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[195.171.43.25]) by mx.google.com with ESMTP id k8si11364739wje.69.2013.12.27.00.09.12 for ; Fri, 27 Dec 2013 00:09:12 -0800 (PST) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org; dkim=pass (test mode) header.i=@comcast.net Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1VwS4k-0004eb-51 for rs_out_1@blacksheep.org; Fri, 27 Dec 2013 07:43:18 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1VwS4i-0004eQ-W1 for rsgb_lf_group@blacksheep.org; Fri, 27 Dec 2013 07:43:16 +0000 Received: from qmta03.westchester.pa.mail.comcast.net ([76.96.62.32]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1VwS4f-00013O-SY for rsgb_lf_group@blacksheep.org; Fri, 27 Dec 2013 07:43:15 +0000 Received: from omta16.westchester.pa.mail.comcast.net ([76.96.62.88]) by qmta03.westchester.pa.mail.comcast.net with comcast id 6XjB1n0021uE5Es53XjBMw; Fri, 27 Dec 2013 07:43:11 +0000 Received: from Owner ([166.137.182.216]) by omta16.westchester.pa.mail.comcast.net with comcast id 6Xip1n00Q4gYbxS3cXiwLx; Fri, 27 Dec 2013 07:43:06 +0000 From: "hvanesce" To: References: <2f507c1ff91346b2b8adba0518611224@kabelmail.de> <39966C71EF4543899F81399598C190F7@Extensa> <52BBFDC4.3010507@psk31.plus.com>,<52BC272F.7040803@iup.uni-heidelberg.de> <52BC683B.5030107@iup.uni-heidelberg.de> In-Reply-To: <52BC683B.5030107@iup.uni-heidelberg.de> Date: Fri, 27 Dec 2013 00:42:46 -0700 Message-ID: <032001cf02d7$462ca970$d285fc50$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQF4gPz2ZsKVrt05Wvg22cCZ2bAEHQIVWltfAe40wD4CAiw8mQCLmYQeAIqD1Xqa28YjAA== Content-Language: en-us DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20121106; t=1388130191; bh=AL/Wu10l2qROYvVZV5zoqUByI74feReyu+IUfQzTUo8=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=fNYkcQEee6jz6B+ea/zvVo3HkGW2AAzJcAdvUGqr4CKDAtXayq7llg8O5tdRZ+FX1 XEF3eDKykXgUXaSeLyAH8wsfLQvbDNhyWTrOjcneDUvYjhcqfKH9LpNbZWRHp1NRUV BUidrakeZk9YNOjmO0m7y5Kd/cGqCAcqFdOMK5bYbLm1MezVii2SsTYq+0KpjWFU9K 67J1e5N/JdFqyiuTJE8DXq1WdLK1aJx9qGyCY7mho/LcTqs5u0XDpG6gGrbPaZqmyJ xY4+WT9bBNRamvdORGoUvNYyBdYbCuR5qqCQd9uXkYivEaRTlRRx3vZx7tqT9/4uej dhKpJOAZtr4gA== X-Spam-Score: 1.1 (+) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Stefan, If arc-induced breakdown paths between turns is an issue, have you considered adding a homebrew corona inception detector with feedback to the modulator or switch driver? I haven’t made one for a VLF coil, but it might be worth a try if repairs are an issue; there is good precedent at near-VLF frequencies. [...] Content analysis details: (1.1 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [76.96.62.32 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hvanesce[at]comcast.net) 1.6 SUBJ_ALL_CAPS Subject is all capitals -0.0 SPF_PASS SPF: sender matches SPF record -0.6 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 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: b28d3e72b5adfaf9991664afe0a993a6 Subject: RE: VLF: 8969.99 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0321_01CF029C.99CE6DB0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.0 required=5.0 tests=HTML_40_50,HTML_MESSAGE, SUBJ_ALL_CAPS 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 Status: O X-Status: X-Keywords: X-UID: 1776 This is a multipart message in MIME format. ------=_NextPart_000_0321_01CF029C.99CE6DB0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Stefan, =20 If arc-induced breakdown paths between turns is an issue, have you considered adding a homebrew corona inception detector with feedback to = the modulator or switch driver? I haven=92t made one for a VLF coil, but it = might be worth a try if repairs are an issue; there is good precedent at = near-VLF frequencies.=20 =20 The idea would be to limit voltage or skip cycles before breakdown = occurs; the voltage-limiting method could often be nearly transparent to = real-time operation. =20 If repairs are rare then the above might not be worth it, just thought = I=92d mention the possibility. =20 73, Jim AA5BW =20 =20 From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Stefan = Sch=E4fer Sent: Thursday, December 26, 2013 10:33 AM To: rsgb_lf_group@blacksheep.org Subject: Re: VLF: 8969.99 =20 Hi Bob,=20 Of course, if the coil is protected against rain, then it is no problem. = But the coil is quite large and due to the high voltage, the housing should ideally have a distance of 30cm or more to the coil. So the housing must = be quite large, even more. And that makes it dangerous because of wind = blasts on the to of the building in 35m AGL...=20 Anyway it would be nice and i also thought about using a simple foil = across the coil, without additional distance.=20 However on LF, there are partial discharges on the top of the coil which burns holes into the protecting foil. And the VLF winding is 2000m long. = It is a lot of effort to repair it after a short cut between some turns due = to arcing. So it is a high risk.=20 I think i will make a test in the near future and see if 9 kHz partial discharges are as agressive as 137 kHz partial discharges :-) 73, Stefan/DK7FC Am 26.12.2013 16:32, schrieb Bob Raide:=20 Stefan; Even if you have your coils in weather proof housing rain is no good to transmit on 9 kHz? Bob =20 _____ =20 Date: Thu, 26 Dec 2013 13:55:11 +0100 From: Stefan.Schaefer@iup.uni-heidelberg.de To: rsgb_lf_group@blacksheep.org Subject: Re: VLF: 8969.99 Hi Uwe, Tom, VLF, Best signal ever from Tom, capture attached. Is it due to the = propagation or did it improve your signal? What about some tests in OPDS32 or maybe JT9-30? Unfortunately there is permanent rain here so i have to wait some days longer. 73, Stefan/DK7FC ------=_NextPart_000_0321_01CF029C.99CE6DB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Stefan,

 

If arc-induced breakdown paths between turns is an issue, have you = considered adding a homebrew corona inception detector with feedback to = the modulator or switch driver? I haven’t made one for a VLF coil, = but it might be worth a try if repairs are an issue; there is good = precedent at near-VLF frequencies.

 

The idea would be to limit voltage or skip cycles before breakdown = occurs; the voltage-limiting method could often be nearly transparent to = real-time operation.

 

If repairs are rare then the above might not be worth it, just = thought I’d mention the possibility.

 

73, Jim AA5BW =A0

 

From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Stefan = Sch=E4fer
Sent: Thursday, December 26, 2013 10:33 = AM
To: rsgb_lf_group@blacksheep.org
Subject: Re: = VLF: 8969.99

 

Hi Bob, =

Of course, if the coil is protected against rain, then it is no = problem. But the coil is quite large and due to the high voltage, the = housing should ideally have a distance of 30cm or more to the coil. So = the housing must be quite large, even more. And that makes it dangerous = because of wind blasts on the to of the building in 35m AGL... =
Anyway it would be nice and i also thought about using a simple foil = across the coil, without additional distance.
However on LF, there = are partial discharges on the top of the coil which burns holes into the = protecting foil. And the VLF winding is 2000m long. It is a lot of = effort to repair it after a short cut between some turns due to arcing. = So it is a high risk.
I think i will make a test in the near future = and see if 9 kHz partial discharges are as agressive as 137 kHz partial = discharges :-)
73, Stefan/DK7FC

Am 26.12.2013 16:32, schrieb = Bob Raide:

Stefan;
Even if = you have your coils in weather proof housing rain is no good to transmit = on 9 kHz? Bob
 

Date: Thu, = 26 Dec 2013 13:55:11 +0100
From: Stefan.Schaefer@iup= .uni-heidelberg.de
To: rsgb_lf_group@blacksheep.org=
Subject: Re: VLF: 8969.99

Hi Uwe, Tom, VLF,

Best = signal ever from Tom, capture attached. Is it due to the propagation or = did it improve your signal?
What about some tests in OPDS32 or maybe = JT9-30? Unfortunately there is permanent rain here so i have to wait = some days longer.

73, = Stefan/DK7FC

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