Brian: The end fed I use uses a stub for 20 meters. When I set it up I tuned the antenna for 40 meters. Then I added the stub 1/2 down the antenna and trimmed that for best SWR on 20 meters. Worked exactly as expected with an antenna analyzer.
K On Sat, Feb 11, 2017 at 2:03 PM, Brian Pietrzyk <[email protected]> wrote: > This thread has really given me things to try when earth tilt/absence of > white rain is back in our favour. Great group of folks on this forum btw. > > The many contributions to this thread have given me the confidence to try > end feds (for the first time) on my up coming trip to HI9 land. I'm packing > a few end fed lengths for whatever the trees on the resort will support. > I'll start with Wayne's 25ft radiator and 25 ft wire on the ground > suggestion first. Again this untried for me. > > Before getting my kx3 I used an FT817 and the ATAS25. Worked fine when 20 > to 10m openings were easier to come by a few years ago. Now my thoughts are > about the reactions I'll get throwing something at a tree or two on the > resort near the beach. I've managed to strip my CrankIR down to 12lbs so > I'm taking it anyway only because I've used it/know it. The goal is to no > longer feel the need to cram it into charter flight size and weight > constraints and keep it for car trips instead. I'm guessing throwing a half > full water bottle will suffice. Corrections invited. > > Now my thoughts are about permanent end fed resonant wires (vs dipoles) > for the home shack. I currently have a home brew 80/40 centre fed dipole > tied from the house to a tree in the woods. If that were instead an end fed > resonant wire fed by a 9:1 at house end things could get much simpler (and > less saggy) coax wise. > > Now comes the fantasy thinking... What about making it an end fed multi > band by either putting traps in the 80m end fed or better still adding on a > couple of fan EFHW wires for 40 and 20? Anyone tried this? How would the > efficiencies compare to their centre fed trap or fan dipole counterparts > respectively? > > Then there is that 160m antenna I'm think about putting up this summer... > > Brian ve3bwp > > Date: Fri, 10 Feb 2017 12:05:56 -0600 > From: K9MA <[email protected]> > To: [email protected] > Subject: Re: [Elecraft] EFHW > Message-ID: <[email protected]> > Content-Type: text/plain; charset=windows-1252; format=flowed > > Here's the old trade-off between radiating efficiency and ease of > matching for an end fed wire. The EFHW is more efficient, because little > power goes into the ground system, but its high impedance is harder to > match. A wire of a different length may be easier to match, but more > power goes into the ground system, where it doesn't radiate much. Both > will work but, I believe, on average the EFHW will be a bit better. Is > it worth the trouble? Who knows? > > Antenna discussions have long had a tendency to focus on SWR. Low SWR > does not necessarily mean an antenna is effective. There's an old > saying, "The SWR of a dummy load is 1:1." > > 73, > > Scott K9MA > > On 2/10/2017 09:56, Don Wilhelm wrote: > > Brian, > > > > If your end fed antenna is actually a halfwave (which is what EFHW > > means), the answer is no. > > > > The solution for portable work is to use a length that is not a > > halfwave - 58 feet is known to work well for 40 thru 10 meters when > > used with a 13 foot counterpoise. Double the lengths if you want 80 > > meters. > > > > With that antenna and counterpoise length, dispense with the balun for > > portable operations, and use a BNC to Binding post adapter instead (no > > coax). > > > > If you need to use a short length of coax, you can put the balun at > > the end of the coax, and you can try both the 1:1 and 4:1 positions to > > see which provides the better match. > > > > 73, > > Don W3FPR > ______________________________________________________________ > 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]
