. Practical wireless telegraphy; a complete text book for students of radio communication . e apparatus, as awhole, decreases considerably as the steps of transformation are increased. Another system of transformation has been evolved by Joly, in which the frequency ofthe generator may be tripled by a single set of transformers, which are adjusted to have-when A. C. current flows—unequal degrees of saturation. In this system the D. C. excita-tion winding for the transformer is dispensed with. In systems of this type in order that resonance between the alternator currentand the antenna system m
. Practical wireless telegraphy; a complete text book for students of radio communication . e apparatus, as awhole, decreases considerably as the steps of transformation are increased. Another system of transformation has been evolved by Joly, in which the frequency ofthe generator may be tripled by a single set of transformers, which are adjusted to have-when A. C. current flows—unequal degrees of saturation. In this system the D. C. excita-tion winding for the transformer is dispensed with. In systems of this type in order that resonance between the alternator currentand the antenna system may be maintained, it becomes important that the fre- 274 PRACTICAL WIRELESS TELEGRAPHY. quency of the alternator may remain constant; in consequence, the speed of thedriving motor must be carefully governed and to this end sevesal devices havebeen brought forth, the principal one being a signalling key fitted with a specialset of contacts which, just previous to the closing of the key, add resistance inthe motor field circuit, maintaining a practically uniform speed of rotation. XG ^1. Fig. 285—Marconis Method of Generating Continuous Oscillations. Signalling is accomplished, in the Joly system, by inserting a key in series with the directcurrent excitation winding, or by interrupting the generator circuit to the primary windingof the transformers by a special electromagnetic key, or by cutting in and out a few turnsof the aerial tuning inductance. The first-named method is the one in use at present. Thealternator at the Sayville station has a capacity of 100 kilowatts and gives antenna currentof about 140 amperes. Fair communication is effected with the station at Nauen, Germany,throughout the 24 hours of the day, but the best results have been obtained during the darkhours. At present the Sayville station operates at the wave length of 9,400 meters, theantenna frequency being slightly above 30,000 cycles per second. 219. Marconis System for the Production of Continuous Wa
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
