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Author Topic: 33' "Fiberglass" fishing poles - conduct  (Read 1425 times)
WA5MTQ
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Posts: 14




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« on: June 09, 2008, 08:28:40 PM »

I am entering a year where I hope to be traveling a great deal in my RV and want to operate HF portable using wire antennas.

I know a guy that sells collapsible 33' "fiberglass" fishing poles that are supposedly for crappie (must be some d___ big crappie).  Anyway, I can envision that they would be perfect for a variety of portable antenna uses.

Trouble is, I read on one of these Forums some time ago (can't find it now, of course) that sometimes these poles can possess conductive properties which would present obvious problems for my purposes.

Anyone ever heard about these things being conductive?  How can I tell if they are?

73.

Steve
K5SWB
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KB4QAA
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« Reply #1 on: June 09, 2008, 08:50:19 PM »

True fiberglass poles won't be a problem.  If they are made with carbon fiber, then they aren't suitable.

Take a look at a base section.   Carbon fiber is black, while fiberglass is usually light colored.  Of course the fibers are embedded in the resin, whatever color that is.  You may need to do a little scraping.

Good luck.

p.s. Don't expect poles this long to carry much weight.  Your best bet may be to use them to support a vertical wire with radials laying on the ground.
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K7AAT
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« Reply #2 on: June 09, 2008, 09:43:02 PM »


  Not sure what your purposes are if you think conductive properties would be a problem for you.  If you're only supporting the center of some kind of balanced wire antenna, then any mast,  be it steel or fibreglass should not be any serious issue.   If,  you are contemplating a vertical antenna, I'd recommend telescoping aluminum tubing such as available at Texas Towers.   The home brew 23' vertical mounted on the rear ladder of my RV works superbly.

  Good luck..


 Ed   K7AAT
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WA5MTQ
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« Reply #3 on: June 09, 2008, 09:56:47 PM »

Initially I am planning to use them to hoist the Par End-Fed 20 and 17 meter half-waves as verticals.  The element would be running right against the pole for its entire length so any conductivity would really mess things us.

For lower bands, I would use them to hang the Par antennas as slopers, so the conductivity situation might not matter quite so much.
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WA5MTQ
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« Reply #4 on: June 09, 2008, 10:07:27 PM »

BTW, these poles are dark glossy black from top to bottom.

Here's a stupid question but I might as well ask.  Can a ohm meter be of help here?
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K7KBN
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« Reply #5 on: June 09, 2008, 10:42:52 PM »

If the "glossy black" finish is conductive (and the glossy top coat might be clear and non-conductive, but the black part might have a high carbon content), you could probably use an ohmmeter, judiciously.
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73
Pat K7KBN
CWO4 USNR Ret.
AC5UP
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« Reply #6 on: June 09, 2008, 11:06:39 PM »

Black fiberglass tends to indicate some graphite / carbon content or that somebody thought black would sell faster.

If I were to check a pole for conductivity I'd probably wrap two strips of aluminum foil held snug by rubber bands around the rod and spaced maybe six inches apart.

Measure the resistance with a decent DMM or similar. Let's say (for the sake of easy numbers) I come up with 1,000 ohms across a six inch gap. That would be 2,000 ohms per foot or 66,000 ohms over 33 feet. Sound OK? At 50 ohms it would be, but don't forget that some wire antennas have a very Hi-Z at the tips.

Chances are the actual numbers will be higher. If I couldn't get a reading across a six inch gap I'd slide one of the aluminum strips until I had a three inch gap and measure again just for grins. DC isn't RF but it's one way of getting some idea of what you're working with...
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PD2R
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« Reply #7 on: June 10, 2008, 01:29:27 AM »

Spiderbeam sells great 12 meter long fiberglass poles. They are extra strong at the overlap. I use the poles to put up dipoles (only up to the 10 meter point) and verticals. For the verticals I use some length of wire tied to the pole with tape ore ty-raps. I also made a base plat to connect the radials and the coax too.
It works supper, especially over salt water.

I´d go for the strong poles, not the fishing poles. I have seen quiet a few of these poles break under the load of a dipole. On the other had, for verticals they are just fine.
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W8JI
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« Reply #8 on: June 10, 2008, 02:55:10 AM »

Steve,

If particles are suspended in some non-conductive agent, like carbon or metal in paint normally would be, something with a very tiny conductive particles really won't behave any differently at lower frequencies than something with non-conductive particles. You wouldn't want to use it for a dielectric or as a HV insulator where there is a huge voltage gradient across a small area, but I wouldn't use paint without conductive or metallic particles in that situation either!!

In many cases if it has long continuous strands of carbon fiber it probably won't do much either, such as where it is just a support. It could cause a problem in some situations if the resistance per foot of the strands was low enough it acted like a long string of resistors at HF, but I'm not sure carbon fiber behaves that way.  

I wonder how many people actually had a problem with an antenna because of the pole, and if there are any that actually had a problem I wonder what the antenna was. This is an interesting question, and I wonder how people have tested poles or actually observed problems.

73 Tom
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WA3SKN
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« Reply #9 on: June 10, 2008, 04:08:30 AM »

If the pole IS NOT conductive, mount it and use it to support a vertical wire.
If the pole IS conductive, just insulate it where you mount it, and use it to support a more conductive wire!
Either way you can use these for a portable antenna.
If carbon fiber, the resistance will be too high to use as a good conductor by itself.
73s.

-Mike.
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N3OX
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« Reply #10 on: June 10, 2008, 05:53:25 AM »

From an old rec.radio.amateur.antenna thread about I0JX's carbon fiber rod:

"Initial low-power tests at 10.15 MHz showed a very low SWR. Luckily the antenna length was appropriate.

I then applied a carrier at some 1500W and after a couple of minutes or so I saw the reflected power meter oscillating, until it suddently went up a lot.

I immediately went to inspect the antenna and I found that the rod was fairly hot. Moreover there were clear signs of sparking between the copper wire and the rod here and there, and the tape had melted at some points. "

- - - - - -

Most rods out there are NOT carbon fiber, but I think this starts to answer W8JI's question.  

I think I0JX measured 10 ohms or so between two probes seperated a foot.

I don't think any of the fiberglass rods will have this problem  but if you did chance on a carbon fiber one it would.
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
G8UBJ
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« Reply #11 on: June 10, 2008, 06:00:32 AM »

I built a 4m coaxial dipole using black fiberglass tent poles. I made up the t-support from the poles & zip tied the coax to the support.
Comes up correctly on 70Mhz... maybe its just black coloring in my poles?
plenty of antennas use wood frames which is probably as bad as carbon in fiberglass with no detrimental effect.  
Build it and let us know if it works..?
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IRABREN
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Posts: 273




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« Reply #12 on: June 10, 2008, 08:46:13 AM »

You might consider a DK9SQ Fiberglass pole (33 ft )
         http://www.qsl.net/dk9sq/
73, Ira KE5STP


Fibreglass Telescope Tower

 

Þ total lenght 3.8ft - 33ft

Þ total weight 2.2lb

Þ no tools required

Þ designed for portable purposes

 

The Fibreglass Telescope Tower with an overall mast length of 33 ft (10m) is designed to constract antennas for portable purposes, such as, field day events, during holidays and weekend aways.

Unassembled it is compact and light only 3.8 ft (1.15m) in lenght and weighing 2.2 lb (1kg). The telescopic segments need only be pulled out. No tools are required.

The Fibreglass Telescope Tower has been specially developed for antennas. All 10 segments are reinforced three times. The intensive black pigment of the outer material makes it UV-resistant and the segments are individually grinded to guarantee the vertical loadbearing capacity.

 

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W7KKK
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Posts: 374




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« Reply #13 on: June 10, 2008, 12:32:36 PM »

I am going to operate from my RV too (full time).
I currently feed a 108" whip with an AH-4 tuner but it really needs a full 23' or more for a good antenna.
I wanted to be self contained on the RV as you never know where you will find trees to extend the whip with a clip on wire so I ordered a 31' Jackite fiberglass pole off eBay for $41.
I intend to secure it to my ladder and support a wire in a sloping arrangement back to the whip.
It should work fine.
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W7KKK
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Posts: 374




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« Reply #14 on: June 10, 2008, 12:34:03 PM »

Oh, further info.
The pole is about 4# and collapses to 46" I am told.
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