Linear-Loaded Multi-Band Dipole Patent Pending

DXE-SWA-070 Revision 3

© DX Engineering 2005 P.O. Box 1491 · Akron, OH 44309-1491

Phone: (800) 777-0703 ·Tech Support and International: (330) 572-3200 Fax: (330) 572-3279 · E-mail: DXEngineering@DXEngineering.com

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 Linear-Loaded Multi-Band Dipole (Patent Pending) is a 74 ft, lightweight yet rugged design that is usable with a tuner from 3.5 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 • 3.5 to 30 MHz continuous coverage • 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, 100 feet of premium ladder feedline and 100 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, 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 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 Ω feedline, 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 at least 1/2-wavelength 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 100 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 DX Engineering Linear-Loaded Multi-Band Dipoles include 100 feet of high quality 300 Ω ladder line. Depending on your specific installation, this feedline will need to be shortened or lengthened. The feedline must be in odd multiple lengths of 1/8-wavelength on the lowest operating frequency, in this case 3.5 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 Ω ladder feedline has a VF of 0.88. 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 Ω ladder) 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

Itpf IDcp N

T

Example: To use this antenna from 80m to 10m, the feedline should be in odd 1/8-wavelength

multiples on 80m. The 80m band starts at 3.5 MHz. Therefore, 123/3.5=35.1. Our feedline

VF=0.88, so 35.1 x 0.88=30.9 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 92.7 feet. (30.9 x 3). If we needed 110

feet, we would have to add to the feedline to achieve 154.5 feet (30.9 x 5) to maintain the odd

1/8th multiple-rule for length

f you have excess ladder line, it can be zigzagged while suspended in air, but it can't be closer han a few conductor widths to metallic objects and should not be coiled. If it is necessary to ass closely to a metallic object, twist the line to partially balance the effect on both sides of the eedline.

f you need additional feedline, 100 foot rolls of 300 Ω feedline (DX Engineering part number XE-LL300-1C) and a convenient line coupler (part number DXE-LLC-1P) are available. This

oupler includes a high impact, insulated splice block, ring terminals and stainless hardware, ermitting strong and consistent splices of ladder line. See Figure 1.

ote: If using an external balun, the feedline length should be calculated to the balun.

Figure 1: Ladder Line Coupler

he wire elements are precut to the correct length and should not be trimmed.

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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 The included Dacron rope should be used for the messenger line by forming a loop at the mid-point of the rope. Push this loop through the center-T support top hole, then pull the rest of the rope through the loop. See Figure 3.

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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 B Wire Elements The multi-wire elements must be connework properly. Locate the ends of the wirthe center-T support. With the DX Engineelement wire down through one side of thelement wire back up through the inner slThis terminal will also be used for the fee The black and white wire lug is connectedsame process for the opposite side wire elT support should be removed prior to putt Feedline With the DX Engineering logo facing upslot, then back up through the upper slot, to the lower terminals on the center-T sup

Red Tape

racket

cted exactly as shown in Figure 3 for the antenna to e elements marked with red tape. These ends connect to ering Logo on the center-T support facing up, feed this e notched slot of the center-T support. Next, route the

ot and attach the red wire lug to the lower left terminal. dline connection.

to the top terminal on the center-T support. Repeat the ement. Excess slack in the wire elements on the center-ing up the antenna.

, the feedline should be routed down through the lower leaving just enough slack to permit making connections port.

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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 Ω coax 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 4:1 current balun is ideal for this antenna and is available from DX Engineering (part number DXE-BAL200-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 Table 1 to ensure the ladder feedline is in odd multiples of 1/8-wavelength before connecting to the balun. 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, use of 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 (330) 572-3200. You can also e-mail us at DXEngineering@DXEngineering.com. 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 2005 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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