. Practical wireless telegraphy; a complete text book for students of radio communication . x-^<^ Fig. 211—Diagram for Measuring the Natural WaveLength of an Aerial. PRACTICAL RADIO MEASUREMENTS. 191 tion coil fitted with a vibrator, S-1 a spark discharge gap of simple design con-nected in series with the aerial A-1. L is the inductance coil of the wavemeter; Cthe variable condenser; D a crystal rectifier, and P the head telephone. When the induction coil is set in opera-tion a spark discharge takes place at S-1,the aerial circuit being traversed by groupsof oscillations at a frequency dete
. Practical wireless telegraphy; a complete text book for students of radio communication . x-^<^ Fig. 211—Diagram for Measuring the Natural WaveLength of an Aerial. PRACTICAL RADIO MEASUREMENTS. 191 tion coil fitted with a vibrator, S-1 a spark discharge gap of simple design con-nected in series with the aerial A-1. L is the inductance coil of the wavemeter; Cthe variable condenser; D a crystal rectifier, and P the head telephone. When the induction coil is set in opera-tion a spark discharge takes place at S-1,the aerial circuit being traversed by groupsof oscillations at a frequency determined bythe distributed values of inductance andcapacity of the aerial, or,1N=. Fig. 212—Showing How an Aerial May Be Set IntoExcitation by Buzzer. 4 V LCand a corresponding wave motion is prop-agated through space. Now if the coil of the wavemeter Lbears the correct inductive relation to theaerial wire, preferably placed near to theearth lead, oscillations of maximum ampli-tude will be induced in the wavemeter cir-cuits when the wavemeter and the aerialcircuit are in exact resonance. With thespark discharging at S-1 the capacity of the wavemeter condenser is varied until a clear distinct sound is heard in the head telephones ata definite setting (of the condenser). The wave length tabulated on the scale underneaththe pointer is that of the circuit under test. Generally the resonant adjustment of the wavemeter is sharply defined, so that a slightchange in capacity will cause the signals todisappear. During this measurement, theoperator should take care to distinguishbetween the currents induced in the wave-meter by the oscillations flowing in theantenna circuit
Size: 1794px × 1392px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
