Message-ID: <5AA12CA2.5070004@posteo.de>
Date: Thu, 08 Mar 2018 13:29:22 +0100
From: DK7FC <selberdenken@posteo.de>
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To: rsgb_lf_group@blacksheep.org
References: <3610102492.20180308120003@gmail.com>
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Subject: Re: LF: Can an air cored LPF inductor have as high a "Q" as a toroidal
 wound one?
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Hi Chris,

Just use two cores in parallel and reduce the number of turns to 70%. 
That will reduce the flux and prevent saturation losses.
You may want o use a bigger wire instead.

73, Stefan

Am 08.03.2018 13:00, schrieb Chris Wilson:
>
> Hello  expert LF'ers!
>
> The  centre  toroid  of  my  three  toroid  LPF heats up on the longer
> transmissions  like  WSPR15.  I  have  added  a  small fan as a crutch
> (thanks  N1BUG!) but I guess that's a crutch for inadequate hardware. I
> was  wondering  whether  instead of buying a larger toroid, which seem
> only  to  be  available  from the US at high cost, I could wind an air
> cored  coil  of  similar  inductance. But I am unsure whether it would
> have the required "Q" factor. Your opinions please? Thanks,
>
> Also  I  am  wondering,  looking  at the Micrometals site, whether the
> current -2 material can be bettered by using -3 material?
>
> http://www.w1vd.com/LPF.pdf
>
> and info on frequency range of these cores is at: http://toroids.info/
>
>
>
>