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From: Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>
To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Thread-Topic: LF: iron powder toroid cores
Thread-Index: Ac6lUIT4DYwUt5T1TK64PwAautLaTwAJpVAAAAq7Tkk=
Date: Fri, 30 Aug 2013 18:57:22 +0000
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Subject: RE: LF: iron powder toroid cores
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Hello Stefan,


OK, I will give it a try with a single T200-2.

To ease my consience I will add a fan to have some forced air cooling ;-)


73, Rik  ON7YD - OR7T


________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org=
] namens Stefan Sch=E4fer [Stefan.Schaefer@iup.uni-heidelberg.de]
Verzonden: vrijdag 30 augustus 2013 15:50
To: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: iron powder toroid cores

Hello Rik,

A T200-2 will have no problem with 500W on 475 kHz! Belive me :-)

73, Stefan/DK7FC

Am 30.08.2013 09:30, schrieb Rik Strobbe:

Dear all,


I intend to replace the air coils in the LPF on my 475 kHz transmitter by t=
oroid core coils. I have a stock of T200-2 cores but for the power level wa=
nt to get (500W would be required to get near the 5 W EIRP limit)  one T200=
-2 is just on the edge in regard with the maximum flux (and thus temperatur=
e rise.

To be on the save side I would use 2 T200-2 toroids for each coil, and ther=
e are 2 options:


1. Glue 2 cores together to make one core of the double height.

This would reduce the flux to 70%, well under the limit. It would also redu=
ce the number of windings to 70%, but due to the double coil height the wir=
e length will increase slightly (abt. 10%).

But as the cores have rounded egdes there wil be some air space between the=
 wire an the core, what might increase loss.


2. Put 2 toroid core coils, each of half the inductance, in series.

This will also reduce the flux to 70%, but the total wire length needed wil=
l increase by abt. 40%.


In option 1 I will need lees wire (=3D less loss) compared to option 1, but=
 the air space might undo this advantage.


So my question is: what will be best?

All advice is welcome.


73, Rik  ON7YD - OR7T


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<p>Hello Stefan,</p>
<p>&nbsp;</p>
<p>OK, I will give it a try with a single T200-2.</p>
<p>To ease my consience I will add a fan to have some forced air cooling ;-=
)</p>
<p>&nbsp;</p>
<p>73, Rik&nbsp; ON7YD - OR7T</p>
<p>&nbsp;</p>
<div style=3D"FONT-SIZE: 16px; FONT-FAMILY: Times New Roman; COLOR: #000000=
">
<hr tabindex=3D"-1">
<div id=3D"divRpF120837" style=3D"DIRECTION: ltr"><font color=3D"#000000" s=
ize=3D"2" face=3D"Tahoma"><b>Van:</b> owner-rsgb_lf_group@blacksheep.org [o=
wner-rsgb_lf_group@blacksheep.org] namens Stefan Sch=E4fer [Stefan.Schaefer=
@iup.uni-heidelberg.de]<br>
<b>Verzonden:</b> vrijdag 30 augustus 2013 15:50<br>
<b>To:</b> rsgb_lf_group@blacksheep.org<br>
<b>Onderwerp:</b> Re: LF: iron powder toroid cores<br>
</font><br>
</div>
<div></div>
<div>Hello Rik, <br>
<br>
A T200-2 will have no problem with 500W on 475 kHz! Belive me :-)<br>
<br>
73, Stefan/DK7FC<br>
<br>
Am 30.08.2013 09:30, schrieb Rik Strobbe:
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CTION: ltr">
<p>Dear&nbsp;all,</p>
<p>&nbsp;</p>
<p>I&nbsp;intend to&nbsp;replace the air&nbsp;coils in the LPF&nbsp;on&nbsp=
;my 475 kHz&nbsp;transmitter&nbsp;by&nbsp;toroid core coils. I have a stock=
 of&nbsp;T200-2&nbsp;cores&nbsp;but&nbsp;for the power level&nbsp;want to&n=
bsp;get (500W&nbsp;would&nbsp;be&nbsp;required to&nbsp;get&nbsp;near the 5 =
W&nbsp;EIRP limit)&nbsp;&nbsp;one&nbsp;T200-2 is&nbsp;just&nbsp;on the&nbsp=
;edge in&nbsp;regard&nbsp;with
 the maximum flux (and&nbsp;thus&nbsp;temperature rise. </p>
<p>To&nbsp;be&nbsp;on the save&nbsp;side I&nbsp;would&nbsp;use 2&nbsp;T200-=
2&nbsp;toroids&nbsp;for&nbsp;each coil, and&nbsp;there are 2 options:</p>
<p>&nbsp;</p>
<p>1.&nbsp;Glue 2&nbsp;cores&nbsp;together to&nbsp;make&nbsp;one core of th=
e double height.</p>
<p>This&nbsp;would&nbsp;reduce the flux to 70%,&nbsp;well&nbsp;under the li=
mit.&nbsp;It&nbsp;would&nbsp;also&nbsp;reduce the&nbsp;number of&nbsp;windi=
ngs to 70%,&nbsp;but&nbsp;due to the double&nbsp;coil&nbsp;height the&nbsp;=
wire&nbsp;length&nbsp;will&nbsp;increase&nbsp;slightly (abt. 10%).</p>
<p>But&nbsp;as the&nbsp;cores have&nbsp;rounded&nbsp;egdes&nbsp;there wil&n=
bsp;be&nbsp;some air&nbsp;space&nbsp;between the&nbsp;wire&nbsp;an the core=
,&nbsp;what&nbsp;might&nbsp;increase loss.</p>
<p>&nbsp;</p>
<p>2. Put 2&nbsp;toroid core coils,&nbsp;each of half the inductance, in se=
ries.</p>
<p>This&nbsp;will&nbsp;also&nbsp;reduce the flux to 70%,&nbsp;but the&nbsp;=
total&nbsp;wire&nbsp;length&nbsp;needed&nbsp;will&nbsp;increase&nbsp;by abt=
. 40%.</p>
<p>&nbsp;</p>
<p>In&nbsp;option 1&nbsp;I&nbsp;will&nbsp;need&nbsp;lees&nbsp;wire (=3D&nbs=
p;less loss)&nbsp;compared to&nbsp;option 1,&nbsp;but the air&nbsp;space&nb=
sp;might&nbsp;undo&nbsp;this advantage.</p>
<p>&nbsp;</p>
<p>So&nbsp;my&nbsp;question is:&nbsp;what&nbsp;will&nbsp;be best?</p>
<p>All&nbsp;advice is welcome.</p>
<p>&nbsp;</p>
<p>73, Rik&nbsp;&nbsp;ON7YD - OR7T</p>
<p>&nbsp;</p>
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