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Learn / Amateur Extra course

Lesson 9: Amateur Practices

Lesson 9 of 10, syllabus topic E4. The exam asks 5 questions from this topic, one from each of its 5 groups.

Amateur practices at this level are measurement and receiver performance, which draw on the circuit and signal lessons.

What you will learn

  • E4A Test equipment: analog and digital instruments; spectrum analyzers; antenna analyzers; oscilloscopes; RF measurements
  • E4B Measurement technique and limitations: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of Q; instrument calibration; S parameters; vector network analyzers; RF signals
  • E4C Receiver performance: phase noise, noise floor, image rejection, minimum detectable signal (MDS), increasing signal-to-noise ratio and dynamic range, noise figure, reciprocal mixing; selectivity; SDR non-linearity; use of attenuators at low frequencies
  • E4D Receiver performance characteristics: dynamic range; intermodulation and cross-modulation interference; third-order intercept; desensitization; preselector; sensitivity; link margin
  • E4E Noise and interference: external RF interference; electrical and computer noise; line noise; DSP filtering and noise reduction; common-mode current; surge protectors; single point ground panel

1. Read

No guide covers this topic yet, so the explained questions are the reading for this lesson. Read each one and its explanation before you practice.

  1. All 63 E4 questions with their answers and explanationsEvery group, with the rule or source behind each answer

2. Explore

  • Decibels

    Work out a received signal level in dBm: +40 dBm of transmitter power, plus 6 dBi and 3 dBi of antenna gain, minus 100 dB of path loss, is -51 dBm.

    This is exam question E4D13.

  • Attenuator pads

    Design a 10 dB pad for a 50 ohm system and see the three resistor values it needs.

3. Practice

Practice one group at a time. A group is ready when you have answered every one of its questions and learned at least 80 percent of them; a question counts as learned when your last three answers to it were correct. To review quickly, go through this lesson’s questions as flashcards.

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