I use the "window line" for 3 of my antennas. We have less than 125 days/ yr with precipitation of all types. The "loss wet" is a non issue in my thinking as I'm sure would be about the same for most folks.
Still with extreme loss, under most conditions, coax will have greater loss. Bob, K4TAX Sent from my iPhone > On Jan 7, 2019, at 11:34 AM, Walter Underwood <wun...@wunderwood.org> wrote: > > I think “window line” is less ambiguous for the stuff separated by plastic > with squares cut out. I see “ladder line” being used to mean either window > line or open wire line. > > DX Engineering uses ladder line to mean the plastic dielectric line: > https://www.dxengineering.com/search/part-type/ladder-line > > W7FG uses ladder line to mean 600 Ohm open wire line: > http://trueladderline.com/w7fg-design-600-ohm-open-wire-feedline/ > > wunder > K6WRU > Walter Underwood > CM87wj > http://observer.wunderwood.org/ (my blog) > >> On Jan 7, 2019, at 8:39 AM, Don Wilhelm <donw...@embarqmail.com> wrote: >> >> There is a BIG difference between ladder line and open wire transmission >> line. >> >> Even low loss ladder line can have significant loss, especially when wet. >> >> Open wire feeders can truly be low loss even when operated at high SWR. >> >> So how do you construct proper open wire line? It is most easily done when >> the 2 wires are under tension and spaced about 6 inches apart with as few >> insulators between them as possible - the tension keeps the spacing >> relatively constant - that is practical over a long horizontal run of the >> transmission line. Then bring it up to the antenna feedpoint with wires >> spaced apart with insulators, and likewise on the run to the house entry or >> better yet to the shack - the more insulators, the greater the loss can be. >> You can use ladder-line from there into the shack, or you can put a good >> current mode balun at the house entry and from there run a short length of >> coax to the tuner. >> >> As I have mentioned before, whether a 1:1 balun or a 4:1 balun will work >> better has to be determined - it depends on the feedline length, the >> frequency, and the feedpoint impedance of the radiator for that particular >> frequency. If the feedpoint impedance at the tuner end of the feedline is >> already low, a 4:1 balun will make it 4 times lower and difficult for your >> tuner to deal with. >> >> A G5RV antenna on 160 meters will not be very efficient (the high current >> point will be somewhere down the transmission line and not at the center of >> the antenna). One thing is true, the RF voltage at the ends of the antenna >> is the highest, and the highest current is 1/4 wavelength away from the end, >> even if that is at a point well down the feedline. The equal and opposite >> currents on the feedline will cancle making that highest current point not >> useful for radiating a signal. >> >> Radiator lengths greater than 1/2 wavelength can be efficient, but shorter >> than 1/2 wavelength will be less efficient because the balanced currents on >> the feedline cancel each other out. That is just plain physics. >> >> 73, >> Don W3FPR >> >> >> >>> On 1/7/2019 10:49 AM, Wes Stewart wrote: >>> Try running that 102' long "G5RV" up 50' on 160 meters. Feed it with 100' >>> of Wireman 553 "low loss" ladderline. The 0.1 dB matched loss turns into >>> over 13 db at the input and that's without considering tuner loss. (Source: >>> EZNEC and TLDetails) >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@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 wun...@wunderwood.org > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@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 rmcg...@blomand.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@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 arch...@mail-archive.com
