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It has sometimes been said that the Marconi system contains nothing original; that the apparatus for producing the waves was the oscillator of Righi, that the receiver was that employed for some two or three years by Professor Lodge and Mr Bose, and was founded on an earlier discovery by a French scholar, M. Branly; and, finally, that the general arrangement was that established by M. Popoff.
Where you use one 50 watt oscillator tube you will need a motor-generator that develops a plate potential of 1000 volts and has an output of 200 watts. This machine will stand you about $100.00. A 1000 Mile C. W. Telegraph Transmitter.
"How about the invisibility apparatus? It may prove useful, and it won't cost much. Let's put that in, too." The apparatus he mentioned was simply a high-frequency oscillator tube of extreme power which caused vibrations approaching light frequency to be set up in the molecules of the ship. As a result, the ship became transparent, since light could easily pass through the vibrating molecules.
The disadvantageous features are that: a battery current is not satisfactory, its circuits are somewhat more complicated, and the oscillator tubes burn out occasionally. There is, however, a growing tendency among amateurs to use continuous wave transmitters and they are certainly more up-to-date and interesting than spark gap sets.
The term electric radiation was first employed by Hertz to designate waves emitted by a Leyden jar or oscillator system of an induction coil, but since that time these radiations have been known as Hertzian waves. These waves are the underlying principles in wireless telegraphy.
This consists of: a source of direct or alternating current, a telegraph key, a vacuum tube oscillator, a tuning coil, and a condenser. This kind of a transmitter sets up sustained oscillations instead of periodic oscillations which are produced by a spark gap set. The Wireless Telephone Transmitter.
Any of the receiving sets described in the foregoing chapters will respond to either: a wireless telegraph transmitter that uses a spark gap and which sends out periodic electric waves, or to a wireless telephone transmitter that uses an arc or a vacuum tube oscillator and which sends out continuous electric waves.
The latter is then made to flow through a vacuum tube oscillator when it is converted into high frequency oscillations and these are varied, or modulated, as it is called, by a microphone transmitter such as is used for ordinary wire telephony. The energy of these sustained modulated oscillations is then radiated into space from the aerial in the form of electric waves.
In 1935 George and his father Costas built a one-valve transmitter using a type 59 pentode with suppressor grid modulation, and succeeded in contacting most of the world with this QRP rig. The electron coupled oscillator could not have put more than 4 or 5 watts into the antenna.
You can, however, use 110 volt direct current from a lighting circuit as your initial source of power to energize the plate of the vacuum tube oscillator of your experimental transmitter. Where you have a 110 volt direct current lighting service in your home and you want a higher voltage for your plate, you will then have to use a motor-generator set and this costs money.
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