Wadena Air Force Station Wadena Air Force Station ( ADC ID : P - 17 , NORAD ID : Z - 17 ) is a closed United States Air Force General Surveillance Radar station . It is located north - northeast of Wadena , Minnesota . It was closed in 1970 . History . In late 1951 Air Defense Command selected Finland , Minnesota site as one of twenty - eight radar stations built as part of the second segment of the permanent radar surveillance network . Prompted by the start of the Korean War , on July 11 , 1950 , the Secretary of the Air Force asked the Secretary of Defense for approval to expedite construction of the second segment of the permanent network . Receiving the Defense Secretary ’ s approval on July 21 , the Air Force directed the Corps of Engineers to proceed with construction . Wadena Air Force Station began at Leaf River , Minnesota when the Minnesota Air National Guard 132d Aircraft Control and Warning Squadron was federalized during the Korean War and began operations on 1 June 1951 under the 543d Aircraft Control and Warning Group ; initially the station functioned as a Ground - Control Intercept ( GCI ) and warning station . As a GCI station , the squadron ' s role was to guide interceptor aircraft toward unidentified intruders picked up on the unit ' s radar scopes . The Guardsmen operated AN / FPS - 3 and AN / FPS - 4 radars until relieved from active duty and returned to control of the State of Minnesota on 1 February 1953 . The 739th Aircraft Control and Warning Squadron began the radars in June 1952 , the site being re - designated as Wadena AFS on 1 December 1953 . The AN / FPS - 4 unit was superseded in 1956 by an AN / FPS - 6 height - finder radar . In 1958 this site was operating an AN / FPS - 20 radar . During 1959 Wadena AFS joined the Semi Automatic Ground Environment ( SAGE ) system , initially feeding data to DC - 11 at Grand Forks AFB , North Dakota . After joining , the squadron was re - designated as the 739th Radar Squadron ( SAGE ) on 15 January 1960 . The radar squadron provided information 24 / 7 the SAGE Direction Center where it was analyzed to determine range , direction altitude speed and whether or not aircraft were friendly or hostile . In 1963 , Wadena was switched to the SAGE DC - 10 Data Center at Duluth AFS , Minnesota . 1959 also saw the arrival of a second height - finder radar ( AN / FPS - 6A ) . In 1961 the search radar was upgraded and redesignated as an AN / FPS - 64 . During 1963 the AN / FPS - 6A height - finder radar was modified to an AN / FPS - 90 , and on 31 July 1963 , the site was redesignated as NORAD ID Z - 17 . In 1967 the search radar was upgraded to an AN / FPS - 64 A . The AN / FPS - 90 was removed in 1969 . In addition to the main facility , Wadena operated the following AN / FPS - 18 Gap Filler sites : Over the years , the equipment at the station was upgraded or modified to improve the efficiency and accuracy of the information gathered by the radars . The Air Force inactivated the 739th Radar Squadron ( SAGE ) in September 1970 due to budget reductions . Today , the former Wadena Air Force Station is now the Bell Hill Recovery Center . Many former USAF buildings in - use . Air Force units and assignments . Units : Assignments :