LF: RE: Low pass filter 1 kW 136k 472 k what components to choose?

[Rik Strobbe <Rik.Strobbe@fys.kuleuven.be>]

Hello Hans Albrecht,

 

I do use T200-2 cores for 472kHz. At 600W output a single core gets lukewarm at good SWR but rather hot at SWR > 2. As I had a stock of T200-2's available I did glue 2 T200-2's, then I had no significant temperature rise under any conditions. Wire used was 2mm litz wire. The combination of 2 T200-2's and 2mm litz wire resulted in a Q of 550!

As capacitors I do use 1.5kV polypropylene film capacitors (cost less that 1 Euro).

 

73, Rik  ON7YD

 

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Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Hans-Albrecht Haffa [dk8nd@web.de]
Verzonden: zondag 21 december 2014 16:38
Aan: Langwellen-Reflektor; Hans-Albrecht Haffa
Onderwerp: LF: Low pass filter 1 kW 136k 472 k what components to choose?

Dear OMs,
just a question strait forward: What componnets I should choose for a low pass filter for 136 kHz and 472 kHz, two filters to be designed.

136 kHz:  Pin abt 1,5 kW

472 kHz:  Pin abt 0,5 kW

SWR: s = 1...2,5 when mated, in case of failure more

a five-pole low pass will probably be sufficient.

My Question:

What iron powder cores or air coiles will do it, known or proofed by experiment? Diameter, marterial grade?

What capacitors? max. Voltage.  High voltage caps from Wima (Ucd=4kV or 8 kV) are not available at distributors, mica capacitors will hardly fit in capacitiy value or in voltage, when in my collection.

The calculus of magnetic circuits is not a problem for me, but it is easier to start with components that will fulfill the demands.

Waiting to Your kind anwer,

55, Hans-Albrecht

DK 8 ND