Re: [Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies
Jim, "It was possible to hear "whistlers" from storm centers long before you could hear the thunder." I doubt the whistlers you heard was from a storm that was close enough to hear the thunder: "Very low frequency (VLF) radio waves shoot past the ionosphere and into the next region of space, the magnetosphere. Here, the atmosphere is completely ionized. The Earth's magnetic field controls the motions of charged particles, creating channels of ions aligned with the horseshoe-shaped magnetic field lines. These channels trap VLF radio waves, guiding them between opposite hemispheres along a path that reaches up to 15,000 miles from the surface." http://news.stanford.edu/news/2011/may/robert-helliwell-obit-052011.html I visited the lab when I was a freshman (before the advent of dirt) as part of the tour they gave incoming engineering students. -Rex- K1HI Rex Lint Merrimack, NH WWW.QRZ.COM/db/k1hi __ 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
Re: [Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies
The transmitting station SAQ in Sweden regularly puts their big transmitter on the air at 17 kHz. The "transmitter" is an Alexanderson Alternator - a fascinating mechanical beast that did an excellent job generating pure CW back in the days when most stations were running spark. Google will turn up a wealth of information and photos of it. Of course electromagnetic waves are not sound waves. You can't hear them with only your ears even at such low frequencies. Back in the early days of "radio" the consensus among the experts was that the longer the wavelength (the lower the frequency) the longer the range, so much effort was put into very low frequency systems that operated in the same frequency range in which we hear sounds. And electromagnetic waves at those frequencies do penetrate earth and water better (Navies still use them to communicate with submerged submarines). It was that flawed thinking that got us Hams pushed onto the "useless" Short Wave bands were the experts were certain we'd never "get out of our own backyards" running only a kilowatt or less. Ron AC7AC -Original Message- 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. 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies
On Thu, May 26, 2011 at 1:35 PM, Mike Cox wrote: > ...I also had a CK722...here's a picture... Col! I well remember those little blue gadgets, and the circuits I made to experiment with them, powered by big fat dry-cell batteries. Tony KT0NY __ 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
Re: [Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies
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:Elecraft@mailman.qth.net > > 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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies
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:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies
For your information. --O. Johns W6ODJ Begin forwarded message: > -- > This article was sent to you by someone who found it on SFGate. > The original article can be found on SFGate.com here: > http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2011/05/23/BABK1JIVEQ.DTL > - > Monday, May 23, 2011 (SF Chronicle) > Robert Helliwell, radio science pioneer, dies > "mailto:dperl...@sfchronicle.com";>David Perlman, Chronicle Science Editor > > > When Robert A. Helliwell, a Stanford electrical engineer, heard a > mysterious series of high-pitched, drawn-out whistles coming from his > laboratory's radio receiver more than 60 years ago, his curiosity led him > to a pathbreaking series of experiments exploring Earth's magnetic field > and the belt of energetic particles beyond it. > 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 > sped for thousands of miles through the ionosphere to Stanford. > Professor Helliwell, a distinguished radio science researcher, died May 3 > in Palo Alto of complications from dementia. He was 90. > During his research, Professor Helliwell once enlisted a powerful Navy > transmitter to send signals from Annapolis, Md., to a Chilean listening > post in a lighthouse at Cape Horn. It led him to discover that Earth's > ionosphere was not 200 miles thick, as scientists had believed, but > extended at least as high as 20,000 miles. > Continuing that research, Professor Helliwell sent radio transmitters into > space aboard NASA satellites to explore the radio properties of the Van > Allen Belt, where highly energetic electrons and protons trigger the > aurora borealis, the brilliant northern lights. > In Antarctica, where the atmosphere was unsullied by radiation from urban > power lines and radio noise, Professor Helliwell and his students > installed a very low frequency transmitter at Siple Station, a research > base 900 miles from the South Pole, and deployed an antenna array 13 miles > long. > It sent radio signals to Canada and, because the Antarctic ice sheet is 1 > 1/2 miles thick, the antenna in effect was 1 1/2 miles high above Earth. > Little of the very low frequency radio energy, therefore, was absorbed by > the ground and the signal from Siple was able to follow Earth's magnetic > field lines far out into space before returning to Earth in Roberval, > Canada. > "It was like a lab experiment in space," recalled Donald Carpenter, an > emeritus professor of electrical engineering at Stanford and one of > Professor Helliwell's former students. > "He was always a very curious guy," Carpenter said, "and if you came to > him with a question, he'd answer, but you'd come away with still more > questions. He was a gold mine of insights into the behavior of the > ionosphere and the magnetosphere, and the Van Allen radiation belts." > Professor Helliwell's radio frequency experiments at Siple Station were > "his crowning achievements," Carpenter said. > The scientific world honored him for his work there, and in 1966 the > government's Board of Geographic Names named a stretch of mountains along > the coast of Antarctica's Victoria Land as the "Helliwell Hills." > Professor Helliwell was born in Red Wing, Minn., and joined the Stanford > faculty in 1946 after earning all his university degrees there. > His high school sweetheart, Jean Perham, also graduated from Stanford. And > when Professor Helliwell joined the fencing team as an undergraduate, she > did too - going on to become the university's first female fencing coach. > Mrs. Helliwell died in 2001. > Professor Helliwell is survived by his sons, Bradley of Sedona, Ariz., > David of Arcata (Humboldt County), and Richard of Colorado Springs; a > daughter, Donna of Sunnyvale; four grandchildren; and one > great-great-grandchild. > A memorial service will be held at the Stanford Memorial Church on June 7 > at 3 p.m. E-mail David Perlman at dperl...@sfchronicle.com. > -- > Copyright 2011 SF Chronicle > __ 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
