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| hw-20hp [2026/01/21 15:04] – admin | hw-20hp [2026/03/08 16:35] (current) – external edit 127.0.0.1 |
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| So I foolishly succumbed to the lure of an air-core 'ugly' balun and wound one close to the feedpoint. This ruined the whole thing. Just don't do it. Two theories: it's too narrow band which is true but where is the band? the antenna needs some feed line as an impedance match to 'soften' the resonant peaks. This works like a resistive divider and implies some loss in the feed coax, but saves having to use an antenna tuner and is no less efficient. | So I foolishly succumbed to the lure of an air-core 'ugly' balun and wound one close to the feedpoint. This ruined the whole thing. Just don't do it. Two theories: it's too narrow band which is true but where is the band? the antenna needs some feed line as an impedance match to 'soften' the resonant peaks. This works like a resistive divider and implies some loss in the feed coax, but saves having to use an antenna tuner and is no less efficient. |
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| 17m shows swr 1:1. This looks unlikely to me, but the other bands are reading ok on the same radio, so maybe i'm just lucky? | So to remove the rf buzz I get on the shack power lines, I added a proper broadband rf choke, but it mucks up 17m - goes from 1:1 to 1:2.1. It also reduces receive sensitivity by (just measuring by eye) 1s too. I guess I'll leave it off. |
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