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=HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_MED,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 X-Spam-DCC: : mailn 1480; 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+deb8u1) with ESMTP id v5HC1KoH027233 for ; Sat, 17 Jun 2017 14:01:21 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1dMCMI-0003be-5L for rs_out_1@blacksheep.org; Sat, 17 Jun 2017 12:57:42 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1dMCMH-0003bV-J7 for rsgb_lf_group@blacksheep.org; Sat, 17 Jun 2017 12:57:41 +0100 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1dMCME-0000Xx-UL for rsgb_lf_group@blacksheep.org; Sat, 17 Jun 2017 12:57:40 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 4D53B20A63 for ; Sat, 17 Jun 2017 13:57:38 +0200 (CEST) Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 3wqbMj1s9Jz108q for ; Sat, 17 Jun 2017 13:57:37 +0200 (CEST) Message-ID: <59451931.7040701@posteo.de> Date: Sat, 17 Jun 2017 13:57:37 +0200 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: In-Reply-To: X-Scan-Signature: 5c335215f1b3de26d890ee84d49616ce Subject: Re: LF: WSPR problems 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 2.75 Status: O X-Status: X-Keywords: X-UID: 11997 Hi Chris, Try a 1:1 RF ferrite decoupling trasformer, right behind the PA. Maybe also on the PA input. Try to use a battery for the PA, just for one WSPR sequence, to see if that solves the problem. If it does, then use common mode chokes in the PA supply cable. Avoid ground loops. Use shielded circuits only. 73, Stefan Am 17.06.2017 13:20, schrieb Chris Osborn: > GA LF, > > I have a recurring problem with my home made LF WSPR TX :- > > As the PC's audio signal shuts down (after the nominal 2 minute > transmission time) it picks up RF - this is fed back to the TX input > causing several seconds of instability. > > Has anyone else had this trouble and/or knows of a simple solution? > > I've tried putting ferrite rings around the PC's input and output > cables which solved the problem for a while. > > In desperation I'm considering adding a monostable to ground the TX > input for a few seconds after the PC's AF shuts down, but this will be > a last resort. > > Any useful advice or comments would be most welcome. > > 73 > Chris (G3XIZ)