LF: Fw: Low pass filter 1 kW 136k 472 k what components to choose? Tnx to all

["Hans-Albrecht Haffa" <dk8nd@web.de>]

Dear OMs,

thank You for the quick answer just in one day. Isn t it nice to get replies from technical experts just in a few hours?

I compared Your drafts with an already built construction of me using abt 80 mm ferrit toroids with cut slots and stacked mica caps 150 nF ( I nedded 30 nF, so I stacked 5 of them...). The air gaps I had cut with an saw designed to cut tiles from the home store. I measured transfer function s21 with the Vector-Antenna analyser from "Funkamateur", as it should be for an 7pole-filter.  Just before I had done trash measurements with defective BNC-cables, so I wrote an e-mail to the reflector.

 

 

Gesendet: Sonntag, 21. Dezember 2014 um 16:38 Uhr
Von: "Hans-Albrecht Haffa" <dk8nd@web.de>
An: Langwellen-Reflektor <rsgb_lf_group@blacksheep.org>, "Hans-Albrecht Haffa" <dk8nd@web.de>
Betreff: 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