Skyloop in the city

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N0LOZ, Aug 5, 2009.

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  1. N0LOZ

    N0LOZ Ham Member QRZ Page

    Well, here is my long winded post with some questions.

    First, let’s start off with the operating area.

    Downtown Bellevue, WA house that has high tension power lines down the east side of the property line, and normal power lines on the west and north side. It is a rectangle lot with the longest distance being east to west.
    I used to have around a 300 foot skyloop that was 10 feet high off the ground a foot off from the house, and 20 feet off the ground in the back. There is about a 10 foot gradual drop in elevation from the house to the back property line.

    The skyloop was fed by bending the wire down either side of a plastic pipe to act like a ladder line, which hooked to the MFJ-989 Versa Tuner.

    Alas, the windstorm brought it down, and space in the shack has caused me to not get around to fixing things.

    Well, I have been cleaning the shack out from the computer stuff, and setting back up for ham radio. I also purchased a IC-7000 and a IT-100 for the tuner.

    What I am thinking is putting as large of a loop as I can in the back yard.
    The following link is a sat picture of my house with some lines drawn on it.

    http://www.hackthemind.org/Layout.jpg

    The red line is my property line. The black lines are power lines. The blue line is what I am picturing for the skyloop. The green line is the feed line (window line). The purple box is a 5btv that is not fully setup, and the yellow box is a 2m vertical that is not fully setup.

    The questions are:
    1. Is this layout optimal?
    2. Should I slope the skyloop away from the high tension lines in the back?
    3. What is the best way to mount it to the house? (I was thinking two plastic polls that are 5 feet tall.)
    4. What is the best way to mount it in the rear? (The trees will not work because the ones I am looking at is actually in my neighbor’s yard.)
    5. Will I need a balun, and if so what kind? (Keep in mind I will be using this for as many frequencies as possible, and have a 1:1 Choke Balun on order.)

    Now for the issues, I am a renter. While I am allowed to do pretty much whatever I want to the house, I still have to fit in with the HOA. My direct neighbor’s are really nice, and know I am a ham radio operator. The 5btv has to be hidden, and the 2m antenna I will have to take down if some one complains.

    I cannot put the 5btv in the back yard, or mount it to the house because the radial system and my dogs won’t get along.

    The reason I am going with a skyloop is because on the 5btv, I have a S9 noise floor, and when I was on the smaller skyloop I was only getting a S2 noise floor. I do realize that other factors play in here, but I also can hide a skyloop easier, or explain it another way. (Its how I keep the dogs in the backyard, yeah, that’s the ticket.)

    Anyways, comments, suggestions?

    Keep in mind, I am on a budget as I spent all my money on the new radio and tuner, yet I am not afraid of making pretty much anything. Time permitting.

    Thanks.
     
    Last edited: Aug 5, 2009
  2. AE5TE

    AE5TE Ham Member QRZ Page

    The picture isn't loading.

    The loop should be a full wavelength at the lowest desired operating frequency, so your 300' would get you down to 80M. It should also be a full wavelength above ground but you know that's not practical for most of us and we just put them up as high as we can. Try to get it higher than most of the houses around and you won't pick up as much of their noise.

    I've had some success using 20' lengths of PVC pipe bolted to fences as supports for wire antennas. I think those "military surplus" fiberglas mast sections you see on Ebay will will stack up to 30' or so. You'll have a cloud warmer on the lower bands but at higher frequencies you'll probably have some decent lower angle lobes. Low as it is, the vertical might still get better DX.

    Close to the ground I don't think your orientation as to sloping and feedpoint vs. the power lines is going to be important. Some would suggest avoiding long sections of the wire directly under or parallel to the power lines but you know where they are and how impractical that will be.

    Try to feed all the way from the shack with balanced line if you can. Otherwise, with coax feed you can try with and without a balun and just do what works best.
     
  3. N0LOZ

    N0LOZ Ham Member QRZ Page

    The picture is really large.

    I expect, if I follow from the peak of the house, instead of a foot off like I was before, I will be adding more length to the wire.

    I know that the higher the better, but alas, since I can't put up 4 130' polls for 160m.. yeah.

    The IT-100 is coax only, and that means my ladder line will have to be converted to coax at some point. Otherwise I wouldn't even bother with a balun.

    Thanks. :)
     
  4. W9WD

    W9WD Ham Member QRZ Page

    The link doesn't work
     
  5. N0LOZ

    N0LOZ Ham Member QRZ Page

  6. AE5TE

    AE5TE Ham Member QRZ Page

    You can put a 4:1 at the output of the tuner - home-made or I think LDG & other outfits have small cheap ones that fit right on the SO-239 that would handle barefoot power.
     
  7. W9WD

    W9WD Ham Member QRZ Page

  8. N0LOZ

    N0LOZ Ham Member QRZ Page

    Ok, I have a 1:1 Choke Balun on the way with the IT-100. I was afraid I would need a 4:1. I will look into making one.

    Thanks.
     
  9. AE5TE

    AE5TE Ham Member QRZ Page

    Ya the photobucket works. Looks like you have lots of cover out back so whatever you can stand up at those back corners will get you there, wire threaded through the overhanging foliage best you can & not too much visible.

    I'm in a bit more difficult situation myself. No HOA or restrictions, but a very odd shaped lot that is more difficult for a loop. I have one horizontal dimension big enough for a 80M dipole but would need to erect lots of supports to make a loop. Fortunately I don't have to please anybody with appearance so I can put up anything that fits.

    But what you're doing does give me some ideas - these antenna threads are always good for that. I'm in the process of rebuilding after a hiatus myself. I have a portable vertical I put together that kicks on the higher HF bands and when not traveling I use it at the house, but I do need to build a better low band antenna.

    I'm thinking NM or West TX for retirement :) - just need to find a big parcel with water.:cool:
     
  10. N0LOZ

    N0LOZ Ham Member QRZ Page

    I have been fighting the urge to move back to Alaska myself. I grew up on 50+ acres that was on the side of a mountain. Too bad as a kid I didn't know about ham radio.

    I thought about going with a dipole at one point, but that would mean a feed line that the dogs could jump up and get. With the loop idea, the feed line will be above the house, and then the only thing I have to worry about are the tree rats.

    The last skyloop I had went through all the trees, and worked rather well. The only issue was how I tagged the corners. I didn't really know what I was doing, and used what I had on hand. Needless to say, bungie cords over time break down and wind will speed that up.

    I am still working out how to do the corners now, one of the reasons I am thinking of putting up my own polls for the corners. Then I can use the trees to help with the droop, and still have some control on the corners with out climbing anything.
     
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