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Old September 19th 04, 12:10 AM
Mark T. Kennedy
 
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Default half-wave dipole in the forest

i live in a neighborhood where the sight of a half-wave dipole would
cause a riot. however, a portion of my property is heavily wooded.
i could easily hide even a 160m half-wave among the branches and leaves,
leaving it invisible. is this practical? risky? caveat: i'm still
studying for my technician's license so go easy on me :-).

/mark
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Old September 19th 04, 01:28 AM
K5VSE
 
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I live in the forest, and use a couple of resonant dipoles hiding in the
trees. I have no problems at all. Once, during our ice storm, one of them
came down when a tree broke off and fell. SWR is fine, and get good signal
reports.

Go for it.


--
Mike-K5VSE
Formerly WB6VSE, Senior Tech, Amateur Division, SBE/Linear Systems
Watsonville, CA
All out going Email, scanned with Norton Anti-Virus 2004
"Radios That Glow in the Dark"
"3922 khz".


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Old September 19th 04, 02:11 AM
NN7Kex(NOSPAM)k7zfg
 
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K5VSE wrote:
I live in the forest, and use a couple of resonant dipoles hiding in the
trees. I have no problems at all. Once, during our ice storm, one of them
came down when a tree broke off and fell. SWR is fine, and get good signal
reports.

Go for it.


Only caviet-- You need at least a general for 30 MHz, or below, but
the absorbsion of rf at those freqs is minimal, tho the HEIGHT, at lower freqs
for a good pattern (for long distance) might be a problem. But , say on 80-40
even at around 20 foot elevation, can work reliably several hundred miles!
20 and up meters shouldn't present much of a problem, and at 6 and 2 meters yagi
be best bet, but relatively small size. Have fun- Jim NN7K
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Old September 19th 04, 05:01 AM
Tam/WB2TT
 
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"Mark T. Kennedy" wrote in message
...
i live in a neighborhood where the sight of a half-wave dipole would cause
a riot. however, a portion of my property is heavily wooded.
i could easily hide even a 160m half-wave among the branches and leaves,
leaving it invisible. is this practical? risky? caveat: i'm still
studying for my technician's license so go easy on me :-).

/mark


I have several wire antennas strung between trees, and found that even #14
or #16 wire with black or blue insulation at 50 feet is invisible against
the trees, and almost invisible when viewed against the sky. What sticks out
is the feedline, if it is hanging in the clear. You want that coming down
next to a tree. You really don't want contact between the wire and branches.
However, my 75m antenna goes through branches at one point, and it seems to
be OK. Stay away from white, yellow, or red insulation.

Tam/WB2TT


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Old September 19th 04, 02:35 PM
John DeGood
 
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K5VSE wrote:
I live in the forest, and use a couple of resonant dipoles hiding in the
trees. I have no problems at all. Once, during our ice storm, one of them
came down when a tree broke off and fell.


Please allow me to apologize in advance, but I can't resist asking:

"If a dipole falls in a forest and there's no one there to hear it,
does it make a sound?"

73,

John NU3E :-)


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Old September 19th 04, 03:00 PM
Cecil Moore
 
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Bill Turner wrote:
The voltage at the ends of a half wave dipole can reach thousands of
volts even with relatively low power. Trees have been set on fire with
as low as 100 watts. Be careful!


A rule-of-thumb that I use is: For a resonant half-wave
dipole, the voltage at the ends is *about* 20 times the
feedpoint voltage, nothing to be sneezed at.
--
73, Cecil http://www.qsl.net/w5dxp


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Old September 19th 04, 03:48 PM
Airy R. Bean
 
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That depends upon whether it is a pole (tree) that is dying.

"John DeGood" wrote in message
...
K5VSE wrote:
I live in the forest, and use a couple of resonant dipoles hiding in the
trees. I have no problems at all. Once, during our ice storm, one of

them
came down when a tree broke off and fell.


Please allow me to apologize in advance, but I can't resist asking:

"If a dipole falls in a forest and there's no one there to hear it,
does it make a sound?"

73,

John NU3E :-)



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Old September 19th 04, 03:59 PM
Yuri Blanarovich
 
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I have 160m Inverted Vee in the trees, works fine. Just make sure that the ends
(last third) are in the clear. They have high voltage and prone to ignite fires
when situation favorable. Use insulated wire.

Yuri, K3BU.us
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Old September 19th 04, 04:58 PM
Reg Edwards
 
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"If a dipole falls in a forest and there's no one there to hear it,
does it make a sound?"

===============================

Yes. All falling trees make a sound. But if there's nobody to hear it who
cares?

But this business about 100 watt transmitters causing forest fires is
exaggerated. Even if there's a conjugal impedance match between a dead leaf
and the transmitter there's little to worry about even when its not raining.
And the density of foliage is hardly likely to allow flames, should they
occur, to leap from one leaf to another.

The climate and type of tree involved is, of course, of some consequence.
Deciduous trees and those found in South American and Indianesian jungles
can be disregarded from this discussion,

If you should live in Australia, the home of Eucaliptus trees, during the
dry season, and it's always dry, there is a one in 100 million chance of a
tree catching fire by radio. Always supposing by some remote chance it
hasn't first been struck by lightning.

Eucaliptus trees positively enjoy fire. They depend on it to propagate
efficiently. This may be an unfortunate trait insofar as kangaroos and
wallabies are concerned but alligators are quite happy with the way things
have been arranged. The Aussies themselves take care not to build their
houses too near to eucaliptus plantations. The Abbo's, with their 50,000
years of experience, radio or not, are quite happy and sensible enough to
leave things as they are.

The USA has wide variations in climate and tree population. Thoughtful
citizens ought to concentrate their minds on hurricanes, twisters,
atmospheric pollution and gun laws. 100-watt transmitters and G5RV's can
look after themselves. ;o)
---
Reg.


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Old September 19th 04, 08:01 PM
Jack Painter
 
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"Reg Edwards" wrote

The USA has wide variations in climate and tree population. Thoughtful
citizens ought to concentrate their minds on hurricanes, twisters,
atmospheric pollution and gun laws. 100-watt transmitters and G5RV's can
look after themselves. ;o)
---
Reg.


I assure you we are concentrating very carfefully, Reg! Last week we had
about 20,000 gun laws on the books, counting all federal and state laws.
This weekend we have one less federal gun law, and soon there may be less.
When free people use their minds instead of letting foolish emotions be
their guide, the concept of restricting firearms from law abiding citizens
is one of the first things to go.

Btw, so far my dipole hasn't set the pine trees on fire, or been torn down
by a hurricane, despite three attempts by them so far this year ;-)

73,

Jack


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