[TowerTalk] Ladder Line Spacing from a Steel Tower

[jimlux]

Roger (K8RI) wrote:
> 
> On 12/3/2010 4:58 PM, n8de at thepoint.net wrote:
>> Instead of bringing the ladderline directly down the side of the
>> tower, 'twist' it as you do, thereby changing the distributed
>> capacitance of the two wires to the  tower and 'equalizing' any
>> capacitive problems.
>> 3 or 4 turns should suffice for 50'.
>>
>> One foot sounds good to me, too.
> I'd probably use about 1 turn per yard/meter as it's good for common 
> mode rejection and the extra turns wouldn't hurt (within reason)
> I have no technical basis for choosing  the number of turns/twists other 
> than it being convenient and a tiny fraction of a wavelength at the 
> frequencies they are likely to be used or encounter.
>


spacing out a foot, the coupling is pretty low regardless of how many 
turns..

However, another good reason for twists is that it tends to reduce the 
wind induced vibrations.  That is, you don't want your feedline to be 
aeroelastically vibrated to death like the Tacoma Narrows Bridge.