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Exodus Advanced Communications

Lee de Forest and the Navy
January 1947 Radio-Craft

January 1947 Radio-Craft

January 1947 Radio Craft Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Craft, published 1929 - 1953. All copyrights are hereby acknowledged.

This is another of the articles written about Lee de Forest that appeared in the January 1947 issue of Radio-Craft magazine, in celebration of the 40-year anniversary since the industry-changing Audio vacuum tube was invented. Author George H. Clark, a member of the first "radio-man" to be graduated from the Massachusetts of Technology (MIT), was, in addition to working for Marconi Wireless Telegraph Company, RCA, and the Telegraph and Telephone Company, the U.S. Navy's "Sub-inspector of Wireless Telegraph Stations." He dealt extensively with de Forest regarding installation and operation of radio systems both on ships and on shore. Interestingly, he mentions that the first Audions were used as detectors more so than as signal amplifiers, which in fact was de Forest's original goal (a more sensitive detector) in his experimentation. Also, most of the first Audion tubes were sold to amateur radio operators (Hams) who, as with many aspects of wireless communications, developed some of the earliest applications for the newfangled detectors / amplifiers. Be sure to note the Coral Reef section about the importance of laying a good ground for the antenna, and the water-wave propagation lesson learned.

Check out this New York Times newspaper article entitled "Jury Told of Fraud in Radio Telephone" I found regarding de Forest's wireless sets sold to the U.S. Navy.

de Forest and the Navy

Lt. Weaver using the de Forest radio telephone - RF Cafe

Lt. Weaver using the de Forest radio telephone aboard the U. S. flagship Connecticut.  Courtesy Gerald F. J. Tyne

By George H. Clark

R. Lee De Forest and the wireless companies bearing his name have been associated with the United States Navy's wireless communication system since its early days, and in the opinion of the writer have had more direct and indirect influence on the development of the Navy's wireless than has any other person or company up to the beginning of the recent war.

One honor is not his, however-that of first introducing the U. S. Navy to wireless communication. That is reserved for Guglielmo Marconi, who came to the United States in the fall of 1899 to report the International Yacht Races by wireless. The Navy Department appointed several officers to observe and report on this work, and the first wireless message in the Navy's history was sent by Lieutenant Blish, U.S.N., on September 30, 1899, from the Marconi-equipped observation vessel, the S.S. Ponce, via the Lighthouse Service Station at the Highlands of Navesink, N. J., first U.S. shore station.

Four years later,- however, de Forest came into the picture, submitting to the Navy one of his sets for competitive test against those of Slaby-Arco, Braun, Rochefort, and Ducretet. The Slaby-Arco set worked 70 miles from shore to ship, de Forest's only 42; the others made no record worth mentioning. On the basis of distance attained, the contract went to the German concern.

De Forest Equipment Better

As a matter of fact, de Forest's set was in some ways far superior to that of the Germans, although this was not recognized by the Navy authorities at the time. Two of the features which he submitted were later adopted as standard: (1) the use of alternating current as a power source instead of the interrupted direct current used by Slaby; and (2) the use of a self-restoring detector with telephonic indicator, as opposed to the Slaby coherer. The Navy considered the use of the coherer, with its tape register, essential for the relatively untrained Naval operators , of that time. The message could be read off slowly from the tape at any time after its receipt if the operator were not sufficiently trained to copy . it directly from the buzzing sound of the decoherer, Also - an important factor in those days when operators were few - a bell could be switched into the circuit instead of the recorder, to call the operator if he were away from the set or if messages came in during his sleeping hours.

The advantages of the alternator which became painfully obvious after Navy men had spent weary hours cleaning the mercury-turbine interrupter of the Slaby system, were not appreciated (or rather foreseen) in the early experiments.

George H. Clark is one of  the earliest of radio pioneers - RF Cafe

George H. Clark is one of  the earliest of radio pioneers. He was the first radio-man to be graduated from the Massachusetts Institute of Technology (in 1903). Joining the Stone Telegraph and Telephone Co., he remained till 1908, when he became the Navy's "Sub-inspector of Wireless Telegraph Stations." He remained with the Navy till after World War I, when he joined the Marconi Wireless Telegraph Co., .remaining with it and its successor, RCA, till his retirement from active work in 1946. From the time he started with the Navy, Clark's work led him to value the importance of the written record. First setting up specifications for apparatus, then installing a system of type numbers for equipment, he was drawn more and more toward "a bookish career" till he became the official historian of RCA and the semi-official historian of radio in the United States. His collection of records amounted to more than one hundred volumes when he left the Navy, and has been supplemented since then by purchase and gift. Therefore his article is based on something considerably more solid than recollection, and as such, has more than usual authority.

One of the early tests of de Forest sets was held between the Naval Academy at Annapolis and the Washington Navy Yard, and during the work the Secretary of the Navy visited the former site on an official inspection. The Secretary suffered a slight accident at the time - some sources say he tripped over a wire, another that the horses drawing his carriage ran away; but at any rate the de Forest operator, Harry Mac Horton, sent a little story on the event to de Forest in Washington. The latter, even then publicity-conscious, rushed up the narrow street to, the Navy Yard gate, and telephoned the news to the Navy Department, whence it was sent to the local newspapers. Thus the "first press story" by wireless was in the Navy's realm, using de Forest apparatus. Nor was it the last!

The Slaby system soon became antiquated, and in time American manufacturers were given orders for sets. Thus such well-known inventors as Fessenden, John Stone Stone, and (by no means least) de Forest began equipping Navy ships and stations. Courtesy Gerald F. J. Tyne As early as 1906, there were 12 de Forest spark sets in use by the Navy. Three of these, the 25-kw shore stations installed in the Caribbean and at Puerto Rico, made spectacular records, the last-named being able to communicate directly with the de Forest commercial station at Manhattan Beach, N. Y., a distance of 1,600 miles. This was of course (as we used to say in those days) "at night, in the winter time," but it was a record nevertheless. The U.S.S. West Virginia, equipped with a de Forest set, while en route to the Canal Zone with President Theodore Roosevelt on board carried on wireless communication with ships off Key West, about 1,050 miles away. These were remarkable feats for the time and the apparatus. Nor were these isolated cases; they were repeated many times.

Coral Reef

Much of the success of the de Forest spark transmitters was due to three things: his appreciation of good grounding (at Key West his ground plate was deeply laid, in water, but the water happened to be a man-made lake, with coral between it and the ocean; not until a hole was broken through to the latter did the station begin its record-breaking work); his use of a very large primary condenser and a short spark, thus lessening the resistance of the latter and making for more sustained oscillations; the fairly loose coupling obtained, due to the large primary condenser, between primary and secondary circuits, even with a direct-coupled, set. In addition, the large condenser gave him multiple discharges and hence a spark note more easily readable over static and over the lower tones of sets such as those of Slaby.

This was the peak of de Forest's success with spark sets. He soon was surpassed in technical ways by Stone's loose-coupled sets, with strictly uniwave transmission, and by the giant Fessenden set installed at the Navy's first high-power station, NAA, at Arlington, Va., with its 500-cycle supply and a rotary synchronous gap.

Navy Vacuum-Tube Equipment

De Forest, however, was merely biding his time to go forward to greater successes by a different means. His first crude experiments with a vacuum tube, first as a detector, then as an amplifier, and finally as an oscillator, in time lifted radio to a new era, and his little nickel grid proved to be the electrical level which would move the radio world. There was a gap between the spark era, with its use of trains of waves, and the later vacuum-tube era, this gap being filled for, a time by the continuous-wave Poulsen arc system, as developed by the Federal Telegraph Company. Even this intermediate method owed much of its success to de Forest adjuncts. In time, also, the arc passed out of the picture, and the vacuum tube reigned supreme in all fields of radio. Leaving out all matters of controversy, broadly speaking it was de Forest's invention of vacuum-tube control by means of a grid that caused the vacuum tube to become the universal tool for radio in transmitting, receiving, and amplifying.

De Forest's first contact with the Navy along these lines was before he had brought forward the grid, however. He made his first Government sale of vacuum tubes in 1906, to the United States Navy, in the form of a complete receiving set fitted with audion detectors, with candelabra base. These were, however, of the two-element type, with plate and filament only. These, as well as the, three-element forms which soon followed, bore the name "audion," however.

In 1907 he came closer to the final goal, in that he introduced wireless telephony to the Navy, and with it the three-element audion. In November of that year the famous voyage of "Fighting Bob" Evans' fleet around the world took place. De Forest interested the Navy in having a wireless telephone installed on the bridge of the principal vessels in the squadron, so that officer could speak with officer without an operator-intermediary. This idea, which was technically and strategically correct, failed, for several reasons. First, the standard wireless telegraph set and the new telephone could not operate simultaneously, duplex-diplex operation not having been provided nor indeed thought of. Second, the "new-fangled" installation required a technical man to keep it in operation, and in those days such men were operators, not officers. Other difficulties were present, as might be expected in a pioneer installation, so that the idea did not work as well as its deviser had hoped, yet many good results were obtained with it. One of these was the "broadcasting" of phonograph records by then Chief Electrician H. J. Meneratti from the U.S.S. Ohio to her sister ships, during many nights of the world voyage. This story alone is most interesting, but space does not permit further description.

de Forest "Singer Type" tube - RF Cafe

de Forest "Singer Type" tube used by Navy. Courtesy Gerald F. J. Tyne

The Type H was a 150-watt transmitting tube - RF Cafe

The Type H was a 150-watt transmitting tube.

Not long after this world cruise, de Forest presented the audion to the Navy's attention for use as a detector, and little by little it became more desired; sales became more frequent. An official accounting made for later court proceedings lists a sale of 1,000 single plate and grid audions at $2.50 each, sold on contract dated January 12, 1914; 500 oxide filament tubes, at $12.50, on October 5, 1916; 1,000 ultraudion and amplifying tubes, double plate and grid, at $4.00, on September 25, 1917. These were not the first, nor the last, nor the total of the sales, but are mentioned to give a general idea of usage and price.

There was, unfortunately, one bone of contention between "Doc" - as de Forest is called lovingly by his friends-and the Government from the beginning; he contended that "a little gas in the tube was a good thing," whereas the Navy said it was not. Both were right! De Forest was in some ways an amateur at heart, and sold his first tubes to amateurs. These eager lads wanted the greatest sensitiveness possible, and were perfectly willing to juggle filament current and plate voltage to obtain it. That such tube conditions did not make for stability bothered them not at all But it did bother the Navy; each tube had to have the same constants as its mate, so that if a tube burned out during reception of an important message a second could be switched in and used immediately without readjustment. The controversy ended with the Navy specifying such a standard tube, which de Forest either could not or would not make, and so he lost what might have been a very profitable business during World War I. It was appreciated by those in charge that Dr. de Forest had brought audions into the world and to the Navy Department, and that it would have been only right to reward him in the form of orders; but Navy efficiency of course came first.

Audion Amplifiers

All of the foregoing refers to the use of the audion as a detector for reception of spark signals. Next in line was de Forest's offer of the audion as an amplifier, destined to become an indispensable element in radio operation. For years previous, various forms of amplifiers, all of the. carbon-microphone type, had been tested by the Navy. Not one had proved worth adopting. On November 25, 1912, all this was changed. On this date de Forest sent to the Navy for test a "breadboard" model of a three-stage audion amplifier, the result of his experimentation at the laboratory of the Federal Telegraph Company, Palo Alto, Calif. This was brought to the Arlington station, NAA, by Charles Logwood, Dr. de Forest's assistant, and others. Chiefs W. A. Eaton and J. W. Scanlon, and the author, tested it for distance, and also for degree of amplification. Stations hitherto unheard at NAA, especially some on the West Coast, came in readably, even in the daytime. Technical measurement s showed an amplification of 4 for the first stage (in terms of "audibility") and a value of 10 for two stages. The third stage "squealed" so that it could not be used. This model, although crude, showed so much promise that de Forest was encouraged to develop it into practical form, and during the ensuing years many purchases were made. In December, 1913, the Radio Telegraph and Telephone Company, one of de Forest's companies, quoted $475 for an amplifier, and that same month a requisition was made by the Navy for ten amplifiers with four relays and bells and two loud-speaking horns. (The relays were of the Weston galvanometer type, and the bells showed that de Forest had at last caught up with Slaby's coherer and bell of 1903!)

The third development of de Forest which came into later major adoption by the U. S. Navy was his oscillating audion, particularly when associated with a receiver and used for heterodyne reception. The history of this is indeed involved.

The Navy first became interested in heterodyne reception during 1912, when the 100-kw Fessenden spark set at Arlington and a 30-kw Poulsen arc temporarily installed at the same station by C. F. Elwell were being given a long-distance test by reception on the U.S.S. Salem. The spark set, of course, developed discontinuous waves; the arc was a continuous-wave generator. The Fessenden company installed on the ship the first heterodyne receiving system known to the Navy. It was used to compare the distant spark and arc sets.

The Oscillating Detector

Two of the early pre-grid de Forest audions - RF Cafe

Two of the early pre-grid de Forest audions, each with two plates and filament. Courtesy Clark Historical: Library

Two type 20's and one VT-21, a tube used by the Government - RF Cafe

Two type 20's and one VT-21, a tube used by the Government during the first World War. Courtesy Gerald F. J. Tyne  

Up to that time the arc had been copied by means of a rotary ticker, a fine wire pressing on a rotating drum. Such signals were rustling, "shushy." Spark signals, however, when received on an electrolytic or crystal detector, gave a clear, musical sound, especially when the sending station was powered by a 500-cycle alternator, as was the case at NAA. But with the heterodyne method of reception, all was reversed; the spark signals lost their musical nature, while those from the arc became musical indeed, and with the added advantage that the note could be varied at will by the receiving operator to suit his own ear. To this may be added the fact that the heterodyne signals from the 30-kw arc were heard much farther than any signals from the giant 100-kw spark.

But all was not perfect, despite these advantages. Heterodyning was performed, on the Salem, by mixing the incoming signals with continuous waves produced by a local oscillator. This latter was a small arc, though not so very small, at that! Moreover, the arc was highly temperamental, and worked only when it wanted to, as the writer well remembers. With the Navy's insistence on dependability and uninterrupted communication, such a device was not usable, even though desirable. What, then, could be substituted for the arc as a generator of c.w.?

As of course everyone knows today, the answer was "an oscillating audion." But, due to reasons which will not be discussed here, no one had at that time brought such a device to the Bureau for test. The writer had heard of such a means, through records shown to him by a company then making tests at Arlington, and he at once made his own tests. He used home-wound feed-back coils, and even went so far as to coin a name for these: "tickler coils" - because they "tickled the audion and made it oscillate." But since no commercial form seemed to be available  for such use, the Navy's work was experimental only.

In April, 1914, the de Forest company wrote to the Navy, stating that it was about to display a new form of receiver at an exhibition sponsored by the Bureau of Standards, and asking that a representative of the Navy Department be present. "This includes the use of the audion as a detector of undamped oscillations," the letter said. This was enough to cause immediate and thorough inspection, and it was found that these receivers fitted exactly the Navy's desire for c.w. reception. It was also said that these receivers "did not include feed-back coils, hence did not violate existing patents." A number of sets were at once purchased from de Forest, and these so-called "Ultraudion" receivers - in which, it was learned later, feedback action did exist, though in a form of capacity coupling - made it possible for the Navy to make fullest use of its arc transmitters, and in a short time to provide a world-wide chain of radio communication.

Had some other company brought to the Navy's attention a coil-coupled form of feedback, the writer can say that as far he was concerned he would certainly have tested it and recommended its adoption; but no one did. That de Forest, who was already recognized as the father of the audion and of the amplifier, should now have brought a third feature of the little tube into play, by using it as an oscillator and thereby making heterodyne reception practicable, seemed but another logical development of this versatile inventor.

Audion Transmitting Tubes

But there was yet another offering which he had to make to the U. S. Navy and to the world. That was the development of the tiny receiving tubes into larger and larger ones, generators of electric waves which in time became the source of high-frequency power for all forms of transmitters. De Forest sold sets of this nature to the Government, particularly for airplane use, but the flood of business arising from the war led to the advent of many other manufacturers, and de Forest by no means reaped a rich reward for what was later proven to have been legally his offspring.

Of the later work of de Forest in pioneer broadcasting, of his untiring efforts along other lines such as motion pictures, television, diathermy, and the like, this article does not treat. His invention of grid control of the vacuum tube was the tiny forerunner of a new era of radio communication, replacing other too ponderous types of continuous-wave production by smaller, more controllable devices, in the form of small and large vacuum tubes. He was first to produce a successful type of amplifier, long the goal of inventors. His success in setting up persistent oscillations by means of the vacuum tube made the heterodyne reception of radio telegraphy possible, and later these tubes, enlarged, supplied the other end of the chain by becoming the creative part of the distant transmitters themselves. On the basis of successful achievement alone, Dr. "Aladdin" de Forest, as he should have been called, deserves a world's praise in these electronic days, and he in turn undoubtedly will admit that much of his success in those earlier years was due to the pressure of the needs of the United States Navy.

The foregoing represents the author's memories of his personal experiences, and is not intended to refer in any way to the possible viewpoint of any other person or organization.

 

 

Posted February 26, 2020

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