For pre-built antennas, HyPower is a good choice. He has lots of options, fan dipoles, loaded dipoles, even combinations. I have a fan dipole made from a full-size 40m element and an element that is full-size for 80 and loaded for 80. He also sells the loading coils if you would rather DIY.
http://www.hypowerantenna.com/ wunder K6WRU On Jun 26, 2014, at 5:30 AM, "Charlie T, K3ICH" <[email protected]> wrote: > Don't rule out traps. > > Also, the RF Connection and probably others, sell a nice stranded copperweld > wire that has a black polyethylene insulation. If I remember correctly, it > is 13 ga and is ideal for antennas. For all practical purposes, it doesn't > stretch, is fairly slippery and only a little "springier" than hard drawn > copper. > > I use those double ferrule aluminum crimp on's that are designed for flexible > wire cable to hold everything together. I was concerned about them holding > through the poly insulation, but the following antenna has been up for about > ten years now. It consists of a double (fan) dipole with a pair of 80 meter > traps in the top leg for 160 & 80 M coverage and a pair of 40 meter traps in > the lower leg for 60 & 40 M coverage. It is fed thru a 1:1 balun with RG-213 > and is tuned for resonance. Basically, I operate SSB 99% of the time, so the > antenna is tuned for that end of the bands. An MN-2700 tuner in the shack > takes care of small excursions from resonance. It's only up about 50 feet, > so performance is what you'd expect. It's not straight either and is sort of > a lazy Z, being strung between two 55' telephone poles that are 105 feet > apart. The ends droop down at about 45 degrees to tie-off points in trees. > A compromise? Yes, but it works. > > 73, Charlie k3ICH > > > > > ----- Original Message ----- From: "Jim Brown" <[email protected]> > To: <[email protected]> > Sent: Thursday, June 26, 2014 1:55 AM > Subject: Re: [Elecraft] RF in the Trees > > >> On 6/25/2014 5:43 PM, Dauer, Edward wrote: >>> So, I've been selecting two of the tallest >>> candidates a couple of hundred feet apart and stringing a stout nylon rope >>> between them. In the middle of the cord I attach the balun for the Vees, >>> thereby allowing the legs to be in the clear, moveable from side to side, >>> and tied to smaller (8') trees at their distal ends. In one variation on >>> the theme I had a 40 meter dipole as the center section of the supporting >>> rope, tied to the same balun as an 80 meter vee. In another I tried a >>> linear-loaded 80-meter Vee, about 45' on a leg; it loaded fine but didn't >>> perform as well as the full length version. >> >> If you can suspend a flat antenna between two tall trees, why would you want >> an inverted vee, which is a less effective radiator? >> >> Your two trees 200 ft apart could support a full size 80/40 fan and a >> 20/15/10 fan, in line with each other. A high 80/40 fan is a VERY good >> antenna, and is easy to build. >> >> My technique has evolved to starting with #8 bare copper from the big box >> store, stretch it VERY slowly between a tree and a trailer hitch until it >> breaks. Do this carefully where there's no one around to get hurt. Now you >> have #10 hard drawn copper, which is pretty strong, and pre-stretched. Use >> that for the longest dipole in each fan. Use #12 or #14 THHN (house wire) >> for the other elements. I make spacers by cutting 1/2-in PVC conduit into >> lengths of about 16 in for 3-wire fans, and about 12 inches for 2-wire fans. >> 5-6 ft between spacers is a good rule of thumb. Hold the spacers in place by >> soldering short lengths of copper around the spacer to the bare copper of >> the long element. >> >> The higher your antenna is, the more robust your center insulator should be. >> A high 80/40 dipole (80 ft or more) will be closer to 75 ohms than 50 ohms. >> A 20/15/10 fan will be close to 50 ohms. Use RG8 or RG11 depending on the Z >> at resonance. Don't waste a dB or two with small coax. My 110 ft 80/40 fans >> are fed with Belden 8213. >> >> For weights, I fill 6 gallon water jugs with dry sand, and tie one to one >> end of each span. The other end can be fixed. I have pulleys high my trees. >> If you don't have a pulley and weight, your antenna WILL end up on the >> ground, and it won't take a big storm for that to happen. >> >> My HF antennas are all at the 110-120 ft level in a dense redwood forest >> that towers 50-75 ft above them. They work. My "seat of the pants" >> observation is that attenuation increases with frequency, and is greatest >> with vertical polarization. 432 MHz is a waste of time, 2M sort of works, >> and 6M works pretty well. >> >> For an analysis of the value of height, study this. It supports the >> statement earlier in this thread that a high dipole beats a low tri-bander. >> >> http://k9yc.com/VertOrHorizontal-Slides.pdf >> >> When Fred observes that the ends of antennas are "hotter," he means that >> this is voltage maxima and a current minima, so good insulation is needed to >> whatever the antenna is attached. I once melted heavy dacron rope that was >> tied directly to the end of said dipole (well, twice, actually). The extra >> ingredient was that it was wet. Duh. >> >> 73, Jim K9YC >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] -- Walter Underwood [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
