US Naval Radio Station Pearl Harbor - NPM

Naval Radio History of 14th Naval District (Hawaii) - by LT George Todd, USN RET - pdf

1919 report - 
   Located at Navy Yard, Pearl Harbor, Oahu, Territory of Hawaii. Equipped with one 350 KW arc set adjusted to the following waves: 6100, 8100, 11200 and 14100. These waves are used for both calling and working; and one 5 KW 500 cycle quenched spark set adjusted for the following waves: 300, 600 (commercial), 752, 952 (calling and working), 1900 and 2400 (working) meters. The acceptance tests for the 350 KW arc transmitter were completed on 4 October 1917, but owing to defects developing in the arc chamber, the final acceptance was not approved until 6 March 1918 and turned over to the Communication Service on that date.
   At present (1918) this station is operated by distant control from Koko Head. Inasmuch as Koko Head will soon revert to the Marconi Company, a new control station must be obtained. Effort is being made to obtain a site as free from interference from the several transmitting stations as possible. Exploration work is now in progress. It is probable that a site on Waialae Bay, between Honolulu and Koko Head (where NPM control was later located at Wailupe), or in Honolulu, will be chosen - at least for temporary control.
   Arc set: Communication is effective with San Diego, San Francisco, Cavite, Funibashi, Japan, and Tutuila, American Samoa. Regular daily schedules are maintained with all these stations. Communication with Darien, Canal Zone is practicable but no schedule has been established. This can be done if necessary. Can also communicate with ships equipped with arc sets when required, dependant on their range.
   Spark set; Communication is effective with Kawaihae (KHN), Lamina (KHL), Kaunakakai (KHO), and Lihue (KlM) in the Hawaiian Islands. Cannot be satisfactorily effected with Wahiawa (KHK) spark set. Also effective with ships equipped with spark sets dependent on their range.
   A master clock, chronometer, time ball, and other equipment necessary for transmitting time signals by radio are now being installed at Pearl Harbor and, when completed, time will be broadcast at least twice daily on both spark and arc sets. Time of broadcasting and wave lengths used will be determined later.
   Telegraph connections: One arc control , one spark control, one communication wire, and one telephone circuit that can be used as a control or communication wire. These circuits all come in to a plug board at the Naval Communication Office, Honolulu, and can there be cut over to any other station of the system, which is very flexible.
   Comment. This station is a superprimary, primary, and coastal station and is the headquarters for the District Communication Superintendent of the Pearl Harbor District. Pearl Harbor now handles practically all the long distance commercial radio work of the district, as it has taken over the Marconi and Federal business with the Pacific Coast, the Marconi business with Japan, and handles the new commercial business with Guam and Cavite. Some of this load will soon be taken over by the new arc at Heeia. The greater part of it will revert to the commercial companies when their stations are returned to them. The military value of this station is of the greatest importance, offering direct radio communication with the United States, Guam, and the Philippines, supplementing the cable, and affording the only direct communication with Tutuila. It would also be of primary importance in broadcasting messages to the Fleet in the Pacific.
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Federal Arc Converter
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Helix addition to the Power House at the High Power Radio Station. Yard labor, August 1917
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High Power Radio Station. The Power House showing addition for helix, looking north. 6 September 1917
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High Power Radio Station. Pit excavated for ground plates. Southwest side of the Power House. 6 September 1917
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High Power Radio Station dormitory, Building Number 454, looking east. 6 September 1917
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High Power Radio Station Operator's Quarters, Building Number 456. 6 September 1917
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Pearl Harbor antenna towers 1925
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From 1922 article
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NPM Tower Insulators - ~1922
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NPM Tower Insulators - ~1922
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