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What is the easiest way to match a 50 ohm coax with a 75 ohm antenna? I have a Yagi-Udi built with a 2 meter dipole, a reflector, and 3 directors.

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  • $\begingroup$ Have you done any basic research? Even the most basic research should turn up a number of methods, any of which could be considered "easy". $\endgroup$ – Phil Frost - W8II Feb 12 '14 at 19:08
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The easiest way is to simply connect them without any matching. You'll suffer an additional SWR of 1.5:1 due to the mismatch, but that's well within most transmitter's capability without damage.

The second easiest is to simply employ a tuner.

Neither method will give you the best output power, but they are certainly among the easiest methods of matching.

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    $\begingroup$ To match the coax with the antenna, the tuner would need to be at the feedpoint, not at the transmitter as more commonly done $\endgroup$ – Phil Frost - W8II Feb 12 '14 at 21:39
  • $\begingroup$ Why so? For HF, its near the transmitter $\endgroup$ – Skyler 440 Feb 13 '14 at 2:33
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    $\begingroup$ @Skyler440 you can put the tuner at the transmitter, and people do that all the time because it's easier to operate the tuner when its inside. But that's not matching the coax to the antenna like you asked: it's matching the transmitter to the coax. The coax, because of the mismatch at the antenna end of it, no longer looks like a resistive 50 ohms to the transmitter. The difference is relevant because if you leave the mismatch between the coax and the antenna, the SWR on the coax will be greater than 1:1, with attendant losses. $\endgroup$ – Phil Frost - W8II Feb 13 '14 at 3:25

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