Steve Yates, AA5TB, has a very informative web page on EFHW antennas and how to build a parallel tuned circuit with a link coupled feed at the radio end to reduce the 1800 to 5000 ohm impedance to a 50 ohm non-reactive load. He has examples of both QRP and QRO versions of the circuit. I built the QRP version which uses a polyvaricon capacitor (available through Hendrix Kits among other sources) to create a very small tuning device that will match resonant End Fed half wavelength antennas on 40m, 30m, 20m, and 17m. I use it mostly with a 33 foot wire on 20m raised on a 31 foot Jackite fiberglass pole and have had fun working DX with 5 watts. It is easy to change bands by exchanging the wire with one cut for the band of interest. I do not use a counterpoise and do not have any trouble at the rig. Steve explains why this works. For higher power a one meter counterpoise helps. I use this antenna with a K1 and K2, both with internal antenna tuners. The tuners are not needed, but I leave them activated to easily compensate for any small mismatch across the band.
Steve's page is found at http://aa5tb.com/efha.html William Ravenel, AI4VE ______________________________________________________________ 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
