[TowerTalk] 3/4 WAVE PHASING LINES

[jimlux]

dave arruzza wrote:
> To all,
> I am installing a elevated 40 meter 4 square over somewhat marshy New England soil. 
> 
> My property backs up to a drained 30 acre pond. You can see my QTH on Google Earth. It's the house before the property with the greenhouses.
> 
> Base elevation is 20' above ground utilizing 2 -  Rohn 25 tower sections per element. Elevated ground plane. 
> 
> I wish to use 3/4 wave phasing lines instead of 1/4 wave phasing lines so I can dress the phasing cables down the tower legs and underground to the Comtek box. 
> 
> The Comtek manual states to use only 1/4 or 3/4 wave cables and I understand that. 
> 
> Has anyone observed any determent in using the 3/4 wave cables vs. 1/4 wave cables?  
> 
The real difference is that the phasing will be more narrow band (for a 
given phasing error).  That is, say you cut your cables for 7.1 MHz.  At 
7 MHz, a quarter wave will be 88.7 degrees, the 3/4 will be 266 degrees. 
  The first, an error of 1.3 degrees, the second, 4 degrees.

Neither is particularly huge.  4 degrees will turn a perfect null into a 
-26dB null.. hardly a crisis.

You'll have bigger phasing errors from differences in the ground under 
the antennas and other component tolerances.