Return-Path: X-Spam-DCC: paranoid 1233; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=5.0 tests=BAYES_00,RATWARE_GECKO_BUILD autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id sBLG6XBB003140 for ; Sun, 21 Dec 2014 17:06:33 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Y2iwF-0005Z1-3i for rs_out_1@blacksheep.org; Sun, 21 Dec 2014 16:00:59 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Y2iwE-0005Ys-Bn for rsgb_lf_group@blacksheep.org; Sun, 21 Dec 2014 16:00:58 +0000 Received: from mta31.charter.net ([216.33.127.82]) by relay1.thorcom.net with esmtp (Exim 4.84) (envelope-from ) id 1Y2iwC-0002pd-G5 for rsgb_lf_group@blacksheep.org; Sun, 21 Dec 2014 16:00:57 +0000 Received: from imp09 ([10.20.200.9]) by mta31.charter.net (InterMail vM.8.01.05.02 201-2260-151-103-20110920) with ESMTP id <20141221160054.WSOI10321.mta31.charter.net@imp09> for ; Sun, 21 Dec 2014 11:00:54 -0500 Received: from mtaout003.msg.strl.va.charter.net ([68.114.190.28]) by imp09 with smtp.charter.net id WG0u1p0040dCcRg05G0uVe; Sun, 21 Dec 2014 11:00:54 -0500 Received: from impout006 ([68.114.189.21]) by mtaout003.msg.strl.va.charter.net (InterMail vM.9.00.015.01 201-2473-143-101) with ESMTP id <20141221160054.GCJM15216.mtaout003.msg.strl.va.charter.net@impout006> for ; Sun, 21 Dec 2014 10:00:54 -0600 Received: from [192.168.1.100] ([68.118.229.27]) by impout006 with charter.net id WG0u1p0030c6mLs01G0ucE; Sun, 21 Dec 2014 10:00:54 -0600 X-Authority-Analysis: v=2.1 cv=Xq10OD19 c=1 sm=1 tr=0 a=WLV0DKOOKFWiVcf2giHCRw==:117 a=WLV0DKOOKFWiVcf2giHCRw==:17 a=hOpmn2quAAAA:8 a=DgqbUt__V68A:10 a=IkcTkHD0fZMA:10 a=u1vQ2dj7AAAA:8 a=ghueaqahFt6vlM6Imz0A:9 a=QEXdDO2ut3YA:10 a=3cLkciXEHk4A:10 X-Auth-id: dzF0YWdAY2hhcnRlci5uZXQ= Message-ID: <5496EEBC.3070108@charter.net> Date: Sun, 21 Dec 2014 11:01:00 -0500 From: John Andrews User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: In-Reply-To: X-Scan-Signature: f38d515a9cad1e977fcfe251941a8120 Subject: Re: LF: Low pass filter 1 kW 136k 472 k what components to choose? Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false X-Scanned-By: MIMEDefang 2.56 on 10.1.3.10 Status: O X-Status: X-Keywords: X-UID: 1555 Hans-Albrecht, W1VD and I use the "half-wave" filters described at: http://www.w1vd.com/LPF.html Jay's method of construction probably has a better HF/VHF stop-band, but I have gotten away with a single chassis for all components. In terms of practical harmonic suppression, the 2nd and 3rd harmonics offer no interference to weak AM broadcast signals on our street about 100 meters from the antenna while operating in the 472 kHz band. There are definite AM interference problems at my house, however. I have done no other measurements. John, W1TAG On 12/21/2014 10:38 AM, Hans-Albrecht Haffa wrote: > 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