Hmmmm. A big RF choke?--Matt, N1IBB.
At 09:16 PM 6/25/2015 -0400, you wrote:
> Hello, again, all.
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>Well, my Alpha Delta DX CC antenna is finally up out here at the RV camp
>site.
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>It is up a good 30 feet in the trees, with the center and ends being at
>about the same height.
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>I have done some preliminary testing of the antenna, and all looks good,
>with one exception.
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>Specifically, the antenna tunes with the TS480 internal auto-tuner across
>the 10, 15, and 40-meter bands. It even tunes across much of 80 meters,
>from about 3600 to about 3900 KHZ.
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>However, I cannot get it to tune at all on 20 meters, once again, using the
>TS480 internal auto tuner. I even put my MFJ auto-tuner extender in line,
>with no luck.
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>This is a bit disappointing to me, since 20 meters is one of my favorite
>field day operating bands.
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>As I am scratching my head here to try to determine what might be going on,
>I have two theories. First, it has to be understood that I am limited to
>keeping the antenna within my lot space, and have to work with the available
>trees. This means that the legs of the antenna are probably only about at a
>60-degree or so angle from the center. In other words, the antenna is kind
>of like a folded dipole in some ways. I wonder if this could be de-tuning
>the antenna on 20, although I'm not sure why it also would not bbe de-tuning
>it on the other bands I mentioned.
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>My second theory has to do with my coax feed line. It turns out that I
>probably have about 40 extra feet of coax that I have coiled up underneath
>my station operating area. I wonder too if this might have something to do
>with the strange 20-meter behavior.
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>Obviously, I'm happy that the antenna is usable on 10, 15, 40, and 80, so
>I'm sure I'll have a good Field Day exxperience. But, the 20-meter problem
>does puzzle me.
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>Does anyone have any thoughts, or suggestions that I might try to get things
>working on 20 meters?
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>Tom Behler: KB8TYJ
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