E4: Amateur Radio Practices
Subelement E4 covers the practical measurement tools and techniques used in advanced amateur radio station operation: test equipment (oscilloscopes, spectrum analyzers, antenna analyzers, frequency counters); measurement accuracy, S parameters, and vector network analyzers; receiver performance including noise figure, dynamic range, and image rejection; receiver interference mechanisms including intermodulation, desensitization, and reciprocal mixing; and noise and interference suppression including common-mode currents, DSP filtering, and grounding practices.
The Extra exam draws five questions from E4 — one from each group. These questions are heavily quantitative and technical, requiring precise recall of instrument capabilities, measurement techniques, and interference mechanisms.
Study These Topics
E4A: Test Equipment
Oscilloscope sampling rate and aliasing, probe compensation and ground lead practice, spectrum analyzers vs. network analyzers, antenna analyzers, frequency counters and prescalers, SWR measurement methods, trigger modes for ripple measurement.
Study E4AE4B: Measurement Techniques
Frequency counter time base accuracy, voltmeter sensitivity and input impedance, S parameters (S11, S21), VNA calibration with short/open/50-ohm loads, reflected vs. absorbed power, measuring Q, filter frequency response, intermodulation distortion testing.
Study E4BE4C: Receiver Performance
Phase noise and reciprocal mixing, noise figure and noise floor (-174 dBm), MDS (minimum discernible signal), bandwidth and noise floor relationship (13 dB per 20x change), SDR overload threshold, roofing filters, IF shift, capture effect, image rejection.
Study E4CE4D: Receiver Characteristics
Blocking dynamic range (1 dB gain compression), intermodulation from nonlinear devices, cross modulation and desensitization, preselector function, third-order intercept point, odd-order intermodulation products within the band, link margin calculation, received signal level, dBm to power conversion.
Study E4DE4E: Noise and Interference
Automatic notch filter and CW signals, digital noise reduction and noise blankers, automotive charging system noise suppression with ferrite chokes, AC motor RFI, computer network equipment interference, common-mode currents, switch-mode power supply interference, single point ground panel and surge protectors.
Study E4EE4A: Test Equipment →