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Author Topic: My Take on The NVIS X-Pole  (Read 1835 times)

Andywragg

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My Take on The NVIS X-Pole
« on: January 19, 2018, 05:37:04 PM »
Hi Folks

Finally finished my attempt at an NVIS antenna for use in the field. Based on a mashup of designs from the military, Commsguy (via another social medium) and a paper by DX Engineering, here it is...(see attachments)

The X-Pole as I'm calling it is good for 80 and 40m and is self supporting. The mast (a lightweight fibreglass 6m telescopic flag pole) threads through the hole in the middle and stops at 15 feet where the diameter of the pole equals the hole in the middle. The 2 inverted V dipoles at 90 degrees support the mast when pegged out at 42 feet from the mast centre.

Made from 6mm Perspex (from my radio club), M6 stainless wing/nuts and bolts, and some bits from SOTABeams, plus a bit of 2mm Grizly Cub cord. I've got 30m of feeder cable to go with it as well, just need to put the BNC ends on it.

I hope to test it out once the weather calms down and gets a little warmer.


Design Doc from DX Enginneering can be found here...

http://static.dxengineering.com/pdf/WP-NVIS-Rev2.pdf

Cheers

Andy

Once a 'STAB in the Dark'
M6UAW

gil

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Re: My Take on The NVIS X-Pole
« Reply #1 on: January 20, 2018, 03:26:20 AM »
Great. I saw the dxengineering page a while ago and some others, even using coils. I might give it a shot some time...

Gil

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scarr

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Re: My Take on The NVIS X-Pole
« Reply #2 on: January 20, 2018, 07:45:33 AM »
Nice work Andy - I'm working on something similar, basically a doublet cut for 80M with the legs in an Inverted-V config, also working from a 6M flag pole.

My yard is only 11M long, so this will mean putting a backpack on and finding a field!

It would be great to try and organise a sked at some point, since we're at a low ebb in the solar cycle, working other Irish or UK stations on HF is a real challenge. I think the low 1/2 wave doublet for 80M should allow it.

I don't intend operating in the dead of night, otherwise I'd probably need to look at 160M... that would be fun trying to set up.
« Last Edit: January 20, 2018, 08:05:55 AM by scarr »

cockpitbob

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Re: My Take on The NVIS X-Pole
« Reply #3 on: January 20, 2018, 06:05:19 PM »
That looks nice.  Since this antenna requires a tuner I suppose it could be used for the higher ham bands too.  Of course they would be more for DX than NVIS, but it's always nice to have lots of communication options.

I'll have to remember this one.  Here in New England we have more trees than we know what to do with, so I could leave the poles at home and throw a line over a 15' branch.

Andywragg

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Re: My Take on The NVIS X-Pole
« Reply #4 on: January 22, 2018, 09:09:36 AM »
Quick video I did over the weekend.

https://youtu.be/xq7PU5oLWh8

Just need to mod the hole in the middle as its a bit too big and it sits at 13 feet not 15 as per the design.


Enjoy..
Once a 'STAB in the Dark'
M6UAW