= A Reactance Modulator =
A reactance modulator changes the frequency of the tank circuit of the oscillator by changing its reactance. This is accomplished by a combination of a resistor, a condenser, and a vacuum tube (the modulator) connected across the tank circuit of the oscillator as in Fig. 33 A, and so adjusted as to act as a variable inductance or capacitance. Fig. 33 A. Principle of a reactance modulator The net result is to change the resonant frequency of the LC circuit by amounts proportional to the instantaneous a.f. voltages applied to the grid of the modulator tube, without changing the resistance of the LC circuit or the amplitude of the oscillations. A modulator circuit is shown in Fig. 33 B. Fig 33 B. A reactance modulator The voltages supplied to both the modulator and oscillator must be carefully stabilized to prevent undesired frequency changes. The speech amplifier (Fig. 33 A) does not have to deliver any power and need supply only a small output voltage, say 10 or 15 volts. A pentode and triode, R-C coupled, will be sufficient even with a sensitive microphone and a high-powered oscillator. The frequency change of LC per volt change on the a.f. grid of the modulator tube will be greater when C1,Fig. 33 B, is made smaller. The blocking condenser C2 has a comparatively high value, and hence offers but small reactance to r.f. currents. Fig. 19 H. An RC phase shifter In Fig. 33 B, the radio-frequency voltages which are developed across the tank in the oscillator circuit also appear across the RC1 circuit and across the parallel 6L7 modulator tube. Now look up the phase-shifting circuit of Fig. 19 H. The resistance r has been replaced by the internal resistance of the modulator tube of Fig. 33 B. The voltage drop across C1 is 90° out of phase with the tank voltage. It is applied to the control grid of the 6L7 whose r.f. plate current responds in the same phase. Thus this current is made to lag 90° behind the tank voltage. The r.f. plate current flows through the tank circuit and, combined with the current therein, is equivalent to a new current whose phase differs from the normal value just as though an additional reactance (not resistance) had been connected in with L and C. This, of course, changes the frequency of the LC circuit and hence of the transmitter. When a.f. is fed into the modulator tube, it causes proportionate changes in the r.f. plate current and hence in the equivalent reactance of the LC circuit.
Inductive reactance.
Inductive reactance does NOT have it own sign or symbol. Rather, it uses Ohms as a quantifier. But Capacitive reactance ALSO uses Ohms as a quantifier. Fortunately, 1 Ohm of Inductive reactance is cancelled by 1 Ohm of Capacitive reactance at the same frequency of measurement.
reactance relay is used for distance protection of the transmission line....
Xc(capacitive reactance) = 1/(2piFC)XL(inductive reactance) = 2piFLWhere pi=3.14etc.,F=frequency and C and L are capacitance and inductance.Please pardon lack of proper symbology.
Inductive reactance case of ac) is equivalent to resistance (in case of dc) for inductors.So if resistance increases current decreasesas well as if inductive reactance increases current decreases
Inductive reactance, as well as capacitive reactance, is measured in ohms.
Inductive reactance.
The reciprocal of reactance is susceptance, expressed in siemens.
The symbol for inductive reactance is XL.
A diode modulator is a type of AM modulator constructed using diodes. One type of diode modulator is the ring modulator shown in the image.
A diode bridge modulator is one kind of balanced modulator.
for inductor, reactance XL = 2*pi* f *L, if frequency doubles then reactance increase. But for capacitor, reactance Xc = 1/(2*pi*f*C). In this case if frequency doubles the reactance decrease.
The overall reactance of the armature winding is the sum of its leakage reactance plus fictitious reactance, which is known as synchronous reactance (Xs).Xs=XL+Xarwhere XL and Xar are in Ω/phase. Therefore, Xs is in Ω/phase.The impedance of armature winding is obtained by combining its resistance and its synchronous reactance.
Inductive reactance does NOT have it own sign or symbol. Rather, it uses Ohms as a quantifier. But Capacitive reactance ALSO uses Ohms as a quantifier. Fortunately, 1 Ohm of Inductive reactance is cancelled by 1 Ohm of Capacitive reactance at the same frequency of measurement.
Because it is. Capacitive reactance is a form of resistance, along with inductive reactance. All are measured in ohms.
A 1999 Jeep transmission does not have a modulator valve.
Resistance is a concept used for DC. the current through a resistance is in phase with the applied voltage Reactance is used for AC the current through a inductive reactance lags the applied voltage by 90 degrees. the current through capacitive reactance leads the applied voltage by 90 degrees. the net reactance is the difference between inductive and capacitive reactance