Friday, September 8, 2017

That Last Minute Ham Radio Thing to Do...

...Before tropical storm force winds take down the antenna farm...
Yes, this is a Post about the W3EDP antenna.
In roughly 36 hours tropical storm force winds from Hurricane Irma will be affecting my area. I only have one HF antenna deployed right now, my W3EDP. I keep another one handy, just in case the first one gets damaged in the storm. If you find yourself wanting a quick antenna project to have ready to deploy "Just in Case", but find yourself working last minute, here's an idea.
1. Prep work: You'll need an antenna tuner with a "Balanced line" input. If you don't have one right now, you're not entirely hosed, just design your antenna carefully, use low power, and use the principle of tuning by maximum racket (The louder the static/noise you receive means your antenna is working more better). If you can cobble together a tank circuit to use to tune the antenna, all's the better!
2. Go to Radio Shack (if it exists in your area) , and buy a 100' roll of speaker wire. I prefer the 18 gauge stuff with clear insulation. Size doesn't matter at 100 watts or less, as long as you can create two legs by pulling the wire apart. It will also help if you can get some banana plugs, one red, one black (color not critical as long as you pay attention.) Also acquire some sort of string, fishing line, small rope, for deploying the antenna
3. Once home, take the speaker wire, and pull about 5" apart, tie an electricians knot. This is your input side to the tuner. The knot is not critical, but it can help keep the wire together. That might not be what you want to do, so after you build the antenna, you can untie the knot if you want.
4. From the point of the knot, measure 17' of speaker wire. The parallel strands of wire are usually marked, one side a solid color (or no color at all) and the other side has a stripe. Sometimes, this mark isn't done with color but with texture molded onto the insulation. The important thing is that you want to be able to tell one side from the other. Cut one strand of the speaker wire at 17'.
5. Continuing from the knot, measure 85' of speaker wire, and cut both sides. You now have one short leg, and one long leg with some extra wire attached. Pull the extra wire apart from the long leg of the antenna. Save it! Doing some math (85-17) You'll realize that you have about 68' of speaker wire now. After the crisis is over, you can play with that wire by building an End Fed Half Wave Antenna for 40m.
6. Improvise an end insulator for the long leg of the antenna. I prefer using buttons from old milsurp BDUs.
7. On the input side, strip the insulation off of both wires, about 2"-3" and attach the banana plugs (if you have them). Red on the long side, black on the short. If you don't have them, no worries, just remember that you want to attach the long side to the "Antenna" side of the tuner/transceiver, and the short side to the "Ground".
8. Deploy your antenna. I try to use at least two supports. How isn't important, just get it in the air, with as few bends and turns as possible!
9. Tune and enjoy. You may have better results pulling the short leg apart from the long.

One final warning:

DO NOT EXCEED 100 WATTS TRANSMITTED POWER WITH THIS ANTENNA WITHOUT UNDERSTANDING WHAT YOU ARE DOING.

There are some funky voltages generated by this antenna at certain loads, so please be mindful. I'd suggest staying off of 30m entirely until you can play. The antenna works really well on 40 and 20. It's decent on 15, and poor to outstanding on 10. For 80m you will need to detach the short leg (black plug) and work the antenna against the station ground. This technique may also get you better results on 10m, especially in the technician class voice portion of the band (28.300-28.500).
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