Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=0.0 required=5.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,T_DKIM_INVALID,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=3 Fuz1=3 Fuz2=3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id v73ETsrf009004 for ; Thu, 3 Aug 2017 16:29:55 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ddGxZ-0005lL-VF for rs_out_1@blacksheep.org; Thu, 03 Aug 2017 15:18:45 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ddGxW-0005lC-UK for rsgb_lf_group@blacksheep.org; Thu, 03 Aug 2017 15:18:42 +0100 Received: from mail-wr0-x22b.google.com ([2a00:1450:400c:c0c::22b]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1ddGxS-0007L5-Tj for rsgb_lf_group@blacksheep.org; Thu, 03 Aug 2017 15:18:41 +0100 Received: by mail-wr0-x22b.google.com with SMTP id 33so6315080wrz.4 for ; Thu, 03 Aug 2017 07:18:38 -0700 (PDT) X-DKIM-Result: Domain=gmail.com Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:message-id:to:subject:mime-version :content-transfer-encoding; bh=FvnILtlGGfsGPC+HQptXlaUebKJtPycPJH7hNlKv/G8=; b=LpgHoQ8h8mTT7lGAnUvjs4Lcad69dIpozLAJWYblh+e+8UlHUW5W/6eyAaXiWOG7Y/ s4SeFJ/6MlS18BFZMgKfpBTGGHhMQpJlNRyRSYv7k+l2sRR8QRUPIHZUkjnyeQAzRpSX VksurcpM+spiZey4vdFtPOWksPv8i9Q5jJp4qnvp2qEPrUe4OgUuhCtN8+Mz0UBHLdgR TfCUuiPkk8mXG+bjzuVgdr4/IIKJe66krobuWOdsufW9Hu21KvbpbiJdE4STRvmtZoGD xG28l2b1SB7pkqrXrX9ksDE6BdkSrvsnKH+CzpKVNQOf9QKZ3enKtjdyz7fxUn1dC+Gz CyXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:message-id:to:subject:mime-version :content-transfer-encoding; bh=FvnILtlGGfsGPC+HQptXlaUebKJtPycPJH7hNlKv/G8=; b=M3sFKcFUbNmRuqsgV2jBAtFz/4kIAQd3OkSxcqJx/Yj/NJgIttqpWv8AWOWIrpWmMv J/wOF7fKyJKvSjwvBiw8DBHo2rN6jizYJIciSA7BJciZ/RjDxKfwsTbYqt6TdvTX5y+2 CTcD7JEWEkQavUThMV/HdFNQAH2b61IRxVOvW/Ok6DNYXxYv5cIl0LTteL+YBZOO7TvD z/evRDI+/CcZ2/0mGQjBPeGY83wDgOGuUq2uRShUGJGNFXMB5wbagGQJIe845UQX5WQ8 OUY4jI/asIk+p0OmGjzKzQsFXftLQ7rbwv4PASCK7yqgujL8DORrqNsAjvvgZGTCG7EN qSUQ== X-Gm-Message-State: AIVw113Zke++joW5E5MruQ5y/1sxJS3QgzifbP9PzYAo1YZ3CtPWAgmk 8xsHPCo+4mACt+g0 X-Received: by 10.223.173.117 with SMTP id p108mr1450967wrc.149.1501769916521; Thu, 03 Aug 2017 07:18:36 -0700 (PDT) Received: from OfficeWin7.lan (82-70-254-222.dsl.in-addr.zen.co.uk. [82.70.254.222]) by smtp.gmail.com with ESMTPSA id 52sm478131wrt.38.2017.08.03.07.18.35 (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 03 Aug 2017 07:18:35 -0700 (PDT) Date: Thu, 3 Aug 2017 15:18:34 +0100 From: Chris Wilson X-Priority: 3 (Normal) Message-ID: <791401561.20170803151834@gmail.com> To: rsgb_lf_group@blacksheep.org, rsgb_lf_group@yahoogroups.co.uk MIME-Version: 1.0 X-Scan-Signature: 2e2f7cbbe9f38dd7bf3fac4fc012e6fc Subject: LF: LPF for a valve based (tube based) LF amp? Content-Type: text/plain; charset=us-ascii 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 2.75 Status: RO X-Status: X-Keywords: X-UID: 12315 Hello LF'ers, My next contemplated project is a GS35B valve based LF amp. I have the HT supply, a couple of GS35B's to play with and a suitable filament supply. My question is can I build an air wound LPF based on exactly the same values as the one I use on my W1VD FET based Class D amp? That gets pretty warm and I use a small PC processor fan on the centre toroid, but I am unsure if the filter characteristics are specific to a FET based amp in some ways? W1VD amp schematic here: http://www.w1vd.com/137-500-KWTX.html (1 kW amplifier) http://www.w1vd.com/137-500-KWRev3.0.pdf W1VD LPF details here: http://www.w1vd.com/LPF.html http://www.w1vd.com/LPF.pdf -- Best regards, Chris mailto:dead.fets@gmail.com