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T7A01

PRACTICAL CIRCUITS · Station equipment: receivers, transceivers, transmitter amplifiers, RF preamplifiers, transverters; Basic radio circuit concepts and terminology: sensitivity, selectivity, mixers, oscillators, Push-To-Talk (PTT), VFO, modulation

T7A01T7A →

Which term describes the ability of a receiver to detect the presence of a signal?

  1. ARF gain
  2. BSensitivity
  3. CSelectivity
  4. DTotal Harmonic Distortion
Why Sensitivity is the measure of how weak a signal a receiver can still detect and turn into usable audio. It is usually specified in microvolts or dBm for a given signal-to-noise ratio, so a receiver rated 0.2 microvolts is more sensitive than one rated 1 microvolt. It depends mostly on the gain and noise figure of the front end stages.
Watch out Selectivity is the other common receiver spec, but it describes how well the receiver rejects adjacent signals, not how weak a signal it can hear. RF gain is just a front-end level control, and total harmonic distortion is an audio or transmitter purity measure.
Sensitivity = Sense the weak signal. Selectivity = Select one signal out of many.
HamSandwich explanation, first draft. The question and answers are the NCVEC text.
All of T7A T7A02 →

The rest of T7A

  1. T7A01 Which term describes the ability of a receiver to detect the presence of a signal?
  2. T7A02 What is a transceiver?
  3. T7A03 Which of the following is used to convert a signal from one frequency to another?
  4. T7A04 Which term describes the ability of a receiver to discriminate between multiple signals?
  5. T7A05 What is the name of a circuit that generates a signal at a specific frequency?
  6. T7A06 What device converts the RF input and output of a transceiver to another band?
  7. T7A07 What is the function of a transceiver's PTT input?
  8. T7A08 Which of the following describes combining speech with an RF carrier signal?
  9. T7A09 What is the function of the switch which selects either SSB or CW-FM on some VHF power amplifiers?
  10. T7A10 What can be added to the output of a transceiver to increase the transmitted output power?
  11. T7A11 What is the function of the Variable Frequency Oscillator (VFO) circuit in a transceiver?
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