For what portion of the signal cycle does each active element in a push-pull Class AB amplifier conduct?

  1. More than 180 degrees but less than 360 degrees
  2. Exactly 180 degrees
  3. The entire cycle
  4. Less than 180 degrees


What is a Class D amplifier?

  1. A type of amplifier that uses switching technology to achieve high efficiency
  2. A low power amplifier that uses a differential amplifier for improved linearity
  3. An amplifier that uses drift-mode FETs for high efficiency
  4. A frequency doubling amplifier


Which of the following components form the output of a class D amplifier circuit?

  1. A low-pass filter to remove switching signal components
  2. A high-pass filter to compensate for low gain at low frequencies
  3. A matched load resistor to prevent damage by switching transients
  4. A temperature compensating load resistor to improve linearity


Where on the load line of a Class A common emitter amplifier would bias normally be set?

  1. Approximately halfway between saturation and cutoff
  2. Where the load line intersects the voltage axis
  3. At a point where the bias resistor equals the load resistor
  4. At a point where the load line intersects the zero bias current curve


What can be done to prevent unwanted oscillations in an RF power amplifier?

  1. Tune the stage for maximum SWR
  2. Tune both the input and output for maximum power
  3. Install parasitic suppressors and/or neutralize the stage
  4. Use a phase inverter in the output filter


Which of the following amplifier types reduces even-order harmonics?

  1. Push-push
  2. Push-pull
  3. Class C
  4. Class AB


Which of the following is a likely result when a Class C amplifier is used to amplify a single-sideband phone signal?

  1. Reduced intermodulation products
  2. Increased overall intelligibility
  3. Signal inversion
  4. Signal distortion and excessive bandwidth


How can an RF power amplifier be neutralized?

  1. By increasing the driving power
  2. By reducing the driving power
  3. By feeding a 180-degree out-of-phase portion of the output back to the input
  4. By feeding an in-phase component of the output back to the input


Which of the following describes how the loading and tuning capacitors are to be adjusted when tuning a vacuum tube RF power amplifier that employs a Pi-network output circuit?

  1. The loading capacitor is set to maximum capacitance and the tuning capacitor is adjusted for minimum allowable plate current
  2. The tuning capacitor is set to maximum capacitance and the loading capacitor is adjusted for minimum plate permissible current
  3. The loading capacitor is adjusted to minimum plate current while alternately adjusting the tuning capacitor for maximum allowable plate current
  4. The tuning capacitor is adjusted for minimum plate current, and the loading capacitor is adjusted for maximum permissible plate current


In Figure E7-1, what is the purpose of R1 and R2?

  1. Load resistors
  2. Voltage divider bias
  3. Self bias
  4. Feedback
Circuit Diagram


In Figure E7-1, what is the purpose of R3?

  1. Fixed bias
  2. Emitter bypass
  3. Output load resistor
  4. Self bias
Circuit Diagram


What type of amplifier circuit is shown in Figure E7-1?

  1. Common base
  2. Common collector
  3. Common emitter
  4. Emitter follower
Circuit Diagram


Which of the following describes an emitter follower (or common collector) amplifier?

  1. A two-transistor amplifier with the emitters sharing a common bias resistor
  2. A differential amplifier with both inputs fed to the emitter of the input transistor
  3. An OR circuit with only one emitter used for output
  4. An amplifier with a low impedance output that follows the base input voltage


Why are switching amplifiers more efficient than linear amplifiers?

  1. Switching amplifiers operate at higher voltages
  2. The power transistor is at saturation or cutoff most of the time
  3. Linear amplifiers have high gain resulting in higher harmonic content
  4. Switching amplifiers use push-pull circuits


What is one way to prevent thermal runaway in a bipolar transistor amplifier?

  1. Neutralization
  2. Select transistors with high beta
  3. Use a resistor in series with the emitter
  4. All these choices are correct


What is the effect of intermodulation products in a linear power amplifier?

  1. Transmission of spurious signals
  2. Creation of parasitic oscillations
  3. Low efficiency
  4. All these choices are correct


Why are odd-order rather than even-order intermodulation distortion products of concern in linear power amplifiers?

  1. Because they are relatively close in frequency to the desired signal
  2. Because they are relatively far in frequency from the desired signal
  3. Because they invert the sidebands causing distortion
  4. Because they maintain the sidebands, thus causing multiple duplicate signals


What is a characteristic of a grounded-grid amplifier?

  1. High power gain
  2. High filament voltage
  3. Low input impedance
  4. Low bandwidth