About this Unit
The 7th Radio Research Field Station (7th RRFS) was a United States Army signals intelligence unit based at Ramasun Station near Udorn Thani, Thailand, during the Vietnam War. Activated in the mid-1960s, the unit played a crucial role in intercepting and analyzing enemy communications, providing timely intelligence to U.S. and allied forces in Southeast Asia. The 7th RRFS operated advanced electronic equipment and worked closely with other branches of the U.S. military and intelligence agencies. The station remained active until the U.S. drawdown in the region, officially ceasing operations in the mid-1970s.
Historical Facts
• Origins: The 7th Radio Research Field Station (7th RRFS) was a U.S. Army signals intelligence (SIGINT) unit located at Ramasun Station near Udon Thani, Thailand, during the Vietnam War era.
• Mission: Its primary mission was intercepting and analyzing enemy radio communications, particularly North Vietnamese and Viet Cong transmissions, to provide intelligence for U.S. and allied operations in Southeast Asia.
• Massive Antenna Array: The site was famous for its massive Wullenweber AN/FLR-9 "Elephant Cage" antenna, which could intercept radio signals from thousands of miles away.
• Secrecy: The 7th RRFS was officially designated as an Army Security Agency (ASA) unit, and its operations were highly classified, with most personnel sworn to secrecy.
• Multinational Cooperation: The station worked closely with other U.S. intelligence agencies and with Thai military counterparts, enhancing regional intelligence sharing.
• Self-Contained Community: Ramasun Station was a self-contained base, complete with living quarters, a PX, swimming pool, bowling alley, and even a cinema, supporting over 1,000 personnel at its peak.
• Nicknamed "Ramasun": The name "Ramasun" comes from the Thai word for "thunder," reflecting both the region's weather and the powerful listening capabilities of the station.
• Operation Handover: After the U.S. withdrawal from Vietnam and changing U.S.-Thai relations, the base was handed over to the Royal Thai Army in 1976 and continues to see use by Thai intelligence services.
• Unusual Stories: Ramasun Station has become the subject of local legends and ghost stories, with some claiming the site is haunted due to its secretive past and unexplained incidents.
• Legacy: Veterans of the 7th RRFS maintain active associations and reunions, sharing stories and preserving the history of this unique intelligence outpost in Southeast Asia.
