The E4 section of the Amateur Extra test contains information on amateur practices.
section covers test equipment: analog and digital instruments; spectrum and network analyzers, antenna analyzers; oscilloscopes; testing transistors; RF measurements.
section covers measurement techniques: instrument accuracy and performance limitations; probes; techniques to minimize errors; measurement of Q; instrument calibration.
section covers receiver performance characteristics: phase noise; capture effect; noise floor; image rejection; MDS; signal-to-noise-ratio; selectivity.
section covers receiver performance characteristics: blocking dynamic range; intermodulation and cross-modulation interference; 3rd order intercept; desensitization; preselection.
section covers noise suppression: system noise; electrical appliance noise; line noise; locating noise sources; DSP noise reduction; noise blankers.