hal electronics and communication, hals question papers,hal electronics previous year exam papers,

Hindustan Aeronautical Limited

Management Trainee

Electronics And Communication

Q.1.When a large number of analog signals is to be converted to digital form, an analog multiplex or is used. The A to D converter suitable in this case will be ..“

• dual slope type
• up down counter type
• Successive approximation type
• forward counter type

Q.2 .In the formation of Routh's array the situation of a row of zeros indicates that the system-

• has symmetrically located roots
• is not sensitive to variations in gain
• is stable
• is unstable

Q.3 Mark out wrong statement. Modulation is used to-

• Reduce the bandwidth used
• Separate differing transmissions
• Ensure that intelligence may be transmitted over long distances
• Allow the use of practicable antennas

Q.4.Mark out a wrong statement for two phase servo motor-

• The rotor diameter is small
• The rotor resistance is low
• The applied voltages are seldom balanced
• The torque speed characteristic is linear.

Q.5.The frequency deviation in phase modulation is-

• independent of the modulating signal frequency
• inversely proportional to the modulating signal frequency
• directly proportional to the modulating signal frequency.
• inversely proportional to the square root of the modulating frequency.

Q.6.Which power amplifiers has maximum efficiency?

• Class A
• Class AB
• Class B
• Class C

Q.7.Negative resistance characteristics for its operation is used by .....

• TWT
• Klystron
• Magnetron
• MASERS

Q.8..Choose the most appropriate word from the options given below to complete the following sentence. Comparatively few rock musicians are willing to laugh at themselves, although a hint of .......... can boost sales of video clips very nicely.

• self-deprecation
• congeniality
• cynicism
• embarrassment

Q.9.The binary equivalent of 9.37510 is ......

• 1001.011 2
• 1101.101 2
• 100.011 2
• 1111.001 2

Q.10.The output signal amplitudes for1's and 0's in an ADM transmission system ....

• Fixed and the repetition rate is also fixed
• Fixed but the repetition rate is variable
• Variable and the repetition rate is also variable
• variable but the repetition rate is fixed

Q.11.For an RC driving point impedance function, the poles and zeros-

• should alternate on real axis
• should alternate only on the negative real axis
• should alternate on the imaginary axis
• can lie anywhere on the left half place.

Q.12.Mark out wrong statement regarding compndor-

• It compresses the higher amplitude parts of a signal before modulation and expands them back to normal again after demodulation.
• It gives preferential treatment to the weaker parts of the signal
• For weaker signals, it gives a poor ratio of signal strength to quantizing error
• Weaker signals, transverse more quantum steps than they would do otherwise and so quantizing error is reduced

Q.13 .Among other equipment a sub marine cable repeater contains .....

• A dc power supply and regulator
• Filters for the two directions of transmission
• Multiplexing and de-multiplexing equipment
• Pilot inject and pilot extract equipment

Q.14.In a communication system noice is most likely to affect the signal-

• At the transmitter
• In the channel
• In the information source
• At the destination

Q.15.In gunn effect oscillator which mode having lowest operating frequency ....

• mode
• Delayed domain mode
• Quenched domain mode
• LSA mode

Q.16.In Reflex klystron maximum energy transferred to gap by electrons-

• eR
• ee
• el
• eR , ee, el

Q.17.The radio waves get absorbed by atmosphere depends -

• Their distance from transmitter is long
• Wave power is weak
• Improper polarization of wave
• Frequency of waves

Q.18.8085 mP has no of sets of communication lines-

•  2
• 3
• 4
• None

Q.19.The diversity system in Troposcatter links is made use of to-

• a.Increase the bandwidth
• b.Prevent noise effects
• Increase the directivity of the antenna
• d.Detect signal in the presence of fading.

Q.20.The plate efficiency of a class C amplifier is high because-

• A resonant circuit is used as load
• The plate current flows when the instantaneous plate voltage is low.
• The plate current flows only when grid is driven positive
• None of the above

Q.21.The Nyquist plot of G (jw), H (jw) for a closed-loop control system, passes through (-1,j0) point in the GH-plane. The gain margin o the system in dB is equal to

• infinite
• greater than zero
• less than zero
• zero

Q.22. Where is the hole concentration is greatest?

• x = 0
• x = L/2
• x = L
• Uniform

Q.23.Where is the electron concentration is greatest?

• x = 0
• x = L/2
• x = L
• Uniform

Q.24.In a direct election between two contestants, 4% of the votes cost are declared to be illegal. One contestant secures 55% of the valid votes and wins with a majority of 240 votes. What is the total number of votes cost ?

• 2455
• 2400
• 2500
• None of these

Q.25.There are two groups A and B consisting of 30 and 70 students respectively. If the average weight of group A is 30 kg and that of group B is 70 kg. Find the average weight of all the students of group A and group B.

• 58 kg
• 50 kg
• 40 kg
• 12 kg

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PUBLIC SECTOR UNDERTAKING

PSU Study Materials

Electronics & Communication Engg.

Q.1.Power diode is generally made from

• Silicon
• Germanium
• Both
• None of these

Q.2.When the both junction of NPN diode is reverse biased, then the diode is in which mode

• Active
• Cutoff
• Saturation
• inverted

Q.3.Which transistor mode gives the inverted output

• Common Emitter
• Common Base
• Common Collector
• None of these

Q.4.Which coupling gives the higher gain in case of amplifier

• Capacitor coupling
• Impedance coupling
• Transformer coupling
• None of these

Q.5.Which distortion is least objectionable in audio amplification

• Phase
• Frequency
• Harmonic
• Inter mediation

Q.6.A narrow band amplifier has a band pass nearly…………of central frequency

• 33.3%
• 10%
• 50%
• 25%

Q.7.Phase shift oscillator consists

• RL
• RC
• RLC
• LC

Q.8.Multivibrater Produces

• Sine wave
• Square wave
• Smooth wave
• sawtooth

Q.9.Convert the 101101 Binary number into octal no

• 65
• 55
• 51
• 45    

Q.10.The number10 is represented  in BCD Number System

• 10100
• 1100
• 010111
• None of these

Q.11.Which PNP device has a terminal for synchronizing purpose

• SCS
• Triac
• Diac
• SUS

Q.12.Addition of indium in semiconductor crystal makes

• PNP
• NPN
• PNPN
• NPNP

Q.13.Free electron exists in which band

• 1
• 2
• 3
• Conduction band

Q.14.Ripple factor of half wave rectifier

• 1.21
• 0.48
• 0.5
• None of these

Q.15.Transistor that can be used in enhancement mode

• NPN
• UJT
• JFET
• MOSFET

Q.16.Following contributes to harmonic distortion in Amplifier

• +Ve feedback
• –Ve feedback
• Defective active device
• None of these

Q.17.High cutoff frequency

• CB
• CC
• CE
• None of these

Q.18.Which is used as data selector?

• Encoder
• Decoder
• modulator
• Demodulator

Q.19.Read write capable memory

• RAM
• ROM
• Both
• None of these

Q.20.the radix or base of hexadecimal number system is -----------

• 8
• 16
• 5
• none of these

Q.21.the no of 1’s in the binary representation of the expression 162*9+162*7+16*5+3 are

• 10
• 23
• 6
• 4

Q.22.the no of latches in F/F are -------

• 1
• 2
• 3
• 4

Q.23.how many flip-flops are required to construct Mod -12 counter

• 5
• 4
• 12
• none

Q.24.which logic gate has the output is compliment of its input ----------

• OR
• AND
• NOT
• X-OR

Q.25.no.of 2-input multiplexers needed to construct a 210 input multiplexer…….

• 12
• 31
• 20
• 16

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