Deep Dive: T0C11
The correct answer is C: The percentage of time that a transmitter is transmitting. The definition of duty cycle during the averaging time for RF exposure is the percentage of time that a transmitter is transmitting. Duty cycle = (transmit time / total time) × 100%. For example, if you transmit 30 seconds out of every minute, duty cycle is 50%. For amateur radio operators, understanding duty cycle helps calculate average RF exposure. Lower duty cycle means less average exposure, allowing higher power for the same exposure limit.
Why Other Answers Are Wrong
Option A: Incorrect. Duty cycle isn't the difference between lowest and highest power - that's power variation, not duty cycle. Duty cycle is about time, not power levels. Option B: Incorrect. Duty cycle isn't the difference between PEP and average power - that's a power relationship, not duty cycle definition. Duty cycle is about transmission time percentage. Option D: Incorrect. Duty cycle is the percentage of time transmitting, not the percentage of time not transmitting. It's the transmit time, not the idle time.
Exam Tip
Duty cycle = percentage of time transmitting. Think 'D'uty cycle = 'D'uration of transmission / total time. Percentage of time the transmitter is on. Not about power differences, not about time not transmitting.
Memory Aid
Duty cycle = percentage of time transmitting. Think 'D'uty cycle = 'D'uration transmitting / total time. Simple percentage - how much of the time the transmitter is on. Not about power levels or differences.
Real-World Example
You operate SSB and talk for 10 seconds, then listen for 10 seconds, repeating this pattern. Your duty cycle is 50% (10 seconds transmitting out of 20 seconds total). If you operated CW continuously, duty cycle would be 100% (transmitting all the time). Duty cycle is simply the percentage of time you're transmitting.
Source & Coverage
Question Pool: 2022-2026 Question Pool
Subelement: T0C
Reference: 2022-2026 Question Pool · T0 - Safety
Key Concepts
Verified Content
Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T0C topic.