Dear Mal,
yes, it is better to have a gap, but it may be very small, so just an gap of a layer of insulating tape or a layer of varnish. Just to keep low the remanent flux of the core. Do not use carbonyle iron cores (powder cores) or gapped ferrites with a gap of about 1 % of magnetic path length. Use a deflection transformer, the magnetic material is best for 136 k. Its better than a 62 mm toroid without any gap.
55, Hans- Albrecht
DK 8 ND
[email protected] schrieb am 27.12.04 16:00:07:
----- Original Message -----
From: "Hans-Albrecht Haffa" <[email protected]>
To: <[email protected]>
Sent: Sunday, December 26, 2004 8:34 PM
Subject: LF: RE: M0BMU mods for G0MRF 300 W Tx is this a gap?
> Hello Lowfers,
> yes it is a gap. A residuous gap of two core halves with lapped surfaces
is still a gap. It will reduce relative permeability and remanent flux. It
is better to use core halves with a bit greater gapmade of a layer of
insulating tape (0,05 mm thickness ) on both sides of a core half.
Lowering remanent flux from 180 mt (ungapped ring core) to about 30 mT
gapped will rise magnetic swing in mMilli-Tesla. Thats what counts. If You
take out the spacers of a deflection transformer, You get agood core for a
forward converter SMPS or a 136 kHz PA.
Hi Hans
If I understand you correctly, it is better to have a gap for a 136 khz PA.
de Mal/G3KEV
>
> 55, Hans-Albrecht
> DK 8 ND
>
>
> [email protected] schrieb am 24.12.04 10:55:28:
> >
> >
> > ----- Original Message -----
> > From: "james moritz" <[email protected]>
> > To: <[email protected]>
> > Sent: Thursday, December 23, 2004 11:31 AM
> > Subject: LF: RE: M0BMU mods for G0MRF 300 W Tx
> >
> >
> > Dear Gary, LF Group,
> >
> > You need one without an air gap - the air gap will drastically reduce
the
> > winding inductance, unfortunately.
> >
> > Hi All
> > I have used these cores and noticed no difference between them and a
> > continuous type core. I put the two core halves together tightly and
used
> > the same number of turns as used on the continuous core, maybe I was
lucky.
> > What does Jim call a gap? If they are tight together is that considered
a
> > gap? Must the core be totally continuous?
> > de Mal/G3KEV
> >
>
>
>
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
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