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

[Gary Hoffman]

Perhaps one might consider that the design should handle the rated power
without getting hot.  Then this temperature rating would be moot.

73 de Gary, AA2IZ


----- Original Message ----- 
From: "Marinus Loewensteijn" <zl2ml at hotmail.com>
To: "Tentec list" <tentec at contesting.com>
Sent: Monday, July 07, 2008 6:18 AM
Subject: [TenTec] OT: Selection of ferrite material (was SWR and Coax)


>
>
> 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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