5 Band Cobweb Feeder?

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acting_strange
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5 Band Cobweb Feeder?

Post by acting_strange » 19 Aug 2019, 19:56

Hi

Is there any reason why, when I build my own 5 Band Cobweb, Instead of using a 4:1 Balun inside the links box, I just use my favourite, the good old Ladder Feeder and use my home built Z Match ATU to get the balance I need to keep the SWR down?

FAFFER
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Re: 5 Band Cobweb Feeder?

Post by FAFFER » 20 Aug 2019, 10:58

Because it's a nest of folded dipoles and you'll cock the impedance up, and the performance.

The balun is a 1:4 btw.
Build a man a fire, he'll be warm for a night. Set a man on fire and he'll be warm for the rest of his life.

acting_strange
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Re: 5 Band Cobweb Feeder?

Post by acting_strange » 20 Aug 2019, 19:43

FAFFER wrote:
20 Aug 2019, 10:58
Because it's a nest of folded dipoles and you'll cock the impedance up, and the performance.

The balun is a 1:4 btw.
But surely with an ATU I can match the impedance to any of the antenna used?

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ch25
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Re: 5 Band Cobweb Feeder?

Post by ch25 » 20 Aug 2019, 19:55

The point is to have resonant antennas, not to tune barbwire with ATU. That's why Cobweb is built the way it is.

Chris
You can't have too many antennas...

FAFFER
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Re: 5 Band Cobweb Feeder?

Post by FAFFER » 08 Sep 2019, 22:48

acting_strange wrote:
20 Aug 2019, 19:43
FAFFER wrote:
20 Aug 2019, 10:58
Because it's a nest of folded dipoles and you'll cock the impedance up, and the performance.

The balun is a 1:4 btw.
But surely with an ATU I can match the impedance to any of the antenna used?
You could fool the radio into thinking the antenna's 50 ohms, but the antenna will still be poor.
Build a man a fire, he'll be warm for a night. Set a man on fire and he'll be warm for the rest of his life.

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