Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=5.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_PASS, T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: EATSERVER: mailn 1166; Body=2 Fuz1=2 Fuz2=2 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by lipkowski.org (8.14.4/8.14.4/Debian-8+deb8u1) with ESMTP id v35Cj2Gi008935 for ; Wed, 5 Apr 2017 14:45:03 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1cvkFp-0007VQ-CD for rs_out_1@blacksheep.org; Wed, 05 Apr 2017 13:41:41 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1cvkFp-0007VH-2L for rsgb_lf_group@blacksheep.org; Wed, 05 Apr 2017 13:41:41 +0100 Received: from nm32-vm5.bullet.mail.ir2.yahoo.com ([212.82.97.101]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1cvkFl-0002zf-6b for rsgb_lf_group@blacksheep.org; Wed, 05 Apr 2017 13:41:39 +0100 X-DKIM-Result: Domain=yahoo.co.uk Result=Good and Known Domain DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.co.uk; s=s2048; t=1491396095; bh=tqxnT1KkwptrOILAIWPWhrtlSIa36fOUnpesCz8p4zU=; h=Date:From:Reply-To:To:Subject:References:From:Subject; b=bvT7kmLTMqCAm0blXZoc18NHAzwhjDfFlsYL5vkm4LvGyiZ19uyQQNywxznIIM9Yqs5uJCmL+eyE4dFWVg255/2o/FSaWtPjqH1y73ZHFvO8VqB9hKuc8bnQdEJzRvIKaBsZBA0iCO4gI7cHzPPzMOj5NzZ8lya4YX++LVj1jH0+wSCnxTtFRM8uo7EyKO9Kb5+hcWAzYRKCwh8DMDViZo36u+81b+g+hhEA251tNMGaPwQg5aQh7mrmcW3qi0zRPlOl6XX+5daJrbqBmilfTxLk5YT3EoOFQQpKI0slVCHl/YeZL3ZN/5FCVyX2hmjIjsDf9DD1JJkjZkE7EksMMw== Received: from [212.82.98.63] by nm32.bullet.mail.ir2.yahoo.com with NNFMP; 05 Apr 2017 12:41:35 -0000 Received: from [212.82.98.85] by tm16.bullet.mail.ir2.yahoo.com with NNFMP; 05 Apr 2017 12:41:35 -0000 Received: from [127.0.0.1] by omp1022.mail.ir2.yahoo.com with NNFMP; 05 Apr 2017 12:41:35 -0000 X-Yahoo-Newman-Property: ymail-4 X-Yahoo-Newman-Id: 25916.21593.bm@omp1022.mail.ir2.yahoo.com X-YMail-OSG: jnHH1yYVM1kTH5v3dtm40FeT2PEBeSVZyCfsB8FpfAV5xqVegLOJ7I1prmaEotQ EVPnPGdInSFYn0TaMfxS_GFlJ6nyA9BPqXpbuA0gUjOHyOr9W52wRSdWdVTaAsAuRb70QajuM7D1 hswW0um3xbe.eTCMPzuXLjqtklkcBgM65rqZhOVgf0DFSX..uC3HPexyIOpJx6byW49JnaGAXm45 vCaa9eUe8dbEg1MTxdix0jW3N7szUW6yJckD9aOkfFN9mgk.NTZQDHYhG8C.FtH9OUE8snzF_i8t cij4ihD8PRwzIEa4GS0XSG3FoX9nYQ00K25UDrw5CSH_2XM37HW_t.41LoPLvO1NXx4.iDl72Z_i l6PNDCLcPUz7oN1Byvzjal9ekzSYRmXakbEYdkuG06Z8DTrGlLaUC16QE6AdZA8Q5cuYnfMnu3WI wlV_Mjo9ALyhdD0wTmzwMyRJc_GeTadCHE50eOrxOFE2v4WhBKGPOv_1y.32aWTRgeiJwK_wSxci tAL5qkHa1805bQXflXZyn0CkQ4OLE7c3ZLZfPjg-- Received: from jws700069.mail.ir2.yahoo.com by sendmailws104.mail.ir2.yahoo.com; Wed, 05 Apr 2017 12:41:34 +0000; 1491396094.679 Date: Wed, 5 Apr 2017 12:41:34 +0000 (UTC) From: M0FMT To: Message-ID: <80979655.18056190.1491396094474@mail.yahoo.com> MIME-Version: 1.0 References: <80979655.18056190.1491396094474.ref@mail.yahoo.com> X-Scan-Signature: 4c0633a540d76adc241b9d3cede72a57 Subject: Re: FW: LF: FETs getting sick - why not use tubes? Content-Type: text/plain; charset=UTF-8 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 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by lipkowski.org id v35Cj2Gi008935 Status: O X-Status: X-Keywords: X-UID: 11115 No . -------------------------------------------- On Wed, 5/4/17, Chris Wilson wrote: Subject: Re: FW: LF: FETs getting sick - why not use tubes? To: "M0FMT" Date: Wednesday, 5 April, 2017, 13:28 Hello M0FMT, Wednesday, April 5, 2017 Did you not find the Transorbs added capacitance upset things? I found the  drain  waveform was considerably deteriorated when I experimented with Transorbs to limit spikes. > Hi all > The Decca PA seems to be scattered with spike limiting diode from > memory Transils / Transorb TVS diodes. (don't know the values) I > usually put one in the drain set above the peak drain wave voltage > seen on the scope and below the peak operating value of the FET  So far so good in single ended amps. > Jim M0MBU did a short treatise see > http://www.wireless.org.uk/guard.htm. > The Decca TX "guard circuit" by Jim Moritz, M0BMU. > 73 petefmt mailto:dead_fets@gmail.com