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In a superheterodyne radio receiver | |
A. | RF amplifier normally operates at 455 kHz above carrier frequency [Wrong Answer] |
B. | mixer input must be tuned to the signal frequency [Correct Answer] |
C. | local oscillator operates below signal frequency [Wrong Answer] |
D. | local oscillator frequency is double the IF [Wrong Answer] |
View Answer
Explanation:-
Answer : B Discuss it below : !! OOPS Login [Click here] is required to post your answer/result |
Also Read Similar Questions Below :
⇒ An angle modulated signal is given by s(t) = cos 2p (2 x 10^{6}t + 30 sin 150t + 40 cos 150t). The maximum frequency and phase deviations of s(t) are
10.5 kHz, 140p rad
6 kHz and 80p rad
10.5 kHz, 100p rad
7.5 kHz, 100p rad
⇒ The output V_{R} of the ratio detector is related with the output V_{F} of similar Foster-Seeley discriminator as follows.
V_{R} = V_{F}
V_{R} < V_{F}
V_{R} = 2V_{F}
V_{F} = 2V_{R}
⇒ Which of the following is necessary transistor action?
The base region must be very wide
The base region must be very narrow
The base region must be made of some insulating material
The collector region must be heavily doped
⇒ The fluctuation in the received signal strength at the receiver of a random variation in the received signal is known as
fluctuation
fading
absorption
cycling
⇒ In dc tacho generators used for measurement of speed of shaft, frequent calibration is necessary because
contacts wear off
strength of permanent magnet decreases with age
armature current produces heating effect
there is back emf
⇒
Both A and R are true and R is correct explanation of A
Both A and R are true and R is not the correct explanation of A
A is true but R is false
A is false but R is true
⇒ A generator of 50 Ω internal impedance and operating at 1 GHz feeds a 75 Ω load via a coaxial line of characteristic impedance 50 Ω. The VSWR on the feed line is
0.5
1.5
2.5
1.75
⇒ The first dominant pole encountered in the frequency response of a compensated op-amp is approximately at
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10 kHz
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⇒ Full adder circuit can be implemented by
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⇒ In dielectric heating, the thyristor circuits consist of
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⇒ If the transfer function has zeros only on jω axis or in left half plane, it is a minimum phase function.
TRUE
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⇒ If a sequence is causal then ROC is (where a is any number)
|z| > a
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Entire Plane
⇒ The sum of two or more arbitrary sinusoidal is
always periodic
periodic under certain conditions
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periodic only if all the sinusoidals are identical in frequency and phase
⇒ The superposition theorem is applicable to
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⇒ A balanced modulator is used in the generation of which of the following?
DSB-SC signal
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⇒ In TV system in India IF video and IF audio frequencies are
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38.9 and 33.4 MHz respectively
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⇒ In a series LCR circuit the maximum inductor voltage is twice the maximum capacitor voltage however current lags by 30° and drop across the inductance is v_{L} = 100 sin 377t V. Assuming the resistance being 20 Ω, Find the values of the capacitance and inductance.
235 μF, 61.18 μH
230 μF, 61.18 μH
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⇒ Consider the following
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10, 20, 20, 30 respectively
20, 30, 20, 10 respectively
10, 30, 20, 20 respectively
⇒ In a reactance function
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all poles and zeros are simple
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⇒ The fuse material used in electrical lines must have which one of the following properties?
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⇒ A parallel RLC circuit has ω_{0} = 10^{6} and Q = 30, Given C = 30 pF, the value of R is
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⇒ A Hartley oscillator uses
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⇒ A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm.
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47.33
50.33
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⇒ In a two stage cascade amplifier, each stage has a gain of 10 dB and noise figure of 10 dB. The overall noise factor is
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⇒ The reactance of coupling capacitor for AC signals in an amplifier, should be
as low as possible
as high as possible
neither low nor high
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⇒ Out of the three transforms viz. Z-transform, Laplace transform and Fourier transform
all three are used in continuous time domain
all three are used in both continuous time domain and discrete time domain
Z transform is used in continuous time domain while Laplace and Fourier transforms are used in discrete time domain
Z transform is used is discrete time domain while Laplace and Fourier transforms are used in continuous time domain
⇒
Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true
⇒ An angle modulated signal is given by s(t) = cos 2p (2 x 10^{6}t + 30 sin 150t + 40 cos 150t). The maximum frequency and phase deviations of s(t) are
10.5 kHz, 140p rad
6 kHz and 80p rad
10.5 kHz, 100p rad
7.5 kHz, 100p rad
⇒ The output V_{R} of the ratio detector is related with the output V_{F} of similar Foster-Seeley discriminator as follows.
V_{R} = V_{F}
V_{R} < V_{F}
V_{R} = 2V_{F}
V_{F} = 2V_{R}
⇒ Which of the following is necessary transistor action?
The base region must be very wide
The base region must be very narrow
The base region must be made of some insulating material
The collector region must be heavily doped
⇒ The fluctuation in the received signal strength at the receiver of a random variation in the received signal is known as
fluctuation
fading
absorption
cycling
⇒ In dc tacho generators used for measurement of speed of shaft, frequent calibration is necessary because
contacts wear off
strength of permanent magnet decreases with age
armature current produces heating effect
there is back emf
⇒
Assertion (A): Thevenin's theorem helps us to find current in a branch of a network for different values of impedances of that branch.
Reason (R): Thevenin's equivalent circuit replaces a network by a voltage source in series with impedance.
Both A and R are true and R is correct explanation of A
Both A and R are true and R is not the correct explanation of A
A is true but R is false
A is false but R is true
⇒ A generator of 50 Ω internal impedance and operating at 1 GHz feeds a 75 Ω load via a coaxial line of characteristic impedance 50 Ω. The VSWR on the feed line is
0.5
1.5
2.5
1.75
⇒ The first dominant pole encountered in the frequency response of a compensated op-amp is approximately at
5 Hz
10 kHz
1 MHz
100 MHz
⇒ Full adder circuit can be implemented by
Multiplexers
Half adders
AND or OR gates
Decoders
⇒ FET amplifier is more difficult to analyse than BJT amplifier.
TRUE
FALSE
⇒ In dielectric heating, the thyristor circuits consist of
rectifier-chopper combination
controlled rectifier
ac regulator
rectifier-inverter combination
⇒ If the transfer function has zeros only on jω axis or in left half plane, it is a minimum phase function.
TRUE
FALSE
⇒ If a sequence is causal then ROC is (where a is any number)
|z| > a
|z| < a
|z| = a
Entire Plane
⇒ The sum of two or more arbitrary sinusoidal is
always periodic
periodic under certain conditions
never periodic
periodic only if all the sinusoidals are identical in frequency and phase
⇒ The superposition theorem is applicable to
linear, non-linear and time variant responses
linear and non-linear resistors only
linear responses only
none of the above
⇒ A balanced modulator is used in the generation of which of the following?
DSB-SC signal
FM signal
PM signal
PAM signal
⇒ In TV system in India IF video and IF audio frequencies are
33.4 and 28.4 MHz respectively
38.9 and 33.4 MHz respectively
43.8 and 38.9 MHz respectively
33.4 and 38.9 MHz respectively
⇒ In the given fi
0 rad/sec
2 rad/sec
3/2 rad/sec
None of these
⇒ In a series LCR circuit the maximum inductor voltage is twice the maximum capacitor voltage however current lags by 30° and drop across the inductance is v_{L} = 100 sin 377t V. Assuming the resistance being 20 Ω, Find the values of the capacitance and inductance.
235 μF, 61.18 μH
230 μF, 61.18 μH
61.18 μF, 230 μH
None of the above
⇒ Consider the following
ON GO TO
statement in Ba10, 20, 30, 20 respectively
10, 20, 20, 30 respectively
20, 30, 20, 10 respectively
10, 30, 20, 20 respectively
⇒ In a reactance function
all poles are simple
all poles and zeros are simple
all poles and zeros are simple and lie on jω axis only
all poles and zeros lie on negative real axis
⇒ Out of S, R, J, K, Preset, Clear inputs to flip flops, the synchronous inputs are
S, R, J, K only
S, R, Preset, Clear only
Preset, Clear only
S, R only
⇒ The fuse material used in electrical lines must have which one of the following properties?
High resistivity
Low conductivity
High melting point
Low melting point
⇒ A parallel RLC circuit has ω_{0} = 10^{6} and Q = 30, Given C = 30 pF, the value of R is
0
1 μΩ
2 MΩ
1 MΩ
⇒ A Hartley oscillator uses
a tapped capacitor
a tapped inductor
a tapped inductor for inductive feedback
none of the above
⇒ A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm.
49
47.33
50.33
50
⇒ In a two stage cascade amplifier, each stage has a gain of 10 dB and noise figure of 10 dB. The overall noise factor is
10
1.09
1
10.9
⇒ The reactance of coupling capacitor for AC signals in an amplifier, should be
as low as possible
as high as possible
neither low nor high
either low or high
⇒ Out of the three transforms viz. Z-transform, Laplace transform and Fourier transform
all three are used in continuous time domain
all three are used in both continuous time domain and discrete time domain
Z transform is used in continuous time domain while Laplace and Fourier transforms are used in discrete time domain
Z transform is used is discrete time domain while Laplace and Fourier transforms are used in continuous time domain
⇒
Assertion (A): For a dielectric, P = ∈_{0}(∈_{r} - 1) E.
Reason (R): Dipole moment per unit volume is called polarization of dielectric.
Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true