[TowerTalk] Open wire feed line length

David Gilbert xdavid at cis-broadband.com
Wed Jul 2 12:50:29 EDT 2008

Navigate to 
http://www.dxengineering.com/Products.asp?ID=50&SecID=10&DeptID=9 and 
click on the tab near the top of the page called "Choosing the Correct 
Balun".  It has information on feedlines and lengths for what you are doing.

It should be an odd number of 1/8 wavelengths, by the way.

Dave   AB7E

w4lde wrote:
> After reading several articles both on and off the WEB regarding a 
> center fed antenna, only one article mentioned a recommended length for 
> the feed line.
> My shack is located on the second floor of a new home, (24') #8 ground 
> wire to 8' ground stake  with a further connection to the common ground 
> point for the power and the rebar in the pored walls and flooring of the 
> basement, telephone and cable.  I plan on additional ground rods around 
> the property and at a new tower.  In a new home so progress is on-going.
> The 1:1 current balum used to convert the 450 ohm balance line is 
> external to the tuner, use about two feet of coax  from the balum to the 
> tuner.
> Antenna is cut for 80 meters and using about 60-70 ft of line to center 
> of the antenna.  Where the antenna lines leave the shack is about four 4 
> ft from the location inside of the rig and floor mounted PC.
> I use the antenna on all bands until such time I complete a new tower 
> installation.  I want to minimize stray RF around the shack since I rely 
> on a PC  and digital sound card  as my primary source for ham 
> enjoyment.  I have already had some problems with a USB keyboard that I 
> think may have been effected by RF when running over 50 watts on 20 
> meters only.
> One article recommended odd multiples of a wave length is desirable at 
> the lowest operating frequency while other articles don't address this.
> I am having no problem with a match using the tuner on all bands 80-6 
> meters.
> Have used the center fed antenna since 1976 but always had the shack on 
> the ground level and had a good and effective ground system short runs 
> with feed lines around the 90 to 100ft in length.  never had a RF 
> problem or surge problem.
> Any recommended WEB sites or comments are welcomed.
> 73 de
> Ron W4LDE
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