In its system of radio communication for the Canal Zone, the navy has kept up to the high standard set by the Canal in general in having thoroughly modern equipment. The layout comprises one coastal station at each end of the Canal for ship to shore work, and one high-power station for long distance work.
In 1911, after several unsuccessful attempts by the representatives of the army and the naval interests to agree upon plans for the high-power radio station here, which was so important to the navy for its fleet communication, the matter was submitted to the joint Army and Navy Board. This board, whose report was approved by the President, recommended, among other things, that no private or commercial wireless installations be permitted in the Canal Zone; that the Navy Department have authority to install, maintain and operate under its jurisdiction a high-power wireless station in the Canal Zone, to be used in connection with its other stations in the Atlantic and Pacific, and for controlling the movements of its fleets in waters adjacent to the Panama Canal; and finally, that the wireless stations under the jurisdiction of the Navy Department shall be opened to the public service and shall transmit commercial business.
Darien Radio Station then was built as soon as the department had worked out the engineering features. The Colon station had been built by the Navy Department in 1904. The department then built the Balboa station in 1913 to handle ship to shore work for the Pacific side. These three stations are thus links in the department's comprehensive plan for radio communication with the fleet for purposes of national defence. As all other links of this chain are under naval administration it is necessary that these be likewise under that department.
The department has adopted the policy of making them indispensable to the Canal government both in its operating and military features, with the end in view that it may not be necessary to duplicate the stations with either government or commercial stations. In this way, besides automatically having control of radio already in the hands of the national defence on the opening of hostilities, there is always the least amount of interference possible, time is not wasted by dividing the hours with commercial neighboring stations, and important Messages may be given right of way. The stations further will be manned at the opening of hostilities with the personnel familiar with the local conditions. The usual peace time means of communication being through these stations, the naval ships, transports or merchant auxiliary, at this time, will be thoroughly familiar with the stations as to wave lengths, radius of communication and land line connections. Further, all radio traffic connected with the operation of the Canal is handled in accordance with the governor's regulations and the facilities of the station have been offered to the governor, or his representatives, for Panama Canal or other official radio work.
Both Colon and Balboa stations handle commercial messages with ships and Colon handles messages with neighboring shore stations to which the cable service is unreliable. The low naval rate of six cents a word is charged here. Thus the necessity for commercial stations is obviated.
As is done at all naval radio stations, official messages for any departments of the government are handled free of station charge.
The Canal, as every one knows, is here to handle shipping and to do it in the most expeditious way. Hence Article 40 of Executive Order giving the regulations for the operation of the Canal states that "as soon as radio communication can be established with the Canal, vessels should report their names, nationality, length, draft, tonnage, whether or not they desire to pass through the Canal, require coal, provisions, supplies, repairs, to go alongside of a wharf, the use of tugs, probable time of arrival, length of stay in port, or any other matters of importance or interest. If this information has been previously communicated, through agents or otherwise, to the captain of the port, it will not be necessary to report by radio, but the probable time of arrival should always be sent." Any radio messages relating to any of these subjects are regarded as Canal business and are handled without station charge, whether from the master of a ship or from the Canal authorities. Also all ships are required to keep an operator on watch while making the passage of the Canal. This provision is to allow for transmitting rush orders relating to dispatching the ship through. There are now numerous visual signal stations along the route handled by telephone from the Marine Department, so that radio dispatching is only an emergency measure now. Before the visual signal stations were complete, however, four to six reports were received from each ship making the passage.
As a convenience to responsible steamship companies a monthly account is allowed for charges due on messages sent to their ships. Arrangements have been made with the Panama Canal whereby the bills for these messages may be paid by the Panama Canal from the company's deposit which has been put in the hands of the collector of the Canal, in advance, to cover all charges incurred in the passage of each ship.
During the construction days of the Canal the commission operated a quarry at Porto Bello, just 18 miles north of Colon on the coast. From here was obtained the rock for the building of the Gatun spillway and locks and for the breakwater in Colon harbor. To avoid the expense of installing and maintaining a telephone service there the Navy Department installed and operated a small radio outfit in a building owned by the Canal. Working with Colon this was used instead of telephonic communication for the commission's work.
The radio time service has been found to be of use here. The time signal now received on the Isthmus comes by the Central and South American cable over their line down the west coast. This signal is transferred to the cable from the land line at Galveston and passes through four cable relays before reaching Colon, where it is put on the Panama Railroad telegraph system through another relay. These relays are all automatic except the one at Panama, when the signal is forwarded by hand as the operator watches the syphon beat. In checking this time' signal against that received by radio from Key West, the writer has observed varying errors of from one to three seconds lag even over that from Key West, which itself has the lag due to the land line relays from Washington. The port captain at each terminal port has a chronometer for use of merchant skippers in comparing their chronometers. In his office is also brought an instrument from the Panama Railroad telegraph line over which the time signal is sent from Darien daily by hand as the operator hears the signal in his radio receiver. This crude method has proved .to give better results than attempting to rate the chronometer by cable signal.
This system will be much improved upon the .arrival of the up-to-date time transmitting installation which has been ordered for Darien radio station. It will consist of a transmitting clock, one of the same kind ordered for the Naval Observatory at Washington. This clock will be set by electrically accelerating or retarding the period of the pendulum until the error is corrected. To set the clock, a local signal will be taken from the break of the main sending key of the radio transmitting set and brought into step with the time signal as being received by radio from Arlington. Darien will then transmit shortly after, before the clock has attained an error due to the rate it may have. A well rated break circuit chronometer will carry us over those schedules on which it may be impossible to set the clock by direct comparison. This time signal will probably be transmitted over the land wire for the railroad and made to operate a time ball at the terminal ports. With a bulletin giving the error each day, the installation is expected to be capable of giving a signal in Central and South America within the limits of accuracy suitable for astronomical work.
THE DARIEN RADIO STATION
The Darien Radio Station is located just 25 miles south of Colon on the Panama Railroad. The railroad forms the east boundary of the reservation which contains 872 acres. The southwest boundary is the Canal itself from which is a channel 20 feet deep and 75 feet wide into the center of the station plot. Those who may have visited the Canal before the water was allowed to rise may remember this site as being adjacent (to the southeastward) to the old town of San Pablo. On the "relocation" the nearest stop was Caimito Cabin at the north end of dumps. Thus the site was known variously as the San Pablo or Caimito Radio, or simply as Radio in the early stages, until the department assigned the name Darien, when, by request, the governor named the railroad stop here Darien. Until the name was well known, our mail frequently went astray to the southern most province of the Panama Republic which is known as the Darien section.
This plot was decided upon with the following advantages in view. It was well out of gun range from either end, it was accessible to the railroad and Canal both, it was very close to the source of power (the trans-isthmian high tension line along the railroad), receiving tests showed the ground conditions to be good, and, finally, with the idea in mind of locating the towers on the hilltops and having an arm of the Gatun lake come in under the antenna between the towers, a good effective height could be obtained with moderately high towers.
Work started on construction in December, 1913, by the Quartermaster Department of the Panama Canal. The site was far removed from any of the Canal Zone towns and was mostly jungle when the work started. A spur from the railroad was put in, laborers' barracks built and, as it is unsafe to unload cement in the open due to the sudden rains, a cement shed was erected close to the spur. With a hoisting engine on the hill all material was hauled up a narrow gauge road in De Cauville dump cars. This narrow gauge road continued around the station site for the delivery of material to the buildings and towers. The small locomotives, cars and tracks were relics of the French construction days. Water for the station was pumped to a tank on a hill by a Worthington pump which obtained its steam from the boiler of an old Belgian locomotive side-tracked for that purpose. Drinking water was distilled at this pump station. This equipment supplied the station until the arrival of the electric turbine pump. The Gatun lake water is now used and merely boiled for drinking and cooking purposes.
The dwellings on the site are the house of the radio officer, cottage for the chief electrician in charge and barracks for the operators equipped to house 17 men. Servants' quarters are also provided in the barracks building. Rations are commuted at a dollar a day per man and a mess is run by the operators.
All the buildings are screened, including the porches. There is such a large breeding area for mosquitoes about the site that the cost would prohibit sufficient sanitation work to keep the mosquitoes down entirely. The means we have adopted are (1) keep the screening as tight as possible; (2) every morning a sanitary inspector makes the rounds catching the mosquitoes inside the living quarters and office; (3) no containers are allowed to collect water, in which they may be breeding, on the station site; (4) all drains are kept clear so no water stands in puddles; (5) around the edges of the water the bank is kept skinned to allow the small fish to eat the mosquito larvae (this means is remarkably effective); (6) the force of five laborers allowed the station is kept at work on the grounds- keeping the jungle growth cut down as well as possible. Then when one case of malaria did appear, in order to prevent an epidemic, the whole station crew was put on a quinine diet for 10 days.
The other buildings of the station are of concrete except the boat-house. This was built of old form lumber left over from the concrete work, and corrugated iron roofing robbed from old abandoned shacks on the site, one of which was an old distillery. The transformer house contains only the main transformers (with oil switches and lightning arresters) where the 44,000 volts from the transmission line is stepped down to 440 volts.
The power house is 6o feet by 30 feet and contains the motor generators for the main transmitting set, which uses 500 to 1200 volts direct current, and that for the auxiliaries using no volts direct current. The main distributing and controlling switchboards are here, with the auxiliary transformers. Also this building houses the machine tools, a small lathe, drill press, milling machine and emery grinder and is fitted with a five ton overhead traveling crane.
The operating building contains the arc room (where is located the main transmitting set with its auxiliary electric controlling devices), the receiving room and the office, beside a spare room for an auxiliary sending set if needed later. The arc room and the receiving room both have wire mesh imbedded in their walls, floor and ceiling in order to prevent the induction from the transmitting set injuring the receivers. The building is fire-proof, necessary on account of the action of the continuous oscillations used at such high voltage. The charging current into iron in the vicinity of any live lead heats the iron quickly. Some of the reinforcing had to be taken out of one concrete base because the current jumped to it, and one wall 19 inches away from the end of the helix heats so that the hand cannot be borne on it after a 20 minute run. The reinforcement in this wall is merely metal lathing but is directly in the field of the main helix.
The towers for this station are of structural steel, triangular sections, self supported. There are three 600 feet high each. As mentioned earlier in this article, it was the first intention to locate them on the tops of the hills, but on making the actual location it was found that the thrusts (which come on to the footings at the angle of slightly over 16 degrees from the vertical) would be too nearly parallel to the face of the hills to give solid backing for the footings. They were finally located so that all footings but one butt into the hills. In order to do this, however, the footings were put on about the 120-foot level instead of the 170-foot (the surface of Gatun lake being normally at the 85-foot level).
For each tower the feet form an equilateral triangle 150 feet on the side and taper upward to a triangle ten feet on a side at the top. When first erected there was considerable swaying in the bottom long diagonals, but these and others above were stiffened up by cross bracing so that now they are perfectly rigid. When the antenna was hoisted and adjusted to the sag which would give a pull of about 13,000 pounds, the top of each tower was pulled over only four inches during hoisting and settled back to two inches when hoisting stopped. All the bend was in the upper 200 feet.
The block for each footing is 16 feet deep and 20 feet square, heavily reinforced with old railroad rails. Each block filled entirely the hole excavated for it without back filling in order to have it bearing in solid earth. Each tower leg is insulated from the ground with heavy porcelain insulators. However it has been found that greater radiation is obtained and the arc "pulls" better with the towers grounded, so they are left grounded through a long knife switch. The distance between towers is: one and two, 897 feet; two and three, 751 feet; one and three, 969 feet, the antenna covering about six acres. The capacity, however, of this antenna is just the same as that of Arlington Got M. F.), though much larger in every way. Darien's capacity is evidently between the antenna and the ground, while Arlington's is between the antenna and the towers. The antenna was made at the New York Navy Yard and shipped to Darien, each wire on a separate reel and tagged to mark the points where any other wire crossed. The cables are all phosphor-bronze, the outside ones being 4-inch diameter, the four strain cables through the mat 3/8-inch diameter, and the 66 radiating wires of regular antenna wire. The first 150 feet of the down lead of 26 wires is a fan and then is grouped by spacing hoops to form the rattail. Each corner is insulated with the Arlington type of Locke insulators with, however, two strings in parallel, as the strain was too near the mechanical breaking limit of the insulators. Lightning has already struck the antenna twice without damage, due to the safety gap feature of these insulators and the towers being grounded. An electric winch on each tower furnishes the power needed for handling the antenna.
The Bureau of Steam Engineering generously provided the excellent machine tools mentioned above, and with the help of those and a chief machinist mate in the complement the station is practically self-sustaining, as it has to be, without the usual navy yard facilities.
The variety of up-to-date equipment at this station furnishes a striking example of the wide field in general electricity which the radio service opens to its electricians. The operators of Colon and Balboa stations are given tours of duty here to familiarize them with the special features.
Power for the station is taken from the Panama Canal transmission line. The current is 25 cycle A. C., three phase, supplied at 44,000 volts and stepped down in the substation through transformers to 440 volts. The transmission line is in duplicate and is fed from either the hydro-electric station at Gatun Spillway or from the Miraflores steam power plant. This duplication of lines and power plants both, has given so reliable a service that no gas or oil engine has been put in as a stand-by source of power.
The high tension A. C. equipment is up-to-date, the two lines being controlled by interlocked oil switches. In the system are also aluminum plate electrolytic lightning arresters to which the heavy switching or lightning surges jump through horn gaps on the roof of the substation. All of the motors in the power house are 440 volt, but on account of the trouble with insulation in thee very damp climate, .those for use outside are of 220-volt type To give the 220 volt current there are three single phase 440-220 volt transformers. Further, in order that supplies may be drawn from those standard in the Canal storehouses, all lighting was made 110 volts. This is obtained by stepping down a tap from one phase of the 44o volt current.
The motor generator sets for the main transmitter are in duplicate. To provide for emergency drive a pulley has been provided which fits in the place of either motor. In this event, arrangements have been, made to use a steam engine from some retired Panama Canal equipment, furnishing it with steam from a locomotive to be side-tracked here.
The main set was furnished by the Federal Telegraph Company, and the arc generator is their type of the Poulsen arc. From 600 to woo volts are used across the arc. The set gives Arlington a signal easily readable except during the very worst static periods.
The arc can be controlled entirely from the operator's seat, the main generator voltage controlled there, circuit breakers closed or tripped, the arc struck and starting resistances short-circuited. While running, the arc is regulated to take up the wear of the carbon by foot pedals, so that the operator may not have to interrupt his sending.
The regular receiving cabinets with tikkers, as used by the Federal Telegraph Company, were provided with the outfit, but Dr. Austin's circuits with the oscillating audion are now used exclusively for long waves. For short wave work an oscillating audion detector is used on one of the Federal Company's cabinets.
While these are primarily military stations and are located to best suit the military needs, their peace time activities are what we have to use for shaking them down. This is particularly true in the region of the Canal Zone, where the navy is so far away and the stations do not get into the maneuvers. The traffic handled during the month of July (1915) was: Colon, 2299 messages; Balboa, 396; and Darien, 348. Colon handled over 800 commercial messages—over half with ships, the remainder with the United Fruit Company stations at Port Limon (Costa Rica), Bocas del Toro (Rep. de Panama) and Santa Marta (Colombia). Most of the United Fruit Company messages are in ten letter code words. This, with the messages in Spanish handled for the Panama Government, gives the operators at that station the best of practice. This is particularly true in that the bad static holds for eight or nine months of the year, and it is a fight for each letter when receiving through it. In justice to Darien it may be said that most of its messages are long, and if reckoned by the number of words would make a much better showing. The traffic of this station is rapidly increasing, as the various departments of the government accept the offered services of the naval radio.
The Colon and Balboa stations use as their main sending set a five K. W. Lowenstein spark set. Each station also has a two K. W. auxiliary, and the Colon station has retained its big set for use with Key West in case of an interruption of the Darien-Arlington communication. Both Colon and Balboa stations have been rebuilt in the past 12 months. These stations are equipped with concrete power houses and operating buildings and the navy standard 3oo-foot steel towers. This, with the comfortable living quarters for the crew and the up-to-date radio equipment, places these stations among the best the navy has.
All three of the radio stations are connected to the Panama Railroad telephone system through the local exchanges, Darien being on Colon and Balboa exchanges both. All government messages from Darien, or from the coastal stations which are in code, are delivered by telegraph, three lines of which come into each station. Commercial messages for other towns than the local town are forwarded by wire. This wire work requires the operators to become proficient in American Morse.
Now that the Canal is open, it is hoped that the fleet may visit this vicinity more, in order that the operators here may do more navy work. They have daily excellent drilling in all features of radio, except the actual maneuvers with the fleet.