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 w0QDoS5n008238 for ; Fri, 26 Jan 2018 14:50:29 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ef4Jx-00031c-1C for rs_out_1@blacksheep.org; Fri, 26 Jan 2018 13:45:33 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ef4Jw-00031T-HA for rsgb_lf_group@blacksheep.org; Fri, 26 Jan 2018 13:45:32 +0000 Received: from mail-wr0-x22f.google.com ([2a00:1450:400c:c0c::22f]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89) (envelope-from ) id 1ef4Jr-0006yg-7k for rsgb_lf_group@blacksheep.org; Fri, 26 Jan 2018 13:45:31 +0000 Received: by mail-wr0-x22f.google.com with SMTP id 36so592549wrh.1 for ; Fri, 26 Jan 2018 05:45:26 -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=date:from:message-id:to:cc:subject:mime-version :content-transfer-encoding; bh=9YH7egGj5uyBJj8Lj17RlmHPv8h3hYwTz2sFbtdf97E=; b=tdVWH9TknxvWDaqEPS+fq9gaAOIYAwaKAJO/9ToT97YKtxU7YOK7/kuamAc6bQdV0t gR2N8BDJA96WYj6NTNWXhTT4YsQHIUo9Lz2WBxQ2l3arD+4cexMXo1+SNvP2Cl+mi9cw e3rd8Xd3ZYzWjcvTl4b563/TgZh3LpOcByLJMuc7d7KaAjbviVJfwKzPDrP7H8ttHOPO iXQfch0e42qnldCbd+tppeiuUL2osxu/wyKo6a3utA9G8dtEseA1Vjy3+vgOuq9aWJ4O KDvhhfQdpkWYnZiV83EoYbnLhsPIJYAg+WyHMPqt+CwuYt98mUOl0NvezuyceSYeAKiw mqaA== 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:cc:subject:mime-version :content-transfer-encoding; bh=9YH7egGj5uyBJj8Lj17RlmHPv8h3hYwTz2sFbtdf97E=; b=UnF7BlK7sYPpx83g5zSN6t52lgmTdsnt9DoJbp+rGpJUMJvjA0y4FkaFyE5sb6kdhM edRmHC8O5XlrzsInWjakjlMRMAt7oDO0pM20YDuLC09aG2bSpbZNlVMxkGn8ed8kaCyy nhCpduVFcQZHbav3zND4sJSpxF9dHfx6sf/AclAH3BrysU7CZ4TCJbFgC7SDwq9HRhwo tiXbAXzHrhsnujRmeKCE+7iMAk6RsURiu3TOZLPXJe6IQ5kDA7YNniSou+awu/Fi/FLv kRgMUKitw+0psm295DZ2YDlAUrw7FtRwT1YmsjxJA+jwPueE9S/4dU45mBv9JODJfRJw GfqA== X-Gm-Message-State: AKwxytdQlYVLVSG7eWFCpltKrvLUUCFR45TmtqnRJlwMeyDM2cR8rOxU yI3Sjsx00etmRU5qlhGPIXogOQ== X-Google-Smtp-Source: AH8x225YdB2oz03SbqBr2Hb3d1WdAT0r9CfD1Pp3y6VCXaBNJ51x409kuBYoqPB1ozPkLoFgXkC2Ug== X-Received: by 10.223.165.30 with SMTP id i30mr12996484wrb.84.1516974325821; Fri, 26 Jan 2018 05:45:25 -0800 (PST) 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 a12sm1406365wri.54.2018.01.26.05.45.24 (version=TLS1 cipher=AES128-SHA bits=128/128); Fri, 26 Jan 2018 05:45:25 -0800 (PST) Date: Fri, 26 Jan 2018 13:45:24 +0000 From: Chris Wilson X-Priority: 3 (Normal) Message-ID: <1371247928.20180126134524@gmail.com> To: rsgb_lf_group@blacksheep.org CC: dead.fets@gmail.com MIME-Version: 1.0 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 the administrator of that system for details. Content preview: Hello LF and VLF folk! I have built a couple of Softrock Lite II IF frequency receivers, normally they would be used to view another receiver's IF on a bandscope, but popularly they are also used on low and medium frequencies as stand alone SDR receivers. The MF one works fine. Th LF one was intermittent, then failed with high current draw. I isolated it to a faulty or shorted divider chip. The original one was marked 78C49NM. I couldn't find one of those, so plumped for one from RS Components here in the UK, a CD74AC74M96G4, RS part number 662-6939 The oscillator worked on the bench and from an xtal frequency of 461.5 kHz gave the expected divide by 4 output of 115.364 or very close. Then suddenly it started receiving broadcast stations and the divided outputs Q and /Q were on 153.814 KHz! There they remain. Fiddling I briefly saw a return to 115.36 Khz, but it was not for long. All voltages to it's pins are correct at 5V. I am not sure if it's a faulty divider, or a bad connection or short. [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (dead.fets[at]gmail.com) 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 195b836cb7437e99aa05107459888659 Subject: LF: Softrock RX divider IC problem, unexpected frequency out Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit 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=PRIORITY_NO_NAME 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 Hello LF and VLF folk! I have built a couple of Softrock Lite II IF frequency receivers, normally they would be used to view another receiver's IF on a bandscope, but popularly they are also used on low and medium frequencies as stand alone SDR receivers. The MF one works fine. Th LF one was intermittent, then failed with high current draw. I isolated it to a faulty or shorted divider chip. The original one was marked 78C49NM. I couldn't find one of those, so plumped for one from RS Components here in the UK, a CD74AC74M96G4, RS part number 662-6939 The oscillator worked on the bench and from an xtal frequency of 461.5 kHz gave the expected divide by 4 output of 115.364 or very close. Then suddenly it started receiving broadcast stations and the divided outputs Q and /Q were on 153.814 KHz! There they remain. Fiddling I briefly saw a return to 115.36 Khz, but it was not for long. All voltages to it's pins are correct at 5V. I am not sure if it's a faulty divider, or a bad connection or short. Xtal case is grounded and seems stable. R16 in the oscillator changed on advice from 22.1k to 10k as they apparently tend to stop running with 21.1k there. I attach the schematic. Wrong IC? Details of the divider's operation are at http://www.wb5rvz.org/softrock_lite_ii/03_div The new IC details are at https://uk.rs-online.com/web/p/flip-flop-ics/6626939/ I see these frequencies on these pins: Pin 3 : 464.444 kHz Pin 11 : 464.444 Pin 12 : 153.814 Pin 8 : 153.814 Pin 2 : 307.625 Pin 2 : 307.625 Is this a random IC fault or does it have some mathematical correlation? My maths is pitiful! Not sure what to do now, I have another IC but before risking pad damage thought it prudent to ask, many thanks. Pins 14 and 2 on the mixer IC show good, 90 degree out of phase square waveforms of normal amplitude on a scope, but at 153.814 KHz.... Schematic is at http://www.gatesgarth.com/schematic.jpg -- Best regards, Chris mailto:dead.fets@gmail.com