Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id wAUKVJsh031452 for ; Fri, 30 Nov 2018 21:31:20 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1gSpMY-0003fO-UI for rs_out_1@blacksheep.org; Fri, 30 Nov 2018 20:26:10 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1gSpMP-0003fF-TI for rsgb_lf_group@blacksheep.org; Fri, 30 Nov 2018 20:26:01 +0000 Received: from mail-ed1-x535.google.com ([2a00:1450:4864:20::535]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1gSpMN-00059d-9v for rsgb_lf_group@blacksheep.org; Fri, 30 Nov 2018 20:26:00 +0000 Received: by mail-ed1-x535.google.com with SMTP id f4so5845486edq.10 for ; Fri, 30 Nov 2018 12:25:58 -0800 (PST) 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=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=4XYShkfZEW9pR8GEp+WDDVhN/8G6YwHKgx/4RKl4zZg=; b=F+iOHOlmkw62IUMTNFATcYKN6G3H5+SQDeYBox9bB0Jezrvq2cb1QYK83FLL6u9Y6f Dc+Kb9IvSS8hx4wpYAJmlP3q/gAbuoLHAObLIcODzXJ3BoWXntAu1Dw6fX1SU/07ho/Z ZPX/qmo3HOqt1zAVcLKiCAUBAMkCMzNjMwhsLWXFZ3UiCVAbVHHqzqPZZhWWjSr5Ucz3 2zYfohy7ZB7LS0ygrxjpekr1jPxO1HUy1ywqux1cyybtgMnBj4EvyLOa5wZPuI6QVscX R0hVfHHlrbIq5oXo24Sf93JYxpDCeLgLhf9WCdwDaII11W86CaZJciMxO0PJl/CCxZsi aR8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=4XYShkfZEW9pR8GEp+WDDVhN/8G6YwHKgx/4RKl4zZg=; b=nTZODE4JSiV4tnQAYdiscJFNb30D5cufjyUFFc6af7DUjVJ26/jS9z/g+hvYJWYyfQ NB/EegIEm98A4Z4bxW6PgqVOEl9yr56YhXIE+Bey8eK5qxuWaOEEvNB3ckaiDZVC9EwJ ETKC9+LWWVAmpuP9PITuiRkmMbEI1spMYV7OVNMSu+VK/HBWJcWYwgjPIpoHXxUyXkrP 6LL7EkJhd6iLZDI4PjmLM0r3m0++jnG2XaGYPUoYwvpQRK57dBWgR4fbND0Oe/L6CZI6 IV79d7APiIdwnOrbeJi7ou5g454n6n6UNPUotNBJJkAzhr5nttEI5pmRp+VtJBakSJvT bKWA== X-Gm-Message-State: AA+aEWYhlJ5r0992oxtaqAZtQ5YlXfkLP1g52vN+YcL6VeF/k068z83P 5OLiYHSKfZFzVKes9bcvW9eSGwqh0LtV9UF3QTyj2F5W X-Google-Smtp-Source: AFSGD/WrvGaP/gCLPJqc9Av9dofsBuoJ37iHvIXe4mpE1uTMzNP/sK7hGc09PSQBLfjIfFTAtjcmKeCipnUnf80/aRU= X-Received: by 2002:a50:93c5:: with SMTP id o63mr6324796eda.20.1543609558139; Fri, 30 Nov 2018 12:25:58 -0800 (PST) MIME-Version: 1.0 References: <2133457080.64533.1543584595217@mail2.virginmedia.com> <27270b29-dde1-1207-1158-becc1e4de123@n1bug.com> <1382885588.67051.1543589445229@mail2.virginmedia.com> <530677a9-52b1-0280-128f-4afc58f94536@n1bug.com> In-Reply-To: From: Andy Talbot Date: Fri, 30 Nov 2018 20:25:38 +0000 Message-ID: To: "rsgb_lf_group@blacksheep.org" X-Spam-Score: 0.0 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see @@CONTACT_ADDRESS@@ for details. Content preview: Cross conduction spikes can also be dealt with by inserting a bit of inductance between top and bottom FETs of a totem pole, or in each leg of a push-pull pair. As done in the old Decca transmitters, [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2a00:1450:4864:20:0:0:0:535 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (andy.g4jnt[at]gmail.com) 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 77d68ebd44814a6def4d7158b7296e78 Subject: Re: Re: [Lowfer] LF: Re: FET change, hmmm Content-Type: multipart/alternative; boundary="0000000000006286b8057be79bbe" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.8 required=5.0 tests=HTML_30_40,HTML_MESSAGE, TO_ADDRESS_EQ_REAL autolearn=no version=2.63 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 --0000000000006286b8057be79bbe Content-Type: text/plain; charset="UTF-8" Cross conduction spikes can also be dealt with by inserting a bit of inductance between top and bottom FETs of a totem pole, or in each leg of a push-pull pair. As done in the old Decca transmitters, and I cribbed for my 700 Watt 137 design. The inductor absorbs the short spike and returns the energy via clamp diodes to the supply See http://www.g4jnt.com/137tx.pdf A lot simpler than worrying about generating a special drive waveform with gaps Andy www.g4jnt.com On Fri, 30 Nov 2018 at 20:19, Hans-Albrecht Haffa wrote: > Dear OMs, dear Paul, > > To prevend current spikes by cross conduction of both fets it is necesary > to use a gate drive circuit with dead time, as used in power supplies. But > in this case there is a no current flow time in both transistors, what may > cause spikes in the drain circuit. Damping of oscillations in the drain > circuit may also reached by quiescent current, not used for class D PAs. To > load the spikes to the load is not possible in an LW-PA, like in an > flyback-transformer of an switch mode power supply, as the load is an > LP-Filter that filters by reflections of the applied voltage. > > --0000000000006286b8057be79bbe Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Cross conduction spikes can als= o be dealt with by inserting a bit of inductance between top and bottom FET= s of a totem pole, or in each leg of a push-pull pair.=C2=A0 As done in the= old Decca transmitters, and I cribbed for my=C2=A0 =C2=A0700 Watt 137 desi= gn.
The inductor absorbs the short spike and returns the ene= rgy via clamp diodes to the supply=C2=A0
See=C2=A0http://www.g4jnt.com/137tx.pdf

A lot simpler than worrying about generating a = special drive waveform with gaps



On Fri, 30 Nov 2018 at 20:19, Hans-Albrecht Haffa <= dk8nd@web.de> wrote:
Dear OMs, dear Paul,

To prevend current spikes by cross conduction of both fets it is neces= ary to use a gate drive circuit with dead time, as used in power supplies. = But in this case there is a no current flow time in both transistors, what = may cause spikes in the drain circuit. Damping of oscillations in the drain= circuit may also reached by quiescent current, not used for class D PAs. T= o load the spikes to the load is not possible in an LW-PA, like in an flyba= ck-transformer of an switch mode power supply, as the load is an LP-Filter = that filters by reflections of the applied voltage.
=C2=A0
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