[Elecraft] Elecraft General Interest: SFGate: Robert Helliwell, radio science pioneer, dies

[Jim Dunstan]

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