The Radio Amateurs Hand Book | Page 2

in 1893.
The author was the first to connect an arc lamp with an aerial and a
ground, and to use a microphone transmitter to modulate the sustained
oscillations so set up. The receiving apparatus consisted of a variable
contact, known as a _pill-box_ detector, which Sir Oliver Lodge had
devised, and to this was connected an Ericsson telephone receiver, then
the most sensitive made. A later improvement for setting up sustained
oscillations was the author's rotating oscillation arc.
Since those memorable days of more than two decades ago, wonderful

advances have been made in both of these methods of transmitting
intelligence, and the end is as yet nowhere in sight. Twelve or fifteen
years ago the boys began to get fun out of listening-in to what the ship
and shore stations were sending and, further, they began to do a little
sending on their own account. These youngsters, who caused the
professional operators many a pang, were the first wireless amateurs,
and among them experts were developed who are foremost in the
practice of the art today.
Away back there, the spark coil and the arc lamp were the only known
means for setting up oscillations at the sending end, while the
electrolytic and crystal detectors were the only available means for the
amateur to receive them. As it was next to impossible for a boy to get a
current having a high enough voltage for operating an oscillation arc
lamp, wireless telephony was out of the question for him, so he had to
stick to the spark coil transmitter which needed only a battery current to
energize it, and this, of course, limited him to sending Morse signals.
As the electrolytic detector was cumbersome and required a liquid, the
crystal detector which came into being shortly after was just as
sensitive and soon displaced the former, even as this had displaced the
coherer.
A few years ahead of these amateurs, that is to say in 1905, J. A.
Fleming, of England, invented the vacuum tube detector, but ten more
years elapsed before it was perfected to a point where it could compete
with the crystal detector. Then its use became general and workers
everywhere sought to, and did improve it. Further, they found that the
vacuum tube would not only act as a detector, but that if energized by a
direct current of high voltage it would set up sustained oscillations like
the arc lamp, and the value of sustained oscillations for wireless
telegraphy as well as wireless telephony had already been discovered.
The fact that the vacuum tube oscillator requires no adjustment of its
elements, that its initial cost is much less than the oscillation arc,
besides other considerations, is the reason that it popularized wireless
telephony; and because continuous waves have many advantages over
periodic oscillations is the reason the vacuum tube oscillator is

replacing the spark coil as a wireless telegraph transmitter. Moreover,
by using a number of large tubes in parallel, powerful oscillations can
be set up and, hence, the waves sent out are radiated to enormous
distances.
While oscillator tubes were being experimented with in the research
laboratories of the General Electric, the Westinghouse, the Radio
Corporation of America, and other big companies, all the youthful
amateurs in the country had learned that by using a vacuum tube as a
detector they could easily get messages 500 miles away. The use of
these tubes as amplifiers also made it possible to employ a loud speaker,
so that a room, a hall, or an out-of-door audience could hear clearly and
distinctly everything that was being sent out.
The boy amateur had only to let father or mother listen-in, and they
were duly impressed when he told them they were getting it from
KDKA (the Pittsburgh station of the Westinghouse Co.), for was not
Pittsburgh 500 miles away! And so they, too, became enthusiastic
wireless amateurs. This new interest of the grown-ups was at once met
not only by the manufacturers of apparatus with complete receiving and
sending sets, but also by the big companies which began broadcasting
regular programs consisting of music and talks on all sorts of
interesting subjects.
This is the wireless, or radio, as the average amateur knows it today.
But it is by no means the limit of its possibilities. On the contrary, we
are just beginning to realize what it may mean to the human race. The
Government is now utilizing it to send out weather, crop and market
reports. Foreign trade conditions are being reported. The Naval
Observatory at Arlington is wirelessing time signals.
Department stores are beginning to issue programs and advertise by
radio! Cities are also taking up such programs, and they will doubtless
be included soon among the regular privileges of the tax-payers.
Politicians address their constituents.