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[TowerTalk] Half-slopers using a tower

To: <>
Subject: [TowerTalk] Half-slopers using a tower
From: (
Date: Thu, 3 Jan 2002 23:36:00 -0600
On Thu, 3 Jan 2002 writes:
> In a message dated 1/3/02 6:08:30 PM Pacific Standard Time, 
> writes:
> > N4KG said:
> >  
> >  > My view of Half Slopers, better described as Quarter Wave 
> Slopers, is that the best way to get them to perform and provide a 
> reasonable match to 50 ohm coax is to attach them BELOW a fairly large 
> TOP Load (Yagi) such that the TOP Load plus the vertical separation
> between the load and the feed point is an electrical 1/4 
> wavelength.
> >  
> >  
> >  I disagree.  I have installed 1/4 wave slopers within inches of 
> large yagis and they worked fine.  I would agree that people that 
> have  large antennas on top of the tower tend to have better luck.  
> >  
> >  I was able to use 160M and 80M 1/4 wave slopers at my last QTH 
> and they worked great.
> >  
> >  95' ----> Cushcraft 2 ele 40M
> >  85' ----> TH7
> >  84' ----> Fed 2 80M and 1 160M 1/4 slopers
> >  35' ----> TH6
> >    
> >  73
> >  
> >  Bill, W4AN
> >  
I disagree with your claim that the sloper is ONLY 
" within inches of  large yagis".   I contend that
the MAJORITY of the top loading comes from
your 2L40 that resides 10+ ft above the attachment
point.   You have 10+ ft of mast, 11+ ft of boom
(in both directions) and 22 ft of element (on each 
side) with an inductive load in each half element.
That comes to 43 ft to the element tips plus about
10% due to the additional loading of a T shaped
load.  That's a pretty significant top load, not 
even counting the TH7 that is "within inches"
of the sloper feed.  My guess is that is pretty
close to being equivalent to the loading from
being 20 ft below a single TH6 as I described
for my original sloper installation.

Tom  N4KG

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