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Antenna Project

JDemoret

Member
Mar 5, 2009
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Well after a couple of weeks experimenting with an end fed wire antenna for 11 meters and trying to get the matching cicuit right (and fighting with my OCD :blink:) I have started the "final" design of my vertical ground plane antenna. Once I got the matching circuit right (photo 1), I ended going with an air wound coil and a coax capacitor which brought the SWR down to 1.5:1 on the wire antenna and I'm pretty confident I can get this setup to work with the vertical. I was able to pickup some aluminum tubing that is 7/8" in diameter and about 5' long. I joined them with a two foot wooden dowel and a coupler made from conduit and hose clamps (photos 2 & 3). The overall length is 22.5 feet and seems to be very strong and lightweight. Photo 4 is the completed radiator attached to the base and the enclosure for the matching cicuit. Photo 4 also shows the mount and support which is pressure treated 2x4's I had laying around which is designed to transfer the wind stress around the base and enclosure straight to the antenna mast which will be 1.25" conduit extending all the way to the ground from the roof peak. Photo 4 shows the antenna attached to my pool deck and is currently going through wind testing. So far so good, had a good windy one on Saturday and the only thing I had to change was the length of the radiator support, the weight of the antenna was pulling it over from upright.
More to come. Any suggestions welcome.

John
 

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JDemoret

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Mar 5, 2009
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More pictures.
 

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JDemoret

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Mar 5, 2009
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and more pictures.

Photo 1 is the original support (sagging bad)

Photo 2 is the extended support (much better)

Photo 3 is the ground radials. They are 6' aluminum tomato stakes which i ran 102" of 14ga copper wire down the length and it extends about 2' off the ends.
 

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HomerBB

Supporting Member
Jan 4, 2009
3,865
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Rogers, Ar
Very cool. It seems you've worked out the mechanics of it all. Looking forward to your results.
My 5/8 vertical has worked out well after trial and error. It is going to be up for a long time I think.
Tell us more.
 

JDemoret

Member
Mar 5, 2009
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Will keep you updated. I've been working on making it as beefy and lightweight as possible. Have not made any "electrical" connections yet, I am going to leave it up as is for a few days as we are supposed to get some wind and storms and want to see how it does.(y)

John
 

W5LZ

Crotchety Old Bastard
Apr 8, 2005
6,832
824
173
Oklahoma
After what happened to the last one, a wind tunnel test doesn't seem completely unreasonable, huh? :)
And I also think you will find that since it's so close (touching) that wooden support, the tuning/matching is going to be slightly different, and will change when things get wet. Probably not a large change but still a change, which is normal.
- 'Doc
 

JDemoret

Member
Mar 5, 2009
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Doc, I haven't had a failure yet but I did see what Homer's did and wanted to avoid that if at all possible. All the wood is going to painted with exterior paint, should I insulate the antenna from the support or will that make any difference? The support goes up the antenna about 3' so very little of the radiator if physically blocked by the support.

John
 

W5LZ

Crotchety Old Bastard
Apr 8, 2005
6,832
824
173
Oklahoma
Oops! So I got the two of you confused. I'm real good at that sometimes! (Oh $#;+, now which one do I apologize to??)

I think painting that wood would be a good idea. Not because it'll change what happens with the antenna, but to keep it from the normal weathering process. How it will affect that antenna is because of it being 'close' so it won't change that part. Unless that paint is conductive, and don't bother asking, I have no idea. :)
- 'Doc

................
MEMO
From: Subconscious
To : 'Doc
Would you please pay attention! Look how you are embarrassing me. It ain't easy being you, you know. Don't make it any harder!
 

W5LZ

Crotchety Old Bastard
Apr 8, 2005
6,832
824
173
Oklahoma
Just for grins, the attachment is from that 23rd edition with a little modification (added the colors). 'Blue' is for distance between antennas, 'red-ish' if for the phasing lines. It's NOT enough information to do the phasing correctly, just an example of 'wazinda' book.
- 'Doc
 

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JDemoret

Member
Mar 5, 2009
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Thanks for the advise and comments. I'm going to leave it where it is for a couple of days to see how it does in some weather and to get caught up on the honey do list :headbang. Working on getting the ground radials ready to attach. Will post the pogress as it goes along.

John
 

JDemoret

Member
Mar 5, 2009
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Got back to working on the antenna today and got the ground radials attached and the matching circuit hooked up and results were good (y).

Channel 1 1.4:1
Channel 20 1.3:1
Channel 40 1.2:1

Putting in about 22 watts.

Did not have to use the coax capacitor, actually results with it on were really poor. Tap point on the coil was typical, about 2 turns down. First contact was about 50 miles north of me with the feed point of the antenna about 6ft. off the ground (y).

Next job is to get it on the house and about 35ft. up.

More to come.

John
 

JDemoret

Member
Mar 5, 2009
41
0
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Well, for the last week or so I've been putting the antenna through it's paces and doing some tweaking and getting all weather-proofed getting ready to get it up on the house in it's final position. Here are the final results:

Radiator length: 23ft.
4 ground radials at 102" each.

SWR readings:
Channel #1: 1.2:1 (y)
Channel #20: 1.1:1 (y)
Channel #40: 1.0:1 (y)

I think I could fool around and fool around but this is about as practically close as it's going to get and so far with the feed point only about 6ft. off the ground I've gotten some good reports.

Thats all for now. Next step is an antenna raising. ;)

John
 

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