2009-05-29 Tour of George, WA U.S.C.G. LORAN Station скачать в хорошем качестве

2009-05-29 Tour of George, WA U.S.C.G. LORAN Station

ICOM1020 and myself were granted access to tour the still fully functional LORAN station just outside the town of George Washington On May 29th, 2009. LORAN was a type of terrestrial-based, pre-GPS locating system that the governments of the US, Canada, Denmark, Iceland, and Norway operated. While GPS offers error in the data that provides drift in real location, LORAN provided a more constant pinpoint location service. The location may not be totally accurate when cross referenced with real Latitude and Longitude, but the signal always pointed at the same spot where you were, without drift. George began operation on October 15th, 1976 and ended its 33 year operation on February 8th, 2010 and at the time was the US's most powerful AM radio transmitter boasting 1.6 Megawatts. The tour was guided by ETC (Chief Electronics Technician) Benjamin A DiGuilio. It was a great opportunity to meet the people involved with this operation and I hope their futures are as bright as the 1.6 MW transmitter they staffed. A far superior, detailed description of LORAN, how it worked and history can be found at http://www.loran-history.info The video starts with the sound of the LORAN RF at George. It is a direct recording I made from my ICOM R-20 the day of the tour. The stills were a combination of photos from ICOM1020 and myself. The drive into the facility is somewhat strange. Being far inland seeing a USCG sign was a little surprising! The outside of the facility was clean with the omnipresent towers looming high in the background. For those who notice, the cigarette can is a real throwback to earlier days at the main door. Inside we are greeted with the station herald then just off to the right a large format map of the US and Canada detailing the 25 LORAN stations. Next we tour the backup power plant consisting of three diesel generators. Then DiGuilio displays one of the older tubes used back when the site was tube driven. As seen on the loran-history.info page, the area that the tube transmitters and amps were is now just a open space reserved for exercise equipment. Out back of the facility we see what was left over of the water cooling radiators, again, used back when the tubes were in operation. Today, with all solid state equipment heat dissipation is easily done with smaller (in comparison) AC units. Behind the newer building, two backup generators keep at a standby in case the commercial power fails. Looking beyond the fencing the desolate scenery is upstaged by the four 700 foot towers. Most of the cabling you see for the towers is only guy wires used to support the towers, the actual radiating part of the LORAN transmitter is an 'upside-down pyramid' shaped set of cables, radiating out from a base which is seen toward the end of the video. Inside the newer facility a sample of what a LORAN receiving antenna looks like is shown. From there, we see a few shots of scope displays, showing the individual pulse, and a chain of the same pulses signals sent out to the amplifier. Next is a shot of where the amplifier takes over and kicks the signals power up. If I remember correctly, DiGuilio indicated that the first two cycles of the signal were not greatly amplified from the transmitter, only afterward was where the amp took the first stage and greatly boosted the power. Next we have a set of three Cesium standard frequency clocks used to make sure the timing was VERY accurate. Following that was the actual transmitter control stations. Next inside the amplifier room it is a bit noisy. We were required to wear hearing protection as the AC and transmitters make quite a bit of noise. In the first few frames we can see both of the rows that house (I hope I remember this correctly) the 48 individual amplifiers, followed by the 6 final stage amplifiers. The large blue objects off near the walls are the AC units. In the wooden crate is a backup of one of the smaller amps that work in phase to create the LORAN pulses. Behind the final amps, there is a combiner for both rows of transmitters. After that the combined signal is sent to a 6 inch coaxial feed line, then into a PVC pipe to feed the antennas outside. There is 1.6 million watts going through that center conductor! Even at the point where the RF is contained in the feed line, DiGuilio demonstrates that a fluorescent tube can be lit from the escaping RF. Out behind the new facility, the PVC pipe protects the feed line to a junction box were braided wire sends the RF to the insulated base of the antenna and from there up to the inverted pyramid and out to the open sky. Note the spark gap for lightning protection. We thanked ETC DiGuilio and his staff for a great, wonderful, memorable tour and wished them well in their, at the time, uncertain future. Just before we left the property, we decided to check in on local radio stations in the car...we found just a little interference on the AM band.