Jerry I have a real problem with some of these explanations. Unfortunately I
know just enough about antenna stuff to be dangerous. The purpose of a balun
is to transform an unbalanced something to a balanced something. The
feedline feeding a vertical is unbalanced so we are 1/2 way there. A
vertical however is an unbalanced antenna and in most cases more unbalanced
than the feedline feeding it. Something has to give and it's usually in the
form of heat. How does the balun deal with the heat? What happens to all
these crazy impedances when heat, (a lot of heat), becomes a factor?
73
MAL
N7MAL
BULLHEAD CITY, AZ
http://www.n7mal.com
Everyone in the world is
entitled to be burdened
by my opinion
----- Original Message -----
From: K4SAV
To: towertalk@contesting.com
Sent: Thursday, May 15, 2008 4:42
Subject: Re: [TowerTalk] The Vertical and the Balun
Daniel, the balun on the Zero Five is used to reduce the loss incurred
by the coax feedline because of the very high SWR of the antenna. It
does reduce it some but not nearly enough.
A balun is not necessary for a vertical antenna. What is necessary, is
that the antenna be matched to the feedline close enough to make the
losses acceptable. That is difficult to do with a single component,
for all band operation, for a vertical consisting of a fixed length. If
your feedline is very short and low loss coax is used, a tuner in the
shack may provide acceptable coax losses.
Another problem with a fixed length antenna is associated with the
radiated pattern. When a vertical becomes longer than about 5/8
wavelength, the main radiated lobe starts going up at a high angle that
is not useful for communications on the high bands. So although it is
possible to make a matching network that will match a long vertical, it
won't work very well.
With a good matching network (it will be different on each band) and a
good radial system, your 65 ft vertical should work well on 80, 40, and
30. It will also work OK (but not great) on 160. The radial system
will be the determining factor on how well it performs on 160. For 20
meters and up the antenna is too long and the performance will be poor.
It will be easily beaten by a low dipole on those bands.
Jerry, K4SAV
K4SAV wrote:
>I guess you weren't paying attention. I just answered that question 5
>days ago.
>http://lists.contesting.com/archives//html/Towertalk/2008-05/msg00115.html
>
>Daniel Hileman wrote:
>
>
>
>>Hi Everyone,
>>
>>I am here to learn, so I will ask the question. I have been thinking a LOT
>>about building a full size 1/4 wave vert for 75m...I am going to go with
>>the hygain aluminum mast since I have plenty of room to guy it well. I was
>>originally thinking hard about the Zero Five, but it's only 43' and
>>$200.00 more expensive. It said you could get 160m-10m with a 4:1 balun
>>and radials and a tuner. So...my question is, what does the balun do
>>exactly? Can I make the 65' work on 160-10m well without the balun or
>>should I plan on putting one on my 65' vertical as well?? Will it work
>>decent on 160m??
>>
>>Thanks,
>>Daniel N9WX
>>_________________________________________________________________
>>
>>
>>
>>
>
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