Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E1B
E1B04E1B

What must the control operator of a repeater operating in the 70-centimeter band do if a radiolocation system experiences interference from that repeater?

Deep Dive: E1B04

The correct answer is C: Cease operation or make changes to the repeater that mitigate the interference. What must the control operator of a repeater operating in the 70-centimeter band do if a radiolocation system experiences interference from that repeater is to cease operation or make changes to the repeater that mitigate the interference. Repeaters must not interfere with radiolocation systems. For amateur radio operators, this is mandatory. Understanding this helps ensure compliance.

Why Other Answers Are Wrong

Option A: Incorrect. Reducing antenna HAAT doesn't necessarily solve the problem - you must cease operation or mitigate interference. HAAT reduction isn't the requirement. Option B: Incorrect. Filing an FAA NOTAM isn't the requirement - you must cease operation or mitigate interference. NOTAM filing isn't the requirement. Option D: Incorrect. Since A and B are not correct, 'all of the above' cannot be correct. Only ceasing operation or mitigating interference is required.

Exam Tip

Repeater interferes with radiolocation = cease operation or mitigate interference. Think 'R'epeater 'I'nterference = 'R'esolve 'I'mmediately (cease or mitigate). Repeaters must not interfere with radiolocation systems. Not HAAT reduction, not NOTAM filing - just cease or mitigate.

Memory Aid

Repeater interferes with radiolocation = cease operation or mitigate interference. Think 'R'epeater 'I'nterference = 'R'esolve 'I'mmediately. Repeaters must not interfere with radiolocation systems. Mandatory compliance requirement.

Real-World Example

A repeater on 70 cm causes interference to a radiolocation system: The control operator must either cease operation (shut down the repeater) or make changes to mitigate the interference (change frequency, reduce power, etc.). This is mandatory - you cannot continue operating if interference occurs. Cease operation or mitigate interference is required.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E1B

Reference: FCC Part 97.205

Key Concepts

Repeater 70-centimeter band Radiolocation system Interference mitigation

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E1B topic.