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VOLUME 16 NOVEMBER, 1928 NUMBER 11 PROCEEDINGS of 3inntitutr of Kadin Ettgintrion Published Monthly By THE INSTITUTE OF RADIO ENGINEERS Publication Office: 450-454 Ahnaip St., Menasha, Wis. BUSINESS, EDITORIAL AND ADVERTISING OFFICES 33 West 39th Street, New York, N.Y. Subscription $10.00 per Annum in the United States $11.00 in all other Countries General Information and Subscription Rates on Page 1437 THE CHOICE of LEADING MANUFACTURERS For over four years Thordarson transformers have predominated in the receivers and power units of leading radio manufacturers. Such patronage is not an accident. It stands as a positive proof of a superiority of product.It demon- strates the effectiveness of a policy of service rendered to the n'th de- gree by an efficient and smooth running organization. We are at present manufacturing over twelve hundred different types of transformers.Among our cus- tomers are more than a hundred radio manufacturers. Thordarson engineers always stand ready to help you with your trans- former problems. PROMPT DELIVERY RIGHT PRICES dalIJIUDIWIllnumilli[hIUMARVA.611t10011111WAINUI JAI ORDARS1:2ADI ON fupreme in rtnanee TRANSFORMERS THORDARSONTraoriner ELECTRIC specialists MANUFACTURING since 1895 CO. WORLD'S OLDEST AND LARGEST EXCLUSIVE TRANSFORMER MAKERS Chicago, U.S.A. Reliability Even where particularly exacting conditions require capacitors of proven reliability, the usual choice is Faradon. This fact has held true for more than twenty years- convincing evidence of the regard held for Faradon Capacitors by leading electrical and radio engineers. Our staff is always ready to assist in solving your special requirements not covered by the more than 200 types of Faradon Capacitors ready for prompt delivery. WIRELESS SPECIALTY APPARATUS CO. JAMAICA PLAIN, BOSTON, MASS., U.S.A. Established 1907 Electrostatic Condensers for All Purposes 2342 When writing to advertisers mention of the PROCEEDINGS will be mutually helpful. Two New Bulletins Roller -Smithhasrecentlyissuedtwonew Bulletins. No. K -16o covering TypesGSA, HTA and ISA portable, alternatingcurrent ammeters, milli- ammeters, voltmeters, volt -ammeters,wattmeters, frequency meters,power factor meters and trans- formers. No. K-400 cover- ing Types TD and FD, 3%" and 4" panel type,direct current ammeters, milliamm et e r s, voltmeters,milli- voltmeters a n d volt -ammeters. Copies of these Bulle- tins will gladly be sent to anyone on request. "Over thirty years' experience is back of Roller -Smith" OLLER-SMI1TH COMP LrElectrical Measurin and Protective Apparatus Main Office: Works: 2134 Woolworth Bldg. FtalciPiii) Bethlehem, New York t.. Pennsylvania Offices in principal cities in U. S. A. and Canada. Representatives inAustralia, Cuba, and Japan When writing to advertisers mention of the PROCEEDINGS will be mutually helpful. NEITHER great men nor great products require a long story about their virtues. Their very manner of existence and daily accomplishments tell all that the onlooker needs for appreciation and en- dorsement.Certain automobiles, for example, have won such confidence that no high-pressure selling is re- quired. Their makers know that all the world would own them. And so with Kolster Radio.Such faith- fulness in tone quality, such extraordinary selectivity and such distinguished appearance have created, by their presence in thousands of homes in every State in the Union, a powerful structure of confidence within the public mind.Glowing praise is irrelevant when this exists.It is enough to hear on all sides the quiet remark, "Kolster is a fine set." KOLSTER RADIO CORPORATION, NEWARK, NEW JERSEY (c)1928, Kolster Radio Corporation When writing to advertisers mention of the PROCEEDINGS will be mutually helpful. Used by Leaders Because They arethe Leadersintheir Fzeld!_Durham Resistors, Powerohms and Grid Suppressors are used by such organiza- tions as the Western Electric Company, General Electric Company, Westinghouse, and Bell Laboratories, the U. S. Government and by the foremost experimental laboratories in this country.With many forms of resistances from which to choose, it should be highly signifi- cant that the most important radio and electrical laboratories and manufacturers have standardized on Durhams. The reasons are plain. First-there is a Durham resistance unit for every practical need up to 100 volts.Second-the Metallized principle has proved its utter superi- ority over many years.Third-Durham accuracy and uniformity can be relied upon regardless of the type of resistance or the purpose for which itis used.Each succeeding year sees more manufacturers, laboratories, dealers, jobbers and professional radio men using Dur- hams (such leadership must be deserved).Descriptive literature on the entire Durham line gladly sent upon request. 11' irk lif METALLIZED V&A RESISTORS & POWEROHMS International Resistance Company, 2006 Chestnut Street, Philadelphia, Pa. When writing to advertisers mention of thePROCEEDINGSwill be mutually helpful. Iv Official Distributors for Leading Radio Products S the world's largest dis- tributors, jobbersand wholesalersofa varied line of radio products, the W. C. Braun Co. offers to manufacturers, dealers and custom setbuilders,amost usefuland necessary service. For the dealer and custom setbuilder we furnish a quick,easy, convenient and economical means of securing any merchandise desired on instant notice by letter, wire or in person.To be able to secure such service,all under one roof, without going to the trouble of buying from a dozen or a hundred different sources, cer- tainlyisa service thatis well worth while to the manufacturer as well as to the Radio Trade. Selections-Variety-Service Thelistof well-known radiolinesrepresented by us includes practicallyallthe famous names intheradioindustry. Besides carrying large selections of varied lines of products of leading parts, equipment and accessory manufacturers? we dis- tribute well-knownlinesof radiosets and co-operate with our dealersinadver- tising,window and store displays and in furnishing proper sales aidsto insure successful business.In the small-town field as well as in larger radio centers, Braun service means much to the dealer and professional radio man. Headquarters for Custom Set Builders We are headquarters for the parts ofthe country's leading parts manufacturers' products, used in the ieading circuits.Parts and supplies for any published radio circuit, whether short wave or broadcast, are immediately available from our stock. Manufacturers desiring a distributing outlet furnishing world-wide service,arein- vited to take up their problems with us.Dealers, custom set builders and engineers will find here an organization keyed tofilltheir needs promptly and efficiently and a request on their letterhead will bring a copy of the Braun's Radio Buyers' Guide -the bible of the radio industry. W. C. BRAUN COMPANY Pioneers in Radio 600 W. Randolph St. CHICAGO ILLINOIS ll'hen writing to advertisers ment:on of the PROC FEDI NG 3will be mutually hel2ful. V CONDENSERS Universal Precision Instruments Which Are Adapt- able To Any Circuit and Can Be Mounted For All Sorts of Drives and Ganged In Any Number. Let the USL Engineers co- operate with Universal you in solving Compact Type your condenser UXB Brass problems.We Condenser are always glad to quote on (Note Remov- special able Shaft) specifications. Type UXB Three Gang Condenser This fine job, which is small and compact is especially suited for shielded work.The popular type UXB Condensers are used. They can be hadineither .005MF or .00035MF Capacities. UNITED SCIENTIFIC LABORATORIES, INC. 115-C Fourth Avenue, New York City BRANCH OFFICES BRANCH Cincinnati OFFICES Los Angeles St. Louis Philadelphia Chicago San Francisco INITESCIENIAB Boston Canadian Offices Minneapolis London, Ontario When writing to advertisers mention of the PROCEEDINGS will be mutually helpful. VI TESTS SHOW - Current Surge - with Metal Filament with Arcturus (aria,: filament illatnent Current - 1,0 2.0 4,-Tine in Seconds Arcturus Tubes Immune To Line Surge INVESTIGATION establishes that time is worthless.It is no indica- the majority of A -C tubes are de- tion of the performance of the tube stroyed by current surges set up as under actual service (intermittent) the voltage is applied. The extent of conditions. these surges is illustrated in the ac- Under such testsArcturusA-C Tubes, companying graph. regardless of heater voltage, indicate The probable life of a tube can only an average life well in excess of 2,000 be determined by an intermittent life hours-a fact of interest to the engi- test in which the tube is turned on neer and of paramount importance to and off every hour or so, simulating his ultimate judge, the broadcast lis- normal operating conditions. A tener! Arcturus Radio Co., 25S Sher- steady burning over a period of man Avenue, Newark, New Jersey. Engineering Facts Have A Utility Significance To The Ultimate Listeners AARCTURUS -C LONG LIFE TUBES When writing to advertisers mention of the PROCEEDINGS will be mutually helpful. VII R ADIO PARTS ESEARCH and experimentation are vital fac- tors in the radio business.The individual manufacturer must be up-to-date in every re- spect-must take advantage of each progres- sive step in the industry.Scovill places at your disposal a department of research and experimentation that has contributed items of unquestioned value to the modern radio.In addition, when you place orders with Scovill, you get the services of a modern efficient organization where scientific control