Radiotelegraphy: U.S. Signal Corps, 1914 |
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adjustment aerial alternating current amperes amplitude antenna circuit armature binding post C₁ C₂ called capacity changes charged closed circuit closed oscillating circuit connected counterpoise cuit curve cycles per second damped desired wave length detector direct current discharge electric electromagnetic electrostatic energy fundamental wave length gaskets ground high-frequency inch increased inductance coil inserted insulated kilowatt loading coil logarithmic decrement loosely coupled magnetic field mast maximum measured microhenrys millihenry motor natural logarithm necessary number of turns open circuit operator oscillation transformer oscillations per second pitch plates plug potential primary circuit quenched spark quenched-spark radiation radio radiotelegraphy reactance receiving circuits receiving set resistance resonance rheostat rotating secondary circuit shown in figure shunt Signal Corps single wave length spark frequency spark gap sparking surfaces static switch telephone terminals tion transformer secondary transmitting tuning variable condenser variometer vibration voltage volts wattmeter watts wave meter wave train
Popular passages
Page 49 - The antenna wires are generally stranded, thus giving somewhat greater strength than a solid wire of the same weight. For permanent stations a phosphor-bronze or silicon-bronze wire is generally used consisting of seven strands of either No. 20 or No. 14 B. & S. gauge, and for the portable stations, such as the Signal Corps fieldpack sets, an antenna cord made up of 42 phosphor-bronze wires stranded around a hempcord center. A very low resistance in the antenna wires is not as necessary as it might...
Page 110 - 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 " is often used as its symbol. In commercial alternators used in radio telegraphy the frequencies are generally 60, 120, 480, or 500 cycles per second;...
Page 95 - ... amperes. CODING OF WAVE LENGTHS The great advantage of this set lies in the fact that any desired wave length from 675 to 2,220 meters can be sent out at will and if the wave length is changed after every word of a message, according to a pre-arranged code of wave lengths — for example, the first word sent with 700 meters, the next with 2,100, the next with 1,400, etc. — it will be difficult for any eavesdropping operator who has not the wave-length code to follow the changes of wave length...
Page 105 - ... and the sparking surface be kept true and plane, as shown by a straightedge. Great care should be exercised in reassembling the gap to set the mica washers accurately on the annular surfaces of the disk and to put on enough tension with the clamping screws to render all of the gap spaces air-tight. Tuning of Sending Set The tuning of the closed and open circuits to resonance, and the determination of the correct coupling between them are the two most important adjustments in a quenched spark...
Page 5 - One of static electricity, when the electrical charges are at rest, and the other of dynamic or current electricity, when the charges are in motion along a conductor. When an insulator, such as sealing wax, is rubbed with fur, or a glass tube with silk, it acquires the property of attracting light bodies near it, and is said to be charged. This action shows that forces exist in the adjacent space, and there is said to be an electrostatic, or, more briefly, a static field of force about the charged...
Page 108 - ... 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 98 - 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 103 - Gen." and the smaller plug into the socket on the underside of the gear case, also marked "Gen." The sending key is in the circuit of the alternator fields and the exciter armature, and is so connected by means of the light pair of leads, the larger plug of which being put into the socket at the left end of the chest marked "Fid.
Page 112 - ... ventilator at either end of the tent, and a tube attached to the center for admitting the antenna lead. When in use, sufficient slack should be left in the antenna lead to form a drip loop outside of the tent, and if found necessary a piece of heavy insulated wire can be used as a leading-in wire. PACKING. The set is normally packed on three mules, but in emergency may be packed on two. In normal packing the first mule carries the generator and six sections of the mast. The second mule carries...