At 08:18 AM 1/26/98 -0500, you wrote:
>
>Pete, adding the second C3 is a great idea...even better if it rotates.
>Your spacing is a little close for 20, even with the short boom of the C3,
>but will still be better than only the single yagi.
Thanks, Ty. Actually, my modeling of the C-3 stack shows that 28 ft is
about the optimum compromise between 15 and 20-meter F-B and gain.
10-meter FB is significantly degraded at this spacing. Note that short
booms like the C-3 optimize at somewhat closer spacing than TH-7s, and even
more so than your KT34XAs.
I wouldnt worry about
>the spacing on 10 at all. If anything you might want to add a yagi below
>the 69 footer. As is, I think you'll find that most of the time the single
>yagi at 69 feet will outperform the top one most of the time once the flux
>starts climbing.
As you say, the lower antenna looks better alone than the stack,
particularly on 10.
>
>I'd recommend using a broadband transformer switching scheme such as the
>WX0B Stackmatch for any situation involving mixing and matching of
>multiband antennas.
Definitely planning on it. I mentioned the quarter wave multiples only
I've heard they equalize current for single-band use. You're right though
-- they're no use on tribanders. I plan to wind my own 2.25 to 1 unun for
the stack, if I do it.
>
>73, Ty K3MM
>
>
>
>
>To: Towertalk@contesting.com
>cc: (bcc: Tyler G Stewart/BENN/CEC)
>Subject: Re: [TowerTalk] Stacked tri-banders vs. Single mono-banders
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>I've been toying with adding a second C-3 at 69 feet to my current one at
>97 feet. The 2-stack appears from modeling to be pretty decent for 20 and
>15, but leave a lot to be desired on 10, given the over-wide spacing. Do
>the assembled antenna wizards have any opinions on the idea of adding a 3
>or 4-element 10-meter yagi halfway between the two tribanders? If I
>understand things correctly, I would need to have odd 1/4 wave multiples of
>feedline from the common feed point (UNUN box, presumably) to ensure that
>all 3 antennas would get equal current on 10, despite their dissimilarity.
>I'd also try to make the 3 driven elements line up with each other, more or
>less, to mibnimize phasing errors from that source. On 15 and 20, the
>10-meter antenna would be effectively disconnected, of course, but with the
>two C-3s my hope is that feedpoint currents will be similar even if I can't
>follow the 1/4 wave rule for them. Right/wrong?
>Any opinions, caveats, things to avoid?
>
>
>
>73, Pete Smith N4ZR
>n4zr@contesting.com
>"That's WEST Virginia. Thanks and 73"
>--
>FAQ on WWW: http://www.contesting.com/towertalkfaq.html
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>
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73, Pete Smith N4ZR
n4zr@contesting.com
"That's WEST Virginia. Thanks and 73"
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
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