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[TowerTalk] OCF mystery?

Subject: [TowerTalk] OCF mystery?
From: VO1HP <>
Date: Mon, 05 Dec 2011 21:05:05 +0000
List-post: <">>
I am using a new Comtek 41130ET   4:1 balun  from  to build an 80-40-30 
OCF dipole as per the data on the W8JI web page regarding ICF dipoles.  
Primarily to use on those three bands....any other bands that it might 
work on would be a bonus!

I am using 134 ft of #12  electricians solid copper wire (insulated) fed 
at the 20% point or approx 27ft from one end.   The antenna is arranged 
in Inverted Vee format.  The center of the wire is at 52ft and each end 
is approx 17ft off the ground on posts.   Both legs are in approximately 
the same vertical plane.  The balun is suspended in mid air in the 
antenna leg to the south of my tower and the center of the wire is held 
up by my  tower.

After some pruning the wire today the antenna has the following SWR 
measured on a Drake WH7 wattmeter in my shack....Approx 150ft of 50ohm 
cable length to the balun from the tx.

3.5     5:1   unacceptable
3.8     5:1   unacceptable
7.0     1:1   wow!
7.1     1.02:1   wow!
10.1   2.2 :1    acceptable
14.1   2:1         acceptable
18.1    4:1        unacceptable
21.1    3:1       acceptable
24.9    1.4 :1   wow!
28.0     1:1      wow!
28.5      1:1     wow!

Anyone have  any clues as to why the SWR on 3.5 and 3.8 is so high?.  
The antenna is not useable on that band except for listening.  I do not 
use antenna tuners and expect to operate all resonant atnennas.  I 
expected 80M to be the best band in terms of SWR based on the info on 
the W8JI website.   Could there be an issue with the balun.   Why does 
the dipole appear to match the W8JI info more or less except on 80?

Mystified --  Please help

Frank VO1HP

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