FCC Exam Question: 3-60I3
What capacity in amperes does a storage battery need to be in order to operate a 50 watt transmitter for 6 hours? Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.
A. 100 ampere-hours.
B. 177 ampere-hours.
C. 249 ampere-hours.
D. None of these.
Correct Answer: B
Explanation: To determine the required battery capacity, first calculate the total current draw. The transmitter's continuous load is 70% of its key-locked demand: 0.70 * 40 A = 28 A. Next, add the emergency light load to find the total current: 28 A (transmitter) + 1.5 A (lights) = 29.5 A. Finally, multiply the total current by the operating time to find the required ampere-hour (Ah) capacity: 29.5 A * 6 hours = 177 Ah. This calculation ensures the battery can supply the combined power needs for the specified duration, a crucial consideration for emergency or portable amateur radio operations. Therefore, a 177 ampere-hour battery is needed.
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