1. Romex Dual-Band J-Pole Antenna

Introduction

This project was discussed at the September 19, 2013 DARA Thursday Night Group meeting. For a meeting summary click HERE. The antenna is based on the QST article "The DBJ-1: A VHF-UHF 

Dual-Band J-Pole" by Edison Fong, WB6IQN. A drawing by the author follows. In addition, a link to the QST article is included near the bottom of this page. Finally, YouTube videos by KK4RZX are provided showing a commercial version inserted in a PVC tube. 

Substitute Romex where twin-lead is stated in the article(s). The DARA Thursday Night Group version will vary slightly from the design in the QST article. The information is still useful to familiarize members with the antenna in preparation for the build.

Dual Band J-Pole Antenna Drawing

The DARA Thursday Night Group version will use Romex for the wire. The final product may vary from the drawing. 

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Materials Members Should Bring

Supplied by Steve, KB8STB:

• Used Romex cable

• Coax for UHF sleeve cut for effective 1/4 wavelength at UHF frequency; i.e. take velocity factor into consideration. More on this in article below.

Supplied by Builder:

1. Pipe and Caps. Five (5) feet of 3/4" PVC (white) or CPVC (off-white) pipe with matching flat bottomed pipe caps. Please notice that the actual diameter of the 3/4" PVC pipe (sold at Menards) and 3/4" pipe CPVC pipe (sold at Lowe's) are different, even though they are labelled 3/4". The CPVC pipe listed below is smaller in diameter than the PVC pipe listed below. The importance of this information is that the end caps need to be purchased to fit the pipe. Try the caps on the pipe at the store to make sure that they are a firm slip fit. If they are a sloppy fit, they will not glue up properly. 

Here are two different pipe and cap combinations that may work for you:

• • PVC - Menards $1.49 White PVC Pipe-3/4"x10' thinwall, Model Number: PVC200070600HA, Menards® SKU: 6899684

  • PVC - Menards $0.35, White 3/4" PVC Cap, Model Number: F01890, Menards® SKU: 6896687

  • --OR--

• CPVC - Lowe's $2.65 Off-White Color, Silver-Line Plastics 3/4-in x 10-ft 100-PSI CPVC Hot Cold Pipe, Model #: 37.071, Item #: 23813

• CPVC - Lowe's $0.34 Off-White Color, Genova 3/4-in Dia Cap CPVC Fitting, Model #: 50157Y, Item #: 23773

2. Connector for bottom of antenna. This can always be purchased and added after the meeting. It is your choice to use either UHF (SO-239 style) or Type N Female. The connector may be flange mount with 4 fastener holes or threaded panel mount type with a nut. Another idea is to directly solder a long piece of coax (builder supplied) to the antenna element and run through a hole in the pipe cap and then solder or crimp a male connector to the end of the coax.

3. Optional. Tools that would be helpful (Don't go out and buy all this from Harbor Freight, surely several hams will be able to help you at the meeting if you do not own these):

Soldering Gun 200 watts or higher

Soldering Iron, temperature controlled

Solder

Utility Knife

Pliers

Open End Adjustable Wrench/Spanner ("crescent" wrench)

Wire Stripper

Coax Stripper

Shrink Tube

Vinyl Electrical Tape

PVC/CPVC Compatible Cement

Drill for making hole in pipe cap, for coax connector.

Cable Ties

PVC Pipe Cutter

Tape measure or ruler 

Fine tip felt marker

QST Article, February 2003

 "The DBJ-1: A VHF-UHF Dual-Band J-Pole" by Edison Fong, WB6IQN. Please note the errata on the DBJ-1 in the "Feedback" item following the article.

 "The DBJ-2: A Portable VHF-UHF Roll-Up J-pole Antenna for Public Service" by Edison Fong, WB6IQN.

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