The "Differential" One Origin of the "S.O.S."

Radio Record, Volume IV, Issue 25, 2 January 1931, Page 30

The "Differential" One Origin of the "S.O.S."

(Concluded from last week.) To make a fixed coil by the simplest manner obtain 4in. of 2in. tubing. About jin. from the top wind on #in. of 24-gauge D.S.0. wire. By making holes through the former the wire can be threaded through and held in position. Now, leaving a.space of about gin., wind on the tuning coil consisting of isin. of the same,’ This can similarly be fixed to the former. Now come to the tickler. This is wound on at about 4in. from the main tuning coil. Just about an inch of wire is required for this winding. All the wires are brought out on the side, as can be seen from the photograph published last week. The connections can very clearly be seen in the theoretical diagram,

Care of Accumulators

RASS terminals on batteries ean be kept in good condition for years if they are frequently wiped and greased, but even the most conscientious of us are likely to neglect such tasks, especially during the summer months. It wants only a week or two of neglect of such a nature in order for acid to corrode such metals as brass, and an accumulator terminal that corrodes and binds up is a most awkward item to deal with. Often the reward of a little gentle persuasion is the complete wrecking of the terminal, and that generally means the end of the life of the accumulator as a useful accessory.

‘Marine Distress Call

‘HE precise origin and history of the famous distress call "SOS" has puzzled many an enthusiastic. radio amateur, How, one often hears asked, did those now-celebrated letters come to be accepted all over the world as the acknowledged radio call-sign for a ship in dire distress at sea It would appear that the first suggestion of a distress call for vessels at ‘sea came from a party of Italian delegates who attended a conference on Wireless Telegraphy at Berlin in 1908.

They suggested the universal adoption of the signal "SSSDDD": to be employed by ships in cases of emergency, and they advocated, also, the formulation of a number of rules governing the use of such a distress call. Not very long after this suggestion had been broached, the Marconi Company, recognising the vital need for some type of distress call, instituted its at one time well-known "CQD" call on all its ships, the signal being a combination of the company’s general call "OQ" with the addition of the letter "D," which signified distress. The instructions of the Marconi Company were that the signal "CQD" was to bel used only at the order of the captain of a distressed vessel or by a land station re-transmitting the signal. Radio operators who abused the call were to be dismissed. Another radio conference was held in Berlin in the year 1906, and during the sitting of that body the German Government put forward the suggestion that a universal standard distress eall for ships at sea should be adopted. The German Government further suggested that the distress call "SOS" should.be made use of. Why, it may be ‘asked, were the letters "SOS" suggested for an international distress call At this period German ships desiring to communicate with all vessels in their neighbourhood would, particularly if the names of such vessels were

o-- — unknown, transmit an inquiry call "SO," or, in Morse, ...---. The adoption of this call. signal ad ! an international marine distress signal had first been considered, but it was obvious that the signal was not distinctive enough, the final letter "H" being represented merely by a dot, which could easily be overlooked in times of atmospheric disturbance or of heavy radio traffic. For this reason, therefore, . the distres call "SOS" (in Morse «see---\-...) was Submitted for the consideration of the delegates to the Berlin Conference of 1906. It was adopted officially, and it was put into effect by the International Radio-tele-graphic Convention of Berlin in 190s. Thus the very apt interpretations, such as "Save Our Souls" and "Save Our Ship," which have been put on the "SOS" distress call are untrue It was a matter of much re the old Marconi operators that t old signal "CQD" had not been addpted as the international distress Indeed, many of these operators continued to follow up their "SOS" signals with "CQD." Gradually, however, the latter signal was relinquished, and now it is almost forgotten.