Description : ECE Board Exam November 1996 What is the applied power if a thermal RF wattmeter is connected to a transmitter through a variable attenuator? The wattmeter reads 84 mW when 15 dB of attenuation is used. A. 4.656 watts B. 2.656 watts C. 3.656 watts D. 2.856 watts
Last Answer : B. 2.656 watts
Last Answer : A. PAM
Description : What is the most common form of coupling for an rf amplifier?
Last Answer : Transformer coupling.
Description : The most common source of excitation for synchronous motors is a/an _____________. A. low voltage battery B. motor attenuator set C. DC exciter generator D. AC supply
Last Answer : Answer: C
Description : What is the most common method of testing resistive terminations?
Last Answer : Reading their resistances with a standard ohmmeter
Description : What two methods are used to compensate for the problems that cause low gain in an rf amplifier?
Last Answer : . RF transformers are used and the transistor is neutralized.
Description : What problem is caused in an rf amplifier by a loosely coupled transformer?
Last Answer : A too-narrow bandpass.
Description : Can a parallel LC circuit be used as the frequency determining network for an rf amplifier?
Last Answer : Yes.
Description : What is the purpose of a frequency-determining network in an rf amplifier?
Last Answer : To provide maximum impedance at the desired frequency.
Description : If current gain is required from an rf amplifier, what type of component should be used as an output coupling element?
Last Answer : A step-down transformer.
Description : What is the result of pulsing a pulsed rf amplifier when no rf is present?
Last Answer : Oscillations at an undesired frequency.
Description : The Doppler effect causes a change in what aspect of rf energy that strikes a moving object?
Last Answer : Frequency.
Description : Rotation of an rf-feed source to produce a conical scan pattern is identified by what term?
Last Answer : Nutation.
Description : Atmospheric interference with the travel of electromagnetic energy increases with what rf energy characteristic?
Description : At what point on an open-circuited rf line do voltage peaks occur?
Last Answer : At 1/2 wavelength from the end and at every 1/2 wavelength along the line
Description : If the rf amplifier discussed has an 80 milliwatt input, what would be the maximum output?
Last Answer : 800 watts.
Description : Normally, how are high-power rf tubes tested?
Last Answer : In their circuit.
Description : Name the three main sections of a typical rf signal generator.
Last Answer : Oscillator circuit, modulator, and output control circuit.
Description : If a wave's electric lines of force rotate through 360 degrees with every cycle of rf energy, what is the polarization of this wave?
Last Answer : Circular polarization.
Description : How does the reactance-tube modulator impress intelligence onto an rf carrier?
Last Answer : By changing the reactance of an oscillator circuit in consonance with the modulating voltage.
Description : For what class of operation is the final rf power amplifier of a plate-modulator circuit biased?
Last Answer : Class C
Description : Repressor binds to DNA sequence and regulate the transcription. This sequence is called (A) Attenuator (B) Terminator (C) Anti terminator (D) Operator
Last Answer : Answer : D
Description : A component that samples the microwave signal travelling in one direction down to the transmission line A. Isolator B. Combiner C. Directional coupler D. Attenuator
Last Answer : C. Directional coupler
Description : Circuit used to amplify the optical signal in fiber optics communications links. A. Attenuator B. Optical repeater C. Optical amplifier D. Generator
Last Answer : B. Optical repeater
Description : A device that reduces the intensity of light in fiber optics communication systems. A. Reducer B. Quality factor C. Optical attenuator D. Compressor
Last Answer : C. Optical attenuator
Description : Which of the following circuit is used as a 'Memory device' in computers? 1) Rectifier 2) Flip-Flop 3) Comparator 4) Attenuator
Last Answer : 2) Flip-Flop
Description : Which of the following circuit is used as 'Memory device' in computers ? (1) Rectifier (2) Flip-Flop (3) Comparator (4) Attenuator
Last Answer : Flip-Flop
Description : A method of multiple accessing where a given RF channel bandwidth is divided inot smaller frequency band. A. CDMA B. ANIK-D C. TDMA D. FDMA
Last Answer : D. FDMA
Description : The ac bypassing of RF by CF in a common emitter configuration : (A) increases ac signal across emitter -base junction (B) decreases ac signal across emitter -base junction (C) decreases voltage amplification (D) stabilizes the Q -point
Last Answer : The ac bypassing of RF by CF in a common emitter configuration : increases ac signal across emitter -base junction
Description : What is the most common method of terminating and splicing wires?
Last Answer : The use of preinsulated splices and terminal lugs
Description : The most common method of creating a backup for a microcomputer is what?
Last Answer : Use a floppy disk and the diskcopy procedure.
Description : What is the most common method for erasing a hard disk?
Last Answer : Reformat the disk.
Description : When you are testing the gain of an audio-frequency transistor with an ohmmeter, what is indicated by a 10-to-1 resistance ratio?
Last Answer : Normal gain.
Description : What must be done to a circuit before you can use an ohmmeter for testing?
Last Answer : It must be de-energized.
Description : When you are testing a piece of equipment for intermodulation distortion, what should the output of the equipment look like?
Last Answer : An exact reproduction of the input.
Description : When you are testing an inductor with a Hay bridge, the characteristics of the inductor are compared with what type of device?
Last Answer : A standard capacitor
Description : In swept-frequency testing the impedance of a transmission line, what electrical characteristic is actually being measured?
Last Answer : Swr on the transmission line.
Description : What is the purpose of swept-frequency testing?
Last Answer : To determine various characteristics of a component, piece of equipment, or system over its operational frequency range
Description : When you are testing individual components in a circuit, what may cause a defective component to appear good?
Last Answer : A parallel resistor or diode of similar value.
Description : When testing an SCR with an ohmmeter, the SCR will conduct if what two elements are shorted together?
Last Answer : Gate and anode.
Description : Why are digital multimeters well suited for testing sensitive devices?
Last Answer : The current flow through the component is limited to 1 milliamp.
Description : Which of the following helps in monitoring the Test Progress:- i. Percentage of Test Case Execution ii. Percentage of work done in test environment preparation. iii. Defect Information e.g. defect density, ... ii,iii are correct and iv is incorrect c) i,ii are correct and iii,iv are incorrect
Last Answer : b) i,ii,iii are correct and iv is incorrect
Description : What signal is used to synchronize the coherent oscillator to a fixed phase relationship with the transmitted pulse?
Last Answer : Coho lock pulse.
Description : What type of target has a fixed phase relationship from one receiving period to the next?
Last Answer : Stationary.
Description : Which of the two types of deflection coils (fixed or rotating) is used most often?
Last Answer : Fixed.
Description : When are fixed skew errors most likely to show up?
Last Answer : When you record on one tape recorder and then reproduce on a different recorder.
Description : How can you minimize fixed skew?
Last Answer : Adjust the recorder’s electronics or realign the magnetic heads
Description : The multi-track tape recorder in your computer system has a fixed skew error. What does this mean and what is the probable cause?
Last Answer : Skew means there are time differences between the individual tracks of a multi-track recorder’s magnetic head. It happens when the tape isn’t properly aligned with the head. Fixed skew happens when the tape passes over an improperly aligned magnetic head.
Description : What are three advantages of adding an ac bias voltage to the input signal instead of adding a fixed dc bias voltage?
Last Answer : a. Reproduces a stronger output signal. b. Greatly improves the SNR. c. Greatly reduces the natural tape hiss.
Description : What gyro property causes the gyro to remain in a fixed position?
Last Answer : Rigidity.