At 10:49 AM 5/26/2011 +0100, you wrote: > > With great delight over the years, he regularly welcomed visitors to his > > lab to listen to what he called his "whistlers," the eerie electrical > > warbling generated by lightning flashes in Canada's Arctic and that had
Hi, Just a short line (off elecraft topic ... forgive me) ... when I was15 years old I bought my first CK-721 transistors (Raytheon) and built a '"whistler" receiver after reading a Scientific American article. Maybe the article was written by Professor Helliwell ... I can't recall. The receiving setup is a large 4' diameter loop of many turns (maybe 30-50) of copper wire (salvaged from old transformers) connected to a diode detector and high gain audio amplifier. Essentially an audio frequency crystal set followed by a high gain audio amplifier. I hung the loop vertically in the attic. It was possible to hear "whistlers" from storm centers long before you could hear the thunder. Whistlers appear to be electromagnetic waves that fall within the the audio frequency spectrum, but they cannot be detected directly by the ear. By the way the CK-22 which I originally ordered was priced at over $20.00 ... by time I sent away for one, similar CK-721's were already surplus and I could get a handful for $5.00 ... an early indication of the speed of technological change !! Back to Elecraft topics hi Jim VE3CI ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
