US Army, Air Force, Navy, and Coast Guard stations will participate in the annual Armed Forces Day Crossband Communications Test on Saturday, May 13. This annual HF communication interoperability event, sponsored by the Department of Defense since 1934, challenges Amateur Radio operators to contact military stations across the US.

The event marks the 66th annual Armed Forces Day (AFD), officially on May 20. The AFD Crossband Military-Amateur Radio event takes place a week earlier in order to avoid schedule conflicts with those attending Hamvention.

Radio amateurs will transmit on Amateur Radio frequencies and listen on military frequencies, while military stations will transmit on military frequencies and listen on Amateur Radio frequencies. The annual event tests two-way communication between radio amateurs and military stations (authorized under §97.111 of the Amateur Service rules). It features traditional military-to-amateur crossband SSB voice, CW, practice using legacy interoperability waveforms, and the opportunity for participating hams to utilize more modern military modes, such as MIL-STD Serial PSK and Automatic Link Establishment (ALE). Military stations and Amateur Radio stations are authorized to communicate directly on certain 60-meter interoperability channels — 5,330.5, 5346.5, and 5,371.5 kHz.

Select stations will transmit the Armed Forces Day message using Military Standard mode M188-110A. Amateur Radio operators may download software to receive the broadcast.

Shortwave listeners are welcome to participate. Complete details, including stations, times, and operating modes are on the US Army MARS website. Read more.