High Frequency Apparatus Page 240

240 HIGH FREQUENCY APPARATUS Hard Rubber Tubing. Price is per inch in less than one-half foot. Outside Diameter Inside Diameter Price per ft. Price per in. $0.03 18" 18" $0.22 1/4" 1/8" .40 .06 18" .48 .06 ½" fa" .82 .10 5/8" " fe' .88 .10 3/4" ½" 1.00 .15 14" 2 " 1 " 1.50 .20 3 " 1½" 214" 2.65 .40 6.00 .70 Note: Most sizes rubber tube are not carried in stock and are supplied only at reasonable delay. Bakelite Fibre Sheet. For electrical work this material is unequalled. Hard rubber will turn green and rusty with age and will melt with heat; black fibre will absorb moisture, will warp and shrink, and will not take a good finish, while this new substance will not absorb moisture, will not warp or shrink, is not affected by heat, cold or acid, will take a beautiful satin finish, and will not lose its color or lustre. While more expensive in first cost it will prove cheapest in the long run, and as an insulator will be found better than rubber or fibre. Thickness Price per sq. in. per sq. ft. Cat. No. B. D. 18. ½ inch $0.02 Cat. No. B. D. 14 4 inch .03 Cat. No. B. D. 12 ½ inch .05 Cat. No. B. D. 34 3/4 inch .07 for 1 ft. or more $1.40 2.80 5.50 7.75 Silicon Steel for Transformer Cores. Thickness, .017 inch, averages 60 pieces to 1 inch thickness, weight, about ½ lb. per cu. in. Price, per lb. $ .15 Cut in any size pieces at 50c per 100 pieces extra.