The History of InfoAge Science & History MuseumsMARCONI TRANOCEANIC RADIO TELEGRAPHY
Practical Wireless Telegraphy
for STUDENTS of
by ELMER E. BUCHER
Marconi Wireless Telegraph Co. of America May 1920 edition wireless Press – 326 Broadway, NYC, NY
Page 292-293 (1917-1920 edition) 294+ (1917 edition)
Web editor: This post was taken from photocopies Mr. William Brahms made from the original book while researching the history of Franklin Township. The New Brunswick Station lies in Franklin Township. The account is a contemporary description of the stations and how they worked as a pair with counterparts in Wales. Thanks to Mr. James Stewart we have pages 294-307 and other parts of the book from the 1917 edition…
Nice information about the Belmar masts removed in 1925, from the page below…
“The receiving aerial for this station at Belmar, New Jersey, consists of two wires 6,000 feet in length, suspended on six tubular masts, 400 feet in height.”
On page 296 is a description of the equipment at Belmar…
“The receiving station at Belmar, New Jersey is completely equipped with a Marconi balanced crystal receiving set, Brown amplifying relays, a balancing out aerial for eliminating interference, dictaphone receivers, and a set of telegraphic instruments for connection with the landline telegraph and telephone companies. These transmitting and receiving stations not only have the necessary buildings for the housing of the apparatus, but hotels and individual dwellings are supplied for the employees as well.”
Also on page 299, there is a description with photos of the erection of the 400 Foot Belmar wireless masts.
292. PRACTICAL WIRELESS TELEGRAPHY
233. Marconi Directional Aerial. The great success of Signor Marconi’s Trans-oceanic system is in no small measure due to the use of the horizontal directional aerial.* Fully convinced by a series of quantitative experiments that the flat top aerials radiate more freely in the direction opposite to which the free endpoints, particularly if the length of the flat top exceeds the length of the vertical portion by four or five times, Signor Marconi decided that the adoption of this aerial would not only permit the transmission of messages over great distances with small powers but also on account of its directional properties would prevent a considerable amount of interference to the operation of other stations.
In the same series of experiments, it was determined that a flat top aerial receives with greater intensity when the free endpoints in the direction opposite to the free end of the transmitter aerial. Irrespective of its selective directional properties, a horizontal aerial of given capacity and inductance for any required wavelength, is less expensive to erect than a vertical aerial of similar electrical dimensions; hence, from this consideration alone, the flat top aerial is the one that would be adopted.
In order to radiate the energy of a 300 K. W. transmitter, the aerial should have a fundamental wavelength of at least 6,000 meters; in fact, the greatest distances are covered when such aerials radiate near to their fundamental wavelength.
The great Marconi station at New Brunswick, New Jersey, U. S. A., for example, has an aerial of 32 wires connected in parallel, 5,000 feet in length. The aerial is supported by 12 tubular steel masts, 400 feet in .height, arranged in two rows of six each. The fundamental wavelength is approximately 8,000 meters, but the initial transmitting experiments were carried on at the wavelength of 15,000 meters.
The receiving aerial for this station at Belmar, New Jersey, consists of two wires 6,000 feet in length, suspended on six tubular masts, 400 feet in height. The aerial has a general direction favorable for reception from the giant transmitting station at Carnarvon, Wales.
234. Marconi Transoceanic Stations. By far the greater number of high power radio stations here and abroad have been designed and erected by the
*An explanation of the cause of the unsymmetrical radiation of an inverted L aerial appears in Page 167 of Fleming’s Elementary Manual of Radio Telegraphy.
MARCONI TRANOCEANIC RADIO TELEGRAPHY 293 Marconi Company. In fact, their stations only have maintained a continuous operating schedule from day to day, from continent to continent. Individual concerns may have carried out spectacular experiments here and there, but nothing has been evolved by them that would tend to make long-distance communication a success commercially. The mere fact that a message may, for instance, be sent across the ocean by a low-powered transmitter and received on a small aerial at certain hours of the day is no indication that such equipment could be used for continuous 24-hour service because experiment reveals that very large powers are required for continuous operation when the sender and receiver are 3,000 miles apart.
Those who are familiar with the great globe-girdling scheme of the Marconi Company cannot help but be impressed with the stupendous undertaking involved in the construction of their high power stations, for not only is the task of designing the apparatus, buildings, and power machine.-y one of the extraordinary undertaking, but the actual installation of such has, in many instances, called for painstaking labors and effort largely due to the location, the nature of the soil, and the topography of the surrounding country.
In view of the universal interest manifested by students of radio in behalf of high power radio stations of the Marconi Company, a brief description of their equipment will be presented, together with such additional information, as will make clear the general plan and mode of operation. First let it be explained that although these stations could all be made intercommunicating, it is more usual to construct a pair of stations to cover a specific route or to join together two continents only.
With the idea in view of showing which of these stations was intended for communication with the other, they shall be grouped into “radio circuits” or routes, as follows
Since the apparatus for the Glace Bay station has been very briefly described in paragraphs 274 and 275, it will not be gone over again, except to mention that the Duplex System has been installed and thoroughly tested. Because these two stations established the first successful trans-oceanic commercial radio service, they are purposely grouped at the head of the list.
The transmitting station at New Brunswick is of 300 K. W. capacity and can be operated at various wavelengths from 7,000 to 15,000 meters. Power is taken in the station from a commercial powerhouse at 1,100 volts, 3 phase 60 cycle alternating current, stepped down to 440 volts, and led to the terminals of a 60 cycle, 440-volt 3 phase 550 H. P. motor, which drives a 300 K. W. 120 cycle generator.
The current is led from the generators to a bank of high voltage transformers, the secondaries of which may be connected in series or in parallel according to the power required.
In the usual manner, the current from these transformers charges a large bank of high voltage oil plate condensers which, in turn, discharge through an oscillation transformer and rotary disc discharger of uncommon proportions. As in the Glace Bay Station, the circuit from the transformer secondaries to the condenser is interrupted by a specially designed set of high tension relay keys which, in turn, are actuated by a small sending key and a source of direct current.
Arcing at the contacts of the main signaling key is prevented by a heavy blast of air forced directly at the contact points by specially designed motor blowers. The advantages
294. PRACTICAL WIRELESS TELEGRAPHY derived in interrupting of the high voltage current lies in that it permits 300 K.W. to be handled at various speeds of transmission up to 100 words per minute without error.
A more detailed description of certain apparatus of the circuits of radio frequency for the New Brunswick station and others with like equipment (damped wave apparatus) will be given in paragraph 236.
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