Radiotelegraphy |
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adjustments aerial alternating current amperes amplitude antenna circuit armature binding post C₁ C₂ called capacity changes charged closed circuit closed oscillating circuit connected copper counterpoise cuit curve damped desired wave length detector direct current discharge electrical electromagnetic electrostatic energy fundamental wave length gasket ground high-frequency hot-wire ammeter inch increased inductively coupled inserted insulated jars kilowatt loading coil logarithmic decrement loosely coupled magnetic field mast maximum microhenrys millihenry motor natural logarithm necessary number of turns open circuit operating chest oscillation transformer oscillations per second pack sets plates plug potential primary circuit quenched spark quenched-spark radiation radiotelegraphy reactance receiving circuits receiving set resistance resonance rheostat rotating secondary circuit sections shown in figure Signal Corps single wave length spark frequency spark gap sparking surfaces static switch telephones terminals tion transmitting tube tuning variable condenser variometer voltage volts wattmeter watts wave meter wave train wire
Popular passages
Page 83 - It is of 2-kilowatts output and is carried on a two chest pintle wagon, one chest with the engine and generator and the other with the transmitting and the receiving apparatus. The range of these sets varies from 75 to 800 miles, depending on favorable weather conditions, time of day or night, character of the land between the sets, etc. FORT SAM HOUSTON STATION SET. The following description of the Fort Sam Houston station is given as an illustration of the type of the 10-kilowatt sets installed...
Page 110 - ... secondary circuits, galena, or other similar detector, high-resistance telephones, etc., provided with the necessary switches for tuning to different wave lengths. The primary circuit includes the antenna, primary coil, series condenser or not as may be needed, and counterpoise. The antenna is connected to the primary coil through switches which put into circuit a variable number of turns, steps of 10 turns being inserted by one dial switch and single turns by the other. The total number of primary...
Page 112 - SHORT WAVES. Primary condenser in series. Switch on "In" contact.] LONG WAVES. Primary condenser short-circuited. [Switch not on "In" contact.] TUNING OF THE RECEIVING SET. First, the detector must be adjusted to a sensitive point by means of the test buzzer, the note of which should be clearly heard in the receiving telephones when it is held near the antenna or counterpoise wires or the coil windings. When the wave length of the sending station is known, the number of turns in the primary and secondary...
Page 26 - RADIOTEI.EGRAPUY. the alternator is varying. Figure 21 represents the manner in which these quantities vary, where the set of values ABCDE, half of which is positive and half negative, is called a cycle of voltage or current, the symbol for which is often thus written — . The number of cycles per second is called the frequency and the letter " n
Page 83 - The range of these sets under normal conditions is about 25 miles over land, but much greater over water. Thus one of the one-eighth kilowatt sets, with a 100-foot mast, at Habana has worked with the naval station at Key West, a distance of about 110 miles.
Page 106 - To put the chest in operation for sending, connect the double contact plugs of the leads from the hand generator field antenna and counterpoise to the receptacles marked
Page 29 - There are certain advantages in a high spark frequency which appear both at the transmitting and at the receiving stations. If the closed circuit condenser is charged 1,000 times per second to a certain potential, it is evident that more energy will be required than if charged only 120 times, the formula for the energy being 1/2 C V2N, where C is the capacity, V the potential, and N the number of times per second. If the same amount of energy is available in the two cases — that is, if 1/2 C V2N...
Page 99 - The-- telephones are'm shunt to the stopping condenser. The detector supplied is of the iron pyrites variety, which lacks the sensitiveness of the Perikon. Any other detector may easily be substituted for the detectors supplied with the set, the range of which may be thereby easily increased. With the switch thrown to "Long waves" the operator will get the best results when using a small number of degrees of the variable condenser and as large primary as possible, and, vice versa, with the switch...
Page 109 - DC motor should be protected from "kickbacks" due to the use of the sending key in the alternator fields by two high-resistance carbon rods mounted on suitable bases to be connected as follows : The end terminals of one rod to the two AC leads close to the machine ; the end terminals of the other rod to the two main line DC leads close to the machine, and the middle points of both rods to be connected...
Page 21 - ... circuits are syntonized, or tuned, or are in resonance. POWER CIRCUITS. TRANSFORMERS. After each oscillatory discharge the charge in the condenser is renewed at regular intervals by an induction coil, or alternating current transformer. The former is but little used now, and will not be described here. The transformer is an apparatus for increasing the comparatively low voltage of an alternating current dynamo or generator to the high voltage necessary to cause the condenser charge to jump across...