E4D01:

What is meant by the blocking dynamic range of a receiver?

  1. The difference in dB between the noise floor and the level of an incoming signal which will cause 1 dB of gain compression
  2. The minimum difference in dB between the levels of two FM signals which will cause one signal to block the other
  3. The difference in dB between the noise floor and the third order intercept point
  4. The minimum difference in dB between two signals which produce third order intermodulation products greater than the noise floor

E4D02:

Which of the following describes two problems caused by poor dynamic range in a communications receiver?

  1. Cross-modulation of the desired signal and desensitization from strong adjacent signals
  2. Oscillator instability requiring frequent retuning and loss of ability to recover the opposite sideband
  3. Cross-modulation of the desired signal and insufficient audio power to operate the speaker
  4. Oscillator instability and severe audio distortion of all but the strongest received signals

E4D03:

How can intermodulation interference between two repeaters occur?

  1. When the repeaters are in close proximity and the signals cause feedback in the final amplifier of one or both transmitters
  2. When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters
  3. When the signals from the transmitters are reflected out of phase from airplanes passing overhead
  4. When the signals from the transmitters are reflected in phase from airplanes passing overhead

E4D04:

Which of the following may reduce or eliminate intermodulation interference in a repeater caused by another transmitter operating in close proximity?

  1. A band-pass filter in the feed line between the transmitter and receiver
  2. A properly terminated circulator at the output of the transmitter
  3. A Class C final amplifier
  4. A Class D final amplifier

E4D05:

What transmitter frequencies would cause an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?

  1. 146.34 MHz and 146.61 MHz
  2. 146.88 MHz and 146.34 MHz
  3. 146.10 MHz and 147.30 MHz
  4. 173.35 MHz and 139.40 MHz

E4D06:

What is the term for unwanted signals generated by the mixing of two or more signals?

  1. Amplifier desensitization
  2. Neutralization
  3. Adjacent channel interference
  4. Intermodulation interference

E4D07:

Which describes the most significant effect of an off-frequency signal when it is causing cross-modulation interference to a desired signal?

  1. A large increase in background noise
  2. A reduction in apparent signal strength
  3. The desired signal can no longer be heard
  4. The off-frequency unwanted signal is heard in addition to the desired signal

E4D08:

What causes intermodulation in an electronic circuit?

  1. Too little gain
  2. Lack of neutralization
  3. Nonlinear circuits or devices
  4. Positive feedback

E4D09:

What is the purpose of the preselector in a communications receiver?

  1. To store often-used frequencies
  2. To provide a range of AGC time constants
  3. To increase rejection of unwanted signals
  4. To allow selection of the optimum RF amplifier device

E4D10:

What does a third-order intercept level of 40 dBm mean with respect to receiver performance?

  1. Signals less than 40 dBm will not generate audible third-order intermodulation products
  2. The receiver can tolerate signals up to 40 dB above the noise floor without producing third-order intermodulation products
  3. A pair of 40 dBm signals will theoretically generate a third-order intermodulation product with the same level as the input signals
  4. A pair of 1 mW input signals will produce a third-order intermodulation product which is 40 dB stronger than the input signal

E4D11:

Why are third-order intermodulation products created within a receiver of particular interest compared to other products?

  1. The third-order product of two signals which are in the band of interest is also likely to be within the band
  2. The third-order intercept is much higher than other orders
  3. Third-order products are an indication of poor image rejection
  4. Third-order intermodulation produces three products for every input signal within the band of interest

E4D12:

What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?

  1. Desensitization
  2. Quieting
  3. Cross-modulation interference
  4. Squelch gain rollback

E4D13:

Which of the following can cause receiver desensitization?

  1. Audio gain adjusted too low
  2. Strong adjacent channel signals
  3. Audio bias adjusted too high
  4. Squelch gain misadjusted

E4D14:

Which of the following is a way to reduce the likelihood of receiver desensitization?

  1. Decrease the RF bandwidth of the receiver
  2. Raise the receiver IF frequency
  3. Increase the receiver front end gain
  4. Switch from fast AGC to slow AGC