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
----- Original Message -----
From: "Chris Wilson" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Thursday, March 08, 2018 12:00 PM
Subject: LF: Can an air cored LPF inductor have as high a "Q" as a toroidal
wound one?
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/
--
Best regards,
Chris mailto:[email protected]
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