Page:Popular Science Monthly Volume 89.djvu/295

 A Built-Up Wireless Mast

���THE followiiiR artick' tells how any- one possessing ordiaary working tools, can easily, quickly and inex- pensively construct a mast of a distinctly modern t>'pe not usually found at amateur stations. Since it is built of wood, the mast is light anil easy to erect. It can be readily usotl in close quarters, since it requires few guys, and consequently it can be placed quite close to a fence, building or wall.

The material should all be clean, straight, white pine, since this wood will with- stand severe weather. All the strips are i in. by 2 ins. in cross-section, and may be bought at any lumber yard. The prices range from i to 3 cents per lineal foot.

T li e mast should be built on a perfectly flat i)la(e, sueli as a large floor or level concrete sidewalk. First, three pieces of the material about I in. long are sawed off and nailed on the floor to form an equilateral triangle measuring 24 ins. on a side, as shown at A Fig. 2. Next cut off 39 pieces, each 24 ins. long, for the cross-pieces B, C, D, shown in Fig. 2. The ends of these pieces are notched to fit in the triangle formed by the pieces A, as shown in Fig. 3. l-"ach cross- member should be fitted, and when three are finished, they should be marked as one set and put aside. In this manner 13 sets arc made.

When these cross-members are all done, start work on the uprights. Each upright should be 47 ft. long and made by joining several strips by means of scarf joints at least 6 ins. long, using No. 14 wire brads 3 ins. long.

Having completed the uprights, the cross-members may be put in. The first set is l foot from the bottom, ancl

��Note how the mast is built up in sections

��the remainder are 4 ft. apart. The last section, F in Fig. i, will be 2 ft. long in the 50-foot mast. Ne.xt put in the braces from corner to corner, having tiii'm tight and butting against the cross-members. They must be firmly nailed in place, both to cross-members and uprights. The ends are to be chamfered off to fit the corners, as shown in Fig. 4. The main part of the mast is now finished, and the pole may be put on top. This is a piece, preferably of oak, 2 ins. by 2 ins. and 18 ins. long. The top is chamfered off to shed water and the bottom made triangular in shape, so as to fit the step on the top of the mast, as shown in Fig. 6. The three pieces, P, P, P, are of the same material as the mast, and are fastened on the bottom side of the top cross-member, set by means of screws, as shown. The six-sided piece F is fastened under the . three pieces P, P, P, and acts as a bottom for the step. The mast is l)raced by three pieces shown at G in Fig. I. These rest on the ends of the

���Concre/e

��Diagram showing the construction of the built-up wireless mast

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