Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-ma01.r1000.mx.aol.com (Internet Inbound) with ESMTP id B6F4F380000F1; Fri, 26 Apr 2013 19:30:26 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UVs4v-0003rH-0G for rs_out_1@blacksheep.org; Sat, 27 Apr 2013 00:29:21 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UVs4u-0003r8-ET for rsgb_lf_group@blacksheep.org; Sat, 27 Apr 2013 00:29:20 +0100 Received: from mail-ob0-f182.google.com ([209.85.214.182]) by relay1.thorcom.net with esmtps (TLSv1:RC4-SHA:128) (Exim 4.77) (envelope-from ) id 1UVs4p-0006w7-Hw for rsgb_lf_group@blacksheep.org; Sat, 27 Apr 2013 00:29:19 +0100 Received: by mail-ob0-f182.google.com with SMTP id dn14so3958895obc.41 for ; Fri, 26 Apr 2013 16:28:52 -0700 (PDT) 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=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:content-type; bh=heTElrgRVQFT1FoQCofddt+E+7muQ8HncAMaPNTdMHA=; b=OwPvKBp2P4CDAc9efsj+Rt6xsoggok7q9xkChvR5lqYhhDC6RPaWJUKsgbIyv4O2Kl wScPRyi/yKLupx/qIzOdgJutuT5aRrQMcJGdbsUAsfIHJcuprdDFPdILccad1tMAL4BY cA6jj64MgSJg5+N0IUSoZqPdwMRzyvq6Jr7lfyzKeU/BshCO6hzUrS4r46hJlUOaw1WI 3UUJtb7Gf8U4QonTKXxgLul5j6A/MetwKotmRJPj/C9R9WaJJ4fxVlY6ptEKMxBzTDN4 Dd0aAtSOOyjisq5flwy4QxQVAOPE7YPwYQuVKpR67CxYN+VTKERwvbxliu5ij1qz8G0h Y0qw== MIME-Version: 1.0 X-Received: by 10.60.62.70 with SMTP id w6mr25493417oer.38.1367018931569; Fri, 26 Apr 2013 16:28:51 -0700 (PDT) Received: by 10.60.135.199 with HTTP; Fri, 26 Apr 2013 16:28:51 -0700 (PDT) In-Reply-To: <20130426.161506.1606.39499@mailpop02.vgs.untd.com> References: <20130426.161506.1606.39499@mailpop02.vgs.untd.com> Date: Fri, 26 Apr 2013 19:28:51 -0400 Message-ID: From: Warren Ziegler To: rsgb_lf_group X-Spam-Score: -0.7 (/) 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: Hi Bob, Yes but Bill always worked at the 1W level. I forget the exact numbers but the loop has an inductive reactance of 100-200 ohms, when you multiply that by a loop current of 50A you can get 10kV. [...] Content analysis details: (-0.7 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [209.85.214.182 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (wd2xgj[at]gmail.com) -0.0 SPF_PASS SPF: sender matches SPF record 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: 3df6620ae1cf83b986cf2fc02407da16 Subject: Re: LF: Fire in the wire Content-Type: multipart/alternative; boundary=089e01294f30d14e6704db4be5ab 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=HTML_MESSAGE 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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-ma01.r1000.mx.aol.com ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d6009517b0e112a36 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --089e01294f30d14e6704db4be5ab Content-Type: text/plain; charset=ISO-8859-1 Hi Bob, Yes but Bill always worked at the 1W level. I forget the exact numbers but the loop has an inductive reactance of 100-200 ohms, when you multiply that by a loop current of 50A you can get 10kV. BTW, my RG-11 loop was put up by Bill and I in 2005 - no complaints! 73 Warren On Fri, Apr 26, 2013 at 7:14 PM, wrote: > Thought the loop info Bill Ashloch developed pointed to high currents in > the loop > so a large conductor needed ,, but low voltage and I remember ( ? ) his > idea of pushing > soft plumbing copper through trees and just supporting the CU on the > branches > hi voltage on verticals .low current > hi current on loops low voltage > > Bob K3DJC > > > > On Fri, 26 Apr 2013 19:44:01 +0200 =?ISO-8859-1?Q?Stefan_Sch=E4fer?= > writes: > > Warren, > > > > What is the voltage between the tree (GND) and loop? I thought that > > the > > voltages are rather small, i.e. below 100V, especially when a large > > loop > > is used. Isn't it possible to ground the loop? > > > > 73, Stefan > > > > Am 26.04.2013 19:21, schrieb Warren Ziegler: > > > > > > Just a quick report on a failure mode for LF TX antennas. > > > Last Fall my original TX loop made up of approximately 500 feet of > > > > > RG-11 coax suspended from trees went open circuit (both center > > > conductor and shield), some time later part of the wire actually > > came > > > down. I had thought that abrasion from contact with the trees had > > > > > eventually worn through it. > > > > > > What I found was a little more interesting. Looking at the downed > > end, > > > it appeared that the insulation had melted for a considerable > > distance > > > and there were burn marks further up the cable. My hypothesis is > > that > > > the outer insulation was abraded away and the coax shield came > > into > > > contact with the tree limb causing the burning/melting. > > > Will try to get some pictures this weekend and put them up on my > > website. > > > > > > Long term if one wants to operate at the kW level either better > > > insulation or a better way of supporting the antenna than trees > > would > > > be required! > > > > > > -- > > > 73 Warren K2ORS > > > WD2XGJ > > > WD2XSH/23 > > > WE2XEB/2 > > > WE2XGR/1 > > > > > > > > > -- 73 Warren K2ORS WD2XGJ WD2XSH/23 WE2XEB/2 WE2XGR/1 --089e01294f30d14e6704db4be5ab Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Hi Bob,
=A0 =A0 Yes but Bill always worked at th= e 1W level.=A0
I forget the exact numbers but the loop has = an inductive reactance of 100-200 ohms, when you multiply that by a loop cu= rrent of 50A you can get 10kV.

BTW, my RG-11 loop was put up by Bill and I= in 2005 - no complaints!

73 Warren



On Fri, Apr 26, 2013 at 7:14 PM, <riese-k3djc@juno.com> = wrote:
Thought the loop info Bill Ashloch developed pointed to high currents in the loop
so a large conductor needed ,, but low voltage and I remember ( ? ) his
idea of pushing
soft plumbing copper through trees and just supporting the CU on the
branches
hi voltage on verticals .low current
hi current on loops low voltage

Bob K3DJC



On Fri, 26 Apr 2013 19:44:01 +0200 =3D?ISO-8859-1?Q?Stefan_Sch=3DE4fer?=3D<= br> <Stefan.Schaefe= r@iup.uni-heidelberg.de> writes:
> Warren,
>
> What is the voltage between the tree (GND) and loop? I thought that > the
> voltages are rather small, i.e. below 100V, especially when a large > loop
> is used. Isn't it possible to ground the loop?
>
> 73, Stefan
>
> Am 26.04.2013 1= 9:21, schrieb Warren Ziegler:
> >
> > Just a quick report on a failure mode for LF TX antennas.
> > Last Fall my original TX loop made up of approximately 500 feet o= f
>
> > RG-11 coax suspended from trees went open circuit (both center > > conductor and shield), some time later part of the wire actually<= br> > came
> > down. I had thought that abrasion from contact with the trees had=
>
> > eventually worn through it.
> >
> > What I found was a little more interesting. Looking at the downed=
> end,
> > it appeared that the insulation had melted for a considerable
> distance
> > and there were burn marks further up the cable. My hypothesis is<= br> > that
> > the outer insulation was abraded away and the coax shield came > into
> > contact with the tree limb causing the burning/melting.
> > Will try to get some pictures this weekend and put them up on my<= br> > website.
> >
> > Long term if one wants to operate at the kW level either better > > insulation or a better way of supporting the antenna than trees > would
> > be required!
> >
> > --
> > 73 Warren K2ORS
> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XSH/23
> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2
> > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1
> >
>
>




--
= 73 Warren K2ORS
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WD2XGJ
=A0 =A0 =A0 = =A0 =A0 =A0 =A0 =A0 WD2XSH/23
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XEB/2=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 WE2XGR/1

=A0
--089e01294f30d14e6704db4be5ab--