Like Jim, below, I also asked Mike at Lightning Bolt about the
feed system, and got a similar response.
However, there MUST be an interaction between the 10 and 20m
elements. A 2 wave loop emits in exactly the opposite fashion
as a 1 wavelength loop. The result is that the 20m element fills
in nulls on 10. What tends to limit that effect is that the 20m element
is seriously mismatched, so very little actual current flows in it.
Mike denied that this was even a factor. Cebik says it is.
I was seriously considering separate feeds for my 2 el lightning bolt,
fed with 1/4w lines to a central switch. (don't forget to use ferrites
to decouple the feedlines from switch common). Upon further consideration,
I donated the antenna to the red cross and bought an lpda.
Incidentally, I also had the 4 el. add-on kit. It's a monster antenna,
which I am quite sure plays extremely well. Remember how big it is,
when planning the tower site. Trees can be a problem.
Date: Thu, 20 Apr 2006 06:43:26 -0500
From: Jim Rhodes <email@example.com>
Subject: Re: [TowerTalk] Lightning Bolt Quad
To: "denis coolican" <firstname.lastname@example.org>, <email@example.com>
Content-Type: text/plain; charset="us-ascii"; format=flowed
I asked the Lightning Bolt guy about that once and he got very
defensive about his feed system. Said the tuning would be all off and
he wouldn't be responsible. Others have said the opposite, that
quarter wave lengths to a switch were needed. I am sure there are
many opinions on this.
At 12:02 AM 4/20/2006, denis coolican wrote:
>This four element Lightning Bolt Quad covers 20, 17, 15, 12 and 10
>meters. It is fed by a common balum. (one input PL259 and 5 output
>pairs of conductors)
>Does anyone know what type of balum this is and what would be the
>replacement for it?
>I imagine the driven elements for each band has an impedance of
>about 80 to 100 ohms. The feed into the balum is 50 ohms.
>If a person provides a 2:1 balum for each feed, would the unused
>balums be terminated in 50 ohms or left open?
>Any more thoughts on this antenna?
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