Topic G4C Quick Review Audio


Which of the following might be useful in reducing RF interference to audio frequency devices?

  1. Bypass inductor
  2. Bypass capacitor
  3. Forward-biased diode
  4. Reverse-biased diode


Which of the following could be a cause of interference covering a wide range of frequencies?

  1. Not using a balun or line isolator to feed balanced antennas
  2. Lack of rectification of the transmitter's signal in power conductors
  3. Arcing at a poor electrical connection
  4. Using a balun to feed an unbalanced antenna


What sound is heard from an audio device or telephone if there is interference from a nearby single sideband phone transmitter?

  1. A steady hum whenever the transmitter is on the air
  2. On-and-off humming or clicking
  3. Distorted speech
  4. Clearly audible speech


What is the effect on an audio device when there is interference from a nearby CW transmitter?

  1. On-and-off humming or clicking
  2. A CW signal at a nearly pure audio frequency
  3. A chirpy CW signal
  4. Severely distorted audio


What might be the problem if you receive an RF burn when touching your equipment while transmitting on an HF band, assuming the equipment is connected to a ground rod?

  1. Flat braid rather than round wire has been used for the ground wire
  2. Insulated wire has been used for the ground wire
  3. The ground rod is resonant
  4. The ground wire has high impedance on that frequency


What effect can be caused by a resonant ground connection?

  1. Overheating of ground straps
  2. Corrosion of the ground rod
  3. High RF voltages on the enclosures of station equipment
  4. A ground loop


Why should soldered joints not be used with the wires that connect the base of a tower to a system of ground rods?

  1. The resistance of solder is too high
  2. Solder flux will prevent a low conductivity connection
  3. Solder has too high a dielectric constant to provide adequate lightning protection
  4. A soldered joint will likely be destroyed by the heat of a lightning strike


Which of the following would reduce RF interference caused by common-mode current on an audio cable?

  1. Placing a ferrite choke around the cable
  2. Adding series capacitors to the conductors
  3. Adding shunt inductors to the conductors
  4. Adding an additional insulating jacket to the cable


How can a ground loop be avoided?

  1. Connect all ground conductors in series
  2. Connect the AC neutral conductor to the ground wire
  3. Avoid using lock washers and star washers when making ground connections
  4. Connect all ground conductors to a single point


What could be a symptom of a ground loop somewhere in your station?

  1. You receive reports of "hum" on your station's transmitted signal
  2. The SWR reading for one or more antennas is suddenly very high
  3. An item of station equipment starts to draw excessive amounts of current
  4. You receive reports of harmonic interference from your station


What technique helps to minimize RF "hot spots" in an amateur station?

  1. Building all equipment in a metal enclosure
  2. Using surge suppressor power outlets
  3. Bonding all equipment enclosures together
  4. Low-pass filters on all feed lines


Which of the following is an advantage of a receiver DSP IF filter as compared to an analog filter?

  1. A wide range of filter bandwidths and shapes can be created
  2. Fewer digital components are required
  3. Mixing products are greatly reduced
  4. The DSP filter is much more effective at VHF frequencies


Why must the metal enclosure of every item of station equipment be grounded?

  1. It prevents a blown fuse in the event of an internal short circuit
  2. It prevents signal overload
  3. It ensures that the neutral wire is grounded
  4. It ensures that hazardous voltages cannot appear on the chassis