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Hints and Kinks: Unistrut Antenna Support:

from The ARRL Letter on February 11, 2010
Website: http://www.arrl.org/
View comments about this article!

Hints and Kinks: Unistrut Antenna Support:

This idea comes to us from Louis Kobet, WB3DZD, of Camas, Washington.

When considering a center support for the installation of an inverted V antenna I decided on the following requirements: a strong material, easy assembly, corrosion resistant and with tilt-over capability. The initial design was to use several 10-12 foot sections of antenna mast or 2 inch galvanized pipe coupled together. Due to the cost of antenna mast and galvanized pipe being more than anticipated, an alternative, 10 foot sections of 1-5/8 inch Unistrut channel was selected.

Figure 1: The PVC pipe and hoist pulley device mounted to the top of the Unistrut for hoisting the antenna. Unistrut is a ham's Tinkertoy. It is available in 13/16, 1 1/4 and 1-5/8 inch widths, 10 and 20 foot lengths and in 12, 14 and 16 gauge sizes. It is made with dipped surface protective treatments from electro-deposition acrylic green to "hot dipped" galvanized coatings and multiple channel designs (including telescoping sections). A vast selection of brackets and fasteners is available and it is continuously slotted for easy guying. The design and choices for project use are limited only by the creativity of the user.

The tilt over base support consisted of a treated 4x4 inch landscape post anchored in concrete. (The wooden post was moisture sealed at the top using the dipped coating used for hand tools and along the length with several coats of wood sealer.) The Unistrut mast pivot point on the support base was a 3 inch lag bolt about 50 inches above ground. In retrospect, a section of Unistrut could have been set in the concrete as the antenna base support.

The Unistrut mast preparation consisted of black paint (except for areas where the sections were bolted together) and the addition of a hoisting pulley mounted at the end of a 2 foot PVC pipe (see Figure 1). One problem encountered was in bolting the Unistrut together. Bolting back-to-back against the base of the "U" was not possible because I couldn't get a socket on the bolt head inside the Unistrut channel. To get around this the Unistrut was bolted with the open "U" ends face to face. Square Unistrut channel would have eliminated this issue. The three Unistrut sections were bolted together with about a 12 inch overlap.

An antenna hoisting line was fed through the pulley and mast section carried to the base support for mounting. After attaching the mast to the pivot point it was tilted up into position, plumbed and secured in place with three additional lag bolts.

The V antenna was spread out, transmission cable attached and hoisted to the top of the mast. The ends of the V antenna were attached to a 12 foot landscape treated 4x4 that was secured to the property fence.

Do you have an idea or a simple project that has improved your operating? Maybe you've taken something commonly found around the home and developed a ham radio use for it? Why not share your hints with fellow hams in "Hints and Kinks," a monthly column in QST. If we publish your hint in QST, you will receive $20. Send your hints via e-mail h&k@arrl.org or to ARRL Headquarters, Attn: "Hints and Kinks," 225 Main Street, Newington, CT 06111. Please include your name, call sign, complete mailing address, daytime telephone number and e-mail address.

Source:

The ARRL Letter

Member Comments:
This article has expired. No more comments may be added.
 
Hints and Kinks: Unistrut Antenna Support:  
by K4MOA on February 12, 2010 Mail this to a friend!
I would be interested in learning a bit more about this or a similar project. Such as how tall this particular Unistrut Antenna Support is? I would also like to know if the Unistrut had to be cut down in length at all or if it was the full 10' or 20' lengths were used.

I have been looking for a project like this that I could use to get a wire antenna up about 35' or so. I had been considering the SATERN Pushup Pole Project using nested EMT Conduit ( http://68.107.217.60/westsat/PushUp/index.html )which would be secured to a 4x4 post then guyed.

Thank you for posting ideas such as this for folks like me who are looking for a easy to do project.

Mike, K4MOA
 
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