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Author Topic: My antenna install - See diagram  (Read 605 times)
N0XJO
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Posts: 34




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« on: October 03, 2008, 01:54:52 PM »

I’d like some thoughts/idea/advice on my antenna.  I uploaded a quick diagram to www.scottandjenny.com/antenna.pdf

I’m in Minneapolis and use primarily 20/40/80 meters with about 100w max.  I have a 102’ G5RV antenna about 20 feet off the ground.  It does okay, but the antenna is not real high.  I seem to hear and be heard the best to the southeast, like KY, TN, FL, GA.  It is rare that I hear foreign calls on any bands, but I’m interested in that.  I have a decent size lot but have a lot of trees to run wire through.  

On the diagram, it looks like the antenna cuts across the house, but it really is about 5-7 feet apart.  

My questions:
1.   What effect, if any, is the aluminum siding on the house going to have?

2.   How much of a difference will it really make if I can get the antenna above the roofline?  The trees are pretty tall, but I'm worried it's going to be a pain to get the antenna higher.

3.   How important really is it for the dipole to be straight?  If you look where the right side is attached, I’d like to attach it the next tree to the south, however I have another large tree in the way.  Wife won’t let me cut down any trees.  

4.   What general things can I do to improve performance with minimal investment?
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WT0A
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Posts: 922




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« Reply #1 on: October 03, 2008, 02:26:49 PM »

hieght will make a huge difference.
Glen WT0A
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WW5AA
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Posts: 2086




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« Reply #2 on: October 03, 2008, 02:37:57 PM »

The hardest part of putting up a good wire is getting it high. Even on 20 meters, your antenna is too low to be very effective. The G5RV is a good antenna on 20 meters only, although it may tune on 80/40 or others. In your situation, I would go for an all band doublet if you have the room. Use insulated wire if going through tree branches. A dipole or doublet does not have to be perfectly straight; my 252' doublet is configured as a straightened out "Z" because of my small city lot. You will get a big increase in effectiveness by raising the antenna as far as possible above the roof line. At 7' from the siding, your antenna is not working efficiently. Good luck.

73 de Lindy
P.S.  You can see my doublet by searching "Articles" for "Antenna primer"
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KZ1X
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« Reply #3 on: October 03, 2008, 02:40:42 PM »

At 20 feet, your antenna is (sorry to be blunt) a worm warmer.  

Yes, it is a lot of work, sometimes, to raise a wire antenna with heavy tree cover ... don't I know it!  But your efforts will be greatly rewarded.

There are clever ways to work the antenna up into the air.  I use a WB6ZQZ type tennis ball launcher, and multiple vertical 'pull' lines to help thread a leader line, which then pulls the wire into place.  Can take hours to do all this, and really needs two people (or three).
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K9WJL
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« Reply #4 on: October 03, 2008, 03:22:06 PM »

Hi,
 I had a G5RV, and it worked pretty well, It was set up pretty weird to. The Apex of the thing was at about 30' up in a pear tree in the backyard, and one of the ends was about 45' up in the rear part of the yard, and the other end was actually run over the house, and tied down to one of the roof vents. It actually touched the chimney at about 25 ft, and thats why it's down now, it rubbed itself in half on the corner of the chimney (I had saw it coming, but oh well). I used it and had contacts on every continent except Antartica, running about 1KW, but some were 100 watts. it depends on conditions.
 When I bought my vertical, I was amazed how well it worked compared to the G5RV. The vertical beat it everywhere except for 40 & 80. The G5RV is now in the garage awaiting repair, and an OCF Dipole has taken its place. The OCF dipole is pretty even with the vertical on 20 and 40, and way better than both on 80.
 I'm saying this because there's way better multi-band antennas than a G5RV IMHO, and you should look at the OCF dipole, and the Windom's and the 43' verticals as a project for the future.

 My questions:
1. What effect, if any, is the aluminum siding on the house going to have?

 It will affect the tuning and the radiation angle of the antenna adversely.

2. How much of a difference will it really make if I can get the antenna above the roofline? The trees are pretty tall, but I'm worried it's going to be a pain to get the antenna higher.

 You will see a big difference if you can get to 40', The higher the better. I believe if you modeled this antenna on EZNEC, you'll see a lower angle of radiation on 20m and maybe four directional lobes. This may be a pain, but I believe it will be worth the effort. Get yourself one of those painters extension poles at the local home center, and buy a 6" roller handle. Bend the perpendicular end where the roller goes parallel to the axis of the handle, with the open end up. This is a great tool for placing wire antennas in trees and I use it to retreive the Dog's frisbee when I throw it over the fence also Smiley

3. How important really is it for the dipole to be straight? If you look where the right side is attached, I’d like to attach it the next tree to the south, however I have another large tree in the way. Wife won’t let me cut down any trees.

 Based on your diagram, it'll be fine. It wont effect much of anything at all. Route the antenna through the large tree's limbs.

4. What general things can I do to improve performance with minimal investment?

 Getting higher in the air will help the pattern, and also keep the ladderline off the ground (very important I've been told)
 Cut off any cheap coax, and splice on some good stuff like 9913 or LMR 400.

 I wonder why you don't hear much DX. Is it that you have a lot of local noise? Is it the time of day you listen? I can hear DX all the time here in IL, and my antennas really arent anthing special. I would think that even if they cant hear you, you should be able to hear them. Alot of these stations are extremly strong. Maybe you should look through your feedline to see if anythings amiss, using a tuner, you might be matching a bad connection somewhere.
 Hope this helps you.
 
 
 
 
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W7ETA
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« Reply #5 on: October 03, 2008, 04:17:34 PM »

"2. How much of a difference will it really make if I can get the antenna above the roof line? The trees are pretty tall, but I'm worried it's going to be a pain to get the antenna higher."

If low antennas were good performers, everyone would have low antennas.

You can conduct an experiment be either making a sloping dipole or ground plane wire antenna for 20 meters and stringing it up at your 20 foot point.

This experiment will allow you to judge if your 20 meter G5RV at 20 feet functions better than a vert or sloping dipole.

Come to think of it, you can probably string up a Delta loop antenna and play around feeding it feeding it to get vert or horizontal radiation.

73
Bob

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KB9CRY
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« Reply #6 on: October 03, 2008, 05:14:00 PM »

One wavelength up in height for your band in question always works well.  You do the math; you've already done the real time homework.  You may want to investigate ground mounted vertical arrays if you can't get height.
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N6AJR
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« Reply #7 on: October 03, 2008, 07:49:28 PM »

put up a fan dipole ( homebrew for under 30 bucks,) and spend the rest of the money on a couple or 3 of the 40 foot push up masts.  run the center of the g5rv up  with the ends going North and South and put the 3 band ( 20/40 80) fan dipole up going east -west for 80, and the 20 and 40 yires  in the 45 to 135 degree and the other way caddy corner.

you will have something good pointing some where on most every band, and slap a tuner in the shack and go for it. get the center sand ends up as hi as you can, and use light rope to gets the ends to their tie off's

pound a pipe in the ground about 3 feet and drop the push up mast in the hole.  now the top is at 7 feet and you can tie on antennas standing on the ground.  use the antennas as a top set of guys and tie some parachute cord to the 20 foot level of the mast and tie off to something strong in 3 different directions.

run up 10 feet and lock the pin, shove up another 10 fee and lock the pin shove up the last 10 feet and lock the pin, then tie off the guys and the antennas.
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W4VR
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« Reply #8 on: October 04, 2008, 08:09:00 AM »

Get it away from the house and as far up as you can.  The way to thread wire through the trees is to use either a sling-shot or bow/arrow launcher.  I use the sling-shot method and it works well for me.  I have photos of my home made sling shot launcher on my website if you're interested.
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N0XJO
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Posts: 34




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« Reply #9 on: October 06, 2008, 11:07:14 AM »

Thanks for all the replies everyone!  

Anyone in Minneapolis (or west of want to help me hang this thing?  

I've already got 3 tennis balls stuck up in the trees from trying to re-hang the dipole this weekend!  
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N4JTE
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Posts: 1156




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« Reply #10 on: October 06, 2008, 05:26:40 PM »

A casting rod fishing pole with a 2 ounce lead sinker and 10lb testline will acheive at least 70 ft with ease. Paint the sinker orange and pull back thru with masonry string and attach final rope. Been there and did that many times.
Bob
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