Topic T7C Quick Review Audio


What is the primary purpose of a dummy load?

  1. To prevent transmitting signals over the air when making tests
  2. To prevent over-modulation of a transmitter
  3. To improve the efficiency of an antenna
  4. To improve the signal-to-noise ratio of a receiver


Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency?

  1. A VTVM
  2. An antenna analyzer
  3. A Q meter
  4. A frequency counter


What, in general terms, is standing wave ratio (SWR)?

  1. A measure of how well a load is matched to a transmission line
  2. The ratio of high to low impedance in a feed line
  3. The transmitter efficiency ratio
  4. An indication of the quality of your station's ground connection


What reading on an SWR meter indicates a perfect impedance match between the antenna and the feed line?

  1. 2 to 1
  2. 1 to 3
  3. 1 to 1
  4. 10 to 1


Why do most solid-state amateur radio transmitters reduce output power as SWR increases?

  1. To protect the output amplifier transistors
  2. To comply with FCC rules on spectral purity
  3. Because power supplies cannot supply enough current at high SWR
  4. To improve the impedance match to the feed line


What does an SWR reading of 4:1 indicate?

  1. Loss of -4 dB
  2. Good impedance match
  3. Gain of +4 dB
  4. Impedance mismatch


What happens to power lost in a feed line?

  1. It increases the SWR
  2. It comes back into your transmitter and could cause damage
  3. It is converted into heat
  4. It can cause distortion of your signal


What instrument other than an SWR meter could you use to determine if a feed line and antenna are properly matched?

  1. Voltmeter
  2. Ohmmeter
  3. Iambic pentameter
  4. Directional wattmeter


Which of the following is the most common cause for failure of coaxial cables?

  1. Moisture contamination
  2. Gamma rays
  3. The velocity factor exceeds 1.0
  4. Overloading


Why should the outer jacket of coaxial cable be resistant to ultraviolet light?

  1. Ultraviolet resistant jackets prevent harmonic radiation
  2. Ultraviolet light can increase losses in the cable's jacket
  3. Ultraviolet and RF signals can mix, causing interference
  4. Ultraviolet light can damage the jacket and allow water to enter the cable


What is a disadvantage of air core coaxial cable when compared to foam or solid dielectric types?

  1. It has more loss per foot
  2. It cannot be used for VHF or UHF antennas
  3. It requires special techniques to prevent water absorption
  4. It cannot be used at below freezing temperatures


What does a dummy load consist of?

  1. A high-gain amplifier and a TR switch
  2. A non-inductive resistor and a heat sink
  3. A low-voltage power supply and a DC relay
  4. A 50 ohm reactance used to terminate a transmission line