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Author Topic: A Couple of Questions Regarding W5YI Mystery Antenna  (Read 1642 times)
K4HS
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Posts: 4




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« on: March 01, 2013, 08:29:42 PM »

Question 1 - It's going to take probably about 75-100 ft. of LMR400 coax to get from the transmitter to the attachment point of the antenna (the ladder line).  In anyone's experienced opinion is that length of feedline to the xmtr going to have an adverse effect on antenna performance??

Question 2 - I've always liked baluns; used a 4:1 with the center-fed zepp years ago.  I know no balun is suggested for the Mystery Antenna but I don't think a 1:1 as a coupling point between the coax from the xmtr and the ladder line could hurt plus it provides for good coupling.  Does anyone familiar with the antenna have a strong opinion positive or negative about using the balun??  As with question #1, I'm open to thoughts/suggestions.

Thanks,

Randy
K4HS 
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AC2EU
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Posts: 393


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« Reply #1 on: March 01, 2013, 09:10:20 PM »

I didn't know what a W5YI mystery antanna was, so I googled it and found this:
http://vk1od.net/antenna/W5GI/
which answers your questions and then some...

Anything that has 'mystery" in its name implies to me that it's 'snake oil" anyway... and so seems to be the case here as well.
If I were you, I would reconsider the project. There is no magic bullet antenna that will be good on all bands.
Pehaps you have some bands that are more interest than others that you can focus on to find a good compromise design?
Some of the OCD designs are OK, but they have their limitations as well.
The balun choice depends on what the average impedance of the antenna models to be.

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KB4QAA
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Posts: 2371




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« Reply #2 on: March 02, 2013, 02:06:35 PM »

100ft of LM400 is reasonably low loss.

Owen has a transmission line loss calculator which is handy for planning
http://vk1od.net/calc/tl/tllc.php

The world wants one antenna to cover every frequency.  I did too when I was a novice.  But I proceeded to prove it impossible!  Every new ham must re-learn this lesson.  Smiley_
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