From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
References: <1456380282.20170524154713@gmail.com>
In-Reply-To: <1456380282.20170524154713@gmail.com>
Date: Wed, 24 May 2017 18:58:21 +0200
Message-ID: <099A424C9760447D9BCA0472F83FCA7C@Clemens0811>
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Subject: LF: RE: Iron dust toroids and heating
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Status: RO

Hi Chris, 

It no longer
>functions as an LPF, and I suspect the T225A-2 toroid is compromised
>in its crystalline structure, through the very high temperatures, now.

Can you measure the input VSWR and Z with the filter terminated by a 50 Ohm load?

73
Clemens
DL4RAJ 


>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org 
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Chris Wilson
>Sent: Wednesday, May 24, 2017 4:47 PM
>To: rsgb_lf_group@blacksheep.org
>Subject: LF: Iron dust toroids and heating
>
>Hello LF'ers,
>
>24 May 2017
>
>
>If I run the combiner on my 2 amps the LPF centre toroid heats up. I
>made a silly mistake with setting my U3S driver the other night and
>instead of TX'ing every 30 minutes it went on an every two minute
>rampage before it soon self halted. The centre toroid winding has lost
>most of its enamel coating and the Kaptan tape is crispy. It no longer
>functions as an LPF, and I suspect the T225A-2 toroid is compromised
>in its crystalline structure, through the very high temperatures, now.
>115uH seems to be the calculated figure, if not actually measured (73
>turns 14 AWG enamelled wire) of the centre inductor. An air core coil
>of similar inductance isn't THAT big, (at least not the size of a
>"small car" as someone on a US forum estimated :)) Is an air cored LPF
>viable, or do i need to look at different core sizes or materials?
>Thanks. LPF is at:
>
>
>http://www.w1vd.com/LPF.html
>
>Thanks.
>
>  
>
>-- 
>Best regards,
> Chris                          mailto:dead_fets@gmail.com
>
>
>
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