[amsat-bb] Re: EZ-lindenblad info

[James Duffey]

Tim - What you need to do is calculate the reactance of the elements  
with the diameter of the specified elements. Then calculate the length  
of the element with the new diameter so that the reactance of the new  
element is the same as the old one. I think that the corrections may  
not be significant if the diameters are not too far apart.

L. B. Cebik wrote how to do this in his web page on scaling Yagis form  
one frequency to another. I wrote a spreadsheet to calculate these  
lengths for Yagis, mostly to go from 432 MHz to 144 MHz. You could use  
that with the appropriate diameters I think. If I can find it I can  
send it to you.

The calculations are straight forward, but the equations are not  
short. It can be done though and will be reasonably accurate as long  
as your diameters are similar. - Duffey
On Dec 3, 2008, at 1:20 PM, Tim Tuck wrote:

> Nigel Gunn G8IFF/W8IFF wrote:
>> What's the difference between a metric version and any other version.
>> Just multiply the inches by 25.4 and it will be metric.
>>
> While it would be nice if it was that easy the problem arises when
> trying to buy aluminium in those odd sizes. i.e. 1/4inch is 6.45mm.
> Local aluminium suppliers don't have imperial sizes so I'm stuck with
> 5mm, 10mm, 15mm etc. thus the math needs redoing for the different  
> sizes
> and I was wondering if anyone had done that before I attempt it. :)
>
> regards
>
> Tim
>
>
> -- 
>
> VK2XTT :: QF56if :: BMARC :: WIA :: AMSAT-VK :: AMSAT
>
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--
KK6MC
James Duffey
Cedar Crest NM