Fort Stevens WWII Radar Site
Fort Stevens WWII Radar Site (1944-1946) - A World War II U.S. Army Radar Site established in 1944. Used to provide fire control information to large caliber (6" and above) coastal gun batteries in the Harbor Defense of the Columbia against enemy warships. Located on Fort Stevens in Clatsop County, Oregon. Closed in 1946.
Part of the Harbor Defense of the Columbia.
Constructed under project No. RAD 9-1013 and transferred for use on 5 Apr 1944 as Fort Stevens SCR-296A Radar Site. Construction costs to the date of transfer were $7, 413.41. The physical plant consisted of a transmitter building, two powerhouses each with a 1000-gallon fuel tank, a 100' steel tower, and an antenna housing disguised as a Water tank atop the tower. The three buildings and the tower were prefabricated steel units furnished by the Signal Corps. The buildings and the tower were placed on concrete pads and footings installed by the Corps of Engineers who erected all of the structures. Access to the antenna on top of the tower was by a small elevator operated by a 4-horsepower electric motor. The engineering construction work was done by government forces which started on 26 Nov 1943 and finished on 15 Mar 1944.
The radar equipment was installed by the Signal Corps. It required 16.3kW of 120/240 AC, 1 phase, 60 cycle power furnished by commercial power backed up by the two on-site generators. The two 25 kW generators were furnished and installed by the Signal Corps. A small barracks was located between the two generator buildings (not part of the project).
In operation, the SCR-296-A radar could only track one target at a time. Target assignments were made from the harbor HECP/HDCP command posts by telephone, citing the approximate range and azimuth of the target using the SCR-582/SCR-682 search radar and/or optical spotters. The SCR-296-A radar operators would then find the target and pass the precise range and azimuth to the plotting room at the gun battery by phone. Two operators were required, one for the range position and one for the azimuth position. The radar operators would continue to track the target and update the plotting room as the range and azimuth changed. Once the shore battery fired, the SCR-296-A could detect the water splashes of near misses and provide adjusting information by voice commands such as "300 short" or "500 long".
In operation, the range accuracy was about ± 30 yards while azimuth accuracy was about ± 0.20 degree under the best conditions. The set had a dependable range of 20,000 yards on a destroyer size target when properly sited between 150 to 500 feet above sea level.
The operating crew consisted of 5 men plus a power plant operator and radar maintenance man.
The Radar track data was provided by telephone to support Battery 245 as the primary battery and secondary batteries including Battery 246 and Battery 247. Battery 245 was a 6" gun battery located on Fort Stevens.
The SCR-296A Radar equipment was declared obsolete by AG letter on 17 Jan 1946. The Tower and radar equipment were to be disposed of while the buildings were to be retained.
Closed in 1946.
Foundational remains of tower base and buildings. Note the remains do not correlate with the above Corps of Engineers drawing and that may be because of site considerations or later changes. The major difference is that the transmitter building is under the tower rather than behind it. The building itself collapsed and the site behind the antenna falls off rapidly on the West and fronts on a road on the East. The generator pads were not located.
Visited: 15 Jul 2023