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" <[email protected]> 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
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