From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
References: <1571552606.20170324191313@gmail.com> <15b01dc2110-79d2-20114@webprd-a48.mail.aol.com>
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Date: Fri, 24 Mar 2017 21:32:54 +0100
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Subject: RE: LF: Stacking toroids
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Another way - a bit more complicated - to reduce heating significantly is to 
feed DC not via the center tap of the output XFM but via separate DC chokes.
This would eliminate the DC bias of the core(s).

73
Clemens
DL4RAJ  

>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org 
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus Vester
>Sent: Friday, March 24, 2017 8:48 PM
>To: rsgb_lf_group@blacksheep.org
>Subject: Re: LF: Stacking toroids
>
>Yes Chris, this will work. Doubling the core cross section 
>will halve the flux density, and reduce the per-core 
>dissipation by at least a factor of four. The improvement may 
>be more if the flux was so high that losses were dominated by 
>hysteresis (up to a factor of 8).
>
>73, Markus (DF6NM) 
>
>
>-----Ursprüngliche Mitteilung----- 
>Von: Chris Wilson <dead.fets@gmail.com>
>An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
>Verschickt: Fr, 24. Mrz 2017 20:15
>Betreff: LF: Stacking toroids
>
>
>Hello LF people,
>
>If I have a ferrite toroidal output transformer for a push
>pull Class D 136kHz amp, that gets warmish after a WSPR15
>session, what would happen if I wound the same number of
>primary and secondary turns on two cores stacked together,
>all else remaining the same? Would it run cooler, but
>retain its transformation ratio, or would other things
>occur to make it not that simple? Thanks.
>
>-- 
>Best regards,
>Chris 2E0ILY mailto:dead_fets@gmail.com <mailto:dead_fets@gmail.com?> 
>
>
>
>