Is a Balun needed or helpful - EF Antenna
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| Aug 8th 2017, 17:16 | |
KI7LFDTotal Topics: 0 Total Posts: 0 |
I'm currently considering a EFHW-8010 End fed antenna for use with a new FT-1200 transceiver. (Still under negotiations) The antenna will be strung across several trees on my property. The average height of the antenna will be about 20' off of the ground in a rather thick woods. From my reading it seems that some have used baluns with a end fed antenna. One article indicated the use of 9:1 balun. I'm trying to make sense out of all this. Any suggestions or ideas would be appreciated. Thanks in advance. Rich KI7LFD |
| Aug 11th 2017, 09:39 | |
W1VTSuper Moderator Total Topics: 0 Total Posts: 0 |
An important part of that antenna is the sealed matching unit. It can be a challenge to come up with a design that works efficiently. Many simple homebrew designs can only handle low power. If you discover that the SWR is drifting, that is a sign the balun or matching unit is dangerously overheatingm, so you should stop transmitting. It is a good idea to insulate an end fed wire well from the trees. An end fed multiband antenna will have high impedance points at several points along that wire. Capacitive coupling to trees will not only steal power from the antenna, but may adversely affect the SWR performance of the antenna. Zack Lau W1VT ARRL Senior Lab Engineer |
| Aug 13th 2017, 22:43 | |
KI7LFDTotal Topics: 0 Total Posts: 0 |
Zack: Thanks for the response, information and suggestions. Given what you've told me, I'll prevent the antenna from coming even close (~ 5 ft.) to the trees themselves, using both ropes and insulators, thereby preventing capactive coupling. This approach will also make it easier to raise and lower the anntena. Thanks again. |
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