Kieth, This is a portable field antenna for me, and I have made the feedline from a pair of twisted #22 teflon insulated wires. Some years back, someone on QRP-L did some tests on various feedlines, and this turned out to have good loss characteristics, and it is flexible and lightweight which are two major advantages for my use. It rolls up nicely and the teflon insulation helps keep it from tangling and snarling on other objects. YMMV. Jim N2GO is my source of the teflon wire, he posts occasionally on QRP-L.
If I were using either a 44 or 88 foot flatop as a permanent antenna, I would do it differently. I would use #14 wire for the radiating section and well positioned 450 ohm ladder line (or homebrew parallel line spaced about 4 inches apart) for the feedline. The advantage of the 44 foot antenna is that you know that the radiation is broadside to the antenna and without side lobes for operation on 40 through 10 meters, and the 88 foot length is similar for 80 through 20 meters. Yes, it is only 2/3 of a half wave long on the lowest band, and is not as efficient there, but this is a multiband antenna, and some compromises must be made for any antenna, particularly a multiband one. In my case, I have accepted compromises both for portable usability and multi-band use, but 'it don't work too bad'! The feedline length of 25 feet is just what is convenient for my situation. The proper feedline length should always be 'long enough to reach from the shack to the antenna'! The feedline length will change the impedance seen at the shack end, but if your tuner will match that impedance, the exact value is unimportant. If you want information on how this impedance transformation works in laymen's terms, take a look at the Antenna, Transmission lines, and Tuners article on my website http://w3fpr.qrpradio.com - There really is no magic in antennas, it just seems that way at times especially if you do not know some basic principles - at least enough to be aware of the ridiculous claims made by some. The fact that someone worked DXCC in 2 months with a wet noodle does not say anything about the real characteristics of that antenna. 73, Don W3FPR > -----Original Message----- > > Right now my feedline length is 0. I have not built the antenna > yet. I work about 20 mins from HRO and hope to swing over > there at lunch. I have seen ladder line there before. > > It sounds like the 22 feet per side is a common length that > works for people. I will start with that. It also sounds like I > should test different feedline lengths as well to get the best > setup. I also like the idea that was posted about using > Anderson Power Pole connecters to extend the dipole for good > 80M coverage. I have those lying around and will see about > giving that a try. > > I have a bunch of wire ready to cut to various lengths to try > this stuff out. The goal is to get a couple of antennas built so I > can operate outside and hone the CW that I have been > practicing. After that...I can move into experimentation mode. > > With your 25 foot feedline, are you using open ladder line or > some twinlead from Radio Shack etc? > > Thanks for all the advice. I am learning a lot. > > 73 de Keith KB3ILS > _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
