2015_05_23_syd-akl-lax-sfo_248z : 無料・フリー素材/写真
2015_05_23_syd-akl-lax-sfo_248z / Nfrastructure
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | The KNBR/680 transmitter site, in a tidal marsh at the end of Redwood Shores, on San Francisco Bay. (Redwood Shores is in the city of Belmont.)The tall tower is the working antenna, built in 1949. It replaces a vertical wire radiator suspended between two towers, one of which is still standing, and was repurposed as an auxiliary antenna. The base of the removed tower is still visible an equal distance on the other side of the main tower. The tower itself is sectionalized: one radiator atop another. The upper one has a capacitive "hat" giving it a longer electrical length. Specifics from the license:Site Location: 37-32-50.0 N 122-14-00.0 W (NAD 27)Power: 50 kW, Non-DirectionalSectionalized Tower A: 99.5° B: 0° C: 136.83° D: 50.32°RMS Theoretical: 362.1 mV/meter (per kW) or 2560.43 mV/meter at 50 kWI believe A is the lower section and C is the upper one, which includes D as the "hat."KNBR is one of the original "clear channel" stations, meant to cover most of the U.S. at night without interference. While the station is now only protected out to 750 miles, its signal is one of the biggest on the AM band in the U.S. In fact I have a recording of it somewhere, made in Maywood, New Jersey, in the early '60s.The four structures that each spell HAZ are warnings to pilots, and mean "hazard." The facility is not far from the approach to San Francisco's airport, SFO. (And how I got such a good view on an inbound flight.) It's also very close to San Carlos Airport.Next to KNBR on the left (or south) is the old site of KGEI, a General Electric shortwave station. You can see the concrete bases of some of the towers that stood in that field. This page at the Bay Area Radio Museum shows how the KGEI transmitter building and field of towers looked in 1960.Here are the history cards for KNBR, which was born as KPO and was also known for awhile as KNBC. The call letters now also repose on 104.5fm, long the home of KFOG. |
| 撮影日 | 2015-05-23 17:42:18 |
| 撮影者 | Nfrastructure |
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| 撮影地 | |
| カメラ | Canon EOS 5D , Canon |
| 露出 | 0.002 sec (1/500) |
| 開放F値 | f/4.0 |
| 焦点距離 | 105 mm |