David, Sorry I can not find a computer program you are requesting. From my
note taken from ON4UN's books, Low Band DXing, I have some values that might
be a good starting point to work from.
Quote.
High-impedance Matching System
Unbalanced high-impedance feed point, a half-wave vertical fed against
ground, voltage point, can best be fed using a parallel-tuned circuit on
which the 50-ohm cable is tapped for the lowest SWR value.
ON4UN gives two sets of values. High-C or High-L. I have used the High-L to
feed my 160 meter 1/2 wave wire vertical supported with a balloon. I believe
you should be able to derive for the bands not give by following the
relation of the known values.
High-L
160M---160PF---49uH
80M---80PF---24uH
40M---40PF---13uH
As with anything it always looks good on paper. I have had to at times
insert a capacitor in series with high side of the tuner to reach a match.
Best of luck with your project. I will say I have found the 1/2 wave
vertical to be a great performer. You might want to consider one or two 1/4
wave radials as part of the RF ground system.
Rich AA2MF
----- Original Message -----
From: "David Douglass" <vk2dpd@bigpond.com>
To: <towertalk@contesting.com>
Sent: Wednesday, August 29, 2001 1:11 PM
Subject: [TowerTalk] halfwave verticals
>
>
>
>
> Hi all,
>
> I'm in the process of building some halfwave verticals to use portable on
HF
> with the aid of a DK9SQ telescoping fibreglass pole.
>
> I am building the LC matching system to convert the high impedance at the
> end of the halfwave down to the 50ohms to match the coax.
>
> My question is this! I'm sure in the past I have seen a computer program
> that allows you to key in the frequency and it will give you the length
> required and the values of inductance and capacitance required.
>
> Does anyone know were I can locate this program or if there is a manual
> calculation I can use for the LC values.
>
> Regards
>
> David, VK2DPD
> vk2dpd@qsl.net
> vk2dpd@bigpond.com
>
>
>
>
> List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
> Trylon Titan towers, coax, hardline and more. Also check out our self
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http://www.anwireless.com
>
> -----
> FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
>
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 96 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
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