How can a radio operator signal that a message will be repeated?

A radio operator can signal that a message will be repeated by stating "I say again." This phrase is a standardized protocol widely recognized among radio operators, indicating that the information previously transmitted is about to be repeated for clarity or confirmation. Its use helps to ensure that the receiving party recognizes that a key point or entire message is being reiterated, which is essential in maintaining effective communication and avoiding misunderstandings.

When a message is critical or if there is any doubt regarding its reception, using this phrase provides a clear cue to the listener, prompting them to pay special attention to the forthcoming repeated message. This practice enhances operational effectiveness, especially in challenging communication environments.

The other options do not serve the purpose of indicating a message will be repeated. "Signal lost" implies that the transmission has failed, and "Proceed with caution" suggests a warning rather than a repetition. "Out" typically indicates that the conversation is finished and does not indicate a repeat action. Hence, "I say again" is the appropriate and correct phrase to use in this context.