On Sun, 27 Jun 2004 22:53:09 GMT, "Dave Stadt"
wrote:
"AES/newspost" wrote in message
...
In article ,
(Kevin Darling) wrote:
Larry Dighera wrote in message
. ..
Frankly, I didn't know that radio direction finding was employed for
aviation use before the '20s. I'd sure like to know more about this
subject.
Not ADF, of course, but DF existed from the early 1910s, and was
shortly thereafter installed on some naval vessels.
Apparently by 1914 DF was being tested on winged aircraft. The
British looped a wire from the cockpit out along the top wings, and
back via the lower wings... thus creating a loop antenna on each side
of a biplane. This allowed the pilot to easily home into his base's
radio station. ("Most Probable Position, a History of Air
Navigation")
Question: At what point in time did electronic amplification (i.e.,
vacuum tube technology) come into those systems -- or any other military
or commercial systems -- whether at the RF, audio, or any other stages?
My impression is that as of the early 1910s the transmitters would have
been either spark-gap or rotary mechanical in character, with crystal
detectors at the receiving end. When did vacuum tube amplifiers or
oscillators come into regular use in any part of these systems?
Around 1913 Deforest sold an audion tube to the general public.
The first triode vacuum tube, which was a signal amplifier, was
invented in 1906 by Lee DeForest:
http://rds.yahoo.com/S=2766679/K=%22....edu/~mooreiii
Tube development took off during WWI and they made their way into transmitters
and receivers during the war.
Three Western Electric VT-1 triode vacuum tubes (first vacuum tube)
were used in the SE950.
There were an untold number of detectors back then.
Transmitters would have been spark gap, quench gap or arc. The Alexanderson
alternator came out around 1918. There was a huge Alexanderson transmitter
still in operating condition in Sweden up to a couple of years ago. It
still might be in operating condition and put on the air for special
occasions.
Though a student of early radio, I was surprised to learn that the
first commercial radio station was put into service before the
invention of the triode vacuum tube:
1902: World's first commercial wireless station is opened on Santa
Catalina Island.
http://www.notfrisco.com/calmem/catalina/chrono.html
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