Return-Path: Received: from mtain-di06.r1000.mx.aol.com (mtain-di06.r1000.mx.aol.com [172.29.64.10]) by air-db03.mail.aol.com (v127_r1.1) with ESMTP id MAILINDB034-86974b97da9e33; Wed, 10 Mar 2010 12:45:03 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-di06.r1000.mx.aol.com (Internet Inbound) with ESMTP id B9B8738000103; Wed, 10 Mar 2010 12:45:00 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NpPx0-0002xl-Q0 for rs_out_1@blacksheep.org; Wed, 10 Mar 2010 17:44:06 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NpPx0-0002xc-7B for rsgb_lf_group@blacksheep.org; Wed, 10 Mar 2010 17:44:06 +0000 Received: from mail-bw0-f215.google.com ([209.85.218.215]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NpPwx-0005ag-Em for rsgb_lf_group@blacksheep.org; Wed, 10 Mar 2010 17:44:06 +0000 Received: by bwz7 with SMTP id 7so6899523bwz.4 for ; Wed, 10 Mar 2010 09:43:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=iOQ8fJ5Qe3noV7eDHAIgvVscIhN4rEdTh1utEfz6dCo=; b=BoY1umxFs1KuRDkDLOvDihT4VEGvN5GuQ4lp64sMcENYIyBQSxrGOONHIESMRWY6kU n5973ySZ+8ajxoK0fqg44+35Hmr6Hf1nYkQG6a/BK1c5dggIOsZsQbKS7Fs/fgJFwgyb A+3MPw8ne1WZ4aLKQq/lm5PBzbGeHby30CYgM= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=Q6rmVKEu3wYoguS+a65z2Y8elZU6VwA36jn3Fhun7+Tehpjd0ZOHfylm/trcO5IiYN T6sJ1iyOQ7vZuSpGgYDPKj8MChNf2toU1APXtmcSJTXrl0LRZ4cQ2tAVrN0jOI+HnzwC BpFlHBlIABwYGuo4IlRYCk2rR9s0+w+u62IKY= MIME-Version: 1.0 Received: by 10.204.9.6 with SMTP id j6mr2148666bkj.37.1268243037050; Wed, 10 Mar 2010 09:43:57 -0800 (PST) In-Reply-To: <43850.17054.qm@web86702.mail.ird.yahoo.com> References: <4B978B2E.70404@iup.uni-heidelberg.de> <43850.17054.qm@web86702.mail.ird.yahoo.com> Date: Wed, 10 Mar 2010 17:43:56 +0000 Message-ID: From: Andy Talbot To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.9 (/) X-Spam-Report: autolearn=disabled,HTML_10_20=0.945,HTML_MESSAGE=0.001 Subject: Re: LF: KITE ANT Content-Type: multipart/alternative; boundary=0015175884aeb65742048175d734 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: mail_rly_antispam_dkim-d248.1 ; domain : googlemail.com DKIM : pass x-aol-sid: 3039ac1d400a4b97da9c154a X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015175884aeb65742048175d734 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 73kHz I originally used nylon strimmer cord as the antenna insulator. Worked fine until one day I was testing using PSK (100% duty cycle, long transmission) with G4GVC and it was raining. The antenna fell down and I found the nylon had melted due to HV tracking. Replaced with a ceramic dog-bone and its been up ever since. The voltage then was around the 15= - 20kV from 200 Watts of RF Andy www.g4jnt.com On 10 March 2010 16:56, Dave Pick wrote: > Stefan > > Just one warning, I have used kite-supported aerials on 136 many times= and > you have to be careful what insulating material you have between the kit= e > and the top of the wire. One day the kite was flying well but there was= a > little rain, I transmitted and the wire fell out of the sky and the kite > fluttered down (fortunately I could find it!). When I looked to see what= had > happened the thin rope holding the wire to the kite had burned through > because the rain had made it conductive. I think monofilament fishing li= ne > may be better... > > Dave G3YXM > > > > ----- Original Message ---- > From: Stefan Sch=E4fer > To: rsgb_lf_group@blacksheep.org > Sent: Wednesday, 10 March, 2010 12:06:06 > Subject: Re: LF: KITE ANT > > ...In Germany you can use a maximum braid length of 100m without a speci= al > licence. If 200m would be allowed, my vertical would be a 200m ;-) > But with a special permission you can relatively easy go up to 300m! I > still try to get that permission for the next weeks. Then, the VLF signa= l > would even be more than 10dB stronger, what would give the chance for th= e UK > to get the VLF signal, i hope so... > > Static HV dangers are well known to all of us i assume. But the upper kV > range is nothing mystic. 10kV is just a factor 10 of 1kV, just like 10V= is a > factor 10 of 1V. You can die if you touch a 10kV power line or if you to= uch > a 100kV power line. So there is just that rule: Do not touch when under > voltage and assure that there can be no voltage when you think that ther= e is > no voltage (measuring, earthing during operating). I've worked almost 6 > years in the HV group of the institute of electrical energy systems ( > http://www.hst.tu-darmstadt.de/index.php?id=3D10&L=3D1) and had almost= each > week to work with voltages well above 20kV (up to 3MV, 1,2/50=B5s), so= i think > i have the necessary respect without beeing afraid or careless. On my hi= ll > there are no schools, no roads and no neighbours but i will keep in mind > what you caution on! :-) > > 73, Stefan/DK7FC > > > Am 10.03.2010 09:16, schrieb Jean-Louis.RAULT@fr.thalesgroup.com: > > Hi all > > > > May I ask you to pay some attention on the three following issues rela= ted > to balloon/kite aerials ? > > > > - using "high" altitude kites or balloons is often subject to a formal > authorization (at least in France, and specially if you expect to use th= e > aerial close to an airfield) > > > > - even when weather is very good, very high DC voltages (many kV) can > appear (from natural local electric field) on the antenna wire. DC groun= ding > of the wire is therefore mandatory > > > > - avoid any AC HV lines (or schools, or roads, or irritable neighbours= ) > in the vicinity of your experiment area. > > > > Regards > > > > Jean-Louis F6AGR > > > > --0015175884aeb65742048175d734 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
On 73kHz I originally used nylon strimmer cord as the antenna insulat= or.=A0=A0 Worked fine until one day I=A0was testing using PSK (100% duty= cycle, long transmission) with G4GVC and it was raining.=A0 The antenna= fell down and I found the nylon had melted=A0due to=A0HV tracking.=A0 Rep= laced with a ceramic dog-bone and its been up ever since.=A0=A0=A0 The vol= tage=A0then was around the 15 - 20kV from 200 Watts of RF
On 10 March 2010 16:56, Dave Pick <davepick@btinternet.co= m> wrote:
Stefan

Just one warning= , I have used kite-supported aerials on 136 many times and you have to be= careful what insulating material you have between the kite and the top of= the wire. One day the kite was flying well but there was a little rain,= I transmitted and the wire fell out of the sky and the kite fluttered dow= n (fortunately I could find it!). When I looked to see what had happened= the thin rope holding the wire to the kite had burned through because the= rain had made it conductive. I think monofilament fishing line may be bet= ter...

Dave G3YXM



----- Original Message ----
From: Stefan= Sch=E4fer <St= efan.Schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Wednesday, 10 March, 2010 12:06:06
Subject: Re: LF: KITE ANT
<= br>...In Germany you can use a maximum braid length of 100m without a spec= ial licence. If 200m would be allowed, my vertical would be a 200m ;-)
But with a special permission you can relatively easy go up to 300m! I sti= ll try to get that permission for the next weeks. Then, the VLF signal wou= ld even be more than 10dB stronger, what would give the chance for the UK= to get the VLF signal, i hope so...

Static HV dangers are well known to all of us i assume. But the upper= kV range is nothing mystic. 10kV is just a factor 10 of 1kV, just like 10= V is a factor 10 of 1V. You can die if you touch a 10kV power line or if= you touch a 100kV power line. So there is just that rule: Do not touch wh= en under voltage and assure that there can be no voltage when you think th= at there is no voltage (measuring, earthing during operating). I've wo= rked almost 6 years in the HV group of the institute of electrical energy= systems (http://www.hst.tu-darmstadt.de/index.php?id=3D10&= amp;L=3D1) and had almost each week to work with voltages well above= 20kV (up to 3MV, 1,2/50=B5s), so i think i have the necessary respect wit= hout beeing afraid or careless. On my hill there are no schools, no roads= and no neighbours but i will keep in mind what you caution on! :-)

73, Stefan/DK7FC


Am 10.03.2010 09:16, schrieb Jean-Louis.RAULT@fr.thalesgroup.= com:
> Hi all
>
> May I ask you to pay some attentio= n on the three following issues related to balloon/kite aerials ?
>
> - using "high" altitude kites or balloons is often= subject to a formal authorization (at least in France, and specially if= you expect to use the aerial close to an airfield)
>
> - even= when weather is very good, very high DC voltages (many =A0kV) can appear= (from natural local electric field) on the antenna wire. DC grounding of= the wire is therefore mandatory
>
> - avoid any AC HV lines (or schools, or roads, or irritable= neighbours) in the vicinity of your experiment area.
>
> Rega= rds
>
> Jean-Louis F6AGR
>

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