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Re: [TowerTalk] help with shunt feeding

To: W5JMW John <>
Subject: Re: [TowerTalk] help with shunt feeding
From: Bill Coleman <>
Date: Fri, 7 Oct 2005 23:36:18 -0400
List-post: <>
On Oct 6, 2005, at 7:09 PM, W5JMW John wrote:

> With all the talk about shunt feeding.I have a question.I am  
> currently using
> 3 slopers,(80,40,160) comming off my hdx-555 at abt the 50 ft  
> level.I also
> have a hy-gain hy-tower that is midified for a 40 meter vertical with
> elevated feed.That is to say that a 35 ft element is insulated from  
> the
> lower tower,Third ant is a 140ft dipole fed with open wire.My tower  
> is a
> hdx-555 with a 2 ele 5 band quad on a 12 ft mast.What can I do for  
> 160 that
> would be better?

How tall is the hdx-555 & antenna? How high is the 140 foot dipole?

Hard to say what would be most effective. You can probably feed the  
140 foot dipole, but unless it is a couple of hundred feet high, it's  
going to put most of the radiated energy straight up. (I've got a  
slightly shorter doublet at 35 feet that I've used on 160m)

Verticals are very effective for 80 and 160m.

> Wouls a shunt fed tower be the way to go ?? Should I use the  
> hytower and
> make it back to a 75 meter ant and add a wire to inverted L.All  
> suggestions
> welcome..73,john...BTW my city lot is abt 40 x 80...tnx

Vertical antennas are more about radials. What do you have for a  
radial field for the hytower? How many 100 ft radials can you put  
down around the hdx-555? If you can get 12-25 radials of this size  
down, you should have a very effective antenna, regardless of its  
actual length. Even 25 or more 50 foot radials will work, and work  
pretty well.

I have a 15m tower with a small tribander. I have it shunt fed on 80m  
by putting two 12 gauge wires 10 inches apart from ground level all  
the way to the 42 foot level about 15 inches away from the tower. I  
built an omega match by trial and error with two large variable caps.  
Once I found the approximate capacity needed, I used two smaller caps.

I have put down 25 60 foot radials. One radial is slightly longer (it  
bonds the tower to the R7000 out in the yard). The radials cover an  
area of 270 degrees. (90 degrees is blocked by the house)

This antenna rocks on 80m. Very effective for DX. I'm currently  
changing the matching network so it will also work on 160m. For this,  
I needed an L network to match the low impedance. First try was a  
T200-2 core with about 40 turns, tapped every two turns and about  
1000 pf. Not quite enough inductance. Next coil is two stacked T200-2  
cores with 46 turns, tapped every two turns.

I have a relay to switch out the matching networks between 80 and  
160m. So far, it hears pretty well on 160m.

Bill Coleman, AA4LR, PP-ASEL        Mail:
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901


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