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Show To Make Coil Having Low Electrical Losses The following is a description of a coil having very low electrical losses, and sufficient mechanical strength to enable It to be used under the most exacting conditions. This coil eliminates elim-inates two undesirable features found In other low-loss colls, viz., the danger of short-circuiting turns, as In the "basket-weave" type, and the high distributed capacity, as In the "pickle-bottle" "pickle-bottle" type. Any size of wire between Nos. 12 and 20 will be satisfactory for winding wind-ing the coll. However, it Is recommended recom-mended that No. 10 or 18 be used If possible. Obtain a bottle whose diameter diam-eter Is equal to that of the coll to be constructed. From a piece of gum-paper gum-paper tape cut out three strips, 5-18 inch wide and approximately three times as long as the finished coil Is to be. Several rubber bands will come in handy here, to hold the tape strips on the bottle wMle the wire is being wound on. The turns should be spaced by a string which Is wound on along f RUBBER BANDS HOLD I 1 3 GUMPAPER STRIPS IN PLACE BOTTLE WIRE'-' 1 STRIN0 Showing Method Employed In Wind ' ing the Low-Loss Coll. with the wire. Ordinary wrapping twine will be satisfactory for the smaller wire, but something bigger should be used for the larger sizes. When the correct number of turns have been wound on, fasten the end of the wire by another rubber band and remove the string. Apply a thick coat of collodion on the wire over the tape strip. Allow this to dry and put on a second thin coat. Moisten the tape not covered by the wire and collodion col-lodion and press down while It is still sticky. When this dries, break the bottle and remove the completed coll. Radio News. |