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 w7NKcCxf013528 for ; Thu, 23 Aug 2018 22:38:15 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1fswIv-0007gA-Lp for rs_out_1@blacksheep.org; Thu, 23 Aug 2018 21:34:05 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1fswIv-0007g1-9M for rsgb_lf_group@blacksheep.org; Thu, 23 Aug 2018 21:34:05 +0100 Received: from mout01.posteo.de ([185.67.36.65]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91_59-0488984) (envelope-from ) id 1fswIt-0005aH-38 for rsgb_lf_group@blacksheep.org; Thu, 23 Aug 2018 21:34:04 +0100 Received: from submission (posteo.de [89.146.220.130]) by mout01.posteo.de (Postfix) with ESMTPS id 53C0B20DF7 for ; Thu, 23 Aug 2018 22:34:02 +0200 (CEST) X-DKIM-Result: Domain=posteo.de Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1535056442; bh=PhJyAtLYB5D7NHJv+MEzi/dDjtHpQLqyzwCdC/0W6Os=; h=Date:From:To:Subject:From; b=YaTHzOhj999hl6zVlSnhhnfT1lNw90B6vJPZbn1nWxtJfwwCydZW0Sdcqj6Fggp7r MkQ80y9yfiTNz9EcWuQoHBmK3dYFBG8zyGhOYIM2jzy5QqVMvZjP/+kWPJPGF4oqUU BXbBL/Hj3x0Aq5cJMdL71eZlNuox52jTMyhOfY6bviHn5A9RAw/hWP7gv94yM8knoV Z4NDdq7enkqs1nrYhrkcitvlh87BE0kYjYsucbFcENXTkr676Noyj5oNGByBKzokiI Hm0tX41Z4n/or7tZtfP/fpG1yVm7FgOQMbJBalKxZtVE9WoP/ox8ce5iYmZz6F1p3h 5ld2zCBocFdkQ== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 41xGN96rMJz6tmB for ; Thu, 23 Aug 2018 22:34:01 +0200 (CEST) Message-ID: <5B7F1A39.8030107@posteo.de> Date: Thu, 23 Aug 2018 22:34:01 +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: <1613303827.20180823120801@gmail.com> <88af04ed-ef1c-03e3-464f-fc5e4155d0eb@n1bug.com> <539641811.20180823210420@gmail.com> In-Reply-To: <539641811.20180823210420@gmail.com> X-Spam-Score: -2.3 (--) 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: Am 23.08.2018 22:04, schrieb Chris Wilson: > Hi Chris, > > I added a 470pF cheap disc ceramic across each > of the 2000pF polystyrene caps, and indeed the filter moved lower, to > pretty much the optimum spot (thank you Stefan). But I see a lot more > attenuation with these two caps added. I presume disc ceramics are not > ideal? The Q of them should not be critical but things like temperature coefficients... I prefer to use styroflex caps for such RX filters but others can be fine too. Two caps? There should be 3 in that circuit. If you just tune two of the circuits to 137 kHz then the filter curve will be wider and have more attenuation. Actually there could be two resonance peaks close together, which you may not see due to the low Q. Just try to add a 3rd C. I would expect this improves things. It is good to play arround anyway, then you learn intuitively what causes what result. [...] Content analysis details: (-2.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [185.67.36.65 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid X-Scan-Signature: 5c335215f1b3de26d890ee84d49616ce Subject: Re: LF: Anyone good with Elsie? Content-Type: text/plain; charset=ISO-8859-1; format=flowed 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=0.0 required=5.0 tests=none 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 Am 23.08.2018 22:04, schrieb Chris Wilson: > Hi Chris, > > I added a 470pF cheap disc ceramic across each > of the 2000pF polystyrene caps, and indeed the filter moved lower, to > pretty much the optimum spot (thank you Stefan). But I see a lot more > attenuation with these two caps added. I presume disc ceramics are not > ideal? The Q of them should not be critical but things like temperature coefficients... I prefer to use styroflex caps for such RX filters but others can be fine too. Two caps? There should be 3 in that circuit. If you just tune two of the circuits to 137 kHz then the filter curve will be wider and have more attenuation. Actually there could be two resonance peaks close together, which you may not see due to the low Q. Just try to add a 3rd C. I would expect this improves things. It is good to play arround anyway, then you learn intuitively what causes what result. > The inductors are cheapo pre made ones (look like 1/4 W > resistors), again off Ebay so probably far from optimal. I may need to > look at raising the Q of this thing! Are there high Q commercially > made inductors in 680 and 2.2 uH or do I need to wind my own? Wind your own! I built those: http://www.iup.uni-heidelberg.de/schaefer_vlf/LF/LF_RX_pot%20_cores.jpg > How sub > optimal is using disc ceramics for parallelling the branded poly caps? > Quite, but still good for a first test. 73, Stefan