Paul Harvey (KDKA)

Tim Coco
Thu Mar 5 00:43:24 EST 2009

I believe vacuum tubes were in full force by 1920. There are some photos out
there of KDKA's first transmitter
( or The
transmitter, if IIRC, had to be Western Electric because of the (illegal)
patent agreement between AT&T, General Electric, Westinghouse and United
Fruit that gave birth to RCA and the acquisition of American Marconi.

The Alexanderson Alternator must have been an expensive undertaking only to
be made obsolete in a very short time.  Seems to me some group used one in
the last year or so to celebrate its anniversary.

Tim Coco
President & General Manager

189 Ward Hill Avenue
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Telephone: (978) 374-2111
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"WHAVR" and "WHAV.NET" are registered service marks.

Dan Strassberg wrote:

But didn't some citizens of San Jose and San Francisco just celebrate radio
broadcasting's 100th anniversary, based on the 1909 date when "Doc" Herrold
(I think that was his name) is supposed to have begun his broadcasts on what
eventually became KQW and then KCBS? Until I did a little googling, I had
never thought about the technical feats involved in modulating the output of
a spark-gap transmitter with audio. That, however, is what Herrold
apparently did. If I'm not mistaken, 8XK (KDKA) didn't emerge until the
technology had evolved to the point where the audio was used to modulate
sine-wave carriers.
Whether 8XK used vacuum tubes to generate those carriers in 1920 (did vacuum
tubes even exist yet?) or used an electromechanical device (something called
an Alexanderson alternator, perhaps), I don't know.
But while nobody can deny that radio was still very much in its infancy in
1920, I think you should agree that it had been born more than a decade

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