. Practical wireless telegraphy; a complete text book for students of radio communication . he inductance of the coils in radio-frequenCycircuits, particularly the tuning coils of the receiving apparatus. Knowing the length of the winding and the diameter of the wire,the total number of turns is obtained individing the former by the latter. Multi-plying this by the circumference of thecoil, the number of feet of wire requiredfor a given winding is at once obtained. 178. Measurement of the Ef-fective Inductance and Capacityof an AeriaL—To measure the ef-fective inductance of an aerial, astandar
. Practical wireless telegraphy; a complete text book for students of radio communication . he inductance of the coils in radio-frequenCycircuits, particularly the tuning coils of the receiving apparatus. Knowing the length of the winding and the diameter of the wire,the total number of turns is obtained individing the former by the latter. Multi-plying this by the circumference of thecoil, the number of feet of wire requiredfor a given winding is at once obtained. 178. Measurement of the Ef-fective Inductance and Capacityof an AeriaL—To measure the ef-fective inductance of an aerial, astandard wavemeter and a standardof inductance is required. The lattercan be made up of Litzendraht wireand calculated from the inductanceformula in the foregoing aerial is set into excitation by aninduction coil or transformer S, Fig. 233,and the wavemeter placed ih induCtiVerelation. The reading of the natural w&vfelength thus obtained may be designated dSAi. We next insert the standard indudtance L and take a second reading of th6wave length which may be designatedby ^ Fig. PHONES 233—Diagram of Connections for Measuring tlieInductance and Capacity of an Aerial. V L, then L 179. (X2= —Xl=) where L = inductance of the aerial in microhenries; L = inductance of the standard in determine the effective capacity -of an aerial, first measure the natural wave length Xithen insert a condenser O of .001 microfarads capacity and take a second measurement ofwave length Xa. Obviously Xz is less than Xi. Then the capacity Xi^ — Xe^ C= X C. Xiwhere C = capacity of the aerial in microfarads. Calibration of a Wavemeter from a Standard.—If a calibrated wave-meter can be procured, the wave-meter described at the beginning ofthis chapter can be cahbrated fromit in a simple manner, as shown inFig. 234. Here, L and C respec-tively, are the inductance coil andcondenser of a standard wavemeterwhich is set into excitation by thebuzzer, H, and the batteries B. Thew
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
