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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: AQHOpYEYMfrpRY0yNE+mVvT3vA37zJmts9P6
Date: Fri, 30 Aug 2013 12:50:32 +0000
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Subject: RE: LF: iron powder toroid cores
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Status: O

unless you want to work VK or ZL ;-)

73, Rik  ON7YD - OR7T

________________________________________
Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org=
] namens C. Groeger [aot.aot@gmx.de]
Verzonden: vrijdag 30 augustus 2013 15:01
To: rsgb_lf_group@blacksheep.org
Onderwerp: RE: LF: iron powder toroid cores

Rik,
With 500 w there is no need for qrs anymore ;-)
You can go on CW!
73

Christian Groeger

Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> schrieb:

>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 sufficie=
nt T200-2 cores I prefer to be on the safe side, also taking in mind that m=
odes as QRRS120 and WSPR will require a 2 minute carrier.
>
>For an indentical LPF filter (coil reactance remains the same) the flux wi=
ll drop with the square root of the frequency increase. So on 475 kHz the f=
lux 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
>
>________________________________________
>Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or=
g] namens C. Groeger [aot.aot@gmx.de]
>Verzonden: vrijdag 30 augustus 2013 12:09
>To: rsgb_lf_group@blacksheep.org
>Onderwerp: Re: LF: iron powder toroid cores
>
>Hi Rik,
>One T200_2 is enough for that power. I tried it on 160m at 1000w.
>Temperature was abaout 40C.
>
>Hpe cu on 630
>Df5qg
>
>Christian Groeger
>
>Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> schrieb:
>
>>Dear all,
>>
>>
>>
>>I intend to replace the air coils in the LPF on my 475 kHz transmitter by=
 toroid core coils. I have a stock of T200-2 cores but for the power level =
want to get (500W would be required to get near the 5 W EIRP limit)  one T2=
00-2 is just on the edge in regard with the maximum flux (and thus temperat=
ure rise.
>>
>>To be on the save side I would use 2 T200-2 toroids for each coil, and th=
ere 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 re=
duce the number of windings to 70%, but due to the double coil height the w=
ire length will increase slightly (abt. 10%).
>>
>>But as the cores have rounded egdes there wil be some air space between t=
he 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 w=
ill increase by abt. 40%.
>>
>>
>>
>>In option 1 I will need lees wire (=3D less loss) compared to option 1, b=
ut the air space might undo this advantage.
>>
>>
>>
>>So my question is: what will be best?
>>
>>All advice is welcome.
>>
>>
>>
>>73, Rik  ON7YD - OR7T
>>
>>=