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Subject: Re: LF: toroid cores
From: "Hans-Joachim Brandt" <hajo.brandt.dj1zb@t-online.de>
To: rsgb_lf_group@blacksheep.org
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Date: 23 Aug 2002 18:08 GMT
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Dear Rik,

as my intention had been to design a transformerless PA, I have just two coils in the "peaked low-pass filter" (one coil with two T200-2 stacked because of higher reactive power in this part of the filter, the other coil with a single T200-2) and a transformer from the 50 ohms cable to the antenna feed impedance of about 70 Ohms This core is a FT140-43, for a transmitter output of 100 watts. 

Concerning the antenna transformer, I have never had the opportunity to check the temperature of the core, because it is located outside in a "dustbin" in the garden, close to the variometer. I just know that the first coil with the two stacked toroids in the low-pass filter needs additional air cooling in key down conditions for three hours (when our administration had measured the fieldstrength around my antenna in a campaign to test whether we Germans could also get permission for 1 watt erp).

Thank You in advance for your coordination work.

73 Ha-Jo, DJ1ZB


"Rik Strobbe" <rik.strobbe@fys.kuleuven.ac.be> schrieb:
>Hello LF group,
>
>I am trying to make a list of toroid core material that is suitable for 
>136kHz power applications, for impedance transformers and low-pass filters.
>I would appreciate any information about the material (brand-type), the 
>application (transformer or filter) and the power level it was used/tested.
>
>many thanks in advance,
>
>73, Rik   ON7YD
>
>
>