545:. On 29 November, in response to the war warning sent to all overseas commands, the radar detachment went on continuous watch in three shifts. Even with correct detection of enemy flights from the AAF's operational radar at Iba, command disorganization resulted in many of the defending fighters in the Philippines being also caught on the ground and destroyed, as was the largest concentration of B-17s (19) outside of the continental US. The Iba set was destroyed in the initial attack on Iba on 8 December. After the first day, the effective striking power of the Far East Air Force had been destroyed, and the fighter strength seriously reduced. The Marine unit was withdrawn to
397:, and one in the southeast corner at Koko Head. However, initially no real communications system or reporting chain was set up. At one point the operators of one of the sets were instructed to phone in reports from a gas station some distance away. Although communications were eventually improved, the chain of command was not. And by explicit order of General Short, the radar stations were to only be operated for four hours per day and to shut down by 7am each day. The one operational radar set in the Philippines, by contrast, was put on continuous watch in three shifts in response to the war warning sent to all overseas commands in late November.
441:
406:
557:
834:
498:
689:
305:
27:
293:
381:) were aggressively pushing them to adopt. Except in rare cases, there was little interest in assisting or even cooperating with the goal of setting up the air defense system. On his own initiative, Bergquist along with some other motivated junior officers built a makeshift control center without authorization, and only by scrounging.
796:
As described above, the keyer/modulator produced a grid bias voltage for the transmitter tubes that keeps them in cutoff except for brief positive pulses the keyer produces 621 times a second, The 621 Hz frequency is derived either from an internal oscillator or an external source, typically the
358:
Despite the high-level attention and the excellence of the school in training on the use of the SCR-270 and its integration and coordination with fighter intercepts, the army did not follow through on supporting the junior officers who were trained at this session. Air defense required direct control
713:
In use, the antenna was swung (rotated) by command from the operations van, the azimuth angle being read by observing with binoculars the numbers painted on the antenna turntable. The maximum rotation rate was one revolution per minute. The radar operated at 106 MHz, using a pulse width from 10
476:
The northerly bearing of the inbound flight was not passed along in time to be of use. The US fleet instead fruitlessly searched to the southwest of Hawaii, believing the attack to have been launched from that direction. In retrospect this may have been fortuitous, since they might have met the same
241:
bomber had originally been instructed to fly to a known point for the radar to find it, but could not be located at the agreed upon time. The radar operators then searched for the bomber and located it about ten miles (16 km) from its intended position. It was later learned that winds had blown
1149:
A first step toward co-ordination of air defense was taken early in 1940 when the War
Department created the Air Defense Command. Headed by Brig. Gen. James E. Chaney and located at Mitchel Field, N.Y., the command was primarily a planning agency, charged with development of a system of unified air
845:
searchlight control radar, which shared much technology with the SCR-270, used separate antennas for transmit and receive, For maximum antenna gain at a given size it is desirable to use the same antenna for both functions. One obstacle is the need to protect the receiver from the high power pulses
704:
The original -270 consisted of a four-vehicle package including a K-30 operations van for the radio equipment and oscilloscope, a K-31 gasoline-fueled power-generating truck, a K-22B flatbed trailer, and a K-32 prime mover. The antenna folding mount was derived from a well-drilling derrick, and was
427:
on the morning of
December 7, 1941, manned by two privates, George Elliot and Joseph Lockard. Though the set was supposed to shut down at 7 that morning, the soldiers decided to get additional training time since the truck scheduled to take them to breakfast was late. At 7:02 they detected aircraft
228:
project. William D. Hershberger went to see what they had, and returned a positive report. Gaining the support of James B. Allison, the Chief Signal
Officer, they managed to gather a small amount of funding and diverted some from other projects. A research team was organized under the direction of
722:
being developed in
Germany. This wavelength did turn out to be useful, as it is roughly the size of an airplane's propeller, and provided strong returns from them depending on the angle. Generally it had an operational range of about 150 miles (240 km), and consistently picked up aircraft at
489:
agreed to send Watson-Watt to the United States to advise the military on air defense technology. In particular Watson-Watt directed attention to the general lack of understanding at all levels of command of the capabilities of radar, with it often being regarded as a freak gadget "producing snap
787:
The transmitter used dual WL530 water-cooled triodes configured as a high power push-pull resonant-line oscillator. The grids of the WL530s were connected to the keyer output which provided a high negative bias voltage that was interrupted by 621 Hz pulses which drove the WL530s' grids to
372:
Army Major
Kenneth Bergquist returned to Hawaii after attending the Mitchel Field school intending to set up a coordinated system, but when he arrived he found the local Army leadership was uninterested in the system, and he was reassigned to his former fighter unit. Only when incomprehensible
700:
in
October 1938 to provide production versions under the Westinghouse designation "WL-530" and the Signal Corps type number "VT-122". A pair of these arrived in January 1939, and were incorporated into the first SCR-270 in time to be used in the Army's maneuvers that summer. Several improved
568:
Key commanders responsible for the defense of installations vulnerable to air attack did not appreciate the need for and capabilities of the air defense assets they had, and how vital radar was to those defenses. The vulnerability was well demonstrated in war games—in particular those of
363:
prior to the war, when a demonstration of an early radar system had gone comically wrong even though the radar system itself had worked perfectly. Dowding was well aware of the importance of a unified command, but this knowledge did not result in changes within the U.S. Army structure.
456:
arriving that morning from the US. There were only six B-17s in the group, so this could not account for the large size of the radar echo. The officer had little grasp of the technology, the radar operators were unaware of the B-17 flight (nor its size), and the B-17s had no IFF
879:
controlled by a large hand wheel on the front panel. The delay between the transmitted and received pulses could be measured accurately by placing the transmit pulse under a hairline on the screen and then adjusting the hand wheel so that the received pulse was under the line.
31:
SCR-270: Similar to the model that detected the attacking Pearl Harbor planes (the actual Opana antenna was nine dipoles high by four wide, instead of the eight-by-four configuration shown here). The scale for reading the direction the antenna is pointing to can be seen at the
948:, and was a field of active research for some time. In 1990, after the radar had sat derelict for years, they received a phone call informing them of the historical nature of the radar, and requesting it be sent back to the US for preservation. It is now located at the
709:
backed with reflectors, arranged in three bays, each bay with twelve dipoles arranged in a three-high four-wide stack. (Later production versions of the SCR-270 used 32 dipoles and reflectors, either eight wide by four high (fixed) or four wide by eight high (mobile)).
596:, this radar was used to warn the island of incoming Japanese air attacks and to successfully direct the fighter interception that followed, but the island's radar did not play any significant part in the main carrier-action portion of the battle that followed.
384:
The first SR-270s became functional in July 1941 and, by
November, Bergquist had only assembled a small team, but they were able to build a ring of four SCR-270-Bs around Oahu, with one unit in reserve. The radars were placed on the central north shore
436:
and reported "Large number of planes coming in from the north, three points east". The operator taking his report passed on the information repeating that the operator emphasized he had never seen anything like it, and it was "an awful big flight."
236:
By
December 1936 Watson's group had a working prototype, which they continued to improve. By May 1937 they were able to demonstrate the set, detecting a bomber at night. This demonstration turned out to be particularly convincing by mistake; the
897:
The RU-4 circulated triple-distilled cooling water through the WL530 high power triodes and cooled the return water with a blower. Triple-distilled water was used to minimize leakage current from the high voltage on the tubes' anodes.
874:
television set, the TRK-5, introduced in 1939. The sweep was normally generated from an internal 621 Hz oscillator that also drove the keyer, but an external source could be used. The sweep signal passed through a calibrated
328:'s Taboga Island on the Pacific end of the Canal by December 1940, thus giving radar coverage to the vitally important but vulnerable Panama Canal. Westinghouse quickly ramped up production, and produced 100 by the end of 1941.
284:. After the move, work immediately started on the Air Corps request for what was to become known (in 1940) as the "Radio Set SCR-270". Parts of the SCR-268 were diverted to this new project, delaying the completion of the -268.
705:
mounted on the trailer for movement. When opened it was 55 feet (17 m) tall, mounted on an 8-foot (2.4 m) wide base containing motors for rotating the antenna. The antenna itself consisted of a series of 36 half wave
888:
Two high power WL-531 rectifier tubes provided adjustable plate voltage, up to 15 kV at 0.5 A, to the transmitter. Because of pulsed nature of the transmitter, the small amount of filtration was needed.
355:, was at the school and discussed with the American generals the design and urgency of establishing the Hawaiian system, in particular emphasizing the need for thorough radar site coverage along the coasts.
1777:
373:
equipment began appearing did the army return
Bergquist from his fighter unit and tell him his job was to assemble the equipment when it arrived. The commander in charge of defending Hawaii, General
265:(CSig.), bypassing normal channels of command. The SCR-268 was not really suited to this need, and after its demonstration in May they again received a request for a long-range unit, this time from
534:
502:
220:
detection systems (a popular idea at the time), in 1935 work turned to radar again when one of Blair's recent arrivals, Roger B. Colton, convinced him to send another engineer to investigate the
906:
Later units incorporated an antenna steering control system that could sweep a sector repetitively. Still later systems added additional controls to rotate the antenna at 5 RPM for use with a
1838:
359:
of assets spread out over disparate units; anti-aircraft guns, radars, and interceptor aircraft were not under a unified command. This had been one of the primary problems identified by
1843:
696:
Key to the SCR-270's operation was the primary water-cooled 8 kW continuous/100 kW pulsed transmitting tube. Early examples were hand-built, but a contract was let to
242:
the bomber off course, so what was to be a simple demonstration turned into an example of real-world radar location and tracking. Development of this system continued as the
208:
had been experimenting with some radar concepts as early as the late 1920s, under the direction of
Colonel William R. Blair, director of the Signal Corps Laboratories at
1048:
714:
to 25 microseconds, and a pulse repetition frequency of 621 Hz. With a wavelength of about 3 meters (nine feet), the SRC-270 was comparable to the contemporary
1823:
1645:
TM 11-1510: Service Manual For Radio Sets SCR-270 -B, -C, -D, -E, -BA, -CA, SCR-271, SCR-271-A, -AA, -AAA, -AB, -B, -BA, -D, -E, -F, -G, -H, -J, -K, -L, and -M
1183:
850:
across a "trombone" tuned section of transmission line. The high-voltage power pulses would create a spark, short circuiting the line and creating a resonant
533:
did not fare much better than the defending air force at Pearl Harbor. Though FEAF had five SR-270Bs, only two were functioning on 8 December 1941, one was a
1809:
730:
gives performance statistics for the SCR-270-D, namely "maximum range on a single bomber flying at indicated heights, when set is on a flat sea level site":
669:
331:
Operators of sets that were sent to the Panama Canal, the Philippines, Hawaii and other strategic locations were all gathered for an air defense school at
1833:
723:
that range. A nine-man field operating crew consisted of a shift chief, two oscilloscope operators, two plotters, two technicians, and two electricians.
494:, director of Air Defense at the Army Air Force headquarters referred to the Watson-Watt report as "a damning indictment of our whole warning service".
788:
conduction, thereby allowing a pulse of RF to be produced. The transmission line to the antenna was connected to taps on the filament resonant lines.
821:
included a front panel tuning adjustment. The receiver sensitivity control was remotely located on the oscilloscope. The two RF and four 20 MHz
1014:
956:. A second unrestored unit is in the US Army Air Defense Artillery Museum collection at Fort Sill and will be undergoing restoration in 2020.
1503:
414:
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fate as the ships in Pearl Harbor had they attempted to engage the superior Japanese carrier fleet, with potentially enormous casualties.
1089:
931:
625:
538:
965:
530:
519:
272:
Shortly thereafter the Signal Corps became alarmed that their radar work was being observed by German spies, and moved development to
1571:
1427:
1400:
1373:
1342:
1224:
1103:
697:
205:
343:
to collect all information on the British air defense system and transfer the knowledge as quickly as possible to the US military.
1650:
661:
344:
1789:
1287:
348:
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oscilloscope. The keyed output stages consisted of two 450TH power triodes in series, with the final stage configured as a
1363:
1216:
1772:
1828:
645:
621:
461:) system, nor any alternative procedure for identifying distant friendlies such as the British had developed during the
458:
254:
335:, New York in April 1941. The school was the culmination of efforts begun in 1940, when the War Department created the
1095:
949:
485:
The radars on Oahu were put on round-the-clock operation immediately after the attack. After the Japanese attack, the
312:
The non-portable version, the SCR-271-A, s/n 1 was delivered to the Canal Zone and began operation in October 1940 at
1591:"THE SCR-268 RADAR: Detailed technical description of a unit designed to direct anti-aircraft searchlights and guns"
1187:
927:
637:
72:
677:
673:
653:
336:
609:
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277:
172:
which used the same electronics but used an antenna with somewhat greater resolution. An upgraded version, the
1802:
1332:
907:
273:
161:, since it was an SCR-270 set that detected the incoming raid about 45 minutes before the December 7, 1941,
1463:
405:
1595:
1365:
The Second Attack on Pearl Harbor: Operation K and Other Japanese Attempts to Bomb America in World War II
822:
617:
613:
561:
162:
1604:
506:
1006:
592:
in June 1942, an SCR-270 antenna and shack were located at the western end of Sand Island. During the
1144:
1084:
918:
The generator was driven by a LeRoi gasoline engine and could produce 15 KVA of electric power.
728:"U.S. Radar -- Operational Characteristics of Available Equipment Classified by Tactical Application"
453:
262:
833:
817:
orbital-beam hexode electron-multiplier amplifier tube as the second RF amplifier stage. The local
605:
556:
173:
146:
1590:
1437:
1156:
970:
939:
851:
577:
570:
360:
281:
465:. The Japanese aircraft they detected attacked Pearl Harbor 55 minutes later, precipitating the
1616:
1608:
1567:
1529:
1423:
1396:
1369:
1338:
1283:
1238:
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1117:
1109:
1099:
719:
542:
497:
491:
462:
352:
258:
193:
1778:
U.S. Radar, Operational Characteristics of Radar, Classified by Tactical Application, FTP 217
1215:. Williams-Ford Texas A&M University Military History Series (Second Printing ed.).
727:
176:, was also produced, but saw little use. The -270 versions were eventually replaced by newer
1669:
1310:
1140:
944:
867:
798:
593:
573:
420:
390:
181:
688:
1790:
http://www.campevans.org/history/radar/wwii-radar-array-scr-270-and-scr-271-cs-2005-12-08l
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1246:
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810:
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at a distance of 130 miles (210 km) and Lockard telephoned the information center at
266:
1035:
1796:
1491:
1304:
1266:
1150:
defense for cities, vital industrial areas, continental bases, and armies in the field.
980:
553:
to provide air warning to a small detachment of P-40s operating from primitive fields.
230:
185:
701:
components followed as the Army offered additional contracts for eventual production.
1817:
1079:
986:
876:
825:
stages could produce enough gain to fill the oscilloscope display screen with noise.
550:
466:
332:
243:
209:
41:
1306:
United States Navy fleet problems and the development of carrier aviation, 1929-1933
580:, when the Pearl Harbor fleet was destroyed in a mock attack by 150 planes in 1932.
1767:
1624:
1515:
1348:
589:
470:
449:
433:
374:
317:
313:
304:
261:(CZ), sent a request for a "Means of Radio Detection of Aircraft" to the US Army's
154:
188:. The only early warning system of the sort to see action in World War II was the
1417:
1390:
926:
After its use by the military, the Pearl Harbor unit (s/n 012) was loaned to the
324:
at 117 miles (188 km) in its initial test run. The second set was set up on
452:, who had arrived only a week earlier. He thought they had detected a flight of
394:
238:
1480:
448:
The report was passed on to an inexperienced and incompletely trained officer,
377:, had a faint grasp of the weapons and tactics that Army technologists (led by
818:
715:
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378:
340:
325:
247:
225:
213:
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1242:
1783:
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847:
444:
SCR-270 display showing Japanese planes approaching Oahu on December 7, 1941
321:
217:
177:
150:
26:
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1250:
1121:
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design, with a high-power 832 dual tetrode as its first RF amplifier and a
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in January 1942, where it was successfully employed in conjunction with an
292:
1803:
http://www.monmouth.army.mil/historian/photolist.php?fname=Radar%2FSCR-270
1762:
1213:
Doomed at the Start: American Pursuit Pilots in the Philippines, 1941-1942
718:
system being developed in Great Britain, but not to the more advanced UHF
1643:
1504:
Ring Oscillators for U.H.F. Transmission, January 1947 Radio News Article
1094:. Vol. One: Plans And Early Operations January 1939 To August 1942.
814:
189:
841:
A key innovation in the SCR-270 was a transmit-receive (TR) switch. The
1314:
863:
842:
386:
297:
221:
114:
1392:
A Friendly Invasion (The American Military in Newfoundland: 1940-1990)
935:
706:
546:
424:
854:
that prevented most of the pulse energy from reaching the receiver.
490:
observations on targets which may or may not be aircraft." General
942:
for the first time in 1949. The technique was published in 1950 in
246:, which eventually evolved into an excellent short-to-medium range
1334:
Technical and Military Imperatives: A Radar History of World War 2
832:
555:
496:
439:
409:
Plot made early on December 7, 1941, by SCR-270 operators at Opana
404:
308:
SCR-270 at Opana, Oahu, that detected the Japanese attack aircraft
303:
291:
608:
radar stations were constructed by the United States Army in the
1234:
1113:
429:
1053:
Camp Evans: InfoAge WWII Museum and National Historic Landmark
871:
486:
168:
Two versions were produced, the mobile SCR-270, and the fixed
1085:"Chapter 5: Deployment Of The AAF On The Eve Of Hostilities"
339:
headed by Brig. Gen. James E. Chaney. Chaney was tasked by
16:
Early U.S. Army radar type that detected Pearl Harbor attack
157:
and was deployed around the world. It is also known as the
846:
produced by the transmitter. This was solved by placing a
779:
Components of the SCR-270 system included the following:
520:
Far East Air Force (United States) § Warning systems
368:
SCR-270 radars on Hawaii prior to the Pearl Harbor attack
1773:
Information on World War II radar, including the SCR-270
1422:. Washington, DC: Commander Fighter Group. p. 148.
1184:"Battle of Britain in American Context and Perspective"
393:(northern tip), in the northwest at the highest point-
1797:
http://www.ibiblio.org/hyperwar/USA/ref/FM/index.html
1768:
Information on British Chain Home World War II radar
576:
that annihilated the locks on the Panama canal, and
131:
123:
113:
105:
97:
89:
81:
71:
63:
55:
47:
37:
1642:
1629:A detailed description of a closely related radar.
1083:
1839:Military radars of the United States Marine Corps
1492:Service Manual for Radio Sets SCR-270 and SCR 271
1267:Proceedings of the Roberts Commission – Bergquist
938:), who, unaware of its history, used it to image
1419:A History of the Air Defence of Canada 1948-1997
1844:Military equipment introduced from 1940 to 1944
1395:. St John's: Breakwater Books Ltd. p. 25.
1326:
1324:
192:, which was available in mid-1944, in time for
1494:, War Department Technical manual, August 1944
1481:Westinghouse WL-530 VT-122 Water-Cooled Triode
1206:
1204:
930:in Saskatoon (along with a second unit to the
734:Maximum range at indicated height of aircraft
514:Use of SCR-270 radar elsewhere in World War II
1516:"1630, Tube 1630; Röhre 1630 ID17477, HEXODE"
870:, the same type used in the first commercial
866:) display employed a five-inch diameter 5BP4
401:Use on the morning of the Pearl Harbor attack
253:In April 1937 a LtC. Davis, an officer in an
8:
1036:AN/CPS-1 Microwave Early Warning (MEW) Radar
19:
1262:
1260:
419:SCR-270 serial number 012 was installed at
1808:film of scr 270 at fort bliss/white sands
1564:December 8, 1941: MacArthur's Pearl Harbor
501:1942 photo of the SCR-270 utilized by the
153:'s primary long-distance radar throughout
25:
18:
351:(GCI) air defense system used during the
216:. Although the Army focused primarily on
184:that was introduced to the US during the
732:
687:
1763:Witness Testimony regarding Opana Radar
1748:SNL G703, antenna trailers, K-22, K-64,
1309:(MA thesis). Texas A&M University.
997:
564:on Okinawa after the Battle of Okinawa.
280:, the coast artillery defense site for
1445:
1435:
1165:
1154:
1049:"WWII Radar Array SCR-270 and SCR-271"
726:The declassified US military document
503:Marine Corps' Early Warning Detachment
551:SCR-268 antiaircraft gun-laying radar
7:
1824:Military radars of the United States
1751:SNL G511, truck/van K-30, K-31, K-62
415:Radar warning of Pearl Harbor attack
1091:The Army Air Forces In World War II
1017:from the original on 5 October 2022
535:Marine Corps Air Warning detachment
1566:. Texas A&M University Press.
966:List of U.S. Signal Corps Vehicles
604:A series of five SCR-271-equipped
14:
1834:World War II American electronics
1534:www.nationalelectronicsmuseum.org
1211:Bartsch, William H. (July 1995).
1055:. 12 January 2007. Archived from
692:SCR-270 operations van components
145:was one of the first operational
1788:1942 view of an SCR-271 at the
269:who wrote to them June 3, 1937.
1282:. New York, NY: Carlton Press.
1038:, National Air and Space Museum
983:height finder used with SCR-270
1782:Historical Electronics Museum
1605:McGraw-Hill Publishing Company
1217:Texas A&M University Press
751:25,000 ft (7,600 m)
748:20,000 ft (6,100 m)
349:Ground-controlled interception
347:, one of the designers of the
288:Deployment and Incomprehension
1:
884:High Voltage rectifier RA60-A
745:5,000 ft (1,500 m)
672:under operational control of
1651:United States War Department
1562:Bartsch, William H. (2003).
902:Antenna control unit BC-1011
829:Transmit-receive (TR) switch
459:Identification friend or foe
1607:: 100–109. September 1945.
1096:University of Chicago Press
950:National Electronics Museum
858:Oscilloscope display BC-403
742:1,000 ft (300 m)
316:on the Atlantic end of the
109:8 by 4 dipole array typical
1860:
1389:Cardoulis, John N (1990).
1331:Brown, L. (January 1999).
1303:Wadle, Ryan David (2005).
928:University of Saskatchewan
768:110 mi (180 km)
765:100 mi (160 km)
670:685th Air Warning Squadron
517:
412:
296:Non portable version: the
127:4 mi (6.4 km) 2°
1464:"Other American Stations"
1368:. Naval Institute Press.
1005:Wolff, Christian (n.d.).
932:National Research Council
678:Pepperrell Air Force Base
674:Newfoundland Base Command
24:
762:50 mi (80 km)
759:20 mi (32 km)
610:Dominion of Newfoundland
529:In the Philippines, the
257:Pursuit Squadron in the
1530:"Oral History- NEM-USA"
908:plan position indicator
101:150 miles (240 km)
1278:Williams, Ted (1979).
1082:, eds. (1 May 1983) .
1078:Craven, Wesley Frank;
910:, like modern radars.
838:
693:
565:
562:Air Warning Squadron 6
510:
445:
410:
309:
301:
163:attack on Pearl Harbor
38:Country of origin
837:BC-403-C oscilloscope
836:
691:
684:Technical description
668:, were manned by the
559:
507:Battle of Guadalcanal
500:
443:
408:
307:
295:
200:Building of the radar
85:10 to 25 microseconds
1362:Horn, Steve (2005).
469:' formal entry into
263:Chief Signal Officer
147:early-warning radars
1829:World War II radars
1416:Group, NBC (1997).
1059:on 31 December 2013
735:
612:in 1942 to protect
560:SCR-270 Radar from
539:4th Marine Regiment
345:Air Marshal Dowding
337:Air Defense Command
21:
1653:. 25 August 1944.
1468:www.heritage.nf.ca
1448:has generic name (
1164:Unknown parameter
971:Signal Corps Radio
893:Water cooler RU-4A
862:The oscilloscope (
839:
809:The receiver is a
783:Transmitter BC-785
733:
694:
628:. The stations at
578:Fleet Problem XIII
571:United States Navy
566:
531:Far East Air Force
511:
446:
411:
361:Robert Watson-Watt
310:
302:
282:Lower New York Bay
229:civilian engineer
159:Pearl Harbor Radar
1635:Technical Manuals
772:
771:
622:Ernest Harmon AFB
543:Cavite Naval Base
492:Gordon P. Saville
463:Battle of Britain
353:Battle of Britain
259:Panama Canal Zone
139:
138:
1851:
1745:
1737:
1729:
1721:
1713:
1705:
1697:
1689:
1681:
1673:
1670:Internet Archive
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799:cathode follower
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662:Allan's Island (
638:Elliston Ridge (
594:Battle of Midway
574:Fleet Problem IX
182:cavity magnetron
135:100 kW peak
29:
22:
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1625:Google Books
1623:– via
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1537:. Retrieved
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1192:. Retrieved
1188:the original
1178:
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1139:– via
1133:. Retrieved
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1061:. Retrieved
1057:the original
1052:
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1019:. Retrieved
1010:
1000:
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922:Preservation
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823:IF amplifier
808:
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792:Keyer BC-738
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631:
630:Cape Spear (
618:McAndrew AFB
603:
600:Newfoundland
587:
567:
528:
484:
475:
471:World War II
450:Kermit Tyler
447:
434:Fort Shafter
428:approaching
418:
383:
375:Walter Short
371:
357:
330:
318:Panama Canal
314:Fort Sherman
311:
278:Fort Hancock
271:
267:"Hap" Arnold
252:
235:
206:Signal Corps
203:
169:
167:
158:
155:World War II
142:
140:
67:106 MHz
1792:, Wall, NJ
1596:Electronics
1446:|last=
1315:1969.1/2658
626:RCAF Torbay
614:NS Argentia
525:Philippines
505:during the
421:Opana Point
395:Mount Kaala
391:Opana Point
239:Martin B-10
165:commenced.
77:621 Hz
1818:Categories
1734:TM 11-1470
1726:TM 11-1410
1718:TM 11-1370
1710:TM 11-1310
1702:TM 11-1114
1694:TM 11-1100
1686:TM 11-1033
1678:TM 11-1570
1664:2 February
1539:2016-05-26
1289:0806213221
1194:2006-09-09
1143:. p.
1135:30 January
1063:30 January
1021:24 January
993:References
819:oscillator
775:Components
716:Chain Home
379:Hap Arnold
341:Hap Arnold
326:Fort Grant
274:Sandy Hook
248:gun laying
226:CXAM radar
214:New Jersey
93:1 RPM
82:Pulsewidth
48:Introduced
1659:46533934M
1613:0013-5070
1438:cite book
1243:847855412
1168:ignored (
1157:cite book
1130:46528737M
1007:"SCR-270"
976:G-numbers
954:Baltimore
914:Generator
848:spark gap
739:Altitude
541:based at
481:Aftermath
322:airliners
218:infra-red
178:microwave
151:U.S. Army
124:Precision
64:Frequency
1799:FM 11-25
1742:FM 11-25
1583:Journals
1251:8218183M
1235:91034307
1114:83017288
1015:Archived
960:See also
815:RCA 1630
250:system.
190:AN/CPS-1
106:Diameter
1621:1567758
1122:9828710
864:A-scope
843:SCR-268
707:dipoles
537:of the
387:Haleiwa
298:SCR-271
244:SCR-268
222:US Navy
174:SCR-289
170:SCR-271
143:SCR-270
115:Azimuth
20:SCR-270
1657:
1619:
1611:
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1399:
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1249:
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1112:
1102:
945:Nature
940:aurora
936:Ottawa
756:Range
660:, and
624:, and
584:Midway
547:Bataan
425:Hawaii
119:0–360°
1603:(9).
1555:Books
952:near
664:Cinco
632:Prime
454:B-17s
194:D-Day
132:Power
98:Range
32:base.
1666:2023
1617:OCLC
1609:ISSN
1568:ISBN
1450:help
1424:ISBN
1397:ISBN
1370:ISBN
1339:ISBN
1284:ISBN
1239:OCLC
1231:LCCN
1221:ISBN
1170:help
1137:2023
1118:OCLC
1110:LCCN
1100:ISBN
1065:2023
1023:2023
852:stub
656:Quad
648:Trio
430:Oahu
204:The
141:The
56:Type
51:1940
1311:hdl
1145:152
934:in
872:RCA
676:at
640:Duo
588:At
487:RAF
389:),
276:at
224:'s
90:RPM
73:PRF
1820::
1655:OL
1649:.
1615:.
1601:18
1599:.
1593:.
1532:.
1466:.
1442::
1440:}}
1436:{{
1323:^
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1245:.
1237:.
1229:.
1219:.
1203:^
1161::
1159:}}
1155:{{
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1126:OL
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666:)
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650:)
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634:)
509:.
457:(
385:(
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
