• More info on pages 40-56 of the study guide
• Transmitter + receiver + amplifier + SWR meter/bridge + Antenna tuner + ... = transceiver, but the test treats them as different things
• Power supply and antenna are still mostly considered separate, and are included on the test too

Receiving Signals

• Antenna narrows down the frequencies you’re listening to, oscillators and filters do so further
• An intermediate amplifier boosts the signal strength
• RF to sound/digital signals → demodulation is next
  • Sound/digital signals to RF is called modulation
• Audio amplifier boosts the sound level

Transmitting Signals

• Audio amplifier
• Modulation step
• Frequency filter
• Clean up Morse code signals with a voltage controller to get rid of voltage spikes called “chirps”
• Use an oscillator to actually turn the wave into RF

Tips

• RF amps can be noisy, so sometimes it's useful to have another filter
• For FM, modulators do modulation and frequency discriminators do demodulation
• For AM/SSB, modulator is called a balanced modulator, demodulation is done by a product identifier (this term is also used for CW/Morse)
• Receivers and transmitters always have one or two oscillators. A mixer is used to combine the carrier wave with the data into a modulated output
• To produce AM, you need a VFO (Variable Frequency Oscillator)
  • To transmit, run through balanced modulator and filter the spikes and one of the two side lobes
  • To receive, run through product detector (demodulation), and recreate the spike and side lobe
  • A beat frequency oscillator is an oscillator that creates audible sound-level frequencies to convert the signal into sound