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" <[email protected]>
To: <[email protected]>
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: [email protected]
[mailto:[email protected]] On Behalf Of Alan Melia
Sent: Thursday, March 8, 2018 2:55 PM
To: [email protected]
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
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