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Author Topic: What to do with a 26 foot aluminum pole?  (Read 922 times)
N8DV
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Posts: 60




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« on: August 20, 2008, 10:38:40 AM »

I have a 26 foot aluminum pole divided into 13 foot sections with a center insulator. It's was left of a GAP Titan antenna (you should see what's inside!). Anyway, I was wondering what type of antenna could I make with the 26 foot pole. Could it be used as a rotatable dipole? Maybe the collective good can come up with some reasonable suggestions.
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K5DVW
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« Reply #1 on: August 20, 2008, 10:43:24 AM »

Whenever someone says "I wouldnt touch it with a 10 foot pole" you could loan them this one.
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WB2WIK
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« Reply #2 on: August 20, 2008, 10:55:42 AM »

If it's exactly 26' and split in the center, it would make a great 17m rotary dipole; it will be resonant right there with no tuning or modifications...
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WA3SKN
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« Reply #3 on: August 20, 2008, 10:56:08 AM »

You could use it as a dipole, either horizontal or vertical.  Or, you could operate it against a counterpoise as a vertical, using a coil for matching.
What arrangement and band(s) will work best for you?

-Mike.
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WB6BYU
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Posts: 13240




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« Reply #4 on: August 20, 2008, 11:00:41 AM »

Use it as a portable antenna support?

Sounds like it is pretty close to a 17m dipole, might work
on 15 or 20m with a tuner.

Perhaps the boom for a long VHF/UHF yagi?

Feed it at the base and insert an appropriate loading
coil across the insulator for a 30/40/60/80m vertical.

Make an omnidirectional horizontally polarized UHF antenna
by wrapping a spiral of wire around it like a big spring,
two or three wavelengths in circumference for each turn,
with the top half wound with the opposite sense from the
bottom half.

I'm sure we can come up with more ideas, too...
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KZ1X
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« Reply #5 on: August 20, 2008, 11:41:01 AM »

Wind a coil of roughly 400 ohms reactance (about 6.2 uH) around the center insulator, and you have yourself a superb loaded end-fed halfwave for 30 meters.  No big radial system needed, great performance for DX, covers the whole band easily, just a real hoot to work.  A small matching network would give you a 50 ohm feedpoint with ease.

The load coil would probably be 18 turns of enameled #14 AWG, if the rest of my dimension guesses are correct.
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N3JBH
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« Reply #6 on: August 20, 2008, 12:58:32 PM »

Boy folks could have fun with this one Smiley But it be really fun to experiment with this 17 meters? some loading 20 meters? heck a boom for nice 2 meter antenna??? I sure would have fun playing  
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G8UBJ
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« Reply #7 on: August 20, 2008, 01:32:14 PM »

Yes a 17M dipole.. Feed it with ladder line and it will be easier to load up on the other bands?
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KB6VIV
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Posts: 195




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« Reply #8 on: August 20, 2008, 04:04:14 PM »

The problem with using it as a V dipole is that the closer to the ends you get, the lower the current is.  So you end up with the highest currents at the lowest point (the feedpoint), which is why inverted V dipoles are more popular.  But you don't need radiant poles for that, only wires.

Instead, set the 13 ft. poles to form a V, then run a wire across the top. This gives you 13, or so, feet of additional radiator at the highest point and also, the top ends of the aluminum V no longer are the lowest current points.  It becomes a delta loop with one side of the triangle on top.

You still need to do something to tune to band, either traps or external antenna tuner.
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TANAKASAN
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« Reply #9 on: August 21, 2008, 03:43:11 AM »

I'm tempted to tell you to find your nearest politician then use it on them until they beg for mercy, but I suppose you want an answer to do with ham radio.

I'd use it as a vertical with lots of guy ropes and a big capacity hat at the top. Insulate the base using a nice thick glass jar and feed at the bottom. Add plenty of ground wires and then have fun.

Tanakasan
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KD7HVL
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Posts: 66




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« Reply #10 on: August 21, 2008, 02:13:39 PM »

Well what ever you do please post it, as I also have the remains of a GAP Titian and do not know what the heck to do with it.  I have considered using it as a center feed vertical similar to what the Force12 has done with there sigma series, but so far its' been just to hot to do any antenna work. I to am open to any ideas.  TNX
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W0FM
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Posts: 2055




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« Reply #11 on: August 21, 2008, 02:50:38 PM »

A long range blow-gun that launches poison darts fashioned from badminton shuttlecocks?

Shocked)
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WB7TDG
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Posts: 69




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« Reply #12 on: August 21, 2008, 07:37:48 PM »

Before a bedroom and bath addition at this qth wiped out my vertical antenna experimental site, I used the center portion of a Gap Titan, sans the center coax, to homebrew a 42 ft vertical dipole, fed in the center with 400 ohm twin lead....I used it on 40 thru 10 meters with good to excellent results.
See http://www.titanex.de/frames/vertdipoles.html for details.
The bottom part below the center insulator also has a second section of aluminum tubing in the middle for stiffness...you can pull that out easily enough.
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W4LGH
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« Reply #13 on: August 22, 2008, 07:28:36 PM »

Hmmmm... that s a real "tuffy" trying to think what to tell you ,you can do with a 26" alum. pole. However, you did say it WAS a GAP antenna... so you are IN the right direction. The last GAP antenna I messed with, that same 26' alum. pole became several alum. mast poles, used to hold some serious antennas! One of which is on my house right now.

The only thing that company did, was pick the RIGHT name for their antennas! "GAPS" Since it WAS a GAP antenna, you could call the factory and ask them what you should do with it, or better yet, you could tell them what you are GOING to do with it... Bend over and say..."Awwwwwww" Could possible be the best use of it yet.

73 de W4LGH - Alan
http://www.w4lgh.com
 
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K5PEW
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Posts: 223




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« Reply #14 on: August 23, 2008, 06:19:45 PM »

My personal favorite would be to take 11', 6" of one tube and 9', 4 1/2" of the other, mix in some 14GA radials and PCV pipe and make a pair of VERY effective, slightly elevated 15 and 12 meter verticals.

Here's a couple of links to a neat 20 meter field antenna that could easily be adapted for 15 or 12.

http://mcars.us/AntennaModeling/antennamodeling_000002.htm

http://mcars.us/AntennaModeling/antennamodeling_000003.htm

Don't under estimate the DX capability of a 1/4 wave GP antenna. They are more than capable of putting excellent DX nuggets in your log book.

If you're not into that, the idea of a loaded 1/2 wave 30 meter antenna sounds very good.

Whatever you do, please post your results here so we can all know what you've done.

Good luck!

Graham Welch - K5PEW
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