[Elecraft] 40-80m choices antenna for KX3

[Walter Underwood]

The Hy-Power trap/fan antenna for 80/40/20 is a very clever design. A full length 40 m dipole, then a loaded 80 m dipole where the center portion is cut for 20 m. The loading coils act as traps. The loaded dipole is just about the same length as the 40 m dipole, 70 feet.

Check out the 3B2080SFAN on this page. https://www.hypowerantenna.com/products/fan-dipole <https://www.hypowerantenna.com/products/fan-dipole>

I had to take mine down a few years ago when our walnut tree died. I just figured out how to rig it diagonally across our roof after a few frustrating years with a home-brew non-resonant vertical.

Here are a couple of photos of the previous installation. That is a Balun Designs QRP balun at the feed point. That dropped noise by about 6 dB.

https://www.flickr.com/photos/walter_underwood/5907110302/in/album-72157626885239329/ <https://www.flickr.com/photos/walter_underwood/5907110302/in/album-72157626885239329/>
https://www.flickr.com/photos/walter_underwood/5854609078/in/album-72157626885239329/ <https://www.flickr.com/photos/walter_underwood/5854609078/in/album-72157626885239329/>

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ <http://observer.wunderwood.org/> (my blog)

> On Nov 2, 2022, at 9:18 PM, Jim Brown <jim at audiosystemsgroup.com <mailto:jim at audiosystemsgroup.com>> wrote:
> 
> On 11/2/2022 5:38 PM, Karl W Hubbard via Elecraft wrote:
>> How to rig and which antennas for my KX3 (has ATU) given the following  layout andlimitations:
> 
> When I moved into a new QTH 16 years ago, I made a scaled drawing that included my house, shack in detached garage-apartment, and available supports (in my case, tall redwoods), and in relationship to North. That took a while.
> 
> Antennas have two important functions -- transmit, and receive, and every antenna has some sort of directivity. Many antennas transmit well enough, but pick up so much noise from our neighborhood that we can't hear most of the stations calling us, and if we can't hear 'em, we can't work 'em!
> 
> The most noise resistant antennas are horizontal dipoles that are resonant on the bands where we want to use them, are fed with coax, and have an effective common mode choke at the feedpoint. SO -- study your own possible skyhooks (trees, buildings, a guyed mast you might add to a building) and figure out which combinations might support dipoles. Dipoles are VERY easy to build -- you need plain ordinary wire (I mostly use single-conductor house wire), a center insulator, end insulators, and rope to rig it.
> 
> OCF dipoles transmit OK, but they are terrible for receive noise, and there's no good way to kill that noise. Ditto for end-fed wires. We're moving into a solar maxima, so the higher bands (40-10M) are going to be much better than the lower ones (160-60M).
> 
> It's also possible to build multi-wire fan dipoles that cover multiple bands. Take a look at what I did in Chicago with a fan for 20-15-10. Here in California, I've used 2-wire fans for 80 and 40.
> 
> http://k9yc.com/LimitedSpaceAntennas.pdf <http://k9yc.com/LimitedSpaceAntennas.pdf>
> 
> And it's possible to build 2-band dipoles using loading coils, and 3-band dipoles using traps. Both types are shorter than a simple half-wave dipole for the lowest frequency. In Chicago, I had an 80/40 with a loading coil that was about 100 ft long, that fit between a TV mast on the front of my house and another on the garage at the back of my lot, and it worked pretty well in some directions on 30 and 17M. HyPower Antenna Company (a Pennsylvania ham in his basement, advertising in QST) sold it.
> 
> 73, Jim K9YC
> 
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to wunder at wunderwood.org