ft. per 1/8-wavelength. If 90 feet is needed to get to our
operating position, the nearest odd multiple 1/8-wavelength length is 180.3 feet. (60.1 x 3).
If you need more than that, the next odd multiple is 5, therefore, you would need 300.5 feet.

Assembling the Dipole
Center-T Support
The center-T support has pre-drilled holes for attachment of the wire elements, feedline and
support rope.
Support Line
The center-T support’s top hole is used for the attachment of a messenger line that is used to
provide support for the antenna wire and feedline. The use of the messenger line, which is
strongly recommended, will reduce the stress on the element wires and keep the antenna from
stretching over time, which will change its resonant frequency.
Ideally, the messenger line should attach to the same structure used for the dipole, only above it,
forming at least a 30 degree angle between the dipole and the messenger line to support the
antenna. See Figure 2.
Figure 2: Example Mounting Diagram
Two 100 foot spools of Dacron rope are used for the messenger lines. Use one spool for each
side of the line. Each rope should run through the top hole in the center-T support and tied using
the knot depicted in Figure 5 or some other knot that will hold securely. Figure 3 shows the
rope routed through the top hole.
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The excess rope can be used to attach the antenna end-insulators to the support structures. Use
the same structures used by the messenger line if possible. The ends of the rope should be
cauterized with a small flame to prevent the rope braid from fraying.

Connections
Install hardware on the center-T support as shown in Figure 3. Where the feedline and wire
element connect, use the star washer between the lugs as shown in the inset. Star washers are not
used for the other connections.
Figure 3: Assembled Center Support Bracket
Wire Elements
The multi-wire elements must be connected exactly as shown in Figure 3 for the antenna to
work properly. Locate the ends of the wire elements marked with red tape. These ends connect to
the center-T support. With the DX Engineering Logo on the center-T support facing up, feed this
element wire down through one side of the notched slot of the center-T support. Next, route the
element wire back up through the inner slot and attach the red wire lug to the lower left terminal.
This terminal will also be used for the feedline connection.
The black and white wire lug is connected to the top terminal on the center-T support. Repeat the
same process for the opposite side wire element. Excess slack in the wire elements on the center-
T support should be removed prior to putting up the antenna.
Feedline
With the DX Engineering logo facing up, the feedline should be routed down through the lower
slot, then back up through the upper slot, leaving just enough slack to permit making connections
to the lower terminals on the center-T support.
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Red Ta
p
e

Connection to the End-Insulators
Install hardware and wire element ends as shown in Figure 4.
Figure 4: Assembled End Bracket
With the DX Engineering.com lettering facing down, and the notched edge of the end slot facing
up, route the wire down through the notched end slot, back up through the next slot, down
around the bracket and back up through the slot between the mounting hardware. Make the
terminal connections placing both wire lugs on the bolt assembly. Repeat for the opposite side.
Use the supplied Dacron rope to attach the end brackets to a suitable mounting point using a no-
slip knot such as depicted in Figure 5.
Figure 5:Suggested Knot for End Brackets
Connections to the Tuner
If routing the ladder feedline to the operating position and your tuner, keep the feedline in the
shack as short as possible and away from metal chassis or cabinets to prevent interaction and
unwanted RFI. Connect the ladder feedline to the balanced, two-terminal inputs on your tuner.
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External tuners typically have inexpensive built-in 4:1 voltage baluns to convert the balanced
feedline to unbalanced, allowing the use of 50 Ωcoax for connection to your rig. Current baluns,
rather than voltage baluns, are a much better choice. Current baluns provide better balance,
almost always have lower loss, and tolerate load impedance and balance variations much better
than voltage baluns. To use a current balun, you will probably have to use one that is external to
the tuner.

Using an external current balun has a few advantages. By converting the ladder feedline to coax
away from the operating position, there is no unwanted feedline radiation in the shack. Reduced
noise and improved efficiency of the dipole will result and the structural proximity
considerations of ladder feedline can be greatly reduced or eliminated.
A high quality 1:1 current balun is ideal for this antenna and is available from DX Engineering
(part number DXE-BAL050-H10-AT). This balun provides better balance, often has lower loss,
and is more tolerant to load impedance and balance variations than most internal tuner baluns.
Use a good quality coax, such as Belden RG-213, from the balun to your tuner.
Internal tuners may not have the operating range to tune this dipole on every band; therefore, an
external tuner may be needed.
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DX Engineering Current Baluns
•5, 10 and 10 KW+ Baluns and Current Chokes
•High efficiency, low loss—W8JI design
•All ratios available
Feedline Current Chokes
•Reduce RFI and pattern distortion
•Prevent feedline radiation

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PolyPhaser Lightning Protectors
• 50 Ω DC Block, 1.5-400 MHz, UHF connectors
PPC-IS-50UX-C0 Flange Mount, 2 KW at HF
PPC-IS-B50HU-C0 Bulkhead Mount, 3 KW at HF
PPC-IS-B50LU-C0 Bulkhead Mount, 2 KW at HF
PPC-IS-B50LN-C0 Flange Mount, Type N, 2 KW
PPC-IS-RCT Rotor Control, 8-line
Copper Ground Strap and Clamps
• 2 inch width, 0.011 thickness
• Tinned copper braid available
DXE-CS2-25 25 ft. roll
DXE-CS2-50 50 ft. roll
DXE-CS2-100 100 ft. roll
Double-Braid Dacron Polyester Rope
STI-DBR-94-100 3/32 inch x 100 ft
STI-DBR-125-100 1/8 inch x 100 ft
STI-DBR-187-100 3/16 inch x 100 ft
STI-DBR-187-350 3/16 inch x 350 ft
STI-DBR-312-100 5/16 inch x 100 ft
STI-DBR-312-500 5/16 inch x 500 ft
STI-DBR-437-500 7/16 inch x 500 ft
Silver/Teflon® Connectors
DXE-PL259 Connector, Silver/Teflon
Yagi Boom-to-Element Brackets
DXE-BEB-1* For 3 inch boom, KLM replacement
DXE-BEB-2* For 2 inch boom, 7/8 inch element
*Hardware available, sold separately.
DXE-BMP-2 Boom-to-Mast Plate
Miscellaneous
Yagi Mechanical Design Software
DXE-UT8000-P Quick Coax Trimmer
DXE-STPL-1P Radial Staples, 12-pack
DXE-P8A Penetrox, 8 oz.
DXE-NSBT8 Never-Seez, 8 oz.
DXE-RTV598335, Non-corrosive RTV sealant, 3.3 oz

Technical Support
If you have questions about this product, or if you experience difficulties during the installation,
contact DX Engineering at [phone]. You can also e-mail us at
[e-mail].
For best service, please take a few minutes to review this manual before you call.
Warranty
All products manufactured by DX Engineering are warranted to be free from defects in material and workmanship
for a period of one (1) year from date of shipment. DX Engineering’s sole obligation under these warranties shall be
to issue credit, repair or replace any item or part thereof which is proved to be other than as warranted; no allowance
shall be made for any labor charges of Buyer for replacement of parts, adjustment or repairs, or any other work,
unless such charges are authorized in advance by DX Engineering.
If DX Engineering’s products are claimed to be defective in material or workmanship, DX Engineering shall, upon
prompt notice thereof, issue shipping instructions for return to DX Engineering (transportation-charges prepaid by
Buyer). Every such claim for breach of these warranties shall be deemed to be waived by Buyer unless made in
writing. The above warranties shall not extend to any products or parts thereof which have been subjected to any
misuse or neglect, damaged by accident, rendered defective by reason of improper installation, damaged from severe
weather including floods, or abnormal environmental conditions such as prolonged exposure to corrosives or power
surges, or by the performance of repairs or alterations outside of our plant, and shall not apply to any goods or parts
thereof furnished by Buyer or acquired from others at Buyer’s specifications. In addition, DX Engineering’s
warranties do not extend to other equipment and parts manufactured by others except to the extent of the original
manufacturer’s warranty to DX Engineering.
The obligations under the foregoing warranties are limited to the precise terms thereof. These warranties provide
exclusive remedies, expressly in lieu of all other remedies including claims for special or consequential damages.
SELLER NEITHER MAKES NOR ASSUMES ANY OTHER WARRANTY WHATSOEVER, WHETHER
EXPRESS, STATUTORY, OR IMPLIED, INCLUDING WARRANTIES OF MERCHANTABILITY AND
FITNESS, AND NO PERSON IS AUTHORIZED TO ASSUME FOR DX ENGINEERING ANY OBLIGATION
OR LIABILITY NOT STRICTLY IN ACCORDANCE WITH THE FOREGOING.
©DX Engineering 2006
DX Engineering®, DXE®, Hot Rodz™, Maxi-Core™, Antenna Designer™, Yagi Mechanical™, and Gorilla
Grip™ Stainless Steel Boom Clamps, are trademarks of PDS Electronics, Inc. No license to use or reproduce any of
these trademarks or other trademarks is given or implied. All other brands and product names are the trademarks of
their respective owners.
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