Message-ID: <6793F7B8EC7F493C87174FF4019CD251@gnat>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <3610102492.20180308120003@gmail.com> <98C09BB1F3184387904CD2E8F05043E2@gnat> <CA13B73BD17347D380FBB0E58EAE3BF9@Clemens0811>
Date: Fri, 9 Mar 2018 20:01:27 -0000
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Subject: LF: Re: RE: Re: Can an air cored LPF inductor have as high a "Q" as a toroidal wound one?
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Hi Clemens yes I realised that from later posts I should have realised 
materials 2 & 3 were iron dust. I doubt from the reports that it is getting 
to the kind of temperatures that would give non-linearity in that material.

However heat generated in the inductor indicates loss and reduced Q......and 
Chris was talking about Q levels. I think from previous posts he is using 
toroidal cores to reduce the coupling between the cores. Of course if it is 
IR loss in the wire then even air cored will not help. Litz would but 
previous tests by Dave Pick G3YXM about 15 years ago suggested that the 
difference in using Litz (ex Decca nav TX coils) was quite small at 136kHz.

It will be interesting to see which way he goes

Alan
G3NYK


----- Original Message ----- 
From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Friday, March 09, 2018 4:43 PM
Subject: LF: RE: Re: Can an air cored LPF inductor have as high a "Q" as a 
toroidal wound one?


> Hi Alan,
>
>>One thought I dont know the answer to.......magnetisation is
>>not a linear
>>effect, if you are getting heating you are into the saturation
>>area......what does his non-linearity do to the signal ! It may even
>
> Chris is using #2 material mix,i.e. iron powder toroids,not ferrite.
> Iron powder is essentially not saturable because overheating will
> set the flux limit long before saturation occurs,see attachment.
>
>
> 73
> Clemens
> DL4RAJ
>
>>-----Original Message-----
>>From: owner-rsgb_lf_group@blacksheep.org
>>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Alan Melia
>>Sent: Thursday, March 8, 2018 2:55 PM
>>To: rsgb_lf_group@blacksheep.org
>>Subject: LF: Re: Can an air cored LPF inductor have as high a
>>"Q" as a toroidal wound one?
>>
>>Chris my take on this.....not having used this level of power
>>at LF.....if
>>the core is gettting hot it is not providing a particularly
>>high Q !! My
>>line is that LPF are best made with air cored inductors, the
>>values required
>>are not so high as to need ferrite. (see MRF and YXM filters)
>>It does mean
>>care in layout to avoid coupling between the stages.  You may
>>even be able
>>to use a non-magnetic toroidal core!  Current sensing
>>transformers at Rugby
>>GBR 16kHz  (similar to the transformers in Jim Moritz
>>scopematch) were wound
>>on discs of Tufnol  (SRBF)
>>
>>One thought I dont know the answer to.......magnetisation is
>>not a linear
>>effect, if you are getting heating you are into the saturation
>>area......what does his non-linearity do to the signal ! It may even
>>compromise the effect your are trying to obtain ......actually
>>generating
>>harmonics??
>>
>>Alan
>>G3NYK
>