The radio dealer (Apr-Sept 1922)

94 THE RADIO DEALER September, 1922 Philadelphia Pointers By WM. B. WILKINSON, JR. NEW GRID LEAK Durham and Company, radio engineers of the Philadelphia Radiophone Company, have secured patents on a new variable high resistance grid leak that they contend will revolutionize the field in such condensers. The invention consists of a grid leak condenser to which is attached a plunger making it adjustable over a wide range. It is said to maintain its value permanently after an initial setting. It is non-inductive and has negligible capacity. The Durham Variable High Resistance, as the new product has been named, consists of an insulating tube with metal ends, which is filled with an inert paste of the desired specific resistance. The plunger is inserted into this paste through one of the metal ends, the inserted distance being variable. The further the plunger is pushed in, the lower will be the resistance, and vice versa. These resistances will fit any standard grid leak base. Another advantage of this form of grid leak is the many uses to which it can be put. It can be used as a variable grid-leak; a variable by-pass across phones or primary of transformer; a variable resistance for filter systems ; or as a variable resistance for resistance coupled amplifier. Durham and Company operate broadcasting station WCAU, which recently " put one over " by reporting the Leonard-Tendler fight to radio fans. Other Durham products are making their way into the radio field with great success on the basis of quality and workmanship. " S & S " VARIOMETER Sunday and Scholtz, of Cabot Street, have placed their variometers and vario-couplers on the market at a favorable list price. The policy of this firm is said to be a volume business at a low margin of profit. Their products, they firmly claim, are of quality unexceeded by any. They feel that their products will put radio in the reach of many who otherwise would find it impossible to secure high grade products. All " S. & S." products are guaranteed. This concern has been speeding up production in the slack season to take care of fall business. CLOCK-LIKE PRECISION Among well-known firms of allied industries that entered the radio field during the recent demand, was the American Chime Clock Company, of Germantown. Well known for the high standard of their time-pieces, this concern found their reputation, as well as the quality of their apparatus, was a great aid to them in merchandising their products. New units have been added to their line from time to time, and they are looking forward to doing a big fall business. Among their products are a crystal set of unique construction and high grade workmanship, and a variable condenser, the die-work, and assembling of which has been handled by mechanics who have been trained for years on the highest grade of clockwork. The condenser bears all the ear-marks of a high quality product. The line is being distributed by Lewis D. Breitinger, of Germantown, under the trade-marks " Ell-Dee-Bee " and " Skytone." " SENSORY " ARRESTER The Heinemann Electric Company have issued a special circular on their new lightning arrester, which, with other Heinemann products, is marketed under the trade-mark " Sensory." The circular describes fully the method of installing, with a diagram showing the internal construction, and another showing the installation completed. This is a unique type of arrester, and comes in two styles, one for outdoor use, and a second special type for indoor installation in two colors. The arrester complies with underwriter's regulations, and is protected in full by patents pending. The Heinemann Company has been known for many years as manufacturers of a complete line of electrical products of merit, and in entering the radio field last winter went about it in a way that would insure the same quality that has marked their electrical products for decades. Other Heinemann products of worth are tube sockets, insulators, indoor antennae, panels, ground clamps, variometers and couplers, detector and amplifier panels, cabinets for units and rheostats. Bulletin Number 12 of this company describes with the aid of cuts and wiring diagrams the complete " Sensory " line. NEW RHEOSTAT A new rheostat, modeled and manufactured by a firm of. international repute, is offered to the trade by the Rubicon Company, of Walnut Street. Josef Doerr, of the Rubicon Company, in an interview, told of the function of this new article. The new product is really a micrometer rheostat, quickly adjustable to any minute point in the six feet of resistance wire. Once obtained it is thrown off or on instantly without losing the adjustment. This fine adjustment assures maximum efficiency, and adds to the life of the tube. The rheostat is mounted without the use of mounting screws, requiring but one small hole in the panel. The instrument has ample radiating surface and the wire has free access to the air throughout its entire length, which greatly increases the capacity. The resistance wire is wound on a non-shrinkable moulded porcelain core, resisting high temperatures. The resistance wire used also has a zero temperature coefficient, establishing the same resistance at every temperature. This rheostat controls either detector or amplifier tubes. ENERGETIC WORKERS Spiro Brothers, of the Real Estate Trust Building, are well known to the Philadelphia trade as energetic workers and reliable distributors. They offer a line of quality condensers of their own manufacture, and are national distributors of many well known lines. They are prepared to quote prices on all standard lines in lots from ten to ten thousand, and can sell manufacturers at a right price as well as the dealer and jobber. They are the sort of people, to quote a well known Philadelphia jobber, that it is a pleasure to do business with. SPECIALISTS INCORPORATE The Franklin-Mason Radio Company have recently incorporated for the purpose of manufacturing inductances, resistances, and capacities for radio circuits. By specializing in this field the new company hopes to fill the need in the radio trade for specialists who are competent to offer the best in one field. They feel that too many firms making one high grade piece of apparatus are only too liable to be car