From: Gerhard Hickl <gerhard.hickl@aon.at>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <AANLkTinbxcRAqcrTiYYLVv2qm1N4BRiaTscLACth_ao8@mail.gmail.com>
References: <AANLkTinbxcRAqcrTiYYLVv2qm1N4BRiaTscLACth_ao8@mail.gmail.com>
Date: Thu, 27 Jan 2011 22:03:33 +0100
Message-ID: <1296162213.2168.10.camel@gerhard-desktop>
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Subject: Re: LF: Advisory / Warning
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Hello Andy, group!

I had the VLF-TX running about 2 weeks ago, while I removed the lights
for X-Mas decoration from a tree in the garden. One of the toploads is
passing this tree straight above in a distance of about 8 meters to the
tree-top. The tree is only about 3m high.

Accidentally, I touched the connector of the light-chain while forming a
nice coil...ouch!

To touch any grounded object while standing near the loading coil is
also very painful as I found out recently when I tried to reduce the
loss-resistance by laying a piece of wire fence on the lawn.

You are right, we have to careful, thank you for the reminder!

73

OE3GHB
Gerhard




Am Donnerstag, den 27.01.2011, 15:06 +0000 schrieb Andy Talbot:
> 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
>