From: "Mike Dennison" <mike.dennison@rsgb.org.uk>
To: rsgb_lf_group@blacksheep.org
Date: Wed, 17 Jan 2001 12:36:08 -0000
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Subject: LF: 9kHz DX with no power supply!
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If you have Real Player, go to: http://www.bbc.co.uk and click on the 
link to Concrete Ears. It is fascinating.

Briefly this describes huge concrete acoustic dishes built in the 
1920s, aimed at listening for enemy airplanes up to 25 miles away. 
An artist is building new dishes for Folkestone (G) and Boulogne 
(F). She claims that you will not only hear the sea but also be able to 
talk to the person who is using the other dish 50km away. Hard to 
believe that the QRM from the sea won't be a huge problem as this is 
not even line of sight. As my wife's mother lives in Folkestone, I will 
try it when it is built, and report back.

So, if you fancy breaking the 9kHz record without spending a penny 
on electricty, simply build an acoustic dish!


Mike, G3XDV (IO91VT)
http://www.lf.thersgb.net