HAM Cheat Sheet 2026

The 30 highest-yield HAM facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Why does the 30–300 MHz frequency range have the most stringent RF MPE limits for the general public? → Human body dimensions resonate most efficiently with wavelengths in this range
2. Which of the following describes the function of a circulatory in a repeater system? → It isolates the transmitter and receiver when sharing a single antenna
3. Under FCC Part 97, what is the maximum transmitter power level permitted on the 60-meter band for Amateur Extra licensees? → 100 watts ERP
4. What is the characteristic impedance of a lossless transmission line determined by? → The ratio of distributed inductance to distributed capacitance per unit length
5. Which solar metric is most directly correlated with HF propagation conditions? → Solar flux index (SFI) at 10.7 cm
6. What is the purpose of neutralization in an RF amplifier circuit? → To cancel unwanted feedback through internal capacitances that can cause self-oscillation
7. What is the approximate velocity factor of standard RG-213 coaxial cable? → 0.66
8. What is the purpose of a Beverage antenna? → A long-wire receiving antenna for low-frequency directional reception
9. What is a 22,000 picofarad (pF) capacitor's value in nanofarads (nF)? → 22
10. What is the purpose of a balun at the feed point of a dipole antenna fed with coaxial cable? → To prevent common-mode current on the coax shield
11. Which type of filter response has equal ripple in the passband and a steeper rolloff than a Butterworth design? → Chebyshev filter
12. Why should an amateur transmitter generally steer clear of 14.100, 18.110, 21.150, 24.930, and 28.200 MHz frequencies? → A system of propagation beacon stations operates on those frequencies
13. What is the maximum RF power density allowed in an occupational (controlled) environment at frequencies between 30 and 300 MHz? → 1.0 mW/cm²
14. What is the primary purpose of a DSP notch filter in an HF transceiver? → To eliminate a single interfering carrier or tone from the received audio
15. What is the primary advantage of a Chebyshev low-pass filter design compared to a Butterworth design of the same order? → Steeper rolloff in the stopband
16. Which of the following is a requirement for a station to retransmit signals from the International Space Station? → No prior authorization is needed
17. A pi-network is frequently used in the output stage of a vacuum tube transmitter. What is the primary purpose of this circuit? → To transform the high output impedance of the tube to the low impedance of the antenna
18. What type of circuit is typically used to generate a stable reference frequency from a crystal oscillator for a PLL synthesizer? → Temperature-compensated crystal oscillator (TCXO)
19. What does "QRV" in the Q signal mean? → I am ready to receive messages
20. Which of the following best describes impedance in an AC circuit? → The total opposition to current flow, including both resistance and reactance.
21. What is the purpose of a cascode configuration in an RF preamplifier? → To reduce the Miller effect and improve high-frequency gain
22. What is the function of a Beat Frequency Oscillator (BFO) or carrier insertion oscillator in a receiver? → To reinsert the suppressed carrier at the IF for demodulation of SSB and CW signals
23. What is a 'vanity call sign' in the US amateur radio licensing system? → A specific call sign selected by the licensee from available options in the FCC database
24. What happens to the input impedance of a dipole antenna as it is shortened well below its resonant length? → It becomes capacitively reactive with lower radiation resistance
25. In antenna modeling software like EZNEC or 4nec2, what does the term 'far-field' refer to? → The region where the antenna's radiation pattern is independent of distance
26. What effect does the D layer of the ionosphere primarily have on HF signals during daytime? → It absorbs HF signals, particularly on lower frequencies
27. What is the resonant frequency of a series RLC circuit with an inductance of 10 microhenries and a capacitance of 100 picofarads? → 5.03 MHz
28. What abilities discovered when searching for hidden transmitters are beneficial to the Volunteer Monitoring Program? → Direction finding used to locate stations violating FCC rules
29. Which of the following best describes the radiation pattern of a two-element Yagi antenna? → A cardioid pattern with maximum radiation toward the director
30. What is the maximum permitted transmitter peak envelope power for an Amateur Extra licensee on the 60-meter band? → 100 watts PEP ERP