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.

This demonstration turned out to be particularly convincing by mistake; the Martin B-10 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.

It was later learned that winds had blown the bomber off course, so what was to be a simple demonstration turned into an example of real-world radar location and tracking.

Shortly thereafter the Signal Corps became alarmed that their radar work was being observed by German spies, and moved development to Sandy Hook at Fort Hancock, the coast artillery defense site for Lower New York Bay.

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 Mitchel Field, New York in April 1941.

The school was the culmination of efforts begun in 1940, when the War Department created the Air Defense Command headed by Brig.

[4]: 152  Chaney was tasked by Hap Arnold to collect all information on the British air defense system and transfer the knowledge as quickly as possible to the US military.

Air defense required direct control of assets spread out over disparate units; anti-aircraft guns, radars, and interceptor aircraft were not under a unified command.

The commander in charge of defending Hawaii, General Walter Short, had a faint grasp of the weapons and tactics that Army technologists (led by Hap Arnold) were aggressively pushing them to adopt.

The radars were placed on the central north shore (Haleiwa), Opana Point (northern tip), in the northwest at the highest point- Mount Kaala, and one in the southeast corner at Koko Head.

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.

[6]: 225 SCR-270 serial number 012 was installed at Opana Point, Hawaii on the morning of 7 December 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 approaching Oahu at a distance of 130 miles (210 km) and Lockard telephoned the information center at Fort Shafter and reported "Large number of planes coming in from the north, three points east".

The Japanese aircraft they detected attacked Pearl Harbor 55 minutes later, precipitating the United States' formal entry into World War II.

In retrospect this may have been fortuitous, since they might have met the same fate as the ships in Pearl Harbor had they attempted to engage the superior Japanese carrier fleet, with potentially enormous casualties.

[7] After the Japanese attack, the RAF 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 observations on targets which may or may not be aircraft."

[6]: 225 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 Marine unit was withdrawn to Bataan in January 1942, where it was successfully employed in conjunction with an SCR-268 antiaircraft gun-laying radar to provide air warning to a small detachment of P-40s operating from primitive fields.

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 declassified US military document "U.S. Radar -- Operational Characteristics of Available Equipment Classified by Tactical Application" 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": Components of the SCR-270 system included the following:[17] The transmitter used dual WL530 water-cooled triodes configured as a high power push-pull resonant-line oscillator.

The oscilloscope (A-scope) display employed a five-inch diameter 5BP4 cathode-ray tube, the same type used in the first commercial RCA television set, the TRK-5, introduced in 1939.

The sweep signal passed through a calibrated phase shifter controlled by a large hand wheel on the front panel.

Still later systems added additional controls to rotate the antenna at 5 RPM for use with a plan position indicator, like modern radars.