Jim Creek Naval Radio Station

  • By John Caldbick
  • Posted 5/30/2019
  • HistoryLink.org Essay 20778

In late 1953 the United States Navy came to Jim Creek Valley in Snohomish County and built the most powerful radio transmitter the world had yet seen. It was designed by the Radio Corporation of America (RCA) and could send messages instantaneously to every one of the navy's facilities, ships, and aircraft around the world, including submarines cruising beneath the sea. Ten cables, ranging in length from 5,640 to 8,700 feet, were draped across the valley in a zig-zag pattern between six steel towers on the crest of Blue Mountain and six on Wheeler Mountain to its north, forming a huge dish. At their midpoint, the cables are energized through vertical cables carried by additional towers that rise from the valley floor. The transmitter is fed electricity by a direct transmission line from Bonneville Dam on the Columbia River, and in 1957 a 2,500-kilowatt Worthington diesel-powered standby generator was installed as a back-up power supply. In 2016 several elements of the facility were found to be eligible for listing on the National Register of Historic Places, including the Worthington generator, which after more than 60 years of service was to be removed and replaced in 2019.

Reaching Around the Globe

When Japan surrendered on September 2, 1945, ending World War II, the United States stood as the only superpower. America's military might was projected largely by its navy, which at war's end had more than 6,700 ships (including 232 submarines) cruising every ocean on Earth. Although these numbers were drastically reduced in the post-war years, the navy remained a worldwide force, and it needed a radio-communications system that could instantly, reliably, and securely convey messages to all its assets. Naval Radio Station Jim Creek would be the first to satisfy that need, and a few technical details are useful to an understanding of its uniqueness.

The basic building block of radio communications is a radio wave, which occupies the lower regions of the electromagnetic spectrum. The full spectrum includes everything from radio waves, to visible light, to extremely high frequency, short wavelength gamma rays.

Wavelength describes the distance over which a wave's shape repeats, and is typically measured between two successive crests or troughs. Frequency describes the number of waves that pass a fixed point in a given amount of time. Wavelength and frequency are inversely proportional -- the lower the frequency, the longer the wavelength (see illustration at left).

The frequency of a radio wave is expressed in units called "hertz" (used as both the singular and plural noun), abbreviated as Hz. The radio portion of the electromagnetic spectrum ranges between 3,000 hertz, or 3 kilohertz (KHz), and 300 billion hertz, or 300 gigahertz (GHz). Widely used consumer devices and services -- including mobile phones, GPS, Bluetooth, and TV and land radio -- use either the very high frequency (VHF) or ultra high frequency (UHF) radio bands, measured in millions of hertz (MHz), with a range between 30 and 3,000 MHz. Naval Radio Station Jim Creek achieves its worldwide range by transmitting a very powerful, very low frequency (VLF) signal, one with a wavelength of approximately seven miles and a frequency of only 24.8 KHz. (In subsequent decades, the U.S. military built transmitters that used even longer wavelengths, a technology unavailable in the early 1950s.)

Why Very Low Frequency?

There were several considerations that dictated these specifications. Electromagnetic signals are adversely affected by obstacles that are the same size or larger than the wavelength of the signal. The longer the wavelength, the fewer are the things that can affect it. The seven-mile wavelength of the Jim Creek transmitter's signal means that it can pass undisturbed through most obstacles on and near the surface of the Earth that would interfere with shorter wavelengths, including buildings and other structures, hills, and weather disturbances in the troposphere (the lowest layer of our atmosphere). And the lower the frequency (i.e. the longer the wavelength), the more readily a signal can penetrate liquids, such as seawater. This enables submarines that are shallowly submerged to receive Jim Creek's signal without extending a telltale antenna above the water's surface.

Also, very low frequency waves bounce off positively charged atoms (ions) in the lower layers of the ionosphere, between 37 miles and 56 miles above the Earth's surface. The waves strike the ground on the return trip and are reflected back up again to the ionosphere, then again are reflected downward. The back-and-forth produces a "waveguide" that repeatedly bounces the signal and allows it to work its way over the horizon and around the curved surface of the globe ("The Earth's Ionosphere"). This phenomenon brings the entire Earth within the reach of the Jim Creek station, giving the navy the ability to communicate simultaneously with all its assets, wherever located. Yet another advantage of VLF, and one of particular importance to the military, is that long wavelengths are highly resistant to jamming by natural (e.g. atmospheric) or man-made interference.

But there are downsides as well. VLF transmitting antennas have to be very large and carefully sited. Receiving antennas can be substantially smaller, but the bigger the better, so submerged submarines have to unreel and tow cumbersome antenna cables to pick up VLF signals.

Another limiting factor is that the amount of information a wave can carry is proportional to its frequency -- the lower the frequency, the less information can be contained in the signal. VLF is not suitable for sending audio or large amounts of data, and at first was a simple on-off (Morse code) keying system with a capacity of only 20 words per minute. The Naval Research Laboratory later devised an automatic teleprinter system and other improvements that increased this capacity, but VLF remains an inefficient and time-consuming means of transmitting significant amounts of data.

Because transmitting a long-range VLF signal requires a huge antenna, it is primarily a one-way system, i.e. the recipients of the signals must respond, if at all, using higher-frequency communications modalities. Another drawback is that Jim Creek's VLF signals can penetrate seawater only to a depth of about 65 feet, so submarines, while able to receive a message while submerged, must be relatively near the surface and well within the range of detection by enemy sonar.

The Jim Creek Antenna

The U.S. Navy had been experimenting with very low frequency communication since before World War I, but it was not until July 1946 that the Chief of Naval Operations (CNO) instructed the navy's Bureau of Ships to explore the Puget Sound region for a suitable site to build a VLF transmitter and antenna. One year later, the CNO approved the purchase of 5,000 acres in and around Jim Creek Valley, located in the western foothills of the Cascade Range about nine miles due east of Arlington in Snohomish County. Jim Creek takes its name from a Stillaguamish Indian called "Old Jim" by non-Native settlers in the nineteenth century. He tended a trap line up and down the small waterway for many years, until one day he went upstream and simply disappeared. In time "Old Jim's Creek" became simply Jim Creek, and the name was also attached to the valley through which it ran ("A Special History ...").

On the north side of Jim Creek Valley stands Wheeler Mountain, and on the south side, Blue Mountain, both more than 3,000 feet high. The essence of the navy's plan was make the entire valley between those two peaks into a giant dish antenna, then the largest in the world at approximately 980 acres.

Two divisions of the Radio Corporation of America (RCA) were awarded the contracts for the design and installation of the antenna, transmitter, and associated electrical components. The navy's Bureau of Yards and Docks designed the facility's towers and support buildings, and the public-works officer for the Thirteenth Naval District was responsible for all site preparation, roads, and building construction.

Beginning in the spring of 1949, more than 725 acres of the valley were cleared of trees, mostly Douglas fir. This took more than a year, but was necessary both for fire protection and because trees would "tend to absorb large quantities of energy radiated by the antenna" ("The Navy's Mighty Voice"). After the slopes were cleared, six 200-foot steel towers were erected on the crest of each mountain to anchor 10 catenary cables draped across the valley in a zig-zag pattern. (A catenary is the curved shape that a flexible cable, wire, or chain assumes when hanging freely from two elevated points.) These cables, steel-sheathed copper, are one inch thick, range in length from 5,640 feet to 8,800 feet, and form the "dish" of the antenna. They are divided into two groups of five each to ensure that one-half of the antenna can remain functional even if the other half is damaged or shut down for maintenance or repair.

From the lowest point of each of the ten catenary cables, a vertical cable called a down-lead drops 900 feet to one of 10 towers on the valley floor, which connect the antenna to the transmitter. These vertical cables are the main radiating elements of the antenna; the miles of sagging catenary cables forming the dish serve to increase the power of the signal coming from the transmitter.

The Jim Creek Transmitter

If the antenna is the voice of Naval Radio Station Jim Creek, the transmitter is its heart. Here 2,000 kilowatts (kW) of electrical power that is delivered through a transmission line from Bonneville Dam on the Columbia River is converted to the very low frequency electromagnetic signal in which is encoded the information sent out through the antenna array. The transmitting equipment was built at the RCA Victor plant in Camden, N. J., shipped to Seattle on 27 freight cars, then trucked to Jim Creek Valley on a road prepared by crews from the Thirteenth Naval District.

The transmitter was installed on the second story of a windowless structure built on the valley floor under and midway along the span of the overhead antenna array. The building is earthquake resistant and completely lined with copper sheathing to shield against intense electromagnetic radiation. As with the antenna, the transmitter is divided into two separable halves to ensure uninterrupted operation in the event either half for any reason becomes unusable.

An electrical current, such as that supplied by Bonneville Dam, is not an electromagnetic wave, but it is the source from which they are derived. Electromagnetic waves are created by accelerating (oscillating) electric charges, and this, at the most basic level, is what the transmitter does. Exactly how this is accomplished involves arcane principles of electrodynamics that this overview needn't venture into. It suffices to say that the Jim Creek transmitter uses its input of 2,000 kW of electrical power to produce a VLF signal of 24.8 KHz with a maximum transmitting power of 1,200,000 watts (1,200 kW), although it is usually operated at a somewhat lower intensity. By comparison, commercial radio stations typically have a signal strength in the neighborhood of 100 kW. It is the combination of low frequency, long wavelength, and high signal strength that enables Jim Creek to communicate with naval assets around the world, although in more recent years its primary mission has been one-way communication with submarines submerged in the Pacific Ocean.

Two transmission lines, one for each half of the antenna array, lead from the transmitter building to 13 145-foot feeder-support towers, 10 located on the lower slope of Blue Mountain and three near the transmitter building itself. From these towers, feeder lines connect to the down-lead towers and through them to the antenna's catenary cables. On the opposite side of the valley, on the lower slope of Wheeler Mountain, 10 structures are connected by cables to the down-lead towers as counterweights to the feeder lines.

And finally, the intense electromagnetic field generated by the transmitter requires a huge and carefully planned grounding system, both around the transmitter building and under the antenna array. More than 200 miles of copper -- wire, cables, and screens -- are buried in a specific pattern under the valley floor to meet this requirement.

The Historic First Transmission

When it was completed, the power of the Jim Creek transmitter was twice that of any existing military transmitter and far more powerful than any commercial radio station in the U.S. On November 17, 1953, more than seven years and $14 million after the navy's Bureau of Ships began the search for a suitable site, Naval Radio Station Jim Creek was ready to demonstrate its unique abilities. Sitting at a Morse key tapping out the wireless code was RCA's board chairman, Brigadier General David Sarnoff (1891-1971). In 1912, while station manager for a Marconi wireless station in New York City, it was Sarnoff who first alerted America to the Titanic disaster. Beside him was Chief of Naval Operations Admiral Robert B. Carney (1895-1990), who dictated to Sarnoff the following message:

"With this first message we forge another link between you and your homeland. With it, we build a new security channel from America to the naval units which form its outer ramparts of defense" ("World's Most Powerful Radio ...").

The only way the gathered dignitaries -- about 200 naval, industrial, and governmental leaders -- would know if the system worked as planned was if there were responses to the message. They waited expectantly while the minutes ticked by. As described a few months later in an RCA-published magazine,

"Six minutes later the acknowledgments began to return, some of them relayed four or five stages to reach Jim Creek Valley. The first came from the battleship Wisconsin, operating off Japan. Then came word from the carrier Yorktown, the destroyer Floyd B. Parks and the submarine Bluegill in the western Pacific; the submarine Sablefish in the North Atlantic and the cruiser Pittsburgh in the South Atlantic; the carrier Tarawa in the Mediterranean and the destroyer Charles S. Sperry in Florida waters. As the replies arrived, Admiral Carney and General Sarnoff plotted the location of the units on a world map set up for the ceremony at the transmitter site. Along with the acknowledgments from the naval units, RCA Communications relayed word of receipt of the message at distant locations in its 65-nation radio circuit and aboard passenger liners at sea" ("World's Most Powerful Radio ...").

Naval Radio Station Jim Creek had done what it was designed to do, something that had never been done before. For the first time in the history of radio communications a message had been sent directly and instantaneously from a single transmitter to receivers around the globe. The tactical importance of this accomplishment is illustrated by the fact that the replies, sent in higher frequencies, at shorter wavelengths, and with far less power, took much longer to arrive, and many had to be relayed through several transmitters. But Jim Creek's primary mission was not to receive; its mission was to transmit messages quickly and securely to distant military assets, and at that it was highly successful.

The test completed, Sarnoff presented to Admiral Carney the keys to the control panel, saying "I turn over to you, on behalf of the Radio Corporation of America, the most powerful radio transmitter ever built. May I express the wish, which I know all in our armed forces share, that this powerful instrument for transmitting intelligence, may add to our national security and to the peace of the world" ("World's Most Powerful Radio ...").

This is what Naval Radio Station Jim Creek has done for nearly the last half of the twentieth century and the first quarter of the twenty-first. As of 2019, the facility was operated and maintained by 21 specially trained civilian personnel. Although it is meticulously maintained and updated, much of its equipment, including the generator, can now be considered vintage.

Making It Fail-Safe

The 2,000 kilowatts of electricity that Jim Creek receives from Bonneville Dam, more than 170 miles to the south, is not an entirely secure supply. A range of natural and man-made events -- forest fires, storms, sabotage, an electromagnetic pulse from a nuclear explosion, and others -- could interrupt the flow. Remarkably, it appears that for the first four years after its activation, Naval Radio Station Jim Creek had no back-up power supply in the event the connection to Bonneville Dam was lost. The need was on the navy's mind, however, as evidenced by its purchase in 1952 of a 2,500-kilowatt generator from the Worthington Corporation of Buffalo, New York. Why it was not installed until five years later is unclear, but when it was, in 1957, it worked to expectations.

After more than 60 years of standby duty, the Worthington generator was scheduled to be replaced in 2019. It is among several elements of Radio Station Jim Creek deemed eligible for listing on the National Register of Historic Places (NHRP). Much of the following information about the generator comes from documentation required by that status.

The Worthington Corporation

It made sense for the navy to turn to the Worthington Corporation for the generator -- it had been doing business with the company (by other names in other eras) for more than 100 years. The firm's eponym, Henry Rossiter Worthington (1817-1880), was born in New York City, and although he had only a high-school education, he would become a prolific inventor and a founding member of the American Society of Mechanical Engineers.

The completion of the Erie Canal in 1825 marked the beginning of what historians call America's Canal Era, and by 1840 more than 3,000 miles of built waterways laced together cities and towns throughout the East. Worthington had an early fascination with canal boats, and on July 24, 1844, at age 26, he patented his first invention, an "automatic independent water reciprocating pump" that eliminated the need to use a hand pump to keep the boiler of a steam engine full when a canal boat was at rest ("About Us"). The following year he joined with William H. Baker to establish the firm of Worthington & Baker, and in 1850 the company made its first sale of pumps to the navy, to be used on the USS Susquehanna, a side-wheel steam frigate. In addition to steamships, the pumps would eventually be used in factories, mines, quarries, and even hotels.

William Baker died in 1860 and Worthington assumed full control of the company, which in 1862 became Worthington Hydraulic Pump Works. During the Civil War, Worthington was hired to design pumps for the Union navy, including the famed USS Monitor, the North's first iron-clad warship.

When Worthington died in 1880 his son Charles Campbell Worthington (1854-1944) took over the business. In 1899 the company came under the control of industrialist Benjamin Guggenheim (1865-1912) and was absorbed into his International Steam Pump Company. In 1912 Guggenheim died in the Titanic sinking, and his enterprise fell upon hard times. It recovered, and continued in business under other names, including as the American Worthington Pump and Machinery Corporation. In 1952, the year it sold the Jim Creek generator to the navy, it was renamed simply the Worthington Corporation. Obviously, by that time it had expanded its product line to include equipment other than pumps.

The Jim Creek Generator

Worthington supplied the navy with a 16-cylinder, diesel-powered engine paired with a generator/exciter unit manufactured by the Electric Machinery Manufacturing Company of Minneapolis, Minnesota. The engine was built and the unit assembled at the Worthington Buffalo facility in Buffalo, New York, and delivered to the navy at cost of $1,006,897.

To house it, in 1957 the navy built at Jim Creek what is designated as Building 39, a "concrete frame building with reinforced concrete panels welded to the columns, steel framed clerestory lites, and a concrete panel roof system" ("DAHP Level II Mitigation Report," pp. 4-5). It is located nearly 5,000 feet northwest of the transmitter building and approximately 2,500 feet beyond the edge of the antenna array, distances probably dictated by the need to shield the generator from intense electromagnetic radiation. An underground power cable connects the generator to the transmitter and carries an output of 2,500 kilowatts, 500 kW greater than that provided by the line from Bonneville Dam.

In the most basic terms, a generator converts mechanical rotation into electrical current. The rotation is provided by an engine, in this case the Worthington diesel. In somewhat more technical terms, a generator consists of stationary magnets (the stator) which provide a stationary magnetic field, and a rotating magnet (the rotor), whose spin is provided by the engine. The manner in which Jim Creek's engine, generator, and exciter work together to produce electricity is better explained in the report prepared for the Washington State Department of Architecture and Historical Preservation:

"Power is generated by the engine powering the main drive shaft which in turn rotates the rotor or field coils in the generator, producing the magnetic flux that is essential to the production of the electric power. The rotor is a rotating electromagnet that requires a DC (Direct Current) electric power source to excite the magnetic field. This power comes from the exciter. The excitation system monitors the generator output and regulates the magnetic field to maintain the desired voltage. As the load on the generator is increased, an increase in current flow causes the voltage to drop. The excitation system senses this decrease in voltage and increases the strength of the magnetic field to return the voltage to the desired level" ("DAHP Level II Mitigation Report," p. 12).

At least in part because of its large footprint, Naval Radio Station Jim Creek has never been a top-secret facility, although the details of its operations are closely held. For almost the entire second half of the twentieth century and the first quarter of the twenty-first, it has quietly gone about its job. As of 2019, access to the transmitter and antenna was generally limited to 21 federal civilian personnel, who keep things going 24 hours a day, every day of the year. Given the age of many of the Jim Creek's mechanical and electrical components, some of which date back as far as 65 years, special training is required. As Chief Warrant Officer Mark Gordon, interviewed in 2017, noted, "Our radio maintenance people have to know the older technology down to the component level. That's why we offer in-house, on-the-job training on site" ("Naval Radio Station Jim Creek ...").

A Prime Target?

Naval Radio Station Jim Creek was built long before computers came into wide use and at about the same time a practical transistor was invented. Even though the transmitter relies on some older technologies, such as vacuum tubes, it still fills a vital role in the navy's communications systems. This remained of significant concern to potential enemies, as evidenced by a February 24, 2019, broadcast on Russian state television, hosted by Dmitry Kiselyov, who was reported to have a close relationship with Russian President Vladimir Putin. Using a large map and computer graphics, Kiselyov identified several American sites that he claimed would be initial targets of Russian missiles should nuclear war break out between the two nations. Among those sites were the Pentagon, Camp David, and Naval Radio Station Jim Creek.

Viewed from space, the area cleared for Jim Creek's antenna array resembled an archer's target, with the transmitter building marking the dead-center bull's-eye. But Kiselyov's credibility was highly suspect, and not just because of his role as a propagandist for the Russian government. In the same broadcast, he also identified as first-strike targets two military bases in the U.S. that were closed about two decades earlier, one still sitting abandoned, the other now a business park.


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