E4E01:

Which of the following types of receiver noise can often be reduced by use of a receiver noise blanker?

  1. Ignition noise
  2. Broadband white noise
  3. Heterodyne interference
  4. All of these choices are correct

E4E02:

Which of the following types of receiver noise can often be reduced with a DSP noise filter?

  1. Broadband white noise
  2. Ignition noise
  3. Power line noise
  4. All of these choices are correct

E4E03:

Which of the following signals might a receiver noise blanker be able to remove from desired signals?

  1. Signals which are constant at all IF levels
  2. Signals which appear across a wide bandwidth
  3. Signals which appear at one IF but not another
  4. Signals which have a sharply peaked frequency distribution

E4E04:

How can conducted and radiated noise caused by an automobile alternator be suppressed?

  1. By installing filter capacitors in series with the DC power lead and a blocking capacitor in the field lead
  2. By installing a noise suppression resistor and a blocking capacitor in both leads
  3. By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead
  4. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

E4E05:

How can noise from an electric motor be suppressed?

  1. By installing a high pass filter in series with the motor's power leads
  2. By installing a brute-force AC-line filter in series with the motor leads
  3. By installing a bypass capacitor in series with the motor leads
  4. By using a ground-fault current interrupter in the circuit used to power the motor

E4E06:

What is a major cause of atmospheric static?

  1. Solar radio frequency emissions
  2. Thunderstorms
  3. Geomagnetic storms
  4. Meteor showers

E4E07:

How can you determine if line noise interference is being generated within your home?

  1. By checking the power line voltage with a time domain reflectometer
  2. By observing the AC power line waveform with an oscilloscope
  3. By turning off the AC power line main circuit breaker and listening on a battery operated radio
  4. By observing the AC power line voltage with a spectrum analyzer

E4E08:

What type of signal is picked up by electrical wiring near a radio antenna?

  1. A common-mode signal at the frequency of the radio transmitter
  2. An electrical-sparking signal
  3. A differential-mode signal at the AC power line frequency
  4. Harmonics of the AC power line frequency

E4E09:

What undesirable effect can occur when using an IF noise blanker?

  1. Received audio in the speech range might have an echo effect
  2. The audio frequency bandwidth of the received signal might be compressed
  3. Nearby signals may appear to be excessively wide even if they meet emission standards
  4. FM signals can no longer be demodulated

E4E10:

What is a common characteristic of interference caused by a touch controlled electrical device?

  1. The interfering signal sounds like AC hum on an AM receiver or a carrier modulated by 60 Hz hum on a SSB or CW receiver
  2. The interfering signal may drift slowly across the HF spectrum
  3. The interfering signal can be several kHz in width and usually repeats at regular intervals across a HF band
  4. All of these choices are correct

E4E11:

Which is the most likely cause if you are hearing combinations of local AM broadcast signals within one or more of the MF or HF ham bands?

  1. The broadcast station is transmitting an over-modulated signal
  2. Nearby corroded metal joints are mixing and re-radiating the broadcast signals
  3. You are receiving sky wave signals from a distant station
  4. Your station receiver IF amplifier stage is defective

E4E12:

What is one disadvantage of using some types of automatic DSP notch-filters when attempting to copy CW signals?

  1. A DSP filter can remove the desired signal at the same time as it removes interfering signals
  2. Any nearby signal passing through the DSP system will overwhelm the desired signal
  3. Received CW signals will appear to be modulated at the DSP clock frequency
  4. Ringing in the DSP filter will completely remove the spaces between the CW characters

E4E13:

What might be the cause of a loud roaring or buzzing AC line interference that comes and goes at intervals?

  1. Arcing contacts in a thermostatically controlled device
  2. A defective doorbell or doorbell transformer inside a nearby residence
  3. A malfunctioning illuminated advertising display
  4. All of these choices are correct

E4E14:

What is one type of electrical interference that might be caused by the operation of a nearby personal computer?

  1. A loud AC hum in the audio output of your station receiver
  2. A clicking noise at intervals of a few seconds
  3. The appearance of unstable modulated or unmodulated signals at specific frequencies
  4. A whining type noise that continually pulses off and on

E4E15:

Which of the following can cause shielded cables to radiate or receive interference?

  1. Low inductance ground connections at both ends of the shield
  2. Common mode currents on the shield and conductors
  3. Use of braided shielding material
  4. Tying all ground connections to a common point resulting in differential mode currents in the shield

E4E16:

What current flows equally on all conductors of an unshielded multi-conductor cable?

  1. Differential-mode current
  2. Common-mode current
  3. Reactive current only
  4. Return current