Is it radio? The Heyphone relied on magnetic coupling between a loop underground and another on the surface. At the time the distance was in the 100 to 200m range, ie too short to form an electromagnetic wave, therefore not radio. It's an interesting subject.
David G3UNA -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bill Frantz Sent: 13 July 2018 16:33 To: elecraft@mailman.qth.net Subject: Re: [Elecraft] OT - The HeyPhone For those that might be interested in further information about underground radio communications, the National Speleological Society's Communication and Electronics section has placed back issues of its publication online for free down load at: <http://caves.org/section/commelect/drupal/speleonics> Some of the European radios have had problems in the US because they are sensitive to the harmonics of our 60 Hz power. 73 Bill AE6JV ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
