My experience so far with NVIS communication..

***DISCLAIMER: Once again, this is not THE WAY to do NVIS, it is simply a record of my experience with my methods so far, hopefully you can learn something from my errors.***

 

I set out this summer to start practicing more in the field with my HF communications gear. I have gotten to the point where I can set up my equipment pretty good from my home, which has saved me some frustration and wasting of time in the field, but now I am to the point where it is time to start going into the field more and refining my methods.

The first thing I did was to build a better antenna than anything I was using previously, and that is a linked dipole setup for 20M, 30M, and 40M. After purchasing an antenna analyzer a few months back I was able to build a nice resonant (at home at least) antenna to take into the field.

The reason I went with a linked dipole is the fact that I can set it up as an inverted Vee, and changing bands is very simple. It is just a matter of lowering the feed point until I can reach the links required, and then raise it back up. I don’t have to unwind any more wire, extend guys, or anything. I can do a band change in under a minute, and that’s if I mess up. I used #18 insulated wire so leaves and vegetation hopefully don’t mess with my signal too much. I am feeding it with 50′ of RG8X.

I’m not as worried about operating from my house as much as I am operating portable (on foot), so I had to cut some station weight to do this. This meant my antenna tuner was out, which is another great reason to have a resonant antenna. So far I have set up my antenna in a variety of locations, and different heights, and have yet to have any problems with SWR.

I have to admit, that I am very much an amateur at all things involving radio communications, and this is no different for NVIS communications. There is an excellent series of articles put up by Brushbeater to help out. I can assure you I will be reading these over and over for the next few weeks.

That’s not to say I haven’t had any luck conducting NVIS. My most recent trip out was my best however. I stopped at a location with lots of pine trees and sandstone rock outcroppings. I picked up my station which consisted of my SGC SG-2020, a 7.5AH SLAB, 50′ of RG8X, some earbuds, and my linked dipole. I hiked back a little ways and found a location on top of a long rocky outcrop and began looking for a tree to hang my dipole in.

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My initial plan was to look for a height of 6 to 12 feet and set up my antenna as a dipole or inverted vee because I wanted to try to make an NVIS contact within 400 miles. I looked at a few trees but they all seemed to be more trouble than they were worth. I only had about an hour to set up, make contact, and tear down, so I had to be quick, but spending the time looking for an easier tree to get an antenna into was worth it.

I finally picked a young pine tree about 8 feet tall. It was kind of scraggly for a Christmas tree, but it would work for my antenna support. After a good jump I was able to get my feed point hung in the tree.

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I then went out to the ends of my antenna and looked for any branches to hang them on and a place to guy the ends with. I have about 10 feet of 550 cord tied to the insulators of my antenna with  a loop in the end so I can just grab a tent stake and stake the antenna ends down. For this trip though, I chose to run the legs of the antenna over any low branches or bushes I could find, and then stake the ends down.

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One of the links of my dipole, which is hanging on a 1 foot tall pine tree
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The short pine tree in the center is where my feedpoint is hung

So once I got my feedline ran back to an operating location somewhat perpendicular to my antenna, I set my radio for a frequency fairly low in the 40M SSB portion. I did this because I had read that the lower in frequency you go, the better your NVIS comms should work. In fact, after reading Brushbeater’s articles on the subject, the 40M band isn’t really ideal, but rather 80 or 160. But, hind sight is 20/20.

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I set my radio for 7.225 LSB and began calling CQ with 15 watts of power. No luck. So then I tried searching around the bands to see who I could hear and see if I could get in touch with them. I did hear some folks rag chewing, but nobody calling for CQ and no nets to try to get into. I’ve found that if I can typically hear a station, I can usually talk to them. So, with no luck there and time running out, I went back to 7.225 and started calling CQ. I was nearly ready to shut down when I was responded to by a station only 240 miles away. He wasn’t real strong, only about a 4/5, and that was about as strong as I was to him. I’ve found that a set of head phones is very helpful to have for hearing the weaker stations. While my radio has a decent speaker, it’s alot easier to hear the faint ones when the audio is being piped right into your head.

So an overall success! Our conversation didn’t last very long, but I was able to make an NVIS contact. Now I will be digesting and implementing the advice in the article’s posted by Brushbeater to further improve this very useful skill set.

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My experience so far with NVIS communication..

7 thoughts on “My experience so far with NVIS communication..

  1. Good article Brother!

    A possible solution to the tuner dilemma is investing in an Elecraft T1. The footprint on those are very small, and weigh very little. IIRC, they handle up 20w, so you should be good with that awesome SG 2020.

    Liked by 1 person

  2. Very good article, sir!

    With regard to NVIS and the critical frequency, it varies depending on solar flux, how far south you are, solar flux and all sorts of things. Take a look at the list of ionosonde locations and see whether you can find one a bit closer to you than Wallops Island. actual data from a nearby ionosonde can be helpful.

    As regards the linked dipole, that is a cool idea! I would guess that it is great for SOTA and IOTA contacts where you want the flexibility for the higher HF bands. If you are going to run only 80 meter NVIS then you could save the weight of the insulators and connectors, but the linked dipole is something I may play with, especially for the NPOTA event. Thanks!

    Keypounder

    Liked by 1 person

    1. shocktroop0351 says:

      I will certainly check those out, along with all the other links you put into your article on Brushbeater’s site. The linked dipole has been nice during SOTA activations, I have yet not to activate a summit. So far I’ve only been able to activate on 20M, though I always try 40 first. I’m going to build some 60,80 and 160 links for it sometime soon. Thank you again for that writeup you did, it always helps us knuckle draggers when the gurus take the time to explain and teach like you and Brushbeater do.

      Like

  3. MKT Mike says:

    Have you looked into a BUDIPOLE? New ones are not cheap, but they do come up on e-bay and other sites on a regular basis at much more reasonable prices. There is even a Yahoo group dedicated to them, with bunches of manuals, tips and tricks to choose from. HTH.

    Liked by 1 person

    1. shocktroop0351 says:

      I have a little. I’ve actually got the parts to build the homebrew version sitting in the shack. My first antenna build was a buddistick, but since switching over to a full size resonant dipole, I haven’t really been too interested in any other types of antennas. I’d still like to try out a buddipole though, can’t have too many tools in the toolbox after all.

      Like

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