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Show Novel Aerial Switch Cuts Out the Leaks The weak point of most aerial systems sys-tems is the lightning switch. This is true especially In wet weather, the radiation often being halved, or in very bad cases the spark jumps directly direct-ly to ground, making use of the wet switch base in so doing. Various methods of setting the switch blade and jaws on insulators to overcome this leakage have been described, but In most cases the construction has been rather complicated, and considerable consider-able time and energy have been required re-quired to make a neat Job. The switch Illustrated in thp sketch was made in the spare bprs of an off afternoon, - Cur wr nm to fig I Any msbater Simple Method of Improving Efficiency of Lightning Switch. and the time spent was fully repaid In the comfort derived from It. A regulation 500-volt 100 amp. S. P. T. D- knife switch, mounted on a composition base that leaked badly at the least sign of dampness, was used. Three electrode ball insulators were procured, care being taken to see that the Iron rings were In line with each other and fastened tightly. If they are not in line and rigidly fastened fas-tened the jaws will either be mounted crooked or will wobble. The blade and jaws were removed from the base and three-quarter inch holes were drilled one-half Inch in from the edge, directly opposite the original ones, as shown in Fig. 2. These holes must be countersunk on the under side of the base so that the screw heads will not project beyond be-yond the surface. They must be measured meas-ured accurately, as otherwise the insulators in-sulators will have a certain amount of play and at the least little knock or Jar they will become out of line, throwing throw-ing the jaws and blade out also. A hole must now be cut in the blade support, Fig. 1, to accommodate the nut, B. This Is done by drilling a one-eighth inch hole through both sides of the support and cutting out with a thin-bladed fret. saw to a size that will easily allow the nut to be slipped in. However, care must be taken In turning corners with the saw or there will be a pile of broken blades lying on the bench. The insulators insula-tors are fastened to the base by one-eighth one-eighth Inch brass bolts, nuts and washers. wash-ers. The Jaws and blade are attached to the other end of the insulators in like manner- Looking down on the finished switch It should resemble Fig. 2. Of course larger Insulators mny be used, resulting in a somewhat higher efficiency, but for all practical purposes and moderate powers the small electrode elec-trode ball insulator, retailing at about 85 cents. Is as good as any. The switch may be mounted In any convenient con-venient position and place irrespective of weather, as there is very little cor- r&r 1 rosion, and the losses, even in very wet weather, are practically nil. It Is suggested sug-gested thut If It Is desired to further protect the metal parts from corrosion they may be painted, leaving bare, of course, any parts where contact is made. In actual use the switch has proved Its worth on many a rainy night, as before the Insulators were put on it was an Impossibility to work any but local stations. Now no trouble is experienced ex-perienced In the worst weather. 0 Science and Invention and Radio Newa.) |