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I am a ham radio operator, father, husband, Christian, musician, avid reader, Texan, philosopher, and chronic hamburger fiend. After spending several years exploring the different avenues of Ham Radio I decided to share my ideas, experiments, and activities with my fellow "technically challenged" hams as I humbly present to you: "Ham Radio For the Rest of Us". I hope you enjoy reading it as much as I enjoy writing it.

Sunday, October 9, 2011

When it comes to antennas; Nike has the right idea!

Do you remember Nike's slogan "Just Do It"?  There are times when I believe that is good advice for Ham Radio operators.  I meet with a group of local hams a couple of times a week to cuss and discuss Ham Radio.  Several ideas for antenna projects come up, but often get discouraged for various technical reasons.  "The swr will be off the charts" or "this will react with that" or some other discouraging remark on theoretical antenna design.  To listen to most folks; your antenna most be perfect or the sky will open up and you and your radio will be swallowed up by the radio gods.
     Fall is here and I decided before it gets too cold I would like a little more flexible HF antenna for the winter.  I built a homebrew forty meter last fall which served me well but I wanted a few more options this winter.  I became interested in "fan dipoles" also called "multiband single feed dipoles.  After passing the idea around at coffee with the local guys, I got on my trusty pc and searched the internet for more info.  It seemed that for every site I found with plans there were also nay sayers who diligently explained the short comings of such an antenna.  I finally decided to follow Nike's wisdom and just do it.  My goal was to build an antenna run it up the mast and have it work the first time without a bunch of trimming, tuning, and hair pulling. 
     I ran across and article on Ham Universe which led me to a design I think originally created by KC4TAQ.  It used pvc to separate the legs at the feed point to minimize interaction.  I cut the dipole for 40, 20, and 10 meters.  15 will also work because it's a harmonic of 40 meters.  I figured the lengths using the standard calculations and left plenty of extra on the ends to work with.  My last dipole worked fine without the need for a balun but I thought I'd use one this time just to be different.  I made one of those "ugly baluns".  Cheap and effective.  I built the pvc support, measured and cut the legs for each band, wrapped the extra on each leg back on itself making a loop in the end of the wire and tie-wrapped them.  Made my coax feedline to fit from the mast to my upstairs window, and threw it all up in the air.  I checked the resonance of each band and it was as I expected: not perfect but fairly close.  I decided to go ahead and hook it up to the radio and give it a shot.  Keep in mind that I was running into my Icom 735 with the AT-150 automatic tuner.  I wanted to be careful so I backed the power off to about 50 watts dialed in 20 meters and started listening.  I heard an Italy station calling CQ and I'm not kidding you one bit; I forgot all about the 50 watts, answered his cq and bagged IZ1NPT in Fresonara, Italy as my first contact on my homebrew antenna!  It worked so well that I did pull it back down to solder loops in the ends of each leg so I could tie it off permanently and weather proofed it with some liquid electrical tape and gorilla snot around the connections.  I found a gigantic piece of shrink tube to go around the balun and voila!  I was ready for the winter.  I spent the rest of this weekend making contacts on the bands to test it out and it is working beyond my wildest expectations.  Could it be tuned closer to the center of the band? I'm sure it could.  Is it working as efficiently as it could?   Probably not.  But the point is it is working, and working well.

Various pieces of 1/2" pvc used to build the support loop




Completed support complete with "ugly balun"
Finished antenna on the mast at sundown!








    













2 comments:

  1. That looks like something that I'll have to try before it's all said and done.

    Your buddy W5LDT, (formerly KD5MZE).

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