Osceola Air Force Station
Osceola Air Force Station (1951-1975) - A Cold War U.S. Air Force Radar Station. Located near East Farmington, Polk County, Wisconsin. Named Osceola Air Force Station on 1 Dec 1953. Initially assigned a Permanent ID of P-35 and later a Sage ID of Z-35. Deactivated on 31 Mar 1975.
Established in 1950 and became operational on 1 Jan 1951 as East Farmington radar site and renamed Osceola Air Force Station 1 Dec 1953. Manned by the 674th AC&W Squadron whose name was changed on 15 Dec 1959 to the 674th Radar Squadron (SAGE) and again on 1 Feb 1974 to the 674th Radar Squadron.
Initial equipment included two CPS-6B radars. The CPS-6B radars were replaced by one FPS-7 search radar and two FPS-6A height-finder radars in 1959. This configuration met the requirements for the transition to the SAGE System operation.
SAGE System Transition
The transition of the manual GCI system to the automated SAGE system began with the installation of the FST-2 coordinate data transmitter and search radar upgrades. The FST-2 equipment digitized the radar returns and transmitted the digital returns to the SAGE direction center. Under the SAGE System, interceptor aircraft were directed to their targets by the direction center computers and controllers, greatly reducing the need for local controllers and equipment at every radar station.
The FST-2 was a very large digital system using vacuum tube technology. Over 6900 vacuum tubes were used in each FST-2 requiring 21 air-conditioned cabinets, 40 tons of air conditioning, 43.5 kva of prime power and usually a large new addition to the operations building. The FST-2B modification added two more cabinets but with newer solid state (transistor) technology to process coded responses from aircraft transponders.
SAGE System Operation
The site began operation as a SAGE site on 1 Jul 1959 initially feeding the Duluth SAGE Direction Center DC-10. In 1963 the two FPS-6A height-finders were upgraded to become two FPS-90 height-finders. In the early 1970s the vacuum tube FST-2B was replaced with a solid state FYQ-47 Common Digitizer.
Osceola AFS and the 674th were deactivated on 31 Mar 1975.
Osceola AFS was responsible for the maintenance of three remote unattended gap-filler radar sites. The unattended gap filler sites were placed in locations where the main search radar lacked coverage. These sites were equipped with short range FPS-14 or FPS-18 search radars and FST-1 Coordinate Data transmitters that sent digitized radar target data to a SAGE direction center and to the main radar site. Both the radar set and the FST-1 were dual channel to increase site up time. Maintenance teams were dispatched for regularly scheduled maintenance or when fault indicators on the FSW-1 remote monitoring equipment suggested the site had problems. The FSW-1 also allowed remote operation of specific functions such as channel changes for the radar and for the FST-1, it also allowed remote operation of the diesel generators at the gap filler site. The Osceola AFS gap-filler radars were located at Northfield MN, Jim Falls WI and La Crescent MN. Two additional gap-fillers were contemplated but not built.
The physical plant of the site was divided into the main site, a cantonment area, a housing area and a radio site. The main site housed the operations buildings, the radar towers, and the backup generators. The cantonment area housed the enlisted barracks, the bachelor officer's quarters, the orderly room, the dining hall, the motor pool and other support buildings. North of the main site was a small 27 unit housing area (originally 9 units) for married personnel.
A separate radio site housed the radio equipment for directing aircraft intercepts. Like most early radar stations, Osceola originally had a radio transmitter site and a separate radio receiver site used by local controllers for voice direction of fighter interceptors to their targets. With the SAGE System, the SAGE Direction centers had the primary task of directing intercepts and the local radio sites were reconfigured, usually into a single site that was known as the Ground to Air Transmitter Receiver (GATR) site. The GATR site communicated with the interceptors from either the local site or the SAGE direction center via voice commands and/or a digital data link. The Osceola AFS GATR site was located north of the main site.
Note: Reported dates overlap and may be incorrect or reflect periods of intermittant temporary command.
Now part of the Association Retreat Center - The ARC.