What is the purpose of INT-USA control settings on a VHF?

• A. To change certain International Duplex channel assignments to simplex in the U.S. for VTS and purposes
• B. To encrypt VHF traffic for security
• C. To select weather channels
• D. To switch between VHF and MF bands

Answer: (A)

The INT-USA control on a VHF lets certain channels that are duplex internationally be used as simplex in U.S. waters. This means those channels transmit and receive on the same frequency range, which is important for ship-to-ship and Vessel Traffic Service communications in the United States. It aligns the radio with U.S. frequency allocations and avoids needing a repeater for those channels in many local operations.

This setting isn’t about encryption, weather channels, or switching to MF; it’s specifically about how certain international duplex channels are handled when you’re operating in the U.S.