GROL Cheat Sheet 2026

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

1. In a JK flip-flop, what happens when both J and K inputs are logic 1 and a clock pulse arrives? → Output toggles
2. A vessel is operating in the open sea, but is not required to be GMDSS-equipped. Which VHF channel must this vessel continuously monitor? → VHF Channel 16 (Distress, Safety, and Calling)
3. If three resistors of 10 ohms, 20 ohms, and 30 ohms are connected in a series circuit, what is the total resistance? → 60 ohms
4. A J3E emission designator signifies what type of transmission? → Single-sideband, suppressed-carrier (SSB) voice telephony
5. A technician measures a voltage of 24 volts across a resistor with a current of 2 amperes flowing through it. What is the resistance of the component? → 12 ohms
6. What is the nominal voltage of a single cell in a fully charged lead-acid battery? → 2.0 volts per cell
7. What unit is most commonly used to express receiver sensitivity? → dBm (decibels referenced to 1 milliwatt)
8. At resonance in a series RLC circuit, the total impedance equals: → The resistance R alone
9. What does noise figure (NF) measure in a receiver? → The degradation of signal-to-noise ratio caused by the receiver itself
10. Which violation may result in revocation of a ship station license by the FCC? → Willful transmission of false or fraudulent distress signals
11. What is the primary operational advantage of lithium-ion batteries over lead-acid batteries in marine applications? → Higher energy density and significantly lighter weight for the same capacity
12. A ship radiotelephone station license is issued to: → The owner or operator of the ship
13. In the generation of a single-sideband (SSB) signal, what is the primary output of a balanced modulator circuit? → The upper and lower sidebands, with the carrier signal suppressed.
14. What is the function of a squelch circuit in a VHF marine radio? → It silences the receiver output when no carrier signal is detected
15. Which license authorizes operation of a radiotelephone installation on a compulsory U.S. vessel operating in international service? → General Radiotelephone Operator License (GROL)
16. What is the cutoff frequency of a filter defined as? → The frequency at which output power is 3 dB below the passband level
17. What is the characteristic impedance of typical open-wire parallel feedline (ladder line or window line)? → 300 to 600 ohms
18. Which of the following describes the effect of negative feedback in an amplifier circuit, as opposed to the positive feedback used in an oscillator? → It reduces gain but improves stability and linearity.
19. The second harmonic of a 380 kHz frequency is: → 760 kHz
20. Who is responsible for the proper maintenance of station logs? → The station licensee and the radio operator are in charge of the station.
21. What is the purpose of a frequency counter in radio equipment testing? → To accurately measure the frequency of an oscillator or transmitted signal
22. What type of crystal is most commonly used in oscillators and filters for precise frequency control? → Quartz
23. A transmitter produces 100 watts into a 50-ohm load. What is the RMS voltage across the load? → 100 V
24. Which component in a PLL (Phase-Locked Loop) frequency synthesizer directly determines the output frequency? → The voltage-controlled oscillator (VCO)
25. Which type of memory loses its contents when power is removed? → DRAM
26. What is the approximate usable upper frequency limit of a standard BNC coaxial connector? → 4 GHz
27. What ITU emission designator identifies frequency-shift keying used in radioteletype (RTTY) communications? → F1B
28. What is the maximum allowed transmitter power for a ship VHF station on most channels? → 25 watts
29. In a series LC circuit at resonance, what is the impedance? → Minimum impedance (approaches zero)
30. At 100% amplitude modulation, what percentage of total transmitted power is contained in the carrier? → 66.7%