The main function of the transformer used in the output of a power amplifier is 

(A) To step up the voltage 

(B) to increase the voltage gain 

(C) to safeguard the transistor against overheating 

(D) to match the load impedance with dynamic output resistance of the transistor

1 Answer

Answer :

The main function of the transformer used in the output of a power amplifier is to match the load impedance with dynamic output resistance of the transistor

Related questions

Description : In an IF amplifier, the IF transformer is provided with tapping to  (a) increase the voltage gain (b) increase the bandwidth of the resonance circuit (c) increase the impedance ... resonance circuit to the following cascaded amplifier (d) increase the quality factor of the resonance circuit 

Last Answer : In an IF amplifier, the IF transformer is provided with tapping to increase the voltage gain

Description : An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 would be: (1) 1/11 kΩ (2) 1/5 kΩ (3) 5 kΩ (4) 11 kΩ

Last Answer : An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 would be: 1/11 kΩ

Description : For Cascode amplifier the output impedance becomes 

Last Answer : For Cascode amplifier the output impedance becomes very high

Description : An operational amplifier has an open loop gain of 200,000. Its output exhibits saturation at 10V. The threshold differential voltage of the amplifier is  A) 25 micro-volt B) 50 micro-volt C) 5 Volts D) 10 volts

Last Answer : An operational amplifier has an open loop gain of 200,000. Its output exhibits saturation at 10V. The threshold differential voltage of the amplifier is 50 micro-volt

Description : In Class ‘B’ amplifier, the output current flows for

Last Answer : In Class ‘B’ amplifier, the output current flows for half input cycle

Description : The main component responsible for the fall of gain of an RC coupled amplifier in low frequency range is  (A) The active device itself (tube, or transistor)  (B) stray shunt capacitance Cs  (C) the grid leak resistance Rg  (D) coupling capacitor Cc

Last Answer : The main component responsible for the fall of gain of an RC coupled amplifier in low frequency range is coupling capacitor Cc

Description : In class - A power amplifier, the collector dissipation is maximum when  (a) no signal is present  (b) signal swing is maximum  (c) signal swing is (1/1.414) of its maximum  (d) none of the above

Last Answer : In class - A power amplifier, the collector dissipation is maximum when no signal is present

Description : Just as a voltage amplifier signal voltage a power amplifier.  1.amplifier power  2.amplifier signal  3.converts the signal ac power into DC power  4.converts a dc power into useful AC power 

Last Answer : Just as a voltage amplifier signal voltage a power amplifier.  1.amplifier power  2.amplifier signal  3.converts the signal ac power into DC power  4.converts a dc power into useful AC power 

Description : The unity gain bandwidth of an inverting amplifier is 10 MHz What would be the bandwidth if the gain is increased to 10 V/V? A) 100 MHz B) 1 MHz C) 10 MHz D) 1 kHz 

Last Answer : The unity gain bandwidth of an inverting amplifier is 10 MHz What would be the bandwidth if the gain is increased to 10 V/V? A) 100 MHz B) 1 MHz C) 10 MHz D) 1 kHz 

Description : The ideal operational amplifier does not have: (1) Infinite input resistance (2) Infinite output resistance (3) Infinite voltage gain (4) Infinite bandwidth 

Last Answer : The ideal operational amplifier does not have: Infinite output resistance

Description : The gain of an FET amplifier can be changed by changing: (1) rm (2) gm (3) Rd (4) None of these

Last Answer : The gain of an FET amplifier can be changed by changing: gm

Description : If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is (a) – 13.3 (b) 200 (c) 8 (d) 10 

Last Answer : If the Feedback Factor of an amplifier is 0.1 and its gain without feedback is 40, then feedback is 40,then its gain with feedback is 8.

Description : A low noise amplifier has an effective noise temperature of 50 k. The absolute noise figure is

Last Answer : A low noise amplifier has an effective noise temperature of 50 k. The absolute noise figure is 1.172

Description : An amplifier operating over the frequency range from 18 to 20 MHz has 10 kilo ohm input resistor. What is the r.m.s. noise voltage at the input to this amplifier if the ambient temperature is 27o C

Last Answer : An amplifier operating over the frequency range from 18 to 20 MHz has 10 kilo ohm input resistor. What is the r.m.s. noise voltage at the input to this amplifier if the ambient temperature is 27o C 18.2 microvolt

Description : For a feedback amplifier, if the loop gain is much greater than unity, the closed loop gain will be equal to

Last Answer : For a feedback amplifier, if the loop gain is much greater than unity, the closed loop gain will be equal to inverse of feedback factor

Description : An amplifier without feedback has a gain of 1000. The gain with a negative feedback of 0.009 is  A) 10 B) 100 C) 125 D) 900

Last Answer : 100

Description : In a radio receiver the IF amplifier  (A) is tuned above the stations incoming frequency (B) amplifies the output of local oscillator (C) is fixed tuned to one particular frequency (D) can be tuned to various isolate frequencies

Last Answer : In a radio receiver the IF amplifier is fixed tuned to one particular frequency

Description : Class A amplifier is used when  (A) No phase inversion is required (B) Highest voltage gain is required (C) dc voltages are to be amplified (D) Minimum distortion is desired. 

Last Answer : Class A amplifier is used when Minimum distortion is desired. 

Description : Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will   (A) Amplify the noise as much as the signal (B) Reduce the noise (C) Increase the noise (D) Not effect the noise

Last Answer : Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will Reduce the noise

Description : In a Klystron amplifier, the RF voltage produces  (a) amplitude modulation (b) frequency modulation (c) phase modulation (d) velocity modulation

Last Answer : In a Klystron amplifier, the RF voltage produces velocity modulation

Description : The efficiency of a class B push-pull amplifier is

Last Answer : The efficiency of a class B push-pull amplifier is 75-80%

Description : Which of the following amplifier has the least distortion. • Class E • Class D • Class C • Class A

Last Answer : Which of the following amplifier has the least distortion. • Class E • Class D • Class C • Class A

Description : The battery operated pre-amplifier with a consumption of 10 Watts can work on battery of 12 volt, 100 AH having efficiency of 50% for • 120 hrs. • 60 hrs. • 100 hrs. • 10 hrs.

Last Answer : The battery operated pre-amplifier with a consumption of 10 Watts can work on battery of 12 volt, 100 AH having efficiency of 50% for 60 hrs.

Description : In class-A amplifier conduction extends over 360° because the operating point.  1. Located near saturation point 2. Located at or near cut-off point 3. Located on load line 4. Located in the centre of load line 

Last Answer : In class-A amplifier conduction extends over 360° because the operating point.  1. Located near saturation point 2. Located at or near cut-off point 3. Located on load line 4. Located in the centre of load line 

Description : The voltage gain of a common base amplifier depends on  1. Load resistor RL 2. input resistance of transistor 3. Ac alpha 4. All the above 

Last Answer : The voltage gain of a common base amplifier depends on  1. Load resistor RL 2. input resistance of transistor 3. Ac alpha 4. All the above 

Description : Harmonic distortion of the signal is produced in an RC coupled transistor amplifier. The probable component responsible for this distortion is  (A) The transistor itself  (B) the power supply Vcc  (C) the coupling capacitor Cc  (D) the biasing resistors

Last Answer : Harmonic distortion of the signal is produced in an RC coupled transistor amplifier. The probable component responsible for this distortion is The transistor itself 

Description : Negative feedback in an amplifier is accompanied by (A) Gain less sensitive to component variations (B) Increase in gain (C) Decrease in bandwidth (D) None of the above

Last Answer : Negative feedback in an amplifier is accompanied by Gain less sensitive to component variations 

Description : What is the importance of negative feedback in the operational amplifier? (A) It maintains the gain (B) The voltage difference between the input terminals is maintained at a very small value ( ... value (D) The voltage difference between the input terminals is maintained at a very high value

Last Answer : The voltage difference between the input terminals is maintained at a very small value

Last Answer : The closed-loop voltage gain of an inverting amplifier equal to The feedback resistance divided by the input resistance.

Description : The voltage at the reference electrode of the circuit shown in the illustration is applied to the input of a/an ______________. EL-0090 A. class A detector whose output drives an ... drives an 2-stage isolation transformer D. magnetic amplifier whose output controls a saturable reactor

Last Answer : Answer: D

Description : When the initial slope of input sine wave is greater than the slew rate of an OPAMP, the output: (1) Has no offset (2) Approaches to triangular waveshape (3) Is pure sinusoidal (4) Is square wave 

Last Answer : When the initial slope of input sine wave is greater than the slew rate of an OPAMP, the output: Approaches to triangular waveshape

Description : The transistor configuration to connect 4 W speaker with 600 W output impedance audio amplifier is • Common Emitter • Common Base • Common Collector • None of the above.

Last Answer : The transistor configuration to connect 4 W speaker with 600 W output impedance audio amplifier is Common Collector

Description : Basic operating characteristics of the operational amplifier such as gain and stability are the function of its _____________. A. differential input stage B. power output stage C. feedback circuit D. supply voltages

Last Answer : Answer: C

Description : As shown in the illustration, the circuit which 'shapes' the linear output of the thrust lever so that the steady-state ship speed is linear with respect to that lever's setting is the _____________. EL-0095 A. 'pitch controller' B. 'error amplifier' C. 'function generator' D. 'servo amplifier'

Last Answer : Answer: C

Description : In the illustrated electronic governor, the circuit card connected to the potential and current transformers is for ________. EL-0046 A. increasing the signal strength to the governor to ... from motorization D. conditioning the load through the use of a magnetic amplifier current transformer

Last Answer : Answer: A

Description : In the illustration, the component VR2 on the A1 AMPLIFIER MODULE is _________. EL-0060 A. a zener diode to regulate the +9 volt power supply from common B. a variable resistor diode to control the output to terminal ... 2 at 9.1 volts DC D. a tunnel diode with a breakdown voltage of 6.6 Volts DC

Last Answer : Answer: C

Description : In the illustration, the component VR1 on the A1 AMPLIFIER MODULE is _________. EL-0060 A. a zener diode to regulate the +9 volt power supply from common B. a variable resistor diode to control the output to ... terminal 9 at 6.6 volts DC D. a tunnel diode with a breakdown voltage of 6.6 Volts DC

Last Answer : Answer: A

Description : In the illustrated circuit, what is the phase relationship of the amplifier output compared to the input? EL-0022 A. 0° in-phase B. 180° out of phase C. phase angle of the input divided by power factor D. unable to determine without the value of the bias voltage

Last Answer : Answer: B

Description : To provide its unique characteristics to analog circuits, the operational amplifier is made up of a/an ______________. A. voltage amp, current amp and output amp B. input amp, power amp and output amp C. scaling amp, power amp and voltage amp D. differential amp, voltage amp and output amp

Last Answer : Answer: D

Description : Indicate the false statement. Noise figure is defined as A. the ratio of the S/N power supplied at the input terminal of a receiver or amplifier to the S/N power supplied to the output or ... under test, both working at the same temperature over the same bandwidth and fed from the same source

Last Answer : C. an unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signals

Description : One of the following is a high powered RF ac basic transmitter that has two or more stages, the oscillator stage which determines the frequency opereation and RF amplifier stage orstages that develop the ... to develop a good frequency stability. A. Goldsmith B. MOPA C. Alexanderson D. Hartley

Last Answer : B. MOPA

Description : What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna ... D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

Last Answer : D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

Description : Amplifier produces output with more A. power only B. voltage only C. current only D. power and voltage

Last Answer : power and voltage

Description : In the power amplifier shown in figure 2-10, what two signals are mixed to produce the output signal?

Last Answer : Local oscillator and coherent oscillator.

Description : What type coupling is usually used to couple the output from a power amplifier?

Last Answer : Transformer coupling.

Description : Draw the single stage class A power amplifier circuit diagram and draw the input and output waveforms.

Last Answer : Circuit diagram:- Input / Output waveforms:-

Description : An amplifier has input power of 2 microwatts. The power gain of the amplifier is 60 dB. The output power will be

Last Answer : An amplifier has input power of 2 microwatts. The power gain of the amplifier is 60 dB. The output power will be 2 watts

Description : The type of power amplifier that exhibits crossover distortion in its output is : (A) Class A (B) Class B (C) Class AB (D) Class C

Last Answer : The type of power amplifier that exhibits crossover distortion in its output is  Class B

Description : The diagram shown in the illustration represents a/an _____________. EL-0082 A. stepup transformer B. magnetic amplifier C. autotransformer D. Scott-connected transformer

Last Answer : Answer: A