🔍 Key Concepts

• Radio Direction Finder (RDF) – what its main purpose is on a ship • Difference between a direction-finding receiver and a communications receiver • What an auxiliary receiving antenna adds to the RDF system (not just being a spare)

💭 Think About

• Ask yourself: Is the auxiliary antenna mainly about backup/spare capability, or about allowing two different radio functions to be used at the same time? • Think about which frequency (500 kHz) was historically used for distress/watchkeeping, and whether that relates more to general communications or to direction-finding. • Consider how an RDF system might be arranged so that one part of the system can be used while the other radio equipment is busy.

✅ Before You Answer

• Check which choice actually describes a functional advantage beyond just being a "spare". • Verify which answer connects the auxiliary antenna with the ability to operate one receiver while the other is in use or on watch. • Eliminate any option that doesn’t clearly relate to the direction finder’s ability or the watchkeeping requirement.