[Boatanchors] Fw: Slightly OT: What is the optimum "twist ratio" inwindow-line

[Brian Clarke]

Not so, Jim.

The purpose of the twist in window feedline is to balance the line with 
respect to all possible unbalancing materials, such as metal masts, metal 
downpipes, metal rooves and gutters.
Go to any wind sail manufacturer's wind tunnel results to see the effect of 
uni-directional spiral twisted lines.

73 de Brian, VK2GCE.

----- Original Message ----- 
From: "Jim Wilhite" <w5jo at brightok.net>
To: "Boatanchors Mail List" <boatanchors at mailman.qth.net>
Sent: Sunday, November 20, 2011 3:13 PM
Subject: [Boatanchors] Fw: Slightly OT: What is the optimum "twist ratio" 
inwindow-line


>
> ----- Original Message ----- 
>
> Mac you hit the nail on the head.  The purpose of the twist is
> resistance to air flow not radiation nor pickup of extraneous signals.
> If you have an interfering signal, it won't care what orientation the
> feedline is.  One, obviously, does not want to twist the line
> excessively, that can cause problems.  The amount you suggest is good.
>
> Jim/W5JO
>> ----- Original Message ----- 
>>
>>>
>>> I generally use a full twist around 8 feet. Somewhere,
>>> there is probably some sort of formula that is based
>>> on the wavelength at the highest frequency being used
>>> on that feedline.
>>>
>>> I am more concerned about flutter and accompanying
>>> fatigue of the conductors in high Oklahoma winds than
>>> I am about any radiation or pickup considerations.
>>>
>>> * * * * * * * * * * *
>>> * 73 - Mac, K2GKK/5 *
>>> * (Since 30 Nov 53) *
>>> * Oklahoma City, OK *
>>> * USAF, Ret (61-81) *
>>> * * * * * * * * * * *
>>>
>>>
>>>
>>>> Date: Sun, 20 Nov 2011 00:16:38 +0000
>>>> From: ko6bb1 at gmail.com
>>>> To: boatanchors at mailman.qth.net
>>>> Subject: [Boatanchors] Slightly OT: What is the optimum "twist
>>>> ratio" in window-line
>>>>
>>>> I'm asking this here as I don't belong to any antenna lists right
>>>> now.
>>>>
>>>> If you were using 450 Ohm window-line to feed a dipole, and you
>>>> wanted
>>>> to minimize stray radiation or extraneous pickup from the line,
>>>> about
>>>> how many twists (say per 10 feet of line, or whatever) would you put
>>>> in it?
>>>>
>>>> Thank you.
>>>>
>>>> -- 
>>>> 73 de Phil, KO6BB
>
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