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[TenTec] OT: Selection of ferrite material (was SWR and Coax)

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Subject: [TenTec] OT: Selection of ferrite material (was SWR and Coax)
From: Marinus Loewensteijn <zl2ml@hotmail.com>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Mon, 7 Jul 2008 18:18:38 +0800
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>

First of all thanks to all about rectifying my misconception on SWR and 
radiating coax.

My rig is working again but not much to work tonight on 7 Mhz so am 
up to some more internet investigations. (mischief?)

Need to make a 1:9 broadband impedance transformer and had found
(as reported earlier) a design with the Amidon FT114-61 material.
Someone else muttered that #61 is no good and I need to use #43. 

However one item drew my attention and that is ferrites have a 
temperature which should not be exceeded because then the magnetic
properties of the material is destroyed and hence the toroid becomes
useless. I discovered that the #61 has a Curie temperature of 300 C
and #43 a Curie temperature of 130 C. 

This big variantion means to me that in addition to the magnetic
properties a close eye needs to be kept on the Curie temperature when
selecting a toroid for use in a balun or broadband transformer. I am 
sticking with the #61 design.

73, Marinus, ZL2ML
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