DX Engineering DXE-WA-BMB Instructions manual

Balun Mounting Bracket for

DX Engineering Maxi-Core® 20

Baluns and Wire Antennas

U.S. Patent D744,459

DXE-WA-BMB

DXE-WA-BMB-INS Rev 1

Shown with optional parts

© DX Engineering 2020

DX Engineering - 1200 Southeast Ave. - Tallmadge, OH 44278 USA

Phone: [phone] ∙ Tech Support and International: [phone]

Fax: [phone] ∙ E-mail: [e-mail]

Introduction and General Information

This custom made patented (US Patent No. D744,459) Balun
Mounting Bracket for top terminal DX Engineering Baluns
and Wire Antennas kit includes two DX Engineering End
Insulators (US Patent No. D534,905) and all Stainless Steel
Hardware. Using the optional coaxial cable strain relief
(DXE-CSR213-1 for RG-213 sized coax or the DXE-
CSR8X-1 for RG-8X sized coax) with your optional dipole
wire (DXE-ANTW Antenna Wire) and DX Engineering
rope, this kit is the ideal starting point for building a quality
coaxial cable fed single band resonant dipole, folded dipole
or off-center fed dipole. The custom made mounting bracket
will fit other manufacturers’ similarly packaged Baluns.

The unique design provides minimum capacitive coupling to the wire and field surrounding the Balun
core plus a special UV resistant, strong black plastic compound. The bracket as well as the end
insulators feature an exclusive serpentine wire weave grip for insulated DX Engineering Antenna Wire.
This method of threading the wire provides a grip strong enough to permanently support the antenna
wires without the need for looping or wrapping the wire ends back on to the dipole wires. This allows
fast and easy field adjustments of antenna length without soldering.

This manual does not cover all the types of resonant dipoles that could be built using these components.
The type of resonant dipole to be built is limited only by your imagination. For more complete antenna
theory and for construction of the many different types of wire antennas possible, refer to textbook
material such as the "ARRL Antenna Book" which is also available from DX Engineering.

Features

 All-in-One Wire Antenna Center Insulator and Balun mounting bracket (US Patent No. D744,459)
 Custom molded, UV resistant black poly-resin blend
 Serpentine routing of dipole wires to ensure maximum grip without soldering or other

mechanical restraints

 Includes two DX Engineering End Insulators (US Patent No. D534,905)
 Easily mount a DX Engineering Maxi-Core® 20 Balun with top wing nut terminals
 Adapts easily to other brand baluns built with the same NEMA mounting box
 All Stainless Steel Balun Mounting Hardware

Manual Updates

Every effort is made to supply the latest manual revision with each product. Occasionally a manual will
be updated between the time your DX Engineering product is shipped and when you receive it. Please
check the DX Engineering web site (www.dxengineering.com) for the latest revision manual.

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Parts List

Qty

Description

1

DX Engineering Balun & Wire Antenna Bracket

2

DX Engineering End Insulators

4

6-32 x 3/4” long Stainless Steel Hex Head Bolts

8

#6 Stainless Steel Flat Washers

4

6-32 Nyloc Hex Nuts

Additional Items Needed, but not Supplied:

 DX Engineering Maxi-Core® 20 Balun
 DX Engineering Premium Antenna Wire
 DX Engineering Coaxial Cable Strain Relief
 UV protected rope
 DX Engineering Coaxial Cable with PL-259 connectors installed
 JTL-12555 Jet Lube SS-30 compound - used on the threads of Stainless Steel Hardware to prevent

galling (seizing) and aid in proper tightening

Antenna Installation

Safety Considerations

WARNING!

INSTALLATION OF ANY ANTENNA NEAR POWER LINES IS DANGEROUS

Warning: Do not locate the antenna near overhead power lines or other electric light or power circuits,

or where it can come into contact with such circuits. When installing the antenna, take extreme care not
to come into contact with such circuits, because they may cause serious injury or death.

Overhead Power Line Safety

Before you begin working, check carefully for overhead power lines in the area you will be working.

Don't assume that wires are telephone or cable lines: check with your electric utility for advice.

Although overhead power lines may appear to be insulated, often these coverings are intended only to
protect metal wires from weather conditions and may not protect you from electric shock Keep your
distance! Remember the 10-foot rule: When carrying and using ladders and other long tools, keep them
at least 10 feet away from all overhead lines - including any lines from the power pole to your home.

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, dipole 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.

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For DX, the minimum height above ground should be 1/2 to 1-wavelength at the lowest operating

Note: The following assembly instructions are based on building a typical resonant dipole for 15

meters. Optional items include a DX Engineering Maxi-Core® 20 Balun, DX Engineering
Antenna Wire, DX Engineering Coax Strain Relief, DX Engineering Rope, DX Engineering
Coaxial Cable, suggested Jet-Lube SS-30 for the stainless steel hardware UV protected rope
and weatherproofing materials for coaxial connectors.

frequency. On the low bands, this height becomes impractical for most hams. For example, an 80m
dipole at 70 feet is about 1/4-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 40 Meter dipole at 70 feet is approximately 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" which is
available from DX Engineering.

Basic Assembly

Using the included Stainless Steel Hardware, mount the DX Engineering Maxi-Core® 20 balun (in this
example we’ll use the DX Engineering Maxi-Core® 20 1:1 Balun - part number DXE-MC20-1-1) as
shown below. Note: When installing stainless steel hardware, it is suggested that JTL-12555 Jet Lube
SS-30 be used to prevent thread galling.

Mount the Balun on the side opposite the cupped areas of the dipole wire guides.

When building a single band coaxial cable fed HF dipole antenna, you may easily use the formula
L = 468/F to determine the overall length of the wire (L in feet, F in MHz). The formula takes into
account the end-effect of the antenna wire to give you the overall length of the wire portion.

As an example, using the formula L = 468/F, the overall length of a half wave dipole for 3.800 MHz
would be L = 468/3.800 or 123.2 feet. Cut the overall length of the wire to 125 feet or more to include
the extra length for tuning. Then cut that in half to provide two dipole legs – each 62.5 feet long.

Use this theoretical formula length as a starting point to cut the wire, leaving about one foot extra on
each dipole leg for wire fastening and fine tuning adjustment to allow for anomalies and environmental
effects in your particular installation. Longer length dipole legs may be required for Inverted-V
antennas.

Both of the dipole leg ends should be measured and cut longer than necessary so you have enough wire
to wrap around the Balun terminals and End Insulators, plus a little extra for final tuning. It’s always

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easier to cut excess wire rather than having to solder on extra wire when tuning.

In this example, we are making a 15 meter flat top resonant dipole. The lowest frequency on the 15
meter band is 21.000 MHz.

Example: 21.000 MHz (bottom edge of 15 meters)

Overall Length = 22.29 feet

Leg 1 = 11.145 feet
Leg 2 = 11.145 feet

Overall length would be 22.29 - BUT we add some extra for wire fastening and tuning

Therefore; cut the legs to 13 feet each

Longer length dipole legs (up to 2 feet longer) may be required for Inverted-V antennas.

Trim approximately 1 inch of insulation from the two dipole wires that will connect to the DX
Engineering Maxi-Core® 20 Balun.

Route the dipole wire ends through the mounting bracket in a serpentine manner as shown below.
Note where the wire enters the bracket through the cupped area.

Loosen the connection hardware on the DX Engineering Maxi-Core® 20 balun.
Wrap one of the the trimmed dipole wire ends around the balun connection point between the flat

washers in a clockwise direction. Do not include insulation, just have bare wire under the washers. An
alternate method is to solder a 1/4” ring terminal to the ends of the wire, then place them on the balun
and tighten the wing nuts.

Firmly tighten the balun mounting hardware wing nut. Use an open end wrench to hold the hex nut in
place when tightening the Wing Nuts.

Repeat this for the other wire and balun terminal.

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Install the optional DX Engineering Coaxial Cable Strain Relief - either the DXE-
CSR213-1 or the DXE-CSR8X-1 depending on the type of coaxial cable used.

In this example the DXE-CSR8X-1 Cable Strain Relief is used with the DXE-8X
coaxial cable. Refer to the detailed instructions that are included with the strain relief for
details on the assembly.

Connect the coaxial cable (in this example DX Engineering DXE-8X (with PL-259s attached) to the
bottom of the Balun.

This coaxial connection should be weather proofed using TemflexTM Rubber Splicing Tape with an
overwrap of Scotch® Super33+ tape for a complete weatherproof solution. Detailed information on
weatherproofing connectors is available on-line at www.DXEngineering.com

Dipole Wires and End Insulators

The End Insulators are installed at the far ends of the dipole wires. One on each end. Route the dipole
wire in a serpentine manner as shown below. Note the wire enters the End Insulator at the cupped area.

Once tuning is completed at low power, and the dipole leg wires are trimmed to length you can add an
extra tuck in the wire end to provide even more gripping power on the dipole wires as shown below.
Wrapping and soldering is not required.

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Attaching Rope to the End Insulators

UV protected rope should be secured to the Balun Mounting Bracket and the End Insulators (depending
on your installation) using a non-slip knot. The rope hole (diameter) on the Balun Mounting Bracket is

0.371" and the end insulators are 0.34".

One suggestion for attaching the rope to the End Insulators is shown below. The ends of the rope should
be cauterized with a small flame to prevent the rope braid from fraying.

Non-Slip Knot using UV protected Rope

Support Line

The Balun Mounting Bracket’s top hole is used for the attachment of a support line (also referred to as 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.

When using trees for support, you may want to use counter weights that will allow the rope to move
when the trees sway in the breeze to
avoid stretching or breaking your
dipole. For more hints, consult a
reliable text such as the "ARRL
Antenna Book" which is available
from DX Engineering.

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 as shown.

Flat Dipole Installation between trees using a Messenger Line

UV protected rope is used for the messenger line by forming a loop at the mid-point of the rope. Push
the loop through the Center-T top hole, and pull the rest of the rope through the loop.

Rope Loop for Messenger Line

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

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flame to prevent the rope braid from fraying. The top support hole may also be used for rope to install it
as an inverted-V.

Inverted-V Dipole – Tower Side Arm Installation

Tuning

Once the dipole is completed, raise the dipole to its operating
position. Attach an Analyzer (example: Rig Expert) and determine
the resonant point on the dipole.

It will probably be a bit lower than you want - this is good. You then need to trim a small piece from
each end of the dipole (about 1 inch) and re-measure.

If the resonant point is low - trim the overall length shorter

If the resonant point is too high, you have to add to the overall length.

Once tuned, you are ready to get in the air and make contacts.

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 2020
DX Engineering®, DXE®, DX Engineering, Inc.®, Hot Rodz®, Maxi-Core®, DX Engineering THUNDERBOLT®, DX Engineering Yagi Mechanical®,
EZ-BUILD®, TELREX®, Gorilla Grip® Stainless Steel Boom Clamps, Butternut®, SkyHawk™, SkyLark™, SecureMount™, OMNI-TILT™, RF-PRO­1B®, AFHD-4® 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.

Specifications subject to change without notice.

DX Engineering

1200 Southeast Ave. - Tallmadge, OH 44278 USA

Phone: [phone] ∙ Tech Support and International: [phone]

Fax: [phone] ∙ E-mail: [e-mail]

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