Just for a bit of nostalgia, I also had a CK722 (back in the day) which I paid about $10 for. My 2N107's legs had previously fallen off and this was what I replaced it with. I still have it so here's a picture of one of the prettiest transistors ever made sitting on the screen of a current production version of a truely classic scientific calculator.
http://ab9v.us/a1DSC_2047-1024.jpg 73, Mike, AB9V On 5/26/2011 13:42 PM, Jim Dunstan wrote: > 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 ______________________________________________________________ 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
