FEEDING AN EFHW ANTENNA The EFHW is a convenient way to feed an antenna when QRP on a SOTA peak. There is very little current on the end of the wire so losses to ground are minimized even when the end of the wire is near the ground. The feedline can be short or even non-existent. Impedance at the end of a halfwave antenna is very high, typically over 3,000 ohms. Little or no counterpoise (radial) is required, but an ATU will not handle such a high impedance. I know of three ways to feed it. If one wants to use an ATU, feeding the EFHW through a 9:1 balun should bring the impedance down into a range where the ATU can handle it. There will be loss in both the 9:1 balun and in the ATU. AA5TB pioneered a simple tuner which was later kitted by Eric, KI6J, and then copied by many others including Hendricks, SOTABEAMS, and now QRPGUYS dot com. I did repeated tests with several of my homebrew versions of this tuner. Loss when proper...
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Showing posts from May, 2017