Paul Harvey (KDKA)

Thu Mar 5 07:18:36 EST 2009

Thanks. I suspected that tubes existed in 1920, but I wasn't sure. As
I said in my post, however, Herrold's accomplishments were all the
more remarkable because, in 1909, he broadcast audio over a carrier
that, apparently, he generated with a spark gap (and presumably did so
because tubes--particularly triodes, which could deliver the needed
gain--weren't yet available in 1909). I guess that he might have used
a passive L-C filter to narrow the spark-gap spectrum. I'm quite sure
that simple inductors and capacitors were known and pretty well
understood in 1909, although there weren't nearly as many ways to
build them as there are today.

Dan Strassberg (
eFax 1-707-215-6367

----- Original Message ----- 
From: "Tim Coco" <>
To: "'Dan.Strassberg'" <>; "'Scott Fybush'"
<>; "'Kevin Vahey'" <>;
Cc: "'(newsgroup) Boston-Radio-Interest'"
Sent: Thursday, March 05, 2009 12:43 AM
Subject: RE: Paul Harvey (KDKA)

>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
> Ward Hill, MA 01835-6973
> Telephone: (978) 374-2111
> Fax: (978) 521-4636
> "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
> earlier.

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