E7: Practical Circuits

Subelement E7 covers the practical circuits you will encounter in real radio design and operation. This is one of the most hands-on subelements in the Extra class exam, spanning digital logic, amplifier classes, filter design, power supplies, modulation methods, software-defined radio, operational amplifiers, and oscillator circuits.

Eight topic groups make up E7, each targeting a distinct area of circuit practice. Mastering these topics gives you a complete picture of how the circuitry inside modern transceivers actually works.

E7A: Digital Circuits teaches flip-flops, multivibrators, logic gates, truth tables, frequency dividers, and positive vs. negative logic. You will learn which circuits are bistable, which self-oscillate, and how to interpret logic gate operations.

E7B: Amplifiers covers amplifier classes from A through D, push-pull configurations, distortion and intermodulation, grounded-grid topology, parasitic suppression, and why switching amplifiers are more efficient than linear amplifiers.

E7C: Filters and Matching Networks explains Pi, T, Pi-L, and L-network topologies; Butterworth, Chebyshev, and elliptical filter types; crystal lattice, helical, and cavity filters; and how shape factor quantifies adjacent-channel rejection.

E7D: Power Supplies addresses linear and switchmode regulators, Zener references, three-terminal regulators, dropout voltage, power dissipation calculations, solar panel inverters, step-start circuits, and battery operating time.

E7E: Modulation and Demodulation covers reactance modulators for FM/PM, balanced modulators for SSB, frequency discriminators and product detectors, mixers, pre-emphasis and de-emphasis, and the baseband concept.

E7F: SDR Fundamentals explains direct sampling, Nyquist sampling theory, analog-to-digital conversion, FFT, decimation, anti-aliasing, FIR filters, DSP filter taps, Hilbert transforms, and quadrature signal processing.

E7G: Operational Amplifiers covers op-amp characteristics (very high input impedance, very low output impedance), inverting amplifier gain calculations, gain-bandwidth product, offset voltage, and how adding capacitors creates active filter responses.

E7H: Oscillators and Signal Sources teaches Colpitts, Hartley, and Pierce oscillator feedback mechanisms; phase-locked loops; direct digital synthesizers; microphonics; thermal drift reduction using NP0 capacitors; and high-accuracy oscillator techniques.

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