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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: Thanks Warren - interesting stuff ! Certainly the ground beneath the loop is probably a couple of Kv pd above the conductor at my Kw level - I can create colorful violet coronas :-) - and the capacitive affects of raising the or lowering the horizontal section of the loop just a few feet make a lot of change to the tuning - Ive followed a suggestion to "relieve" earth losses/add a little more tuning stability by shoving a Earth mat under the loop here - at the moment it is untuned but installing it did cause an increase in loop current by a couple of percent - I saw a paper tuning this earth and it is was said to improve the stability and increase the effective power in this NVIS set up at 137. Im using the underslung pulley system on mine at the moment which has survived one Alaskan winter :-) Rough diagram attached - there are two parallel conductors in this loop but a single black line is shown for clarity - adding a second conductor didnt change the efficiency much on 505kHz where its nearly resonant, but helped on 137 http://kl7uk.com/loopy.jpg CheersLaurence KL 1X WE2 XPQAlaska Date: Fri, 26 Apr 2013 17:47:51 -0400 From: Re: LF: Fire in the wire [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [65.55.116.22 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hellozerohellozero[at]hotmail.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.0 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: f9bb43a66658129469273581af35b296 Content-Type: multipart/alternative; boundary="_272e92e2-d683-4dac-8126-91e13d51c8db_" Subject: LF: Was Fire in the wire X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=FORGED_HOTMAIL_RCVD,HTML_20_30, HTML_MESSAGE,TO_ADDRESS_EQ_REAL 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-DMARC: mtain-mp04.r1000.mx.aol.com ; domain : hotmail.com ; policy : none ; result : F x-aol-sid: 3039ac1dc148517b09886460 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --_272e92e2-d683-4dac-8126-91e13d51c8db_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Thanks Warren - interesting stuff ! Certainly the ground beneath the loop i= s probably a couple of Kv pd above the conductor at my Kw level - I can cre= ate colorful violet coronas :-) - and the capacitive affects of raising the= or lowering the horizontal section of the loop just a few feet make a lot = of change to the tuning - Ive followed a suggestion to "relieve" earth los= ses/add a little more tuning stability by shoving a Earth mat under the loo= p here - at the moment it is untuned but installing it did cause an increas= e in loop current by a couple of percent - I saw a paper tuning this earth = and it is was said to improve the stability and increase the effective powe= r in this NVIS set up at 137. Im using the underslung pulley system on mine= at the moment which has survived one Alaskan winter :-) Rough diagram att= ached - there are two parallel conductors in this loop but a single black l= ine is shown for clarity - adding a second conductor didnt change the effic= iency much on 505kHz where its nearly resonant=2C but helped on 137 http:/= /kl7uk.com/loopy.jpg CheersLaurence KL 1X WE2 XPQAlaska Date: Fri=2C 26 Apr 2013 17:47:51 -0400 From: wd2xgj@gmail.com To: rsgb_lf_group@blacksheep.org Subject: Re: LF: Fire in the wire Hi Stefan=2C There are thousands or perhaps tens of thousands of volts from the l= oop to ground.If I grounded the loop with and there was a large potential d= ifference=2C wouldn't that cause a large current to flow to ground and effe= ctively shunt my signal to ground?=0A= 73 Warren On Fri=2C Apr 26=2C 2013 at 1:44 PM=2C Stefan Sch=E4fer wrote: =0A= Warren=2C =0A= =0A= What is the voltage between the tree (GND) and loop? I thought that the vol= tages are rather small=2C i.e. below 100V=2C especially when a large loop i= s used. Isn't it possible to ground the loop? =0A= =0A= 73=2C Stefan =0A= =0A= Am 26.04.2013 19:21=2C schrieb Warren Ziegler: =0A= =0A= =0A= Just a quick report on a failure mode for LF TX antennas. =0A= Last Fall my original TX loop made up of approximately 500 feet of RG-11 co= ax suspended from trees went open circuit (both center conductor and shield= )=2C some time later part of the wire actually came down. I had thought tha= t abrasion from contact with the trees had eventually worn through it. =0A= =0A= =0A= What I found was a little more interesting. Looking at the downed end=2C it= appeared that the insulation had melted for a considerable distance and th= ere were burn marks further up the cable. My hypothesis is that the outer i= nsulation was abraded away and the coax shield came into contact with the t= ree limb causing the burning/melting. =0A= =0A= Will try to get some pictures this weekend and put them up on my website. =0A= =0A= 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! =0A= =0A= --=20 =0A= 73 Warren K2ORS =0A= WD2XGJ =0A= WD2XSH/23 =0A= WE2XEB/2 =0A= WE2XGR/1 =0A= =0A= =0A= =0A= --=20 73 Warren K2ORS WD2XGJ=20 WD2XSH/23 WE2XEB/2 WE2XGR/1 =0A= = --_272e92e2-d683-4dac-8126-91e13d51c8db_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Thanks Warren - interesting stuf= f !
 =3B
Certainly the ground beneath the loop is probably a coup= le of Kv pd above the conductor at my Kw level =3B- =3BI can create= colorful violet coronas :-) - and the capacitive affects of raising the or= lowering the horizontal section of the loop just a few =3Bfeet =3B= make a lot of change to the tuning -
 =3B
Ive followed a suggest= ion to "relieve" earth losses/add a little more tuning stability by =3B= shoving a =3BEarth =3Bmat under the loop here - at the moment it is= untuned but =3Binstalling it did cause =3Ban increase in loop curr= ent by a couple of percent =3B- I saw a paper tuning this earth =3B= and it =3Bis was said to improve the stability and increase the effecti= ve power in this NVIS set up at 137.
 =3B
Im using the underslung= pulley system on mine at the moment which has survived one =3BAlaskan = winter :-) =3B Rough diagram attached - there are two parallel conducto= rs in this loop but a single black line is shown for clarity - adding a sec= ond conductor didnt change the efficiency much on 505kHz where its nearly r= esonant=2C but helped =3B on 137
 =3B
http://kl7uk.com/loopy.jpg
 =3B
Cheers
Lau= rence KL 1X =3B WE2 XPQ
Alaska

 =3B
Date: Fri=2C 26 Apr 2013 1= 7:47:51 -0400
From: wd2xgj@gmail.com
To: rsgb_lf_group@blacksheep.org=
Subject: Re: LF: Fire in the wire

Hi Stefan=2C<= div>
 =3B  =3B  =3B  =3BThere are thousands o= r perhaps tens of thousands of volts from the loop to ground.
If = I grounded the loop with and there was a large potential difference=2C woul= dn't that cause a large current to flow to ground and effectively shunt my = signal to ground?
=0A=

73 Warren



On Fri=2C Apr 26=2C 2013 a= t 1:44 PM=2C Stefan Sch=E4fer <=3BStefan.Schaefer@iup.u= ni-heidelberg.de>=3B wrote:
=0A=
Warren=2C
=0A=
=0A= What is the voltage between the tree (GND) and loop? I thought that the vol= tages are rather small=2C i.e. below 100V=2C especially when a large loop i= s used. Isn't it possible to ground the loop?
=0A=
=0A= 73=2C Stefan
=0A=
=0A= Am 26.04.2013 19:21=2C schrieb Warren Ziegler:

=0A=
=0A=
=0A= Just a quick report on a failure mode for LF TX antennas.
=0A= Last Fall my original TX loop made up of approximately 500 feet of RG-11 co= ax suspended from trees went open circuit (both center conductor and shield= )=2C some time later part of the wire actually came down. I had thought tha= t abrasion from contact with the trees had eventually worn through it.
= =0A= =0A=
=0A= What I found was a little more interesting. Looking at the downed end=2C it= appeared that the insulation had melted for a considerable distance and th= ere were burn marks further up the cable. My hypothesis is that the outer i= nsulation was abraded away and the coax shield came into contact with the t= ree limb causing the burning/melting.
=0A= =0A= Will try to get some pictures this weekend and put them up on my website.=0A=
=0A= 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!
= =0A=
=0A= --
=0A= 73 Warren K2ORS
=0A=  =3B  =3B  =3B  =3B  =3B  =3B  =3B  =3B WD2= XGJ
=0A=  =3B  =3B  =3B  =3B  =3B  =3B  =3B  =3B WD2= XSH/23
=0A=  =3B  =3B  =3B  =3B  =3B  =3B  =3B  =3B WE2= XEB/2
=0A=  =3B  =3B  =3B  =3B  =3B  =3B  =3B  =3B WE2= XGR/1
=0A=
=0A=
=0A=
=0A=



--
= 73 Warren K2ORS
 =3B  =3B  =3B  =3B  =3B  =3B &n= bsp=3B  =3B WD2XGJ
 =3B  =3B  =3B  =3B  =3B &nb= sp=3B  =3B  =3B WD2XSH/23
 =3B  =3B  =3B  =3B &n= bsp=3B  =3B  =3B  =3B WE2XEB/2
 =3B  =3B  =3B &n= bsp=3B  =3B  =3B  =3B  =3B WE2XGR/1

 =3B=0A=
= --_272e92e2-d683-4dac-8126-91e13d51c8db_--