Devil's Slide WWII Radar Site

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Devil's Slide 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 San Francisco against enemy warships. Located on Devil's Slide Military Reservation near Montera, San Mateo County, California. Closed in 1946.

Devil's Slide WWII Radar Site Plan.
Devil's Slide WWII Radar Site in 2019. Power house in Lower Left, Staircase in the Center, Transmitter Building & Later Tower Upper Right.


Part of the Harbor Defense of San Francisco.

SCR-296-A Typical Radar Set Installation.
Devil's Slide WWII Radar Set Transmitter Building.

Constructed under project No. RAD-9-183 and transferred for use at Devil's Slide WWII Radar Site. Construction costs to date of transfer were $31,494.81. The physical plant consisted of a transmitter building, a shared powerhouse, an antenna housing disguised as a Water tank atop the transmitter building. The buildings were constructed of reinforced concrete. The antenna housing was furnished by the Signal Corps and probably installed by the Corps of Engineers.

Devil's Slide WWII Combined Power Building.

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 an on-site generator. One 25 KVA generator was furnished and installed by the Signal Corps for the radar in a combined power building along with with a small 3 KVA generator provided to power the base-end station structures.

Site Operation

SCR-296-A Range Operator Display.
SCR-296-A Azimuth Operator Displays

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".

SCR-582 to SCR-296-A Radar, Seacoast Battery Communications Paths.

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 244 as the primary battery and to secondary batteries including Battery Townsley, Battery 129 and Battery Davis. Battery 244 was a 6" gun battery located on the Milagra Ridge Military Reservation.


Closed in 1946. The SCR-296-A 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. The whole 9.1 acre Devil's Slide Military Reservation was transferred to the U.S. Navy on 25 Oct 1959 and they disposed of it in 1983.

Current Status

Transmitter building and common power building remain as shells. The antenna housing is gone and replaced by a later steel antenna tower. The stairway guard rail is gone and the stairway is exposed to a steep drop off without many restraining trees or brush. The gate to the site is locked and special permission from the State Park officials is required to gain entry. Grafitti is prevalent inside the buildings.

Location: Devil's Slide in San Mateo County, California.

Maps & Images

Lat: 37.57451 Long: -122.51913

  • Multi Maps from ACME
  • Maps from Bing
  • Maps from Google
  • Antenna Elevation: 432.9'
  • Site Elevation: 426'

GPS Locations:

See Also:


  • U.S.Army, Supplement to the Harbor Defense Project Harbor Defenses of San Francisco, (CCA-P-SFB), 15 Nov 1945, CDSG
  • RCW-Corrected to August 1944, CDSG.


Visited: 27 Apr 2019

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