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Author Topic: Please Reccomend: a person's "first" 40  (Read 432 times)
KI4WZO
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Posts: 17




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« on: November 09, 2007, 02:40:55 AM »

Hi,
Hope you are doin OK.

I wish to erect my very first dipole for 40/80 meters.  (thunderous applause)      .......alright.....attempted humor  just failed.....but I can't afford a tower like some of you pro's.   Wink

Seriously, I have the 140 feet to hang a wire in  trees, but  the trees are kind of far away.  The feed line to get to the trees is roughly 130 feet long.  I  wanted (a QST magazine design) one which called for 144 feet of wire and a feed line measuring 86 feet of 450 ohm ladder line. I had to scrap  my  plan because of this wierd 130 foot length of feed line.

Please reccomend a guys first 40/80 dipole.  I'll be using a kenwood at-200 tuner.

Thankyou.
With Regards,
Greg  Ki4wzo



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N0JY
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Posts: 7


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« Reply #1 on: November 09, 2007, 03:30:58 AM »

Greg,
My first dipole was an 80/40 meter and I used insulators to break the wire length on each side at the 40 meter size, which I jumpered over for use on 80 meters.  So the total length was ~130 feet (use your 80/75M frequency) with the dogbone insulators at ~65 feet.  Fed with RG-58 and no balun.  At one tree, I used a pulley and ran the rope all the way down with an old window weight hanging free at the bottom (not tied to the tree) so that the rope/wire could "flex" through the pulley when the wind blew.  When I wanted to change bands, I had to lower the thing by undoing the weight and feeding the rope out so it was low enough to add or remove the jumpers.  Maybe it's a bit more than you want to deal with to change bands, but it worked very well for me for several years!
73
Jerry
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AC5E
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Posts: 3585




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« Reply #2 on: November 09, 2007, 04:15:33 AM »

If I were fortunate enough to have room here I would probably use a "fan dipole." Run a search for it up and to the right of this post.

Since I don't have room, I use a "trap dipole," an Alpha Delta DX-CC - although that is best fed with coax. But it would let me work 20 and up if I did not have better antennas for those bands.

If an "off center fed dipole" will work as well on the fundamental and the first harmonic as dedicated wires for the bands. The pattern goes to pot above that but many hams use "Windoms" and swear by them.

Bottom line, there are at least a jillion good antennas that will work fine for you. And there are a few hundred "all band wonder wires" whose enthusiastic users swear will outperform a standard dipole, repeal the laws of physics, let you walk on water, etc., etc..
Avoid those like the plague and you will be a happy camper.

73  Pete Allen  AC5E
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WA3SKN
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Posts: 5488




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« Reply #3 on: November 09, 2007, 04:18:58 AM »

OK, either a dipole or a loop, fed with the 450 ohm open wire, mounted the higher the better, will work very well for you.
The distance with 450 ohm line will not be a loss problem.  And, using the tuner, you can use this on multiple bands OK.
I am not sure if you will need an external balun with your tuner.  And with the tuner and open wire, you do not have to cut the antenna to a specific length... the longer, the better!  Just keep the tree branches off it and you should be OK.
Good Luck!

-Mike.
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AA4PB
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Posts: 12856




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« Reply #4 on: November 09, 2007, 05:11:19 AM »

The good old standard is an 80M dipole with a pair of 40M traps inserted. You can purchase a pair of 40M traps at most amateur supply stores or you can get info on building your own from the ARRL Handbook.

For 80/40M and 100W you can just use a run of RG58 for the feed line. The loss is minimal on 80/40M for a 130 foot run.
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W9OY
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« Reply #5 on: November 09, 2007, 05:21:54 AM »

135ft of flat top and openwire line to reach your tuner.  You may have to play with the feedline length a little like add up to 15 ft as 130ft is close to half wave on 80 and full wave on 40 but its not a big deal and your antenna will be good.  

If you want DX I would suggest a vertical wire or a T out of the tree fed against a ground rod/radial system will work great  I've used the T on 80 and a straight vert wire on 40 against the same ground fleld.  Worked great, but the dipole will get you started.  

There is almost no loss in 130ft of good coax for a reasonably well matched antenna at 80 or 40M so that is an option too

73  W9OY
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W9OY
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« Reply #6 on: November 09, 2007, 05:23:49 AM »

If you use the kenwood tuner you will also need a 1:1 current balun for the open wire
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AA4PB
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Posts: 12856




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« Reply #7 on: November 09, 2007, 08:32:54 AM »

There are all kinds of antennas, each with its own particular advantages. However, for someone just starting out in HF I always recommend that you do what the majority of us did and start with a simple 1/2 wave dipole. Its inexpensive, easy to get up and running properly, and will get you on the air. There will be plenty of time for experimenting with more complex antenna designs after you get your feet wet.
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N6AJR
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Posts: 9908




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« Reply #8 on: November 09, 2007, 10:06:44 AM »

Bye the way, none of this is mine, Its just stuff I pulled from here and there. thanks to all the folks with the great sites. this is My take on the multi-band, single feed wire dipole ( but fan dipole is easier to type.  a true fan dipole is also called similar to a cage dipole and has 3 or 4 wires of different lengths on the same band , like a 64 foot , 66 foot and 68 foot  double leg wires on the same feed to give wider bandwidth, but bottom line, they are cheap, easy to build, and they work..
 
 
http://www.ku4ay.net/dipole.html
http://www.qsl.net/kd7rem/antdipole.htm
http://www.hamuniverse.com/multidipole.html
http://www.angelfire.com/nb/ni4l/ni4ldipole.html
http://www.arrl.org/tis/info/pdf/9611073.pdf
http://www.geocities.com/n2uhc/2banddipole.html
http://www.qsl.net/na4it/fandipole.html

 
 
 
by N3JBH on October 12, 2006    
FAN DIPOLE OR MULTIPLE BAND DIPOLE SPECS:
(Each leg is shown in length so you will need two legs.)

10 METERS = 8'4"
12 METERS = 9'5"
15 METERS = 11'1"
17 METERS = 12'10"
20 METERS = 16'8"
30 METERS = 23'2"
40 METERS = 32'9"
60 METERS = 43'7"
75 METERS = 60'9"
80 METERS = 65'6"
160 METERS = 123'5"
137 KHZ = 1708'1"  
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K1BXI
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Posts: 812




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« Reply #9 on: November 09, 2007, 10:34:50 AM »

All good answers here..........my add to the mix would be maybe a horizontal loop with one corner near the house and feed it there if you want a shorter feed line. If it is 130 feet to the trees you should be able to get some sort of a loop to cover 160 meters and up. This winter 40 and even 80 drops out soon after sunset here (45 degrees North), that just leaves 160 with any propagation.

Just an idea...........John.....K1BXI
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NA0AA
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Posts: 1042




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« Reply #10 on: November 10, 2007, 02:00:15 PM »

I have a parallel dipole for 80/40 - that's a single center insulator and feed line with both sets of wires in the same vertical plane - I have the 40 hanging about 12" below the 80 using dowels for the support on about 4' centers.

works well, needs no traps or band changing.

also works 15 meters nicely as well.
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KI4WZO
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Posts: 17




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« Reply #11 on: November 14, 2007, 02:06:21 AM »

Would like to thank all of you for your tips , they are appreciated very much.   Thankyou for spending your time to help me!

Best Regards,
Greg KI4WZO
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