This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 Excerpt: ... interfering with the oscillations and can be left in circuit continually. The arrangement is shown in fig. 47. The coil is constructed like ...Read MoreThis historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1914 Excerpt: ... interfering with the oscillations and can be left in circuit continually. The arrangement is shown in fig. 47. The coil is constructed like a helix, about a dozen turns of No. 8 wire wound on a form three inches in diameter and spaced one-fourth inch apart, with a movable contact, being suitable. The lamp used is a small four or six volt carbon filament bulb, and may be had at any supply house. Whenever the transmitter is in operation the lamp lights up. The coil is connected as shown in shunt around six or more feet of the ground wire, the proper amount to be determined by experiment. Only a part of the high frequency current is passed through the coil by this arrangement so that the resistance of the ground wire is not in-, creased. It is really decreased to some extent. The effect is probably due to the resonant relation of the coil and the section of the ground wire. To find the maximum radiation at a desired wave length, place the slider of the indicator coil so that all the turns are in circuit and adjust the antenna circuit until the lamp lights up the brightest. Now decrease the number of turns on the indicator coil, thus decreasing the brilliancy of the lamp, and adjust the transmitting circuits again. Continue this process until the lamp lights up brilliantly with the least possible number of turns of the indicator coil connected in circuit. The transmitting station will then have a maximum radiation for a given wave length. A similar arrangement can doubtless be used by substituting a hot wire meter for the lamp, in which case, the radiation can be read directly. This is likely to be hard on the meter, however. Credit for this shunt indicator with a lamp is due to Mr. A. S. Hickley. We have now considered the transmitter and its several details ...Read Less
Very Good. Hardcover in navy blue cloth lettered in white. 392 pp. with index, plus 42-page publisher's catalogue. Frontispiece photograph and illustrated throughout with diagrams. "New, 1920 Edition". Guide to understand, building and using wireless communication stations, a book that was extremely popular and useful during the First World War. Very good.
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