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ladder line construction methods?



 
 
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  #1  
Old March 30th 04, 08:52 PM
Larry Gagnon
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Default ladder line construction methods?

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

--
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  #2  
Old March 31st 04, 12:38 AM
Cecil Moore
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Larry Gagnon wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?


Spacing is not critical. How about a 4" spacer made out of irrigation
plastic tubing?
--
73, Cecil, W5DXP



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  #3  
Old March 31st 04, 01:28 AM
'Doc
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Larry,
Boy, are you gonna have fun! As Cecil said, spacing isn't
all that critical. Use whatever you can find enough of, to make
the 'spreaders', as long as it's not conductive it should work.
The simplest way to feed ladder line through a window is to
make a 'spacer' board to fit in the window. Drill a couple of
holes in the board, the correct distance apart, feed the line
through the holes, 'hot glue' in place (or however you can get
it to stay put. Have to remove the screen...
'Doc

PS - The real 'trick' is to keep the line from 'swarming' on
you when you finish.
  #4  
Old March 31st 04, 02:43 AM
Tom Bruhns
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Impedance is about 120*ln(2*D/d) ohms, where ln is the natural
logarithm, and D is the wire spacing, center to center, and d is the
wire diameter. Assumes round wires, and air dielectric. You can
rearrange that: if you want x ohms and have d diameter, D =
d*exp(x/120)/2, where exp(x/120) is "e to the x/120 power". If you
don't have a calculator that handles that sort of math, this table
will probably get you close enough:

D/d impedance, ohms
1.9 150
2.8 200
6.2 300
22 450
75 600

Construction depends a bit on how much you're making and what you have
available for materials and tools. People used to use wooden spacers,
boiled in parafin wax. Someone gave me a bunch of PETE
tensile-strength test strips that are a good size. You can make
spacers from PVC pipe. You can thread wires through holes (generally
not so efficient), or fit wires into notches and secure by with a
plastic or wire wrap, or by melting the wire into an undersized notch,
or with various glues. Undoubtedly lots of other ideas, both
tried-and-true and just waiting to be tried for the first time.

You can drill holes through the glass and install feedthroughs (but
probably not if it's double-pane!), or drill a couple over-size holes
through the wall or possibly through a wooden window frame member, or
install a wood or plastic piece in a partially-open window. You can
also possibly inductively or capacitively couple through the window.
If you decide to go through wood or wall materials, plan to make
oversized holes, lined with decent electrical/RF insulation. What
strikes your fancy?

Cheers,
Tom


Larry Gagnon wrote in message ...
Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA

  #5  
Old March 31st 04, 03:37 AM
JGBOYLES
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Default

Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?


One of many ways is to use plastic coathangers for spacers. These are
readily available, and have the added advantage that you can choose your color.
Just chop them up to whatever spacing you desire.
If you are planning on just a single band antenna, I would feed it with coax.
However, if you are going multi-band with a tuner, use the open wire line.
The Impedance is not critical. Use 2" to 6" spacing.
73 Gary N4AST
  #6  
Old March 31st 04, 04:18 AM
Bob Miller
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On Tue, 30 Mar 2004 19:52:50 -0000, Larry Gagnon
wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA


As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg


  #7  
Old March 31st 04, 04:58 PM
Lloyd Mitchell
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Default

I have a G5RV made by W7FG. The construction is great and makes structural
sense. I can recommend his version highly.

Its easy to put up and you dont have to worry about the center connection
coming loose..*there is no center connection*

He uses one continuous wire from feeder to end of the dipole on each
side..smart...

Mitch KD4HTW


"Bob Miller" wrote:
As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg




  #8  
Old March 31st 04, 06:54 PM
KA9CAR
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I made some ladder line last year. It works well, but was very time
consuming. I now buy it.

I purchased wire "staples" These are plastic bridges with holes for nails.
You pull out the nails and install your feed line.

There is a photo of a 1/2 inch section at this URL.

http://user.mc.net/~jdewey/Ham_radio...ding_relay.jpg

I used larger staples for my main feed line.

http://user.mc.net/~jdewey/Ham_radio/doublet.jpg

John
KA9CAR



"Bob Miller" wrote in message
...
On Tue, 30 Mar 2004 19:52:50 -0000, Larry Gagnon
wrote:

Hello to all. I intend to erect an 80 meter full size dipole and feed
it with homebrew open ladder line. Would anyone care to reply as to how
to construct ladder line easily and effectively? How does one determine
spacing to get X ohms impedance line?

Also any ideas on how such line can easily be fed in through a window
with a wood frame would be greatly appreciated.

Larry Gagnon VE7EA


As an alternative, you can try the website for w7fg. He makes and
sells open ladder line, as well as dipoles with the ladder line
attached.

bob
k5qwg




  #9  
Old April 1st 04, 06:54 PM
Drbob92031
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Posts: n/a
Default

The simplest way to feed ladder line through a window is to
make a 'spacer' board to fit in the window. Drill a couple of
holes in the board, the correct distance apart, feed the line
through the holes, 'hot glue' in place (or however you can get
it to stay put. Have to remove the screen...

'Doc
The above sounds very practical and do-able but make sure you put "drip loops"
on the incomming lines.
de wa2eaw...Bob
  #10  
Old April 14th 04, 05:05 AM
zeno
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Default



'Doc wrote:

PS - The real 'trick' is to keep the line from 'swarming' on

you when you finish.


What does this mean? I am unfamiliar with the term.

Zeno


 




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