Author Topic: Backpacking NVIS setup  (Read 4298 times)

Offline Medicineball

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Backpacking NVIS setup
« on: July 26, 2014, 09:17:02 PM »
Somre really good folks on here, and need some advice. Here what I'd like to create, please someone tell me if it's possible. Most of all, I want to create a very lightweight NVIS antenna setup that I can bring backpacking. Second to that, I'd love to be able to create a non- NVIS setup from the same antenna - what would that look like? I'd be happy to stay with 40 meters, unless you talk me into something better. So: NVIS, lightweight, possible DX, lightweight, 40 meters would be great, and did I mention lightweight? Thanks in advance for the good responses I'm sure to get.

Offline Carl

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Re: Backpacking NVIS setup
« Reply #1 on: July 27, 2014, 08:55:36 AM »
Make your own light weight DIPOLE. for 100 watts or less ,some thin wire will do fine with 35 to 37 feet for each half and fishing line or twine for supports. Simple insulators from plastic or from PVC pipe will do fine and height above ground is what makes NVIS so all you need is to place it below 20 feet for NVIS and well above 20 feet for Distance...but as you will soon find out...you can work distant stations with an NVIS antenna too..at just a small percentage less effectiveness that a high (optimum) antenna. 
Much time and sweat is wasted on the last 2% effectiveness.

If coax and such make for too much to carry...an END FED HALF WAVE with a simple tuner also works well..That's right ,just 70 feet of wire and a 17 foot 6 inch counterpoise for balance and you have a one pound or less antenna that has GAIN!! PLUS with a small tuner can cover 80 thru 6 meters well as the EFHW is what I use when weight is at a premium.

Offline Medicineball

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Re: Backpacking NVIS setup
« Reply #2 on: July 27, 2014, 12:00:24 PM »
Thank you! I'd like to look at the end fed - can you provide a link to one that you think is good quality? Many thanks!

Offline Carl

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Re: Backpacking NVIS setup
« Reply #3 on: July 27, 2014, 04:36:23 PM »
The end fed half wave operates with as little as .05 wavelength as a counterpoise. I use an LDG automatic tuner ,but a manual tuner will do also. Cut a half wave of wire for the antenna or about 70 feet for 40 meters and 35 feet for 20 meters etc etc. The counterpoise I use and have found effective is 17 feet 4 to 6 inches (20 meter 1/4 wave) .

The 35 foot wire with 17 foot 6 inch counterpoise tied to a 1 to 1 balun (4 to one will also work) will work 80 meters as a modified 1/8 wave ,and 40 meters as a 1/4 wave ,with  20 meters as a half wave and 17,15,12,10 ,and 6 all working well from the pair of lightweight wires. I use the 35 foot ,with 17 foot 6 inch counterpoise as a portable ,easy antenna and the antenna ties directly to my auto-tuner with NO FEED LINE and just a short jumper to the radio,It has proven to be effective on 6 through 40 meters but I have to admit that most of my time is on 20 meters..

As is my habit ,I will host some info that I found,and give freely  if ownership is claimed I will take the files down. But ,so far, I have had no complaints.

Here is the link,articles just finished loading too my GOOGLE DRIVE,get them while they are fresh..

https://drive.google.com/folderview?id=0B5ZIZLZV4AwIX3ZwckFUeGpEOXc&usp=sharing

Offline Saint-TyR

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Re: Backpacking NVIS setup
« Reply #4 on: July 27, 2014, 08:07:07 PM »
Awesome! Again, thank you for sharing the doc from your Google Drive.

Stay Safe!

The end fed half wave operates with as little as .05 wavelength as a counterpoise. I use an LDG automatic tuner ,but a manual tuner will do also. Cut a half wave of wire for the antenna or about 70 feet for 40 meters and 35 feet for 20 meters etc etc. The counterpoise I use and have found effective is 17 feet 4 to 6 inches (20 meter 1/4 wave) .

The 35 foot wire with 17 foot 6 inch counterpoise tied to a 1 to 1 balun (4 to one will also work) will work 80 meters as a modified 1/8 wave ,and 40 meters as a 1/4 wave ,with  20 meters as a half wave and 17,15,12,10 ,and 6 all working well from the pair of lightweight wires. I use the 35 foot ,with 17 foot 6 inch counterpoise as a portable ,easy antenna and the antenna ties directly to my auto-tuner with NO FEED LINE and just a short jumper to the radio,It has proven to be effective on 6 through 40 meters but I have to admit that most of my time is on 20 meters..

As is my habit ,I will host some info that I found,and give freely  if ownership is claimed I will take the files down. But ,so far, I have had no complaints.

Here is the link,articles just finished loading too my GOOGLE DRIVE,get them while they are fresh..

https://drive.google.com/folderview?id=0B5ZIZLZV4AwIX3ZwckFUeGpEOXc&usp=sharing

Offline Alan Georges

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Re: Backpacking NVIS setup
« Reply #5 on: July 27, 2014, 09:51:18 PM »
Awesome! Again, thank you for sharing the doc from your Google Drive.
^^^ What he said!  Thanks again Carl.

Offline Medicineball

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Re: Backpacking NVIS setup
« Reply #6 on: July 27, 2014, 09:51:46 PM »
Carl,

Besides price (obviously!), how does your homemade one compare to this one in the "trail friendly" version?:

http://www.universal-radio.com/catalog/hamwire/4456.html

Thanks!

Offline Carl

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Re: Backpacking NVIS setup
« Reply #7 on: July 28, 2014, 06:59:00 AM »
Carl,

Besides price (obviously!), how does your homemade one compare to this one in the "trail friendly" version?:

http://www.universal-radio.com/catalog/hamwire/4456.html

Thanks!

That is a good question, I have not had first hand experience with the antenna shown...BUT how does the "efficient matching network" do away with the need for at least some form of counterpoise??? The only way I know to do this(with a power limit also) is with a non-inductive resister. Yep you are probably cooking off much of your power as HEAT rather that passing it to the atmosphere. An antenna like that does work,I've made contacts on my dummy load while testing. But the easy ,wire ,CHEAP antenna I describe puts your power in the atmosphere ...where it should be and does it well.

Any piece of conductive wire will radiate energy. Some do it better than others . I will not 'slight ' the other antenna...but ask yourself "will I spend SEVENTY DOLLARS  for 66 feet of wire and a 'mystery matching network'???

I don't want to buy into a mystery that is so obviously(to me) just a resistor in a box with a wire...There is a company that has a vertical antenna that promises 2 to 1 SWR or less across ALL HF BANDS...DUMMY...you are paying for a resistor (100 ohm non inductive) and some hardware.

Don't mis-understand , I use commercial antennas too, I just gave up on snake oil as a propagation additive.

OH CRAP, now I am back on the soap box....sorry ...I blame it on the chemo and hydrocodone that is supposed to help me.

Check out the 20 to 6 meter NO TUNE article I just added to the end fed antenna folder , link here .

https://drive.google.com/folderview?id=0B5ZIZLZV4AwIX3ZwckFUeGpEOXc&usp=sharing