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Tue, 3 Sep 2013 08:57:04 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster To: "rsgb_lf_group@yahoogroups.co.uk" , "rsgb_lf_group@blacksheep.org" Thread-Topic: [rsgb_lf_group] RE: LF: iron powder toroid cores Thread-Index: AQHOpWc9MfrpRY0yNE+mVvT3vA37zJmtjQEzgAB3KcCABY/uTw== Message-ID: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC38673@ICTS-S-MBX1.luna.kuleuven.be> References: <7E7DFBB4D102A04DB5ADC88D66628A4A0FC36D4D@ICTS-S-MBX1.luna.kuleuven.be>,<3D9F11600DAD49D0889B3F2332B4DA93@Clemens0811> In-Reply-To: <3D9F11600DAD49D0889B3F2332B4DA93@Clemens0811> Accept-Language: nl-BE, en-US Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: X-Originating-IP: 10.193.84.142 X-eGroups-Msg-Info: 1:12:0:0:0 From: Rik Strobbe Sender: rsgb_lf_group@yahoogroups.co.uk MIME-Version: 1.0 Mailing-List: list rsgb_lf_group@yahoogroups.co.uk; contact rsgb_lf_group-owner@yahoogroups.co.uk Delivered-To: mailing list rsgb_lf_group@yahoogroups.co.uk List-Id: Precedence: bulk List-Unsubscribe: Date: Tue, 3 Sep 2013 06:57:03 +0000 Subject: RE: [rsgb_lf_group] RE: LF: iron powder toroid cores Reply-To: rsgb_lf_group@yahoogroups.co.uk X-Yahoo-Newman-Property: groups-email-ff-m Content-Type: multipart/alternative; boundary="_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC38673ICTSSMBX1lunaku_" Status: O X-Status: X-Keywords: X-UID: 1796 --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC38673ICTSSMBX1lunaku_ Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Dear Clemens, >Or otherwise said: on 475 kHz you can only use half the power you can use = on 1850 kHz. I would expect half the voltage for the same flux which is one fourth of th= e power. indeed, for the same flux. But the max. permissible flux drops with the squ= are root of the frequency. 73, Rik ON7YD ________________________________ Van: rsgb_lf_group@yahoogroups.co.uk [rsgb_lf_group@yahoogroups.co.uk] name= ns Clemens Paul [cpaul@gmx.net] Verzonden: vrijdag 30 augustus 2013 19:52 To: rsgb_lf_group@blacksheep.org Cc: rsgb_lf_group@yahoogroups.co.uk Onderwerp: [rsgb_lf_group] RE: LF: iron powder toroid cores Hi Rik, >So on 475 kHz the flux will be double compared to 1850 kHz. Agreed. >Or otherwise said: on 475 kHz you can only use half the power >you can use on 1850 kHz. I would expect half the voltage for the same flux which is one fourth of th= e power. But,according to the mini ringcore calculator *given the same flux* temperature rise is MUCH less on 475kHz than on 1900kHz ( 32=B0C vs 165=B0C !) which seems reasonable because losses increase with frequency while flux decreases with frequency. >But as the cores have rounded egdes there wil be some air space > between the wire an the core, what might increase loss. I can't see any reason why losses should increase due to some air gap. Only the overall effective =B5_rel would slightly decrease and hence the inductance. 73 Clemens DL4RAJ >-----Original Message----- >From: owner-rsgb_lf_group@blacksheep.org >[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Rik Strobbe >Sent: Friday, August 30, 2013 12:44 PM >To: rsgb_lf_group@blacksheep.org >Subject: RE: LF: iron powder toroid cores > >Hi Christian, > >according to the "mini ringcore calculator" (by DL5SWB) it is >just on the edge (a flux of 223 G while 221 G is the max. >flux). But as I have sufficient T200-2 cores I prefer to be on >the safe side, also taking in mind that modes as QRRS120 and >WSPR will require a 2 minute carrier. > >For an indentical LPF filter (coil reactance remains the same) >the flux will drop with the square root of the frequency >increase. So on 475 kHz the flux will be double compared to 1850 kHz. >Or otherwise said: on 475 kHz you can only use half the power >you can use on 1850 kHz. > >73, Rik ON7YD - OR7T > >________________________________________ > --_000_7E7DFBB4D102A04DB5ADC88D66628A4A0FC38673ICTSSMBX1lunaku_ Content-Type: text/html; charset=Windows-1252 Content-Transfer-Encoding: quoted-printable  
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Dear Clemens,

 

>Or otherwise said<= /a>: on 475 kHz you can only use half the power you can use on 1850 kHz.
I would expect half the voltage for the=  same flux which is one fourth<= /a> of the power.

indeed, for the same flux. But the m= ax. permissible flux drops with the square root of = the frequency.

 

73, Rik  ON7YD

 

Van: rsgb_lf_group@yahoogroups.co.uk [rsg= b_lf_group@yahoogroups.co.uk] namens Clemens Paul [cpaul@gmx.net]
Verzonden: vrijdag 30 augustus 2013 19:52
To: rsgb_lf_group@blacksheep.org
Cc: rsgb_lf_group@yahoogroups.co.uk
Onderwerp: [rsgb_lf_group] RE: LF: iron powder toroid cores

 

Hi Rik,

>So on 475 kHz the flux will be double compared to 1850 kHz.

Agreed.

>Or otherwise said: on 475 kHz you can only use half the power
>you can use on 1850 kHz.

I would expect half the voltage for the same flux which is one fourth of th= e power.

But,according to the mini ringcore calculator
*given the same flux* temperature rise is MUCH less on 475kHz
than on 1900kHz ( 32=B0C vs 165=B0C !) which seems reasonable
because losses increase with frequency while flux decreases with frequency.=

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

I can't see any reason why losses should increase due to some air gap.
Only the overall effective =B5_rel would slightly decrease and hence
the inductance.

73
Clemens
DL4RAJ

>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Rik Strobb= e
>Sent: Friday, August 30, 2013 12:44 PM
>To: rsgb_lf_group@blacksheep.org
>Subject: RE: LF: iron powder toroid cores
>
>Hi Christian,
>
>according to the "mini ringcore calculator" (by DL5SWB) it is=
>just on the edge (a flux of 223 G while 221 G is the max.
>flux). But as I have sufficient T200-2 cores I prefer to be on
>the safe side, also taking in mind that modes as QRRS120 and
>WSPR will require a 2 minute carrier.
>
>For an indentical LPF filter (coil reactance remains the same)
>the flux will drop with the square root of the frequency
>increase. So on 475 kHz the flux will be double compared to 1850 kHz. >Or otherwise said: on 475 kHz you can only use half the power
>you can use on 1850 kHz.
>
>73, Rik ON7YD - OR7T
>
>________________________________________
>

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