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Author Topic: Dimensions for Alpha Delta 80m dipole with loading coil?  (Read 1264 times)
VA2FSQ
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Posts: 511




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« on: February 24, 2013, 04:15:32 PM »

Hi,

I dont suppose that someone would know the length between the center insulator and the 80m loading coil that comes with the alpha delta 80m antenna?  I know the overall length is 82 feet but I don't know the distances between.
Is there a way to calculate this? I originally used the antenna without the 80m coils but now I want an 80m antenna but I lost the original dimensions.
Thanks
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VA2FSQ
N4UM
Member

Posts: 480




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« Reply #1 on: February 24, 2013, 05:38:11 PM »

Calculate the  approximate inductance of the coils based upon their diameter, length and number of terms.  Then use EZNEC to systematically vary the position of the coil and note the SWR curves for each position.  I think the free downloadable demo version of EZNEC should be able to provide a good approximation of the coil placement.
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VA2FSQ
Member

Posts: 511




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« Reply #2 on: February 24, 2013, 06:02:20 PM »

Great I'll give it a shot
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VA2FSQ
W8AD
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Posts: 57


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« Reply #3 on: February 25, 2013, 10:27:23 AM »

Hi, the factory length for the DX-DD from the center insulator to the coil is 34 ft. 9 in. each side. From the coil out to the end insulator where the ropes attach is 5 ft. 7 in., each side.

Hope this helps,

Don, W8AD,  Alpha Delta
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VA2FSQ
Member

Posts: 511




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« Reply #4 on: February 26, 2013, 08:05:26 AM »

Hi Don,

Yes!  This is perfect.  Now all I need is a couple of trees!
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VA2FSQ
W8AD
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Posts: 57


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« Reply #5 on: February 26, 2013, 09:40:39 AM »

Hmmmm, maybe we should think about getting into the portable telescoping tree business?Huh?
Anyway, hope you get it up OK and have fun with it.

73,

Don, W8AD
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VA2FSQ
Member

Posts: 511




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« Reply #6 on: March 13, 2013, 07:00:00 PM »

http://www.creativesg.com
Check out the fake "antenna tree" 30 meters high!
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VA2FSQ
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