. Practical wireless telegraphy; a complete text book for students of radio communication . he last oscillationis one-tenth of the initial oscillation. PRACTICAL RADIO MEASUREMENTS. 201 Si = decrement of the circuit under measurement,& =: decrement of the decremeter or wavemeter,Xr =: wave length at resonance, Xi = wave length not more than 3 per cent, to 5 per cent, off resonance,1 ^= current indicated by a measuring instrument connected in series with ,thewavemeter when the wavemeter is adjusted to current indicated as above when the wavemeter is adjusted to accuracy 82
. Practical wireless telegraphy; a complete text book for students of radio communication . he last oscillationis one-tenth of the initial oscillation. PRACTICAL RADIO MEASUREMENTS. 201 Si = decrement of the circuit under measurement,& =: decrement of the decremeter or wavemeter,Xr =: wave length at resonance, Xi = wave length not more than 3 per cent, to 5 per cent, off resonance,1 ^= current indicated by a measuring instrument connected in series with ,thewavemeter when the wavemeter is adjusted to current indicated as above when the wavemeter is adjusted to accuracy 82 must be small as compared with Si. In terms of the condenser capacity of the wavemeter, the foregoing formula can be writtenas follows. Si -\- Sa = ir ■ / h-—V- (3) Where C = capacity of the wavemeter condenser at resonance; & = capacity of the wavemeter condenser of a certain point off resonance. It has been found for all practical purposes, that if the value of V is selected to be one-half the value of I^ the formula is sufficiently accurate; hence, the integers underneath. Fig. 220—The American Marconi Companys Decremeter. the radical may be cancelled and the combined and total decrement of the two circuits obtainfrom the following simple formula: 5i -|- Sa : Cr — CiCr (4) Now, it is found by experiment that the resonance curve of a radio-transmitter is notalways symmetrical and, therefore, different values for the decrement will be found accord-ingly as the measurement is made on either side of the maximum ordinate. Consequently theresults will be more accurate if the capacity of the condenser is taken above and belowresonance at points where the corresponding flow of current as measured by the wattmeteris one-half the value obtained at resonance; then the mean value of the decrement will bedetermined as follows: 202 PRACTICAL WIRELESS TELEGRAPHY. & Cl T Si 4- ai: (S) O 2 where C» = the capacity of the condenser at a value greater than C, the capacitywhere the read
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
