Message-ID: <003e01c079a8$17f6f0e0$d6329fd4@f9.net.uk>
From: "Dave" <dave@picks.f9.co.uk>
To: rsgb_lf_group@blacksheep.org
References: <000101c0798b$032efd00$927a883e@lvm>
Subject: LF: Re: Re. Fire
Date: Mon, 8 Jan 2001 19:20:41 -0000
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Laurie, Jim, Geri et al.

> What about lining the shelter with aluminium foil. This would need gaps to
> prevent shorted turns and would be grounded.But it would be a low loss
path
> for stray currents. I belive that the Decca huts were lined with
> copper,presumably for this reason. 73s Laurie.
>
Jim asked about a loss free fire-proof material and Laurie mentioned the
Decca ATU hut being lined with copper so the answer is obvious... A Metal
Hut!
I have rebuilt the hut and will be lining it with aluminium sheet bonded to
earth in the hope that this will reduce the losses and be more fireproof!

Next job will be the loading coil (I have some Decca litz waiting) and, the
saddest loss, my remote-tuned variometer. It really is a big step going up
from around 1kW to nearly 2 and you just can't get away with any whiskers of
wire at joints where corona can start.....
I'm going to have to call on my experience of large broadcast transmitters
from 30 years ago!

I considered having no shelter but I don't think it's viable at this power
level, also the mechanics of remote tuning and the current monitoring would
suffer from the damp.

Has anyone got a suggestion for a fire detedtion system that would still
work in close proximity to all that RF? I imagine a domestic smoke alarm
would go doo-lally!

Thanks for all the sympathetic messages (and the not so sympathetic...
"tuning for maximum smoke" indeed!) .

73. Dave the arsonist. G3YXM.