"The Radio Re1ay Building is steel frame, concrete block, with concrete foundation and concrete slab floor. Steel truss girders support the corrugated steel roofing over 2" x 6" T & G fir. The walls are 14’ to the eaves. The building has solid core wood exterior and interior doors with good quality hardware. It is heated with a McPhearson oil-fired furnace, 110,000 BTU, that provides forced air heat to the building. The building has no plumbing and no windows.

"The radio equipment room has painted concrete floor, painted concrete walls and is open to the under side of the steel truss girders and roof.

"The standby emergency power room has a painted concrete floor, painted concrete block walls, and is open to the roof. This room houses a 2-cylinder General Motors diesel engine, with 20 KW Delco generator.

"The site has one diesel storage tank with 100 barrel capacity, a 213 sq. yd. vehicle parking lot, and is fenced with 543 lineal feet of 8’chain link fence with 3 barb wires.

"Sanitary facilities are provided by a 16 sf plywood outhouse. This station was built in 1957, is in good condition inside and out, has been well maintained and shows little deferred maintenance" (Follett and Associates 1978: 230).

The Rabbit Creek facility is an active repeater station as shown in photo 1 of the Historic American Engineering Record photographs following this description. After the photographs is a set of representative as-built drawings of radio relay stations. The ones included in this report are from the Sawmill and Cathedral facilities because the Rabbit Creek as-built file is too incomplete to give a good picture of how it works. The as-built drawings are followed by a site plan and floor plan of the Rabbit Creek installation.

An active repeater of the Rabbit Creek, Cathedral, and Sawmill type amplifies a microwave signal and sends it on to the next station. A passive repeater, on the other hand, has no active parts and is merely a billboard which functions as an optically aligned reflector, much as a mirror reflects a beam of light. It deflects its signal off of a series of such billboards to its final destination. In southcentral Alaska, a passive repeater system functions between Anchorage and Seward. A passive billboard is prominent as one drives south along the Seward Highway, leaving Anchorage. One can be seen across Turnagain Arm on Penguin Peak. The Rabbit Creek station, however, is more complex than this system.

Microwave signals are received at the Rabbit Creek facility from the Anchorage toll center near Elmendorf Air Force Base and from Naptowne, another repeater station, on the Kenai Peninsula. When Rabbit Creek was first opened, signals were received from R1-N. All of these installations were part of the WACS and the Anchorage toll center was the Anchorage ACS. The microwave signal enters one of two cornucopia antennas (shown in photos 2 and 3) which sit on top of the 53 foot TD-2 microwave tower. One cornucopia faces Naptowne and the other faces the Anchorage toll center. The signals travel down waveguides, entering the radio relay building (photos 4 and 5). Straight sections of waveguides are constructed of copper while curved sections are coated with dense rubber, with copper inside. Note in these photos that there are four waveguides which converge about 10 feet above the ground as they leave the tower and enter the building. This is because two go to each cornucopia and one receives the signal, while the other transmits it. Photo 6 shows the waveguides after entering the radio relay building. The two which bend immediately toward the back of the top of the photo connect to Naptowne while the two running across the top of the photo connect to the Anchorage toll radio. Photo 7 is a close up of the Anchorage toll center radio. One can clearly see the waveguide terminals. The one on the left is the receiver and the one on the right is the transmitter. After the signal is received it is amplified and then goes through a process of filtering and mixing. It then goes through to the transmitter, passing through a transmodulator and several transamplifiers before ascending the waveguide and leaving the building. Photo 8 is a view down the same bay shown in photos 6 and 7. It shows, on the left, from the front to the back of the photo, a new alarm system, storage locker, Anchorage toll TD-2 receiver and transmitter, a test banks, and the original VHF communications radio which functions to provide service channels to Naptowne. Coming back along the wall is the cooling system for the equipment, a storage cabinet, the Naptowne TD-2 receiver and transmitter, the air supply for the waveguide apparatus, and another storage cabinet. On the sketch plan, note that the two transmitter/receivers each have a cabinet labeled "protect." Each "protect" cabinet contains a duplicate transmitter/receiver complex. Both carry the same traffic, but if there is a problem with one, the other is switched into action from the Soldotna WACS or from the Anchorage Toll Center. The Naptowne WACS, identical to the Rabbit Creek facility, does not have this switching capability. The corridor described above is the heart of the radio relay station.

The equipment in the corridor closer to the door provides power to the office. Photo 9 shows, from right to left (front to back), the AC power panel, a 24 volt volt rectifier and a converter/rectifier which converts AC current to DC current, a 24/48 volt DC-DC converter, a fuse panel and two 12 volt rectifiers. The rectifiers are connected to the 12 volt batteries in the left half of the photo. Photo 10 shows a bank of 24 volt batteries used for back up power. they are connected to the 24/48 volt DC-DC converter. Photo 11 shows the fuse panel next to the door. If a fuse fails, the worker on duty simply matches it to the one on the panel, removes it and replaces it with the correct fuse. Photo 12, the 20 Kw generator (the original one) is located in the emergency power room, adjacent to the radio equipment room. If all else fails, the generator can run the station for several hours. It is serviced twice a month.

What follows are brief descriptions for all 71 WACS facilities. The BMEWS facilities are presented in tabular form because they are so similar. In some instances, particularly tower height or distance to the next station, data are not available. This may be because the data were never recorded for that particular facility, the data have been lost, or the data have not yet been retrieved from the tremendous amount of archival material available. Archival material, mostly as-built drawings, measures in the 1000’s of cubic feet.

Installations are listed by phase of construction (original, BMEWS, Stretchout, Bluegrass, and later additions) and within this category, they are listed alphabetically. Included are as-built drawings and photographs of various installations which are referenced in text and immediately follow it. In referring to communications antennas, the following standardizations are assumed and not always stated. Tropo antennas occur in pairs; 60 and 120 foot antennas are of the billboard shape, while 30 foot antennas are circular; all are parabolic; TD-2 microwave towers occur singly, but have paths to two or more destinations as indicated.

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