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Author Topic: ZS6BKW optimized antenna  (Read 703 times)
KB4OIF
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Posts: 153




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« on: December 07, 2017, 04:10:46 AM »

Antenna is 93 feet.  Back yard is 82.  I have a 43 foot tower.  With it attached to a halyard at or close to the top, will it shorten it enough to fit inside my yard.  Ladder line will be close 4-6 feet from the tower. 
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KC9NVP
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« Reply #1 on: December 07, 2017, 05:12:20 AM »

Is the yard 82 by 82 or 82 by something else? Where is the tower located in relationship to the yard and house?  Is it in the middle or off to one side?  If in the middle and you place the feed point or center of the antenna at the peak of the tower that gives you 46.5 ft per side which could be ran from corner to corner.  It is also possible that you will need to run and secure one down leg somewhere in the front yard such that part of the antenna is over the top of the house.

Good luck,
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AC2RY
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« Reply #2 on: December 07, 2017, 05:23:01 AM »

Antenna is 93 feet.  Back yard is 82.  I have a 43 foot tower.  With it attached to a halyard at or close to the top, will it shorten it enough to fit inside my yard.  Ladder line will be close 4-6 feet from the tower. 

Why do you need wire antenna if you have tower? Just install multi-band yagi on it. You also can use tower as a support for inverted V for 80M.
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KB4OIF
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« Reply #3 on: December 07, 2017, 05:41:28 AM »

OK.  I was not very specific with my post.  Tower is attached to the back of the house about in the middle of the back yard. Backyard is slender.  Only about 26 feet from the back fence to the back of the house. There is a screened in porch on the back of the house near where the tower attaches to the house.  I have a Carolina windom stretched between 2 supports.  no center supports  40 foot pushup on the North end and a 30 foot tower with a 10 foot pole on the south end.  that distance is about 72 feet.    Can't go to the front of the house. 

I am 71 yrs old and have not been able to climb the tower for many yrs.  It is not a tiltover, it's freestanding.  I have a Mosley TA 33 Jr 4 element new in a box that I have had for 4 years.  Can't seem to have the time or anyone willing to help to get it up.  My thoughts are to get a wire up AKA ZS6BKW, I have a 31 foot vertical that I am going to put in the near future and the last think is a hex beam somewhere in the back yard.  80 meter wire is 131 feet long from what I read.  I would have to bend the ends a lot to fit it in my yard.  That's the reason I ask if it would shorten the ZS6 antenna enough to fit it in.   

KB4OIF
John
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WB6BYU
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« Reply #4 on: December 07, 2017, 08:46:27 AM »

If you let the ends of the wires hang down rather than cutting them shorter I think it should work.
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KB4OIF
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Posts: 153




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« Reply #5 on: December 07, 2017, 12:12:17 PM »

BYU.  I am Not being smart here.  How do I let the ends hang down.  Wrap the flexweave around the insulator and just let the end dangle .  Hook the support rope to the other side of the insulator??? 

John.
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WB6BYU
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« Reply #6 on: December 07, 2017, 04:42:33 PM »

I just tie the support rope to the wire some distance in from the end and let the ends hang down.
I find this convenient for dipoles, as I can tune the antenna by trimming the hanging end without
need to retie the ropes holding it.

If the end of the wire is too close to a mast or other metal object, then you might want to tie it
off back down to ground level, or to one side or the other, so it doesn't blow around in the wind.

To get more detailed depends on the specific materials used in your antenna and what you are
tying it off to.   If you have an insulator already tied onto the end of the wire, you can untie it
and slide the extra wire through the hole.  Or I'd use an electric fence insulator that can slip
around the wire rather than having to thread the wire through a hole.  I like these:




 You can't see it very well, but neither end of the egg insulator is closed, so you can slip it around
an existing wire (the fence wire in the photo) then tie a rope around it to the support, leaving the
wire free to slip through the insulator.  However any of these can be used in a similar manner:







There are other ways to do it, too, of course, but having lived in the country I keep a bag (or several)
of the first couple of types on  hand for antenna projects.  Though since I mostly use baling twine for
my support ropes, which serves as an adequate insulator by itself, I'd probably just tie the rope to the
middle of the wire with a sheet bend.


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N7EKU
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Posts: 722




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« Reply #7 on: December 07, 2017, 05:44:35 PM »

Antenna is 93 feet.  Back yard is 82.  I have a 43 foot tower.  With it attached to a halyard at or close to the top, will it shorten it enough to fit inside my yard.  Ladder line will be close 4-6 feet from the tower. 

Hi John,

This should fit, just by hanging it as an inverted V form.  Seems like your side posts are 76' apart with the main tower in the center?  If so, by Jr. High geometry:

Square Root of  46.5^2 - 38^2 = 26.8'

So if you can get the center up 40', then the ends at the side posts would be 13.2' off the ground (nice for safety).

73,


Mark
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Mark -- N7EKU/VE3
KB4OIF
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Posts: 153




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« Reply #8 on: December 08, 2017, 03:17:59 AM »

OK.  thanks everyone.  Mark, I had trouble with math, let alone geometry.  Thanks.  BYU.  Thanks for the pictures and the explanations.  That helps.   Now all I need is some dry warmer weather.  41 degrees with a wind chill of 33.  It's snowing to the west of us.   I live 3 miles inland from the Gulf of Mexico so this is not normal.


John
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N7EKU
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Posts: 722




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« Reply #9 on: December 08, 2017, 06:28:13 AM »

You're welcome John,

Sorry if I sounded uppity about the math.  The weather is weird everywhere I think -- we should be cold and covered in snow by now up here in Ottawa, Canada, but it's clear and sunny and not too cold.  Well, if I was closer I would be happy to help put your antennas up.  I hope you can find someone in a local club that could help.

73,


Mark.
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Mark -- N7EKU/VE3
VK6HP
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Posts: 186




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« Reply #10 on: December 08, 2017, 06:31:59 AM »

You get another slight break from the inverted-v configuration in that the end capacitance to ground will shorten the doublet a bit from the notional 93'. Mine is installed with almost the dimensions mentioned by Mark and I think the doublet lost a couple of feet in the tuning.  To some extent you can play swings and roundabout between the doublet and the stub lengths although it's best to tune it on the bands you most care about.  You'll find the stub is relatively "active" and it's worth securing it so it doesn't flap around too much.  I use a fibreglass mast, and PVC pipe standoffs where the lower portion of the stub starts to run near the house structures.
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KB4OIF
Member

Posts: 153




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« Reply #11 on: December 08, 2017, 09:23:49 AM »

No Mark .  I did not want to come off like """"I"""" was being smart, not you.  When I added 3 + 3 when I was in school. I got 7 sometimes.  I talk at times with a Canadian station VE3SU Paul on the nightwatch net on 7.192.   With the wind chill right now it's 32 degrees. Unreal for us this time of year.  Thanks also Peter VK6.


John
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W5DXP
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« Reply #12 on: December 08, 2017, 11:46:39 AM »

The weather is weird everywhere I think...

It snowed in South Texas last night.
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