AMERICAN PORTABLE MAST

Radio Record, Volume I, Issue 48, 15 June 1928, Page 16

AMERICAN PORTABLE MAST

NEW MILITARY DEVELOPMENT,Engineers of the United States Signal Corps have developed a steel tubular radio mast, eighty feet high, for use with the most powerful mobile sets in the army communication service. Kiasier to erect and much stronger than the wood and steel poles now in use, the new mast overcomes serious deficiencies in the old equipment, the engineers believe. An aerial system which is large in both ground area and height is required for the more powerful portable sets. Weretofore the army has used a sectional mast, made of hollow spruce section 50 inches long, with a steel tube coupling inserted between sections. The method of erection was to lift the mast high enough to slip a section on to the bottom) this process being repeated until the desired height had been attained. For mast heights up to forty feet this method proved satisfactory, but for the larger aerial it was found to have two serious faults, The weight of the larger mast was such that it -was necessary to provide a derrick for lifting, and the eighty-foot mast was susceptible to frequent failure beeause of weaknesses, The new steel mast is made in sections eight and a half feet long. It is assembled on the ground and then raised by a short gin pole and block and tackle, The mast is guyed in four directions, During erection the, two side guys steady the mast, the front guys are fastened to the gin pole to lifé the mast and the rear guys arrest the movement of the mast at the vertical position, The aerial forms an unbrella pattern with twelve wires, These wires are ninety-eight feet long, with a ball connector fastened info the mast cap. The other end is connected through four insulators in series to 150 feet of sash cord rope. A counterpoise is | used instead of an carthe