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Date: Thu, 27 Jan 2011 15:30:21 +0000
Message-ID: <AANLkTineGeZ7+NpZ6z2TPXqy=r3qCtkBtwef46ytUh65@mail.gmail.com>
From: Roger Lapthorn <rogerlapthorn@gmail.com>
To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Advisory / Warning
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Another good reason to sticking to QRP I say!

73s
Roger G3XBM

On 27 January 2011 15:06, Andy Talbot <andy.g4jnt@gmail.com> wrote:

> Thought I'd better warn QRO LF ops about this - something that had never
> occured to me before, and could be nasty.
>
> I'm laying floor panels in my loft space, and this involves rerouting some
> of the upstairs lighting wiring - drilling holes and feeding the wire though
> rather than it laying on top of joists where the flooring will sit.  Anyway,
> there I was, was happily threading twin-and-earth cable by torchlight (*)
> when I suddenly got a nasty RF burn holding one end of a piece
>
> The 500kHz WSPR beacon is running, and the bit I was holding was isolated
> from the house main earth wire.  The Tee antena runs outside over the
> roof, only 3m or so away from where I was working.   So more than enough
> pickup with me and a bit of wire forming a dipole in the near field of 4kV
> at 500kHz
>
> Now, bearing in mind the burnt ATU cabin of a few months ago, it made me
> think...
> Large bits of bare isolated wire or metal in roof spaces where LF antennas
> pass over could be risky.   They could pick up enough voltage to spark - and
> if there's paper/ wood / plastic at the sparking point, an RF spark that
> always seems to turn into an arc, is very hot.
>
> Just a thought.
>
> (*) and BTW, there is a very strong argument for *not* having your
> roofspace light on the same circuit as your normal upstaris lighting
>
> Andy
> www.g4jnt.com
>
>



-- 
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
www.youtube.com/user/g3xbm
<http://vlf_grabber>G3XBM   GQRP 1678    ISWL G11088

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Another good reason to sticking to QRP I say!<br><br>73s<br>Roger G3XBM<br=
><br><div class=3D"gmail_quote">On 27 January 2011 15:06, Andy Talbot <spa=
n dir=3D"ltr">&lt;<a href=3D"mailto:andy.g4jnt@gmail.com">andy.g4jnt@gmail=
.com</a>&gt;</span> wrote:<br>
<blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; bord=
er-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"><div>Thought I&=
#39;d better warn QRO LF ops about this - something that had never occured=
 to me before, and could be nasty.</div>

<div>=A0</div>
<div>I&#39;m laying=A0floor panels in my loft space, and this involves rer=
outing some of the upstairs lighting wiring - drilling holes and feeding=
 the wire though rather than it laying on top of joists where the flooring=
 will sit.=A0 Anyway, there I was, was happily threading twin-and-earth ca=
ble=A0by torchlight (*) when I suddenly got a nasty RF burn holding one en=
d of a piece</div>


<div>=A0</div>
<div>The 500kHz WSPR beacon is running, and the bit I was holding was isol=
ated from the house main earth wire.=A0=A0The Tee antena runs outside over=
 the roof,=A0only 3m or so away from where I was working.=A0=A0 So more th=
an enough pickup with me and a bit of wire forming a dipole in the near fi=
eld of 4kV at 500kHz</div>


<div>=A0</div>
<div>Now, bearing in mind the burnt ATU cabin of a few months ago, it made=
 me think...</div>
<div>Large bits of bare isolated wire or metal in roof spaces where LF ant=
ennas pass over could be risky.=A0=A0 They could pick up enough voltage to=
 spark - and if there&#39;s paper/ wood / plastic at the sparking point,=
 an RF spark that always seems to turn into an arc, is very hot.</div>


<div>=A0</div>
<div>Just a thought.</div>
<div>=A0</div>
<div>(*)=A0and BTW,=A0there is a very strong argument for <u>not</u> havin=
g your roofspace light on the same circuit as your normal upstaris lightin=
g</div>
<div>=A0</div>
<div>Andy</div>
<div><a href=3D"http://www.g4jnt.com/" target=3D"_blank">www.g4jnt.com</a>=
</div>
<div>=A0</div>
</blockquote></div><br><br clear=3D"all"><br>-- <br><a href=3D"http://g3xb=
m-qrp.blogspot.com/" target=3D"_blank">g3xbm-qrp.blogspot.com/</a><br><a=
 href=3D"http://www.g3xbm.co.uk" target=3D"_blank">www.g3xbm.co.uk</a><br>=
<a href=3D"http://www.youtube.com/user/g3xbm" target=3D"_blank">www.youtub=
e.com/user/g3xbm</a><br>
<a href=3D"http://vlf_grabber" target=3D"_blank"></a>G3XBM=A0=A0 GQRP 1678=
=A0=A0=A0 ISWL G11088<br>

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