View source for SK radar

{{short description|Radar of the United States Navy}}
{{Infobox radar|name=SK (radar)|image=File:SK-1 radar on USS Kasaan Bay (CVE-69) 1944.jpg|caption=SK-1 aboard {{USS|Long Island|CVE-1|6}}|country=[[United States]]|type=[[Air search radar|Air-search radar]]|introdate=1944|power=250 [[Kilowatt|kW]]<ref name="nw"/>|frequency=[[VHF Band|VHF band]]|range=160.9 [[Kilometre|km]] (86.9 [[Nautical mile|nmi]])|manufacturer=[[General Electric]]|beamwidth=10°|pulsewidth=5 [[Microsecond|μs]]|PRF=|precision=± {{cvt|100|yd|m|lk=in}}|azimuth=± 3 °}}
'''SK''' was an American-made [[Air search radar|air-search radar]] used during [[World War II]] by the [[United States Navy]]. Models included '''SK-1''', '''SK-2''' and '''SK-3'''.<ref>{{Cite book|last=Robert|first=Buderi|title=The Invention That Changed the World: How a Small Group of Radar Pioneers Won the Second World War and Launched a Technical Revolution|publisher=Touchstone|year=1998|isbn=0684835290}}</ref>
== Overview ==
SK was a [[very high frequency]] search set for large ships. It furnished range and bearing of surface vessels and aircraft, and it could be used for control of interception. The set had both "A" and [[Plan position indicator|PPI]] scopes, provisions for operating with remote PPIs and for [[Identification friend or foe|IFF]] connections, and built-in BL and BI [[Antenna (radio)|antennas]].<ref name=":0">{{Cite web|title=US Radar: Operational Characteristics of Radar Classified by Tactical Application|url=https://www.history.navy.mil/content/history/nhhc/research/library/online-reading-room/title-list-alphabetically/u/operational-characteristics-of-radar-classified-by-tactical-application.html|access-date=2022-02-18|website=NHHC|language=en-US}}</ref>
With the antenna at {{cvt|100|ft|m}}, SK could detect [[medium bomber]]s at {{cvt|1,000|ft|m}} altitude at {{convert|100|mi|km}}. Range accuracy was ± {{convert|100|yd|m}} and [[azimuth]] accuracy ± 3°. There was no elevation control, but elevation could be estimated roughly from positions of maximum and minimum signal strength.<ref name=":0" />
Shipment for SK included spares, with tubes for 400 hours, and a separate generator if the ship's power is [[Direct current|DC]]. SK was not air transportable.
SK had 10 components weighing approximately {{cvt|5000|lb|kg}}. The heaviest unit, at {{cvt|2400|lb|kg}}, was the antenna assembly. The antenna measured {{cvt|15|ft|m}} x {{cvt|16|ft|9|in|m}}. It was mounted {{cvt|100|ft|m}} or more above water. The minimum operators required were one per shift. Primary power required was 3500 [[Watt|watts]], 115 [[volt]]s, 60&nbsp;Hz. The source of power is ship's power of 115 volts, 60&nbsp;Hz.<ref name=":0" />
During the later stages of [[World War II]], a [[parabolic antenna]] called SK-2 replaced the SK-1.<ref name="nw">{{Cite web|title=Radar Equipment of World War II|url=http://www.navweaps.com/Weapons/WNUS_Radar_WWII.php|website=NavWeaps}}</ref>
== On board ships ==
=== {{Flagicon|United States|variant=naval}} United States ===
* [[File:F7U-3 CVB-43 Nov1952.jpg|thumb|SK-2 aboard {{USS|Coral Sea|CV-43|6}}]]{{sclass|Midway|aircraft carrier}}
* {{sclass|Essex|aircraft carrier}}
* {{sclass|Independence|aircraft carrier}}
* [[USS Enterprise (CV-6)|USS ''Enterprise'' (CV-6)]]
* [[USS Saratoga (CV-3)|USS ''Saratoga'' (CV-3)]]
* {{sclass|Casablanca|escort carrier}}
* {{sclass|Bogue|escort carrier}}
* [[File:USS Honolulu (CL-48) at anchor in 1944.jpeg|thumb|SK-1 aboard {{USS|Honolulu|CL-48|6}}]]{{sclass|Iowa|battleship}}
* [[South Dakota-class battleship (1939)|''South Dakota''-class battleship]]
* {{sclass|North Carolina|battleship}}
* {{sclass|Colorado|battleship}}
* {{sclass|Tennessee|battleship}}
* [[USS Pennsylvania (BB-38)|USS ''Pennsylvania'' (BB-38)]]
* [[File:USS Augusta (CA-31) steaming off Portland, Maine (USA), on 9 May 1945 (NH 97932).jpg|thumb|SK-1 aboard {{USS|Augusta|CA-31|6}}]]{{sclass|Nevada|battleship}}
* {{sclass|New York|battleship}}
* [[USS Arkansas (BB-33)|USS ''Arkansas'' (BB-33)]]
* {{sclass|Alaska|cruiser}}
* {{sclass|Des Moines|cruiser}}
* {{sclass|Oregon City|cruiser}}
* {{sclass|Baltimore|cruiser}}
* [[USS Wichita (CA-45)|USS ''Wichita'' (CA-45)]]
* {{sclass|Fargo|cruiser}}
* {{sclass|Cleveland|cruiser}}
* {{sclass|New Orleans|cruiser}}
* {{sclass|Brooklyn|cruiser}}
* {{sclass|Portland|cruiser}}
* {{sclass|Northampton|cruiser}}
* {{sclass|Pensacola|cruiser}}
* {{sclass|Omaha|cruiser}}
* {{sclass|Currituck|seaplane tender}}
* {{sclass|Appalachian|command ship}}
* {{sclass|Mount McKinley|command ship}}
* ''Commencement Bay''-class escort carrier
=== {{Flagicon|United Kingdom|variant=naval}} United Kingdom ===
* {{sclass|Ruler|escort carrier}}
* [[HMS Boxer (F121)|HMS ''Boxer'' (F121)]]
== Gallery ==
<gallery mode="packed">
File:Grumman Avenger landing on HMS Trumpeter WWII IWM A 24282.jpg|SK-1 aboard {{HMS|Trumpeter|D09|6}}
File:Battleship Texas - exterior - DSCN0165.JPG|SK-1 aboard {{USS|Texas|BB-35|6}}
File:USS Wichita (CA-45) underway in the Central Pacific on 2 May 1944.jpg|SK-1 aboard {{USS|Wichita|CA-45|6}}
File:USS Alabama - Mobile, AL - Flickr - hyku (195).jpg|SK-2 aboard {{USS|Alabama|BB-60|6}}
File:USS Macon (CA-132) underway off the Philadelphia Navy Yard on 29 October 1946.jpg|SK-2 aboard {{USS|Macon|CA-132|6}}
File:Radars of USS Princeton (CV-37) in 1952.jpg|SK-3 aboard {{USS|Princeton|CV-37|6}}
</gallery>
== See also ==
* [[List of radars]]
* [[Radar configurations and types]]
* [[Radar|Air-search radar]]
== Citations ==
<references />
== References ==
* [[Norman Friedman]] (2006). ''[https://books.google.com/books/about/The_Naval_Institute_Guide_to_World_Naval.html?hl=ja&id=4S3h8j_NEmkC The Naval Institute Guide to World Naval Weapon Systems]''.  [[Naval Institute Press]].  {{ISBN|978-1-55750-262-9}}
* [[Buderi, Robert]] (1998). ''The Invention That Changed the World: How a Small Group of Radar Pioneers Won the Second World War and Launched a Technical Revolution.'' [[Touchstone Pictures|Touchstone]]. {{ISBN| 0-684-83529-0}}
* Hezlet, Arthur (1975). ''Electronics and Sea Power. New York: Stein and Day''. {{ISBN|0-8128-1811-3}}
[[Category:Naval radars]]
[[Category:World War II radars]]
[[Category:Military equipment introduced from 1940 to 1944]]
[[Category:Military radars of the United States]]