Ham radio questions and possibly answers.

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This is a useful tutorial on NVIS antennas - using HF for short and medium distances.

https://static.dxengineering.com/pdf/wp-nvis-rev2.pdf
Near Vertical Incidence Skywave (NVIS) is a propagation mode which uses high angle radiation to send signals almost straight up to be reflected back to Earth for very effective short to medium distance communications. This mode of operation makes it ideal for in-state communications during disasters or other emergency situations.
 
I will be getting the parts for this one next time I go to Hamilton. It's one I actually have enough room for. I had no idea it was so hard to find 300 ohm twinlead. It was everywhere back in the dark ages of TV :p. Luckily, Rural King has the step in fence posts and RandL has the twin lead.

https://www.hamradiosecrets.com/nvis-antenna.html
 
dademoss said:
I will be getting the parts for this one next time I go to Hamilton. It's one I actually have enough room for. I had no idea it was so hard to find 300 ohm twinlead. It was everywhere back in the dark ages of TV :p. Luckily, Rural King has the step in fence posts and RandL has the twin lead.

https://www.hamradiosecrets.com/nvis-antenna.html
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At only 44 feet long, this is a no-brainer - I gotta build one. Unfortunately, I don't see any measurements of the actual elements. I'm guessing roughly 22 feet each (yes, I'm that good at math), and then fold over the ends shortening them 'til the SWR is lowest for the center (or desired frequency) of the 40m band.

What do you use for an antenna analyzer? Rigexpert? Nanovna? My son snarfed my nanovna and I may never see it again...so I need to factor a new analyzer into the cost of the build.
 
I used the same fancy math :). I just ordered a NANOVNA NANOVNAH4, on sale today for 79.95, from RandL electronics. It's hold for pickup, I'll pick it up when I stop for the Twin lead Monday.

https://www2.randl.com/index.php
 
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My 100' of Radio Shack 15-1175 twin lead finally arrived today. I really don't like dealing with ebay, where I purchased it, but it did finally show.

Is anyone else building the 40m nvis? I'm going to try to work on it this weekend if my family will let me.
 
Need to get me a roll of twin lead and build one of those. I've got some 3 or 4' fiberglass mast poles I got at a hamfest that likely would work well for this. They are part of a old military kit to put up a vertical antenna. I think I've got enough for 28'. Only down side it takes guy wires to keep it stable. I did get 2 aluminum rings with 3 slots each to guy it off.
Have any of you used a NVIS antenna before? How well can you transmit on them? Thinking this might make a workable set up to keep in the camper. I've been scratching my head trying to come up with a simple set up that wouldn't have a big footprint
 
Bacpacker said:
Need to get me a roll of twin lead and build one of those. I've got some 3 or 4' fiberglass mast poles I got at a hamfest that likely would work well for this. They are part of a old military kit to put up a vertical antenna. I think I've got enough for 28'. Only down side it takes guy wires to keep it stable. I did get 2 aluminum rings with 3 slots each to guy it off.
Have any of you used a NVIS antenna before? How well can you transmit on them? Thinking this might make a workable set up to keep in the camper. I've been scratching my head trying to come up with a simple set up that wouldn't have a big footprint
Click to expand...
I have not used one yet. I got 4 foot long push in electric fence posts from Rural king to support mine, 2 bucks a pop it was hard to beat. A few years back ARES played with a 80/40 meter "kinda military" NVIS, it worked well, but I do not have that much room.

Transmit is by design is for "short range", IE <400 miles, Near Vertical Incident Skywave :Near vertical incidence skywave - Wikipedia
 
Didn't even think about those fence post. I've got plenty of them and they'd be much easier to deal with. Just need to design a piece for the center tie in/coax feed. I think I have a small piece of bakelite that would probably work pretty well. 400 miles would be fun. I could talk to you with that range I think. That would be lots of fun down on the coast
 
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Bacpacker said:
Have any of you used a NVIS antenna before? How well can you transmit on them? Thinking this might make a workable set up to keep in the camper. I've been scratching my head trying to come up with a simple set up that wouldn't have a big footprint
Click to expand...
Kinda. I used a Chameleon Emcomm II on 160 meters and the only other station that could hear me was here in Rochester. That's because the antenna is only 25' or so up, so on 160m, it's an nvis. (I can reach all over the world on 40m on that thing.)
 
Bacpacker said:
I wonder about reaching KD4ULW from here. If conditions are good, maybe. The 2 of you wouldn't have much issue I wouldn't think
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You and I should be ok, depending on the propagation. Nice thing about radio with lots of stations are relays of information :)
 
Add another vote to hamstudy.org - I used it to get my General.
 
My electronic communications professor had a 2 meter band setup.

We used tubes from an am radio station to build his linear amp for it and I have no idea what he was putting out, but I would never have climbed the tower and let him key the mike.

He lived in someplace outside of Tupelo Mississippi.

As we worked up the sections of the linear I built digital meters for all of the levels he wanted to monitor.

He had an antenna on his car with two directors beside it, he was a HAM in for the long haul.

He was active in the civil service communications net so he did a lot of good in the area.

Ham radio is not as well known as it once was, but it may have to make a big comeback if things continue down the current path.
 
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