Radiotelegraphy, U. S. Signal Corps

Radiotelegraphy, U. S. Signal Corps

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: ...coupling of the two circuits, the upper curve being for the primary and the lower for the secondary. At the point of correct coupling the primary current was a minimum and the secondary or antenna current a maximum. From these curves it will be seen that the coupling of the two circuits of a quenched-spark transmitter is a very important and critical adjustment, upon the correct value of which the efficiency is largely dependent. Sometimes when the adjustments of a quenched-spark set are not correct it is possible to detect two wave lengths, but of very small amplitude, in addition to the single wave length mentioned above, one of these being of shorter and the other of longer wave length than the normal. The development of these two wave lengths is generally due to excessive coupling so that the spark is not quenched at the proper point but allows one or two transfers of the secondary energy back into the primary during which two wave lengths are produced. After the spark is properly quenched, the energy is retained in the secondary, and the normal wave length of much greater amplitude is developed. Coupling I Sec. Coupling Fig. 57. ARRANGEMENTS AT THE RECEIVING STATION. The electromagnetic waves sweeping across the antenna at the receiving station generate damped alternating currents therein of the same frequency as those in the transmitting antenna. At great distances the oscillations or currents are exceedingly feeble, perhaps only a few millionths of an ampere, and it requires correctly adjusted circuits and very sensitive devices to detect them. The various types of receiving circuits will be described next, and the detectors later. It is evident that the strongest oscillations will be produced in the receiving antenna when it more

Product details

  • Paperback | 40 pages
  • 189 x 246 x 2mm | 91g
  • United States
  • English
  • black & white illustrations
  • 1236897846
  • 9781236897848