Page:Popular Science Monthly Volume 91.djvu/466

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��and message practice, sending the words most used in army practice first, then others later as the operator becomes more pro- ficient.

��Popular Science Monthly

Relieving the Strains on an Aerial Fastened to a Tree

r |^HE amateur who has his aerials sus-

��between a house and a tree

��Careful Sending Is Essential

In sending, strive always to make care- fully and accurately timed dots, dashes and spaces. Give particular attention to the length of spaces between letters and between words, as explained last month. The receiving operator will not be able to write down your letters correctly unless you form them correctly, and without careful sending many serious errors may result. In calling, for example, be sure not to run the call-signal letters together. Each time the call is sent, pause for a word-space before repeating it; otherwise instead of hearing three well separated groups of letters (KSW KSW KSW) the receiving operator will get a jumble of nine letters (KSW KSWKSW) and will not be able to tell whether your call is KWS, WSK or SKW. Similarly, keep the "de" well separated from the call letters themselves, and the "Attention" and "Finish" signals sharp and distinct. Beware especially of making the "Attention" signal sound like KA, or the "Finish" signal like AR, by introducing an extra dot space that should not be there at all.

When copying messages sent from an- other station, even in the very beginning of practice, wait till a single letter is com- pleted and then write down that letter in script. Never write out the dots and dashes themselves; the letters * should be transmitted to you sufficiently slowly, and with enough space between each pair of them, for you to write out the letters them- selves. As you become more and more skilled you will find it possible to carry an - entire word or several words in your mind before writing them down. To do this, however, requires much practice and an excellent familiarity with the Morse code. The two-station practice method de- scribed in this article, according to which two students progress together, is far better than studying for Morse reading by the use of an automatic sending machine alone. The ideal method, however, combines the two. In the next article some further points to be considered in operating will be explained, together with an arrangement for combining several stations and an automatic sender on a practice buzzer telegraph line.

���A tension spring in the holding rope of an aerial to relieve strains on the wires


is often bothered by the breaking of the wires. This is usually caused by the tree swaying and pulling on the aerial. The sudden strain so exerted may be lessened by attach- ing a spring to the aerial rope as shown in the sketch. The spring stretches when the strain becomes greater than the wires will stand with safety. A check rope should be attached to the spring so that if the spring should accidently break the aerial will not fall. — Paul L. Keating.

��An Inexpensive and Quickly Made Detector

HERE is a detector that can be built in half an hour. It is simple to make and easily adjusted. Upon a base 3 Yz in. square, mount two spring connectors on top of small blocks at the sides of the base, as shown. The spring connectors may be taken from an old dry-cell. A piece of cat-whisker wire — mandolin E string — is soldered to a small rod which is inserted in the loop of one of the spring connectors. The end of the rod is threaded and provided

���A detector made of scrap material mounted on a wood base with wire connections beneath

with a small insulating handle. The other spring connector holds a piece of No. 14 copper wire, to which is soldered the cup of an old dry-cell. — E. F. Jaspers.

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