Use of Wireless in the U.S.A. Army.
Page 14
If you've noticed an error in this article please click here to report it so we can fix it.
A remarkable advance in the eonstructioe of portable wireless sets for army field service has been made by the Signal Corps of the United States Army. For the next field operations of the army, or for immediate use in Mexico if necessary, there is available a wireless truck which can be set up for use in 12 mins. and send messages within a radius of 800 miles under favourable conditions. The truck was built specially for the Signal Corps by the White Co., of Cleveland. In tests that have already been made this set has received messages from points 25q) miles distant ; the electrical pressure here reached 00,000 volts at the top of the antennie. The great range of the new equipment and the speed with which it may be brought into action are due to the employment of a powerful electric generator driven through a train of gears by the 30 h.p. petrol engine.
The generator delivers electric current of 500 cycles per second at 110 volts and from 18 to 32 amperes. This current is interrupted by the relay, operated by the sending key, and is transf wined so that it leaves the side of the wireless truck at a pressure of 22,000 volts and an amperage varying from 8 to 12; as the current rises to the top of the antennw the voltage rises to approximately 90,000, whilst the amperage approaches zero. The radiation under these conditiens gives a sending ability from 200 miles, under the worst conditions in day time, up to 800 miles, under good conditions obtained in the early hours of the morning when there is less electrical disturbance due to electrieal plants of various kinds.
The antenme are of the umbrella type, mounted at the top of an 85 ft. mast whieh is built in nine sections. The first, or top, section is raised by hand, but the other sections are lifted by a block and tackle suspended from struts mounted on a platform on the roof of the truck. These struts are quickly detachable when not in use. The guy wires are attached to the fifth section of the mast. When dissembled, the nine sections of the mast are carried in long compartments built
along both sides of the truck. The counterpoise, or artificial ground, consists of heavy insulated wires radiating from a common centre, to which is attached the ground wire of the wireless set. For 'convenience in grounding there is a socket on the outside of the truck body into which a ground-wire plug fits.
The truck has been subjected to many interesting tests, and the wireless officers are pleased with its work. It was sent to the practice camp of the heavy field artillery at Tobylianna, Pa.., last month ; artillery gums set up on one side of a mountain, fired over the obstruction at targets on the opposite side, and during this test the wireless truck was used to send messages from Tobyhanna to Washington. Prior to the artillery practice it was tested in Washington, and messages were received from Boston, Brooklyn, Key West, Porto Rico and ships at sea. At the same time the operators took up one end of a conversation between the operator of the big station at Arlington and the Honolulu station in the Pacific Ocean.