Diamond DA50 RG Checklist

free from these untidy "ghosts" that reproduce on blueprints! The secret of this amazing performance lies in aremarkable new process that defies moisture, and gives PHOENIX an unus- ually durable working surface. You can use harder pencils with this improved cloth and get sharper lines with less tendency to smudge. Even 6H pencil lines show clearly, and reproduce strongly! Erasing does not mar the drawing surface; erased arcas take pencil smoothly—and ink without feathering. The new white color and increased transparency provide excellent draw- ing contrast and produce strong blueprints. Let PHOENIX speak for itself on your own drawing board. See your K&E dealer, or write for agenerous working sample and an illustrated brochure. EST. 1867 KEUFFEL 84 ESSER CO. NEW YORK • HOBOKEN, N. J. CHICAGO • ST. LOUIS • SAN FRANCISCO • LOS ANGELES DETROIT MONTREAL • fee f.1 instrument dia "How can we keep instrument dials from discoloring?" That's a question to which industry has wanted an answer for years. Today the answer is ready. Make this test for yourself—Take an ordinary instrument dial and one of the new Westinghouse permanent white dials. Place them overnight in an oven heated to 300° F. Then look at them. That is how they will look after approximately two years cf service in the average plant. Other destructive conditions, such as exposure to corrosive fumes of excessive humidity, as may be experienced in many instrument applications, will have a similar effect. The Westinghouse dial will stay white because all Westinghouse in- strument dials are faced with aplastic-base material, which resists the effects of time, industrial fumes, heat and moisture. Accurate readings are easier—and panel appearance is neater when the dials are white. The jet-black characters, printed by aspecial process or hand marked, do not flake or fade. This is only one example of the special steps we take to make our instruments the best you can buy. Detailed information on other features, including nonblunting pivots, nonaging springs, permanent magnets, and tubular pointers, is in our Bulletin 3013. Address Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., Department 7-N. J-40334 INDUSTRY'S MOST COMPLETE LINE OF QUALITY ELECTRICAL INSTRUMENTS S-35 is an attractively styled switchboard instrument for projec- tion mounting on medium size panels. Accuracy within 2' ; For flush mounting on small pan- els Type V-35 is an instrument of attractive design. Accuracy within 2' ;. TA Industrial Analyzer—in one case all the instruments needed for complete a-c data in any industrial plant. On large switchboards where it is desirable to have large full-face round type instruments with high accuracy, the Type S is the answer. The Type A recorder with low first cost, low maintenance unit gives good service in a variety of applications. High visibility in a switchboard instrument is one of the features of this KA-25 with flush-mounted 1 case 5' 2 inches square. Accu- racy is PC-135, a through type current transformer gives 1through 250 ampere: in primary, 5 amperes in secondary. Some of the SHALLCROSS Products ... •Ayrton Universal Shunts 'Ratio Boxes •Accurate Wire Wound Resistors (1 ohm to 10 million ohms) •Standard Resistances (0.0025 ohm to 1,000 Megohms) 'Secondary Standards Multi-Resistance Standards 'Megohm Decade Resistance Standards •Potentiometers—Decade Type •Decade Resistance Standards (Heavy Duty) •Megoh m meters •Percent Limit Bridges r itei HALLCROSS APPARATUS FOR ELECTRICAL MEASUREMENTS 'High Voltage Measuring Apparatus •Wheatstone Bridges •Kelvin-Wheatstone Bridges 'Bonding Testers •Milli-ohm-meters •Decade Resistance Boxes •Telephone Transmission Testing Equipment •Kilovoltmeters 'Fault Location Bridges •Ground Resistometers 'Rotary Selector Switches (Solid silver contacts) CONSULT US ON YOUR INDIVIDUAL PROBLEMS. OUR SPECIALTY IS DESIGNING AND BUILDING SPECIAL APPARATUS. June 1942 — ELECTRONICS ENGINEERING • DESIGNING • MANUFACTURING INSTRUMENTS •RESISTORS •SWITCHES COLLINGDALE, PENNA. () MEMBER Constant Voltage .undistorted • • • SOLA Constant Voltage Transformers are famous for low distortion ... Now available in units that deliver an almost Perfect Sine Wave* ...A regulated source of Constant Voltage, free from harmonic distortion ... A final solution to your voltage regulation problems. Harmonic Analysis* Primary 115 Volts 60 Cycles harmonic Full Load No Load 3rd 0.56% 1.34% 5th 0.51 0.56 . 7th 0.21 0.67 What is your problem? SOLA ELECTRIC COMPANY 2525 CLYBOURN AVE., CHICAGO, ILL. ELECTRONICS — June 1942 7 1.5Ce" MAX. .28& CLASS A la CLASS CLASS D Centralato CERAMIC TUBULAR FIXED CAPACITORS Bulletin 597 describes the CENTRALAB CERAMIC TUBULAR Fixed Capacitors with controlled temperature sensitive characteristics. Centralab Ceramic Trimmers feature capacity ranges and stabili- ty, the equivalent of air trimmers, plus a saving in space and weight. Write for bulletins that supply full Ceramic Trimmer data. Centrale CERAMIC TRIMMERS .12670.137 ,11111c 10 12 ELECISONICS Always specify Centralab — whether for ceramic prod- ucts ... Fixed Resistors ... or Volume Controls . . . CENTRALAB DIV. OF GLOBE-UNION INC. MILWAUKEE WISCONSIN 2 MOUNTING HOLE 4-36 mACH SCREW ,f DEEP 328 328' ize —T 750' e One thing above all others makes Formica the valuable material it is in so many industries — electrical, mechanical, aviation, chemical, and that is: once a Formica part is installed it remains unchanged almost regardless of conditions. It really stays put! When you build a part of Formica you can challenge the elements to do their worst and they won't accomplish much. Changes in temperature do not alter its dimensions appreciably. Humidity or lack of it leaves it untouched. Electrical currents can't push through it because it is an excellent insulator for high or low frequency currents. No atmospheric condition, anywhere in the world, can cause it to corrode, or roughen and destroy its surface, because it is inert chemically . . . The Formica data book tells this story in terms of precise engineering tests. Send for it. THE FORMICA INSULATION COMPANY 4628 SPRING GROVE AVENUE CINCINNATI, OHIO ELECTRONICS -- -June 1942 9 LET DUNCO SOLVE YOUR ooe' T miss riits!.•• The NEW DUNCO CATALOG AND RELAY DATA BOOK We sincerely believe this is the finest, most helpful, and most com- plete volume of its kind ever issued. Contains 48 pages, pro- fusely illustrated with photos, dia- grams and charts. Write for your copy today. QUALITY UNITS, TAILOR-MADE TO FIT YOUR APPLICATION Don't engineer "around" Relays and Timers ! Don't waste time and effort trying to utilize units that almost meet your requirements! Come to Dunco where one of the nation's largest relay businesses has been built solely on the ability to supply exactly the right relay or timing device for the job—tailor-made to fit your specifications like a glove. Dunco engineers will gladly cooperate in solving your relay problems. STRUTHERS DUNN, INC., 1326 CHERRY ST., PHILADELPHIA, PA. lo June 1942 — ELECTRONICS ...Anode* and Cathodet Sleeves for the Electronics Industry... * SUPERIOR SEAMLESS t SUPERIOR PATENTED LOCKSEAM AND SEAMLESS SUPERIOR TUBE COMPANY, NORRISTOWN, PENNSYLVANIA Tubing front 5/8"OD down. ..t l'E + Seam le›, in vari tttt sanalyses.WELDHAM N BR t%% N effll NN II d 1 •1. - NI 1- aiiil Iii f1'.SE t‘11 ESS and t• t•I hsl V11 atlande Slee%es. and •Irawi, Stainless. ELECTRONICS — June 1942 11 L' NINE GUARANTORS OF STOUT PERFORMANCE SYLVANIA LOCK-IN TUBE 1. LOCK-IN LOCATING LUG — also acts as shield between pins 2. NO SOLDERED CONNECTIONS—all welded for greater durability 3. SHORT, DIRECT CONNECTIONS — fewer welded joints—less loss 4. ALL -GLASS BASE —low loss and better spacing of lead wires 5. NO GLASS FLARE — unobstructed base for internal shielding 6. IMPROVED MOUNT SUPPORT — ruggedly mounted on all sides noted by separation of getter material from leads 8. NO TOP CAP CONNECTION — overhead wires eliminated 9. REDUCED OVER -ALL HEIGHT — space saying SYLVAN IA RADIO TUBE DIVISION FOR ACTIVE MILITARY SERVICE! A S . battle lines lengthen, as American military might fans out over the globe, radio becomes an increasingly vital artery of our communications system. So naturally, radio tubes must be stronger, more solidly built, better able to ‘‘take it" than ever before. Look at the cross-section of the Sylvania Lock-In, shown in the accompanying diagram. Note its nine outstanding features. Then you'll understand why our armed forces are relying, in growing measure, upon the un- flagging dependability of this great tube. HYGRADE SYLVANIA CORPORATION New York City EMPORIUM, PA. Salem, Mass. Also makers of HYGRADE Incandescent Lamps. Fluorescent Lamps and Fixtures June 1942 — ELECTRONICS ,• SI 1; t * Swing the turrets! Aim! Fire! And, aircraft guns respond to on * GUN SWITCH HANDLES trois by Guardian. Sight! Bomb! It's the order of the day. Guardian * REMOTE FIRING EQUIPMENT stands ready for any assignment that will help to preserve the * TURRET CONTROLS "American Way" of life. * RADIO CONT ROLS Ce rtified by all branches of the war department. •.Guardian * NAVIGATION CONTROLS invites inquiries for samples of Government Approved Controls for * AIRCRAFT CONTROLS e the jobs you are doing today ... for those new designs that must * BOMB RELEASES excel tomorrow. Write—wire — phone. * SOLENOID CONTACTORS GUARDIAN G ELECTRIC16 2 5 WEST WALNUT STREEI L ri ,CAGO, ILLINOIS LARGEST LINE OF RELAYS SERVING AMERICAN INDUSTRY by GUARDIAN ELECTRONICS — June 1942 I3 Co= CD= TYPE PL _ •:• Non inductive, Standard toleitnce U, Maximum . .ince 500,000 ohms, Size '2. diam. u 12'. high .inting-hole through center to clear 6-32 screw, Teitninals 18 Tinned copper wire 112" long. TYPE KL, r2 Watt, Non-inductive, Standard tc,I.,nice '2 0 0, Maximum resistance 500,000 ohms, Size . diam. x 1'y" long, Mounting by terminals, Terminals 18 Tinned copper wire 1r•2: . long. 1) RESISTORS INC Little Fallu New Jersey Made in U. S. TYPE DL, 1 Watt, Non-inductive, Standard tolerance ' 0 0, Maximum resistance 1 Megohm, Size diam. x '4 high, Mounting-Hole through center to clear 6-32 screw, Terminals -18 Tinned copper wire It lon9 TYPE WL, 1 Watt, Standard tolerance ...- mum resistance 50,000 ohms, Size 'if, - dram, x long, Mounting by terminals, Terminals—Strap .015' . thick by wide tinned copper ...Light with high resistance, apopular type for aur.t aue risc- r MOM TYPE AL, 4 Watt, Inductively wound, Standard toler- ance 3 O 0, Maximum resistance 80,000 ohms, Size &rm. x 1- long, Mounting by terminals or center Lurnlold1, 18 Tinned cc-racer ntie 1 1 2- long TYPE AC, 5Watt, Inductively wound, Standard Toler- ance 3 0 0, Maximum resistance 50,000 ohms, Size x1" long, Mounting by terminals or center hole, Terminals choice of -18 Tinned copper wire or 01 T '. slap Specializing in WIRE WOUND RESISTORS If space and weight are factors in your design, check the maximum re- s'stances of these wire-wound resist- ors against their dimensions which are indicated by the rule. Specializ- ing in wire-wound resistors, the type with which it is possible to obtain high resistance in minimum space with minimum weight, we have stand- ardized these and other units in order to give you the price advantage of mass production. As specialists, moreover, we have the experience and equipment to meet your resistor needs whether or not any of our standard units can be used. Write today for file catalog with prices ...and if your resistor prob- lem is unusual, by all means, get our advice and quotations. • INSTRUMENT RESISTORS CO. 25 Amity Street LITTLE FALLS . . . N. J. MICA CARD, Type HN, Standard tolerance 2%, 30 Watt, Maximum resistance 50,000 ohms, Size 11/2" wide x 31/4 " long x ,`," thick, Mounting Insulated eyelet to clear 6-32 screw, Terminals Tinned copper lug. Ideal for limited space-lying close to panel or wall. I1 June 19-12 -ELECTRONICS Untie VARNISHED OIL 'TUBING- meet ing the all-purpose requirements of a slee ve insulation commonly to stand guard against breakdown, moisture absorption—all enc ountered acid and oil influences. VARNISHED GLASS 'TUBING- for those applications hwhaebreo veextremely all conshigh heat res istance becomes te -ideration. EXIRUDED TUBING- where extreme sub-zero temp t becomes a erature resistnc a e to any ofthe effects ofembrittle men prerequisite. ATI WIRE IDENTIFICON MARKERS—Any size, any co lor, any length or any mar king. Strict comp' Navy and Air Corps specifica ance with Army , - tions. ree types o f insulation to ir afeguard the servic e - efficiency of your product or equipment—each "indexed" to of speci f mee tthe requir ements ic applications — are on 24-hour duty to ward off the destructive elements of heat, moisture, al- kalis, acids, fumes, sub-zero etc. temperatures, KeeP your materials cord file up - to-date. Enter the advantageous dielec tric and physical properties of the various TURBO insulations for ready reference when prob- lems arise. You'll find TURBO a dependable, effic ally. ient, For proof as for samples of each; also for new specimen board and list of standard sizes. There is no obligation. WILLIAM BRAND & CO. 276 FOURTH AVENUE. NEW YORK N Y • 375 W HURON STREET, CHICAGO. ILL ELECTRONICS — June 1942 Which would you pick to keep a fastening TIGHT? DEAD-FISH DONALD OR FIRM-FINGERED PHIL? 1001110$0. BONUSES Pesver Phillips the Screws of same 5\16 Ot %he some number of o smalle r site wilt equal the holding power ot stottea screws. Snug fit ot e point in Phitiips recess prevents dangerous burrs• Phillips Screws improve product oppeorance• For a good grip, no matter how hard the going, you'd take Firm-Fingered Phil ... or the Phillips Recessed Head Screw. Long after you would have given up on a slotted head screw (or it would have given up on vim), you can still turn a Phillips Screw. The metal won't ream out ...the driver won't slip out ... and you won't give out. Result: a much tighter fas- tening that will withstand all vibration. Meanwhile, you've been sav- ing time, because Phillips Screws are driven faster — especially when the fastening is awkwardly located. In many cases, pneumatic and electric power drivers can be used, since there is no danger of driver slippage or split screw heads. Taking an average, you can save 50e; by switching from slotted head to Phillips. That's half the time ...and half the cost. Order from any of the firms listed below. Iref4ggeed»g . .Phh /ewer bgeee ashe rze illipS RECESSED S HEAD • • crews t\\ WOOD SCREWS SPECIAL THREAD-CUTTING SCREWS MACHINE SCREWS • SHEfrEoTmManEy of SCREWS • STOVE BOLTS • SCREWS WITH LOCK WASHERS Order stronger, cost-cutting Phillips these sources k issoutts doe American Screw Co., Providence, R. I. The Bristol Co., Waterbury, Conn. Central Screw Co., Chicago, Ill. Chandler Products Corp., Cleveland, Ohio Continental Screw Co., New Bedford, Mass. The Corbin Screw Corp., New Britain, Conn. International Screw Co., Detroit, Mich. The Lamson & Sessions Co., Cleveland, Ohio The National Screw & Mfg. Co., Cleveland, Ohio New England Screw Co., Keene, N.H. The Charles Parker Co., Meriden, Conn. Parker-Kalon Corp., New York, N.Y. Pawtucket Screw Co.. Pawtucket, R.I. Pheoll Manufacturing Co., Chicago, III. Russell, Burdsall á Ward Bolt & Nut Co.. Port Chester, N.Y. Scovill Manufacturing Co., Waterbury, Conn. Shakeproof Inc., Chicago, Ill. The Southington Hardware Mfg. Co., Southington, Conn. Whitney Screw Corp., Nashua, N.H. J6 June 1942 — ELECTRONICS now a Shot in the Dark Finds Ifs Mark A—Square tube coil form sanded to siie; flanges milled, sawed and broached. B—Insulating tube, sawed, drilled, reamed, and milled. C—Sawed, milled and drilled terminal panel. nr HE destruction of enemy planes at night is dependent upon electrical teamwork. Efficient work of battery units and the reliability of the communications between them require adependable insulation. Synthane's combination of physical and electrical properties makes it as useful in war as in peacetime production. Among them are excellent electrical insulating char- acteristics, light weight, structural strength, ease of machining and resistance to corro- sion from solvents, water, many acids and salts. As an aid to essential industries, some of which are using Synthane for the first time, and as a help to peacetime planners, the information on the back of this adver- tisement may prove helpful. We'll be glad to supply additional information if you'll write us. Plan your future with plastics. SYNTHANE CORPORATION, OAKS, PENNA. SYNTHANE TECHNICAL PLASTICS YNTInANEJ „„,‘.„,.. It. i1,48 ell SHEETS •RODS •TUBES' FABRICATED PARTS SILENT STABILIZED GEAR MATERIAL STANDARDS OF QUALITY FOR SYNTHANE BAKELITE- LAMINATED SHEETS BLACK Figures are actual test values ; BROWN figures are RELATIVE values for use in comparing grades-100 indicates the most Favorable relative value. GRADE (1) Tensile Strength (1) Transverse Strength (1) Compressive Strength (2) Dielectric Strength (3) Power Factor (3) Dielectric Constant (3) Dielectric Loss Factor (4) % Water AbsorPtion Impact Strength Recommended Temperatures for Punching * t Short-Time Step-by-Step Test Test Pounds per Square Inch Volts per Mil. (.001") At 1,000,000 Cycles X 12,500 21,000 35,000 700 500 .050 5.5 .27 4.0 Cold to lí32 " Hot to 3/3 2" XX 8,000 16,000 34,000 700 500 .040 5.0 .20 1.3 Cold to 1/3 2' Hot to 3/3 2" XXX 7,000 15,000 32,000 650 450 .032 4.8 .15 1.0 Hot to 1 16 " (Simple shapes, compound dies only) X I le 8,000 15,000 22,000 700 500 .045 5.0 .22 3.0 Cold to 1/16" Warm to 1/8 " XXI' 8,000 16,000 25,000 700 500 .040 5.0 .20 1.3 Cold to 1,à2 " Warm to 1/8 " XXXI. 7,000 15,000 25,000 650 450 .027 4.5 .12 1.0 Warm to 1/3 2" Hot to 3/3 2" C 9,500 20,000 38,000 200 120 .10 7.0 .70 1.7 Cold to 1,j6" Hot to 3/16" CE 8,000 17,000 36,000 500 300 .055 5.5 .30 1.2 Cold to 1/3 2" Hot to 3/3 2" L 9,000 20,000 35,000 200 120 .10 7.0 .70 1.4 Cold to 1/16" Hot to 3/16" LE 8,500 19,000 37,000 500 300 .045 5.0 .22 .90 Cold to 1/3 2" Hot to 3/3 2" ALL VALUES ABOVE REPRESENT MINIMUM AVERAGES FOR STANDARD GRADES. NIACIIINEAHILITY OF SYNTHANE SHEETS FOIL TESTING SYNTHANE 1. Tests were made at room temperature, approximately 25 deg. C., Following the American Society for Testing Materials Method D-229-39. All thicknesses up to 1 inch, inclusive. 2. Tests were made under oil on ,i,." thickness, according to American Society for Testing Materials Method D-149-40-T. 3. Tests were made at a frequency of 1,000,000 (F5 6 ) cycles, according to American Society for Testing Mate- rials Method D-150-41-T. All thicknesses up to 1 inch, inclusive. 4. Tests were made on pieces 3" u 1" n ,',." thick, according to the American Society for Testing Materials Method D-229-39 after immersion in water for 24 hours at approxi- mately 25 deg. C. plus or minus 2 deg. C. (For grades C, CE, L, LE, '. 8"thickness was used.) SYNTIIANE CORPORATION OAKS. PENNA. REPRESENTATIVES IN ALL PRINCIPAL CITIES 'Temperature Standards for Punching. Cold is room temperature, not under 60 F. Warm is 120 F. to 150 F. Hot is 175 F. to 250 F. All grades of Synthane may be easily sawed, drilled, turned, milled, etc. See Synthane folder on machining. d( you CAN HEAR VICTORY ... in the vibrant speeches of the President contrasted to the "intuitive" whining of der führer ...in the defiant roar of American industry geared to all-out production ... in the swift, sure trans- mission of vital radio messages to which Cornell-Dubilier contributes ca- pacitors that are as infallible as thirty- two years' and two World Wars' expe- rience can make them. Today manufacturers must have high priority orders to enjoy C-D's finer performance. But when the war is won, C-D capacitors will again be available to all industry, and C-D's extra de- pendability, which makes it the most widely used capacitor in the world today, will assure more hours of capa- citor use per dollar for industry to- Morrow. Cornell Dubilier Electric Corpora- tion, South Plainfield, New Jersey; New England Division: New Bedford, Mass. Cornell Duédier apacitoly MICA • PAPER • OYKANOt. • WET Oft1 EtEi.iROLYTIC CAPACITURS MORE IN USE TODAY ELECTRONICS — June 1942 THAN MICA TRANSMITTER CAPACITORS Copied, imitated ...but never duplicated. Type 6 Mica Transmitter Capacitors in moulded cases are designed for a wide variety of radio frequency applications, where size and weight must be kept at a minimum. They are specially suited for use as grid, plate, coupling, tank and by-pass units. The type 6 is one of the smallest types employing the Dubilier patented series-stack construction, per- mitting their use on higher r.f. voltages. ANY OTHER The immediate acceptance and widespread use of our Blue Ribbon Resistors exceeded our expecta- tions. Designed on modern lines, compact, efficient and tough,—they offer more than just higher watt- age ratings for unit space required. The resistance wire is accurately wound on a Steatite core and the ends are brazed to terminals of any of our numerous types. Standard mounting is by means of an aluminum thru-bar which is in contact with the entire internal surface of the ceramic core. This thru-bar distributes heat uni- formly along its entire length,—eliminating hot spots normally found in tubular resistors with con- ventional mountings. Our mounting studs are riveted to the ends of the thrn-bar, and tend to conduct heat to the mounting surface—they are designed also as spacers when two or more units are stacked. This resistor and its mounting form an integral unit. Blue Ribbon Resistors cannot rotate or loosen. They are easily mounted in a minimum of space. They are the last word in ceramic core-vitreous enamel construction and design. Intermediate taps, adjustable contact bands, non-inductive winding, non-standard lengths and ratings. There are important exclusive advantages in other types of resistors and rheostats made by us. Please consult us. HARDWICK, HINDLE, Inc., Newark, N. J., U. S. A. 20 June 1942 — ELECTRONICS faiieefreel e e is 4aeiçm .i>tMeRee, PZ-100-QD Dual variable transmitting condenser. 9000 V. spacing. Normal airgaps to 1/2 inch. TC-100-UD Dual variable transmitting condenser. Normal maximum airgap .294 inches. 1/ 2 inch airgap available in 80 mmf. single or 40 mmf. dual. HZ-100-ZD Dual fixed transmitting con- denser. 1/2 inch airgap 100 mmf. per section. A-7220 Micro-capacitor bridge adjuster. Typical of the many special components that are produced to customer specifications. CAR wale. flerteemme- WELL' C011 MRSSpecified and used generously in practically every type of communications equipment from the lowest power transmitters to the highly complex controls of frequency checking devices, CARDWELLS have never failed to justify their selection. THE ALLEN D. CARD WELL MANUFACTURING C [in4ihti (1); 83 PROSPECT STREET BROOKLYN, N. Y. LITTLE THINGS •••AS LITTLE AS .000001" STARTS WITH Surface smoothness (height, depth, pitch of each irregularity) is accurately measured to a millionth of an inch ... precision at its finest .. .by the Brush Surface Analyzer. The movement of the diamond stylus is amplified up to 100,000 times and immediately recorded on a moving paper chart for permanent reference. Readily operated anywhere by plugging into a 110 volt, 60 cycle, A. C. line. BRUSH ........... 111 Ilt fl1tLIl upeveLo IP 11\1 -1". C D. :1311 PEIIKINS AVENUE • • CLEVELAND, OHIO 9 9 June 1942 — ELECTRONICS FACILITIES FOR -PROMPT QUANTITY PRODUCTION - OSCILLATOR TRANSFORMER 400 CYCLES Inductance held to y2 of 1% CHOKE 30 henries TRANSFORMERS: Power up to 2 KVA. Modulation. .Audio CHOKES COILS: Paper Layer or Bobbin Type AUDIO and NOISE FILTERS POWER SUPPLY UNITS ASSEMBLIES: Which Include Transform- ers for Transmitters and Receivers To Signal Corps, Air Corps, Navy Specifications .... COMPLETELY ENCLOSED SHIELDED TRANSFORMER POWER TRANSFORMER Hermetically sealed to pass salt water immersion tests SEND DRAWINGS AND SPECIFICATIONS FOR SPEEDY QUOTATIONS TO TRANSFORMERS UP TO 2 KVA. IN CAST IRON HOUSINGS ,o4\ GENERAL TRANSFORMER CORPORATION CHICAGO, ILLINOIS 1252 WEST VAN BUREN STREET MONROE 4472 ELECTRONICS — June 1942 23 •Graphite Anodes for transmission and rectifier tubes are America's Answer to the call for equipment that can give as well as take. SPEER Graphite Anodes cannot warp, fuse or blow under any possible overload. They help keep tubes gas free, release rare metals for other uses. Both the armed and the armorers of our Nation have learned that anodes mean graphite, and graphite means SPEER. •Graphite Anode Booklet and list of tubes with Speer Graphite Anodes sent on request. SPEERCARBON COMPANY ST. MARYS, PA. CHICAGO •CLEVELAND •DETROIT MILWAUKEE •NEW YORK •PITTSBURGH 2nr June 1942 — ELECTRONICS air raid wardens lives are safer iham12.1 lo aalaitle Ala0gal qhd....r cti IfATIONAL VULCANIZED FIBRE is doing yeoman service in civilian defense. One outstanding use is in Protective Helmets. It is ideally suited for this applica- tion because of its lightness in weight (one- half that of aluminum) but more importantly, because it is tough! It has the remarkable property of absorbing impact blows and dis- tributing their forces over so wide an area that injury is prevented. Protective Helmets made of National Vulcanized Fibre withstand without fracture the impact of an eight-pound ball dropped six feet! And they stubbornly resist wear and abrasion. National Vulcanized Fibre is daily replacing hard-to-get metals and plastics. Our engineering and research facili- ties are available to you on any problem. Wire, phone or write us. Available Notional Vulcanized Fibre now being used extensively for NATIONAL VULCANIZED FIBRE COMPANY WILMINGTON DELAWARE You can use this Hand- book profitably. Write for free copy today. Offices in Principal Cities ...withstood wear and tear of civilian use ..." /I ... retained its lustrous finish ..." "the Signal Corps required extra durability ..." SHOCK- factor in The molding of telephone hand- sets may seem far removed from your manufacturing operations. Yet it may be of direct impor- tance, as an example of the prob- lems you may encounter in using plastics for war production. What happened when the hand- set used in homes and offices had to be adapted to service in the Signal Corps? Molded from phe- nolic plastics, the standard hand- set was sufficiently strong to withstand the wear and tear of everyday civilian use, and it re- tained its lustrous finish despite constant handling. But the Signal Corps required 3Waei "BAKELITE" PLASTICS LITERATURE ON "DO'S" AND "DON'T'S" OF PLASTICS...Helpful technical booklets containing data on types and forms of BAKELITE plastics, and the most efficient methods of fab- rication. This literature will help you to choose the right plastic for each job, save time and avoid errors. RESISTANCE is now the prime selecting plastics for strategic service! "specifications ...called for another type of material ..." ... high impact plastic re- quired higher pressures ..." -study...avoided errors that might have slowed produc- tion..." extra durability, to meet much more exacting service require- ments. Specifications were changed, calling for another type of phenolic molding material providing much greater resist- ance to shock. Use of this high- impact plastic made it necessary to build stronger molds, to with- stand considerably higher mold- ing pressures. This, in turn, brought about important modi- fications in molding technique. This careful study of problems relating to plastics materials, de- sign, and fabricating techniques avoided manufacturing errors that might have slowed produc- prevented waste of valu- able plastics materials" tion and wasted valuable mate- rial. As aresult, production is maintained at ahigh level, and the molded handset provides satisfactory field performance. BAKELITE CORPORATION Unit of Union Carbide and Carbon Corporation E1113 30 Ea.t. t2.11(1 Street, New York, N.Y. GET "HEADQUARTERS HELP" ON PROBLEMS RELATING TO PLASTIC MATERIALS, DESIGN, AND FABRICATING TECHNIQUES HEADQUARTERS Can Help You Speed Production and Conserve Strategic Materials o2 GEARING OUR LABORATORIES TO YOURS ... Bakelite Laboratories offer a two-fold service. They are ready to help you utilize present plastics in war pro- duction. They will also develop new formulas to help solve the problems of highly specialized requirements. 3FIELD WORK ON "FRONTLINE" JOBS ...Located at Unportant industrial centers throughout the nation, Bakelite Field Engineers are ready to give prompt service to manufacturers engaged in war production. Fully qualified, they can frequently solve production problems on the spot. VICTORY BUy ,WAR RO/Vbs • V, STAMps Here is something new for the nSon of Heaven' COMETHING new under the sun? Yes, sir.1— lots of new products to speed up the drive against the Japs . New parts like this (for the time being their use cannot be revealed) are made possible by the use of INSUROK Precision Plastics.This part is but one of many new war- designed products developed by Richardson Plasticians. Because Laminated INSUROK can be machined to close tolerances with existing equipment, it facili- tates sub-contracting—saves other critical materials for other impor- tant uses. Molded INSUROK, too, is serving with the air, land and sea forces because of its versatility and ability to meet the problems of the hour better, faster. The Richardson Company, Melrose Park, Ill.; Lock/and, Ohio; New Brunswick, N. J.; Indianapolis, Ind. Sales Offices: 75 West St., New York City; G. M. Building, Detroit. INSUROK and the experience of Richardson Masada» are helping war products pro- ducers by: 1. Increasing output per machine. hour. 2. Shortening time from blueprint to production. 3. Facilitating sub-contracting. 4. Saving other critical materials for r other important jobs. 5. Providing greater latitude for de- signers. 6. Doing things that "can't be done." 7. Aiding in improved machine and product performance. 28 June 1942 — ELECTRONICS It takes TOP QUALITY armament to build Uncle Sam's War machine it takes a TO P QUALITY dra win g pencil to design it ....... . The choice of pencil craftsmen everywhere WINNEI-ToNE DRAWING PENCIL * Bearing the A. W. Faber name, famous for 181 years * America's highest-priced drawing pencil * America's standard of drawing pencil excel- lence Besides the 4 Freedoms we are fighting for, there are 4 other freedoms vital to that vast army of pencil men, who conceive and design Uncle Sam's mammoth equipment for all-out War: 1. Freedom from Scratching 2. Freedom from Smudging 3. Freedom from Flaking 4. Freedom from Gritty Hard Spots WININEr‘re7ere-TONE Zest ae/ Although the better part of two centuries is back of the FABER name, we don't ask you to take our word for the excellence of WINNER Techno- TONE. We will gladly send you two FREE samples of any degree you desire. Sim- ply write on your letterhead, stating your position. ELECTRONICS — June 1942 29, 30 EXTRA PROTECTION The Army tank shown above is provided with extra protection against almost any War haz- ard. In the same manner, every GAMMATRON tube is designed and built to give extra protec- tion against circuit hazards which would cause ordinary tubes to fail. Full tantalum construc- tion, improved GAMMATRON pumping methods make failure due to internal release of gas impossible. Sturdy mechanical construction prevents handling breakage and provides low internal inductance for bet- ter U H F performance. Get in touch with your nearest GAMMATRON sales representative for further details. GAMMATRON SALES REPRESENTATIVES Wash., Ore., Idaho, Mont. New York State MARSH AGENCIES W. F. SEEMAN 104 Battery Street 523 Ellicott Square Seattle, Washington Buffalo, New York Mo., Kansas, Nebraska Pa., Va., W.Va., Md. H. A. ROES Wash., D. C., Del., N.J. 2017 Grand Avenue S. K. MACDONALD Kansas City, Missouri 1334 Arch Street Ind., Ohio, Kentucky Philadelphia,Pennsylvania W. E. McFADDEN Maine, N. H.,Vt., Mass. 915 Montrose Ave.. Bexley Conn., R. I. Columbus, Ohio TRADE CONTACT Michigan—W. B. SWANK CORPORATION 610 Blaine Avenue 25 Huntington Avenue Detroit, Michigan Boston, Massachusetts Minn., N. D., S. D., Wis. KENNEDY SALES CO. 2362 University Ave. St. Paul, Minnesota Illinois, Wisconsin RALPH M. HILL GORDEN GREY 1North Crawford Ave. Chicago, Illinois Tenn., N.C., S.C., Ala. Ga., Fla. HOLLINGSWORTH & STILL Norris Bldg., Atlanta, Ga. Calif., Nevada, Arizona E. P. DEMAREST 1630 South Flower Street Los Angeles, California Texas, Okla., Ark., La. M. B. PATTERSON & CO. 434 Allen Building Dallas, Texas New York City,NewJersey D. R. B1TTAN SALES CO., INC. 53 Park Place New York City, N.Y. ATAIr SOUTH SAM feu«nco U S A GAMMATRONS of course! June 1942 — ELECTRONICS To industries converting to war production where magnet wire and coils are vital... Anaconda's Central West plants still have unfilled capacity on magnet wire and coil production...for war work. In addition to these facilities, they have experienced personnel to help solve problems you might have with this phase of manufacture. Here is an opportunity to release your time so that it can be devoted to other important problems. Our sales offices, located in all principal cities, are near you. Call today. A representative will be glad to discuss your problem. GENERAL OFFICES: 25 Broadway, New York City CHICAGO OFFICE: 20 North Wacker Drive Subsidiary of Anaconda Copper Mining Company Sales Offices in Principal Cities ANAklet from rteïrdn.e , This familiartrade-mark symbolizes the best ef- forts of modern research and production. These Improved Insulations Are Now Available Nylon —Vitrotex — and Formvar The commercial development of Nylon and Vitrotex insulations is in part the result of Anaconda research ...research that continues with redoubled effort produc- ing new products for war work. Of course, when peace comes, the benefits of this re- search will be ready for industry everywhere. 422611 ANACONDA WIRE & CABLE COMPANY ELECTRONICS — June 1942 31 LECTRONIC Laboratories design and build Vibrator-Type Power Supplies for: "IIGHTING ... Both Fluorescent and "Black Light" are Electronic Powered! 2 MERGENCY Power for radio and electrical devices! CI OMMUNICATIONS ... Marine, Police, Amateur Radio Networks L anmsminv• 3 —Vital at Airports! Lighthouses! Coast Guard! Telephone Exchanges! —depend on Electronic Power Supplies! AN KS! Jeeps! Walkie -Talkies! Planes! PT-Boats! —These are but a few of Electronic's military applications! ELIABILITY proven daily by Allied Armed Forces! —frequencies absolutely constant and stable! 4 6 UNCE -SAVING Electronic Power Supplies are trusted flight companions —in both military and civil aircraft. m Alumnus». 5 EW current capacities! NEW flexibility in input and output voltages! NGENUITY and Resourcefulness are outstanding characteristics of the ... 7 8 USTOM Engineering Service which Electronic invites YOU to use. 1. Operates electric razors in trains and planes. 2. Portable source of 110 AC power. 3. More important thon the bombs in a bomber. 4. Controlled variable frequency for most exacting timing requirements. 5. Battery-operated 400-watt AC Transmitter-Receiver Power Supply. 6. Ounce-saving unit for "Black Light" on planes. 7. AC and DC input and output FM Power Supply. 8. 12-Volt Heavy-Duty Power Supply, Output 425 Volts at 225 Milliamperes. The above illustrates typical types of Electronic Converters. Recent militcny applications not included. ELECTRONIC LABORATORIES, Inc., INDIANAPOLIS, INDIANA 'gceg' for power supplies remember E CT I I NI CERAMIC RESISTORS' If your design calls for aresistor INVESTIGATE "GLOBAR" CERAMIC RESISTORS G LOBAR Ceramic Resistors are non-inductive and have excellent radio frequency characteristics. They are rugged, have liberal overload capacity and are not affected by humid atmospheres. Standard terminals consist of metallized ends; permitting neat, orderly assembly in fuse clips or other types of mountings. Globar Resistors are available in many shapes and sizes in the types whose characteristics are briefly outlined below. To conserve your time and to assist you in •selecting the resistor best suited to your purpose our long experience in specialized resistor manufacture is at your service. Send us full details of your require- ments and your problem will have our immediate consideration. MBAR BRAND CERAMIC RESISTOR CONDENSED SPECIFICATIONS Type Length Diameter Resistance Per Inch Of Length 'Overall Watt Rating •Normal Rating Watts Per Sq. Inch Of Rtd iting S Min.urface Maximum Volts Per Inch Of Length Max. Min. Max. Min. Max. Min. Max. "A" 1/4 " 18' 1/16" 1' 25 ohms 15 megohms 1/4 watt 54 watts 1 watt 400 "B" 1/4 " 18" !ib" l'' 5 ohms 15 megohms 1/4 watt 54 watts 1watt 400 "CX" 1/4" 18" 1,''b" 1" 1 ohm 1000 ohms _. 1/4 watt 150 watts 21/2 watts See Note «These ratings may be substantially increased by artificial cooling. 1. Type "A" has comparatively Straight Line Temperature-Resistance and Voltage-Resistance Characteristics. 2. Type "B" has Negative Temperature-Resistance and Voltage-Resistance Characteristics. 3. Type "CX" has a slightly Positive Temperature-Resistance Characteristic. 4. Other resistor types are available for specialized applications. S. Globar Brand Resistors are usually furnished with plain metallized ends for fuse clip mounting, but may also be supplied with wire leads if desired. 6. NOTE: Type "CX" Resistors have a low specific resistance and cannot be subjected to voltage stresses permissible with Types "A" and "B". maximum allowable voltage is that voltage required to yield the maxi- mum wattage rating for this type of resistor. The Global .Division THE CARBORUNDUM COMPANY Niagara Falls, N. Y. (Carborunduna and Unbar are regiatered trade-mark. oi and 'wheat,. nnasulartlzr, I,, Thr Carborund ELECTRONICS — June 1942 Corstpan ) 33 WARD LEONARD CONTROLS We are proud that Ward Leonard Controls developed during the past fifty years, now contribute their part in increasing safety, comfort and efficiency of men in service. The flyer turns the knob on the little Ward Leonard Rheostat and just the right degree of comforting heat surges through his flying suit. It is not an ordinary com- mercial control but one that has the ruggedness and dependability required by air service in spite of its minute dimensions and extremely light weight. This is but one of the many special con- trol devices that Ward Leonard is pro- ducing in quantities to serve national defense. WARD LEONARD RELAYS • RESISTORS • RHEOSTATS Electric control devices since 1892. WARD LEONARD ELECTRIC COMPANY, 32 SOUTH STREET, MOUNT VERNON, NEW YORK June 1942 - ELECTRONICS STEATITE TEN QUESTIONS... AND ANSWERS tart3FtZi=1 IMPORTANT INFORMATION TO ANYONE CONCERNED WITH DESIGN OR PRODUCTION OF ARMY OR NAVY RADIO EQUIPMENT Q. What is Steatite? A Steatite is the term applied to acertain type of low- , loss ceramic. It also applies to the principal raw material from which such aceramic is made. Q. What are the uses of Steatite? Its low-loss characteristics make it almost necessary A. for radio-frequency circuits. Tube socket bases, switch parts, coil forms, standoff insulators, bowl insulators, rod antenna insulators, etc., are pieces in regular use. Q. Is there ashortage of Steatite? The raw materials of Steatite are available in great A. abundance. In fact, the Lapp supplier of Steatite talc reports his business substantially reduced, due to reduction in output of non-war ceramics. Facilities for the production of finished pieces of certain types are not sufficient to fill the requirements of the armed forces. Q. In what sort of pieces does this shortage exist? Small close-tolerance pieces (tube socket bases, . switch parts, coil forms, etc.) require a precision manufacturing technique for which facilities are not easily amplified. Q. What is Lapp's part in the supplying of Steatite? A Lapp facilities are available for the production of a • large volume of Steatite, in certain types of pieces. Q. Whol sort of pieces is Lapp equipped to make? A Steatite in larger pieces—that do not demand close . tolerances—pieces that can be made by extrusion, formed by turning, throwing, plunging or casting, are producible by regular Lapp processes. These include standoff insulators, rod antenna insulators, bowl en- C 7r1 L i u Q. A. Q. A. Q. A. Q. A. trance insulators, bulk-head insulators, streamline entrance insulators, etc. For production of such pieces in Steatite, Lapp facilities are almost un- limited. What are Lapp qualifications for Steatite production? Lapp engineers have four years' experience in the peculiarities of Steatite production. Shrinkage, glaz- ing and firing problems have been solved. Complete testing facilities in the Lapp laboratory include a radio frequency generator (with range up to 3,000 Kc and 40,000 volts) for making heat runs, corona tests and flashover determinations. By maintaining aclose check on radio frequency characteristics—dielectric constant, power factor, puncture strength, etc.— Lapp can assure performance characteristics of finished pieces. What can't Lapp make? Lapp has limited facilities for pressing, and is not equipped to make small close-tolerance pieces. What of hardware? For pieces requiring sanding and cementing into hardware, Lapp methods are perfectly suited. (This, like the production of alarge volume of heavy Stea- tite pieces, fits right into normal Lapp insulator production methods.) What should you do when you need Steatite pieces? Such pieces as can capably be produced by Lapp should be ordered from Lapp. Other Steatite Manu- facturers, thus released from this part of the load, will be free to increase production on those pieces which they alone can manufacture efficiently. Such a program will reduce the over-all shortage of Steatit e, and will accelerate the war effort. LAPP INSULATOR COMPANY, INCORPORATED • LEROY, N. Y. ELECTRONICS — June 1942 711 eWILL REVEAL NEW TRANSFORM HORIZON AmerTran RS plate transformers and re actors, oil-immersed type, for all large installatIons. AmerTran modulation transformers and re- actors, oil -immersed type, for large broad- cast transmitters. AmerTran W plate transformers and re- actors for all small and medium installa- tions. War-born improvements in design and construction will bring you even better AMER -R AN Products ... AmerTran is in the thick of the fight now, on war production ...and under the stress we are develop- ing improvements that we cannot now reveal. But some day the complete story will be told ...and the better transformers we are shipping to those with priorities today, for wartime production, will be avail- able for all to use. Improved designs and manufac- turing methods, born under the spur of necessity— will bring you even better AmerTran products than those you know now ...will still further confirm the leadership that AmerTran has gained and held during the past 41 years in the communications field, in electronic and radio applications. While the war lasts—plan ahead! Plan for the peace boom with AmerTran improved transformers. AMERICAN TRANSFORMER COMPANY, 118 Emmet St., Newark, N.J. AmerTran transformers are manufactured to meet your exact electrical and mechanical requirements. 36 Manufactured Since 1901 at Newark, N. J. Ad ER14N1 June 1942 —ELECTRONICS tog NORTH DAKOTA SOUTH DAKOTA CENGINEERS spotted in this territory ve correct application assistance Macallen Mica Products — Vartex Var- nished Cloth and Tapes —Varslot Com- bination Slot Insulation —Varnished Silk and Paper — Fiberglas Electrical Insula- tion— Dolph Insulating Varnish— Man- ning Insulating Papers and Press Boards —Slot Wedges —Dieflex Varnished Tub- ings and Saturated Sleevings —National Hard Fibre and Fishpaper — Phenolite Bakelite — Adhesive Tapes — Asbestos Woven Tapes and Sleevings — Cotton Tapes, Webbings, and Sleevings — and Other Electrical Insulating Materials Used in the Manufacture and Repair of Electric Motors,Transfortners, and Other Electrical Apparatus. HEADQUARTERS FOR INSULATION MATERIALS Factories and shops located in this area have the advantage of ¡MC engineering service. ¡MC in- sulation engineers get around. They know how to apply insulation products ...time and material saving methods of application ... which you may find valuable when put into practice in your plant. APPLICATION ASSISTANCE ON NEWER MATERIALS They are especially helpful in the efficient appli- cation of some of the newer insulating materials available today. This service is yours for the asking. Write to us and we'll arrange to have the IMC en- gineer in your district call at once. In the meantime, specify and order ¡MC products. Phone or write to nearest office. Shipments can be made. INSULATION MANUFACTURERS CORPORATION Specialists in Electrical Insulation CHICAGO 565 West Washington Blvd. Telephone Central 7320 MILWAUKEE 312 East Wisconsin Avenue Telephone Daly 5359 DISTRIBUTORS IN OTHER PRINCIPAL CITIES CLEVELAND 1105 Leader Building Telephone Cherry 5338 Representatives in DETROIT 11341 Woodward Avenue Telephone Townsend 8-2577 MINNEAPOLIS 316 Fourth Ave., South Telephone Main 8653 PEORIA 309 Kellogg Avenue Telephone 4-7887 ELECTRONICS — June 1942 37 on leis finy D'nsirumeni pivot! Here the pivot for a W ESTON instru- ment is being scrutinized for exact dimensions by the projection mi- croscope, after meeting all other critical metallurgical standards. The bearings, also, exactly meet high W ESTON standards because they, too, are processed and tested by methods which have been perfected through a half century of instrument speciali zation. "How is it possible for WESTON so success- fully to forestall friction in instrument bearings tvhen the combination of design factors is so critical?" First let's look at these factors. The bearing may measure only 3/32 in. dia. The tiny steel pivot, supporting a mov- ing coil weighing only l/tcm ounce, may have a point several times sharper than the finest needle. The static pressure be- tween them will exceed 20,000 lbs. per square inch; and the starting torque may only be the result of minute energy pro- duced by a few microamper'es. Yet that pivot must swing freely perhaps millions of times during the life of an instrument! Here, again, the answer is to be found in basic WESTON design, and WESTON con- trol of every step in instrument manufac- ture. Despite their extreme fineness pivot points for example, are formed to a true sphere ... then the pivots are heat treated by an exclusive process to the exact hard- ness degree that resists crushing or mush- rooming under the tremendous pressures involved. The "V" bearing, too, is care- fully checked for precise dimensions and flawless surface by aspecial optical method which insures perfect operation of pivot and bearing. But supplementing these and other WrsroN methods is the skill of instrument craftsmen who have acquired the "know how" through years of instrument spe- cialization ...to whom the term "friction- free" is ever an ideal capable of achieve- ment. For only through specialization can the superior techniques be developed, the "know how" be acquired, the ideal be so closely achieved ... to insure that instru- ments provide the accuracy and dependa- bility so typically W ESTON . ..Weston Electrical Instrument Corporation, 618 Frelinghuysen Avenue, Newark, N. J. LABORATORY STANDARDS ...PRECISION DC AND AC PORTABLES ...DC, AC, AND THERMO SWITCHBOARD AND PANEL INSTRUMENTS . . . INSTRUMENT TRANSFORMERS . . . SENSITIVE RELAYS . . . SPECIALIZED TEST EQUIPMENT . . . LIGHT MEASUREMENT AND CONTROL DEVICES . . . EXPOSURE METERS . . . AIRCRAFT INSTRUMENTS . . . ELECTRIC TACHOMETERS . . . DIAL THERMOMETERS 38 June 1942 — ELECTRONICS !MATTE RESISTANCE UNITS MEET TODAY'S CRITICAL REQUIREMENTS f^" Controll•d High Humidity Chamber for all typ•s of Humidity Tests Measuring Inductance with A Radio Frequency Bridge Machine for Rotation Life Tests 1\ICIAs Rheostat And Top Switches Pyrometer Measurement of the Temperature of o Rheostat in a New Device Engineers' and Buyers' Guide SEND FOR 96-PAGE CATALOG AND ENGINEERING MANUAL No. 40 Write on company letterhead for complete guide in the selection and application of Rheostats, Resistors, Tap Switches, Chokes, Attenuators. Especially helpful today to engineers, production executives and purchasing departments. Contains useful engineering data, reference tables, dimension drawings, illustrations and amanual of resistance measurements. OHM ITE MANUFACTURING CO., 4818 Flournoy St. * Chicago, U. S. A. Foremost Manufacturers of Power Rheostats, Resistors, Tap Switches ELECTRONICS — June 1942 ee.- \...xtra quality and extra dependability have always been an integral part of Ohmite Resistance Units. Electrical and physical fitness for heavy-duty service in exacting applications are built-in from the very beginning. Research, engineer- ing, testing, production and inspection all work together to make Ohmite Prod- ucts always alittle better. As a result Ohmite Rheostats, Resist- ors, Chokes, Tap Switches readily meet today's requirements. They are widely used for military, electronic, scientific and industrial purposes. The wide range of types and sizes makes it easier to meet each need. Many stock items. Units produced to government specifications or specially engineered for you. Let Ohmite engineers help you. 39 Main Sound Room at Shure Brothers • THE QUIETEST FIELD OF ACTION In Total War, Microphones are weapons— for planes, tanks, and ships. These weapons are being built to new and higher standards. Very important in the development of Microphones, is the accurate measurement of output level and frequency response. In measuring Microphones, the ideal medium is afree field without interference from atmospheric elements, outside noises, or reflections from nearby objects. To achieve this goal, aspecial new room has been de- signed at Shure Brothers with alarge area of sound absorb- ing surfaces. All four walls, floor and ceiling are covered with thick layers of sound insulation and sound absorption materials. The floor is provided with an open grill to offer good support without affecting the sound absorption prop- p. erties. The room is completely shielded to avoid electrical disturbances. The high fidelity sound field is measured by means of standard Microphones calibrated at the U. S. Bureau of Standards. Electrical equipment for measure- ment purposes is located outside the room. In this room, the response of Microphones is measured with extreme accuracy. In addition to close tolerances in output and response, Shure Microphones must survive electrical and mechanical tests which are far more destructive than any conditions they meet in actual service. Millions of lives may depend on a Microphone. Shure Engineers know this. Shure Microphones are made to do their part. Send for Booklet No. 72M. It describes Super-Cardioid perform, ance and the latest Shure Broadcast Microphone, the Super-Cardioid. SHURE BROTHERS Designers and Manufacturers of Microphones and Acoustic Devices 225 West Huron Street, Chicago, Illinois 40 June 1942 — ELECTRONICS STEATITE and ULTRA-STEATITE RUSH is a badly overworked word in these days of 1942 but it still calls for extra efforts in our plant. That is one reason why we have made a number of new friends in recent months. Other reasons include increased plant facilities; the latest produc- tion methods, under constant laboratory control: and, finally, intelligent service backed by broad experience. GENERAL CERAMICS and STEATITE CORPORATION Keosbey, New Jersey GENERAL CERAMICS COMPANY I SULATORS e Serving with the Armored Force... The tanks are coming ...rolling forts that "go anywhere" and give it as well as they take it. And in the thick of things, wherever direct current is required from an A. C. source, I. T. & T. Selenium Recti- fiers are proving they can take it, too. For all practical purposes these rectifiers are unaffected by dust or moisture, shock or vibration. They have no moving parts to wear out or cause failure at crucial moments. Electrically and mechani- cally stable, they are efficient over the wide temperature and atmos- pheric ranges met in different fields of combat. Consulting engineering services available for specific requirements. Address Rectifier Division for descriptive bulletins. IT a lSelenium RECTIFIERS biteruational 7élepholle (t- Radio Sanufacturing aeporation Cenral Inns: 1000 Punk Art East Newark, New lime 42 June 1942 - ELECTRONICS Here is a LIE DETECTOR for SPRINGS SPRING NEWS ' When the heavy DC current passes axially through the cross section of the specimen a circular magnetic field is produced. The action of the current is only instantaneous, so that the magnetic field disappears when the magnetic reluctance is uniform throughout the cross section. How- ever, any break in the circular path, such as would be produced by a seam, creates a bipolar permanent field at that point. Fine iron powder dusted on to the specimen will be held in place only where this field exists. IRE used in making springs is usually subjected by reliable spring makers to a number of tests .. by Hunter, for example, to atensile test, twist test, bend test, hard- ness test—and many others. Yet even these tests do not reveal a category of defects known simply as "seams". The detection of seams involves ascientific method known as Magnaflux inspection. Sketchily, the procedure consists of magnetizing the HUNTER PRESSED STEEL COMPANY, LANSDALE, PENNA. spring, powdering with iron "dust", and inspection. This method is used to test samples of wire, for "jump" inspection of springs, and occasionally for 100% inspec- tion. A lot of fuss to make over a spring? Not at all. Hunter makes such tests to catch flaws and learn why they occur, to aid in improving materials, to deliver the best springs scientific manufacture can pro- duce for you. 11-1[ 11 rr 1F:. cstrzeica. Zen, 11:›rtleitcr6 WHILE a good looking instrument case, such as those shown here, may be an outward indication of instrument quality, it is by no means the final evidence. The real measure of instrument quality lies deep inside — in the instrument movement proper. This is the real "works" — where ac- curacy and stamina take their beginning. And right here is where you'll find the answer to the outstanding success Simpson Instruments have won in just a few years. The Simpson movement is the basically- better full bridge type, with soft iron pole pieces. The soft iron pole pieces distribute magnetic flux more evenly — make the move- ment inherently more accurate to begin with. GETTING DOWN 2-41) CASES • The two bridges, at top and bottom, lock the moving assembly always in perfect align- ment, for lasting accuracy. Springs are care- fully selected, tempered and tested—magnets heat treated for permanence — pivots com- pletely Simpson-made, specially processed for strength and hardness—all hand crafted into a balanced, practically frictionless, construc- tion that achieves an extremely high torque to weight ratio. If your requirements are essential enough to give you the right to buy instruments, they are essential enough to rate the best. Examine the works of any Simpson Instrument, criti- cally, and you will see why, to so many dis- criminating buyers, best means Simpson. SIMPSON ELECTRIC COMPANY, 5212 Kinzie St., Chicago, Ill. SIMPSON MODEL 260 Fligh Sensitivity Tester Here is a typical example 5000 f Simpson leadership. ecrizges oto Volts, both AC and DC. at 0,000 ohms per volt DC and21000 ohms per readings volt AC. Resistance fm 1z ohm to 10 rnego ro hms. e ranges from -- I0 to Decibl 1-52 DB. 44 June 1942 — ELECTRONICS ERIE SILVER MICAS:MA ERIE RESISTOR manufactures a group of compo- nents, illustrated above, that meet the exacting require- ments for war-time electronic equipment. Erie Resistors have all-round excellent operating characteristics. Sup- pressors prevent the interference of ignition system noise in surrounding radio receivers. Erie Silver Micas are superior condensers with inherently stable capacity. Ceramicons and Ceramicon Trimmers are widely used to compensate for frequency drift due to temperature varia- tions. The plastics division of Erie Resistor is equipped to design and mold any desired article that can be molded by the injection and extrusion process. Technical literature on all of these Erie Resistor products will be sent to interested electronic engineers on request. ERIE RESISTOR CORP., ERIE, PA. LONDON, ENGLAND • TORONTO, CANADA. ELECTRONICS — June 1942 45 CALLITE TUNGSTEN CORPORATION NATIONAL UNION rAturs «TAM 7e 1e in ELECTRONICS and Callite's contribution to their developrnents 10, Redding like a the big nomes "Who's Who- of the Electronic Indus- try, Callit hings, th e e's list of customers includes behind the outstanding develop men ts of the post yea rs. 10, Important advances reflect, among other t most painstaking selection of component materials. Ihot's why Callite's broad back -- grou nd of engineering research — ond precision methods. of manufacture are called upon to did the important undertakings of such leaders as: WERE% DOOM EDISON EITEL-PMCULLOUGIT ELECTRONS INC. FEDERAL meant wean NATIONAL woe PHILIPS METALIX RADIANI RCA UNITED ELECTRONICS SPERTI SONOIONE WESTERN ELECTRIC ond ahost of others. 14 you hove o ,the knowledge special pr oblem a nd resourcefulness of Callite erigineers moy quickly provide the solution.Your inquiries ore cordially invited. Specialitts tie manufacture of rlettrirol (00111[11 of refractor/ and retie." send,. Mein, filamenit and grids--1 °owed f sand roe materials W oc all electronic opplicatimes. DUNION1 UNITED ElECTRONIES 544 39th STREET CALLITE TUNGSTEN UNION CITY, N. J. CABLE: "CALL1TES" •BRANCHES: CHICAGO • CLEVELAND it, June 1942 — ELECTRONICS CORNERSTONE FOR V + 2* Some year the war will end. There will be a swing back to the things we buy because we want them, not because they are a grim necessity. Today's work is to win the war. Executives now driving for all-out production should also be planning for V 2. Products for tomorrow should be designed today. For every new product, the corner- stone is Research The Research Division of American Lava Corpora- tion is outstanding in its field. It welcomes any call for cooperation in planning for today's production ... or for long range planning for the insulation of the future. Meanwhile, for 1942 and as far as we can see, we pledge our utmost efforts to supply our customers with the best in steatite ceramic composi- tions as rapidly as possible under wartime conditions. 2 years after Victory, probable time required to resume full peacetime production. (Bouquets to the G. E. executive who coined this expression.) d.ir . ted AMERICAN LAVA CORPORATION CHATTANOOGA, TENNESSEE CHICAGO • CLEV-LAND • NEW YORK • ST. LOUIS • LOS ANGELES • SAN FRANCISCO • BOSTON • PHILADELPHIA • WASHINGTON, D C ELECTRONICS — June 1942 47 for longest possible service and dependable operation ... at atime when you need it most! PRECISION TESTED svvircliEs *SLIDE OPERATED SWITCHES *ROTARY OPERATED SWITCHES *TOGGLE OPERATED SWITCHES The unexcelled efficiency and sturdiness of Stackpole Switches is the result of precision manu- facturing. Each phase of their assembly is the distinct respon- sibility of skilled operators, trained to do each individual task, well. Special treatment assures moisture resistance, highest grade materials and a 100% mechanical check, assure efficient service and long-life. Ideal for every small circuit job and available in single-pole, single-throw to four-pole double- throw and all in-between com- binations. LABORATORY CONTROLLED ReereS *VARIABLE RESISTORS * FIXED RESISTORS Every step in the process of manufacturing Stackpole Resist- ors is laboratory tested. All raw materials are tested for uniformity and all carbon pro- ducts are tested for hardness and density and all volume con- trols are 100% checked for noise, 100% checked for resist- ance and 100% checked me- chanically. Resistance ranges from 1,000 Ohms to 5 Meg- ohms for every type volume, tone and sensitivity control and in special designs to suit your needs. All highly insulated by special processes which assure protection against moisture and weather conditions. STACKPOLE PRODUCTS SOLD TO MANUFACTURERS 0.\ -t —WRITE AT ONCE FOR SAMPLES AND PRICES— UNIFORMLY CONSTRUCTED decoes * FIXED INDUCTANCE * VARIABLE INDUCTANCE * STATION TUNING Stackpole powdered Iron Cores are noted for their extreme me- chanical strength which is the result of a highly controlled process of manufacture. Iron Cores are available in a wide variety of grades and sizes for use at any frequency up to 100 meg. The wide range of types include those with the "cup type" cores, with and without adjustable centers. When re- questing samples of cores, please send test coils and complete data. 8RhVe VOW? PRODUCT/ON PROBLEMS' TO STACKPOLE 48 June 1942 — ELECTRONICS to Electronic fReaders This issue of ELECTRONICS—largest ever published—includes 125 pages of advertis- ing messages from almost 200 manufac- turers. In these pages is a wealth of information, designed not only to make it easier for you to know more about the equipment and material which you may need in your vital war work, but also to give you ready and intelligent information on the sources of supply. Thus, through this instrument of communi- cation, your valuable time is conserved. Keep this useful issue within hand's reach throughout the year. It will serve you well. A McGRAW-HILL PUBLICATION ABC ABP 330 West 42nd Street, New York, N. Y. ELECTRONICS — June 1942 49 A Simple Blueprint...with a Mallory Complete Contact Assembly ...May Save Many aFlier's Life! One of the principal manufacturers of variable pitch propellers utilizes electrical contacts to actuate changes in pitch. The electrical contact assembly on this job has to be sure-fire ... or apilot, can be in the soup before you stop blinking. Mallory engineers went to work with this aircraft propeller manufacturer's designers when their detailing was still on the drafting boards. Together, Mallory contact specialists and the aircraft engineers developed a new electrical contact assembly, designed for rotary action. Biggest problem was abrasion on the revolving contact surface. Happy solution came when Mallory created atri -metallic contact assembly incorporating three Mallory-developed alloys with exactly the right elec- trical and abrasion-resistant properties. This example of Mallory's complete contact assembly service can mean plenty to you ... if you're planning production of almost any electrically-actuated device. See us before you finish your blueprints. Your Mallory representative is "on call". Data At Your Elbow! Mallory Contact Catalog. Complete information on every phase of electrical contact selection, design and service. You need it for .vour technical library. Write today. No obligation. P. R. MALLORY & CO., Inc., INDIANAPOLIS, INDIANA • Cable Address — PELMALLO €01P, ELECTRICAL CONTACTS AND CONTACT ASSEMBLIES NON FERROUS ALLOYS, POWDERED METAL ALLOYS IS THE CURRENT AC OR DC ? WHAT ARE NORMAL VALUES OF CURRENT AND VOLTAGE THAT MAKE AND BREAK ? WHAT IS THE ACTION OF CONTACT... BUTTING, WIPING OR ROTARY ? WHAT IS THE ALLOWABLE TEMPERATURE RISE? WHAT OVERLOAD CONDITIONS MUST BE SUSTAINED ? WHAT OPERATING LIFE IS EXPECTED ? June 1912 -ELECTRONICS This advertisement also appeare d in: NEW YIMES CLEVELA N ORK D T PLAIN DEALER CHICAGO DAILY NEWS DETROIT FREE PRESS WASHINGTON POST You Expected to Read This NEXT YEAR! L dustry after industry is beating its promise as America's war production sets new world's records . . . Management, labor, W. P. B., Army, Navy, the Maritime Commission and other government depart- ments are cooperating to make next year's headlines come true THIS year. In World War I, the Kaiser feared American manpower. In World War II, Hitler is even more fearful of our rapid transition from peace to war production. ... He has reason to be afraid. Printing press factories are exceeding quotas on anti-aircraft gun parts. Spark plug manufacturers are setting new speed records in machine gun production. The heavy-transportation industry is making giant chassis for big guns at afaster rate than all the Axis powers combined. In this industry, men who used to make loco- motives and tractors are changing "Too Little and too Late" to read "Too Much and too Soon," from the enemy's viewpoint. Starting just afew months ago, with a bale of blueprints and a knowledge of how to build such things as road-scrapers, power-shovels and trucks, the heavy-transportation industry is turning out mobile artillery that will shake the earth in more than aliteral sense. • The story of how this industry joined the army carries asignificance which should be understood and remembered. The significance is that America has solved the problem of exchanging production techniques between specialized industries. This process went on unnoticed in peacetime. War gave it prominence. OVE R* , You Expected to Read This NEXT YEAR! —continued >When the bales of blueprints were first deliv- ered, and the heavy-transportation industry started on its job of producing prime-movers and chassis for big guns in quantity, new production tech- niques were needed in ahurry. >Here are some of the questions that arose: "How do you weld such heavy sub-assem- blies?" "What welding fixtures will handle these parts so that our workmen can always weld down-hand?" "How can we make these long, heavy welds and have sound metal from one end to the other?" "What's the best technique for testing welded parts? Shall we x-ray, or use the magnaflux process?" "What's the best way to support these welded assemblies for machining?" That's just a few of the thousands of questions that arose in the minds of experienced men when they had to solve new problems. They illustrate the fact that American produc- tion methods depend upon specialized techniques and machines. Each man with such aproblem knew that some- one, somewhere, had solved his problem, or might solve it before he could work out his own answer. Therefore he turned to the source of industrial information he had always used when he wanted to know what others were doing ... his industrial magazine. Ever since the Maginot Line was flanked, the In- dustrial Press of America has been helping rookie industries to become veterans in the battle of war production. >It doesn't do this by exhortation or command, but by answering thousands of specific questions. Just as newspapers keep their war correspon- dents at the front, Industrial Magazines keep their "war-production-correspondents" in the plants where weapons and equipment are made. McGraw-Hill editors are mobilized for war as literally as though they were firing weapons instead of helping to produce them. More than 90% of the time of McGraw-Hill's 153 editors and 725 engineer-correspondents is devoted either to visiting war-production plants (to study pro- duction techniques) or in writing "war stories" on how production problems were solved. "Know-how" is the secret of the amazing records now being made by American Industry. And "know -how" comes from thousands of "little facts" like this: Information on tool shapes for cutting the harder steels of war is vital literature to the engineer, de- signer or production man with the particular problem of cutting those steels confronting him. The industrial editor does not work alone in giving vital information to men on the production line. In much the same way, manufacturers are war-converting their industrial advertising to show their readers how to use their products more effectively. For instance: A business-paper advertisement showing how to make old taps and dies last longer has no glamour for anyone but the man who must rush production with an inadequate supply of new ones. To him it has enough "oomph" to be clipped and placed on his office wall. To the casual observer, the Industrial Press is about as exciting as the rows of wires that stretch along every road and railway. ...The simile is very apt. Both exist solely for the interchange of ideas. Both are typically American in the extent to which they have been developed and applied to the whole economy. ...This advertisement pub- lished by the McGraw-hill Network of Industrial Communication. THE McGRAW-HILL NETWORK 23 PUBLICATIONS WHICH HELP MORE THAN 1,000,000 EXECUTIVES, DESIGNERS AND PRODUCTION MEN TO EXCHANGE IDEAS ON WAR-PRODUCTION PROBLEMS American Machinist • Aviation • Bus Transportation • Business Week • Chemical & Metallurgical Engineering • Coal Age • Con- struction Methods • Electrical Contracting • Electrical Mer- chandising • Electrical West • Electrical World • Electronics Engineering & Mining Journal • E. & M. 3. Metal and Mineral Markets • Engineering News Record • Factory Management & Maintenance • Food Industries • Mill Supplies • Power • Product Engineering • Textile World • Transit Journal • Wholesaler's Salesman. Also publishers of thousands of books for technical and engineering schools und college,. a, ,,ell a, for general business use. McGRAW-HILL PUBLISHING COMPANY, INC. 330 WEST 42nd STREET, NEW YORK Electron Tubes in Overalls THE electron tube is one of the most versatile and flexible man has produced. In communi- cation it performs duties ;mpossible for any other mechanism. In industry it saves time, it saves in the cost of things, it protects life and property. The tube does many things better, cheaper, quicker than older devices. Many industrial jobs are performed by the tube which cannot be done in other ways. In wartime, the speed-up of pro- . duction made possible by the electron tube may , prove to'be its greatest contribution. Tubes have gone into overalls. It is impossible to give examples of all of the things tube can do within the confines of a single issue of ELECTRONICS. The applications de- scribed are typical, and the selection is designed to show not only the ingenuity of engineers work- ing with tubes but the versatility and flexibility of these devices whose motivating force is the ultimate building block of tile universe itself— the electron. CONTENTS SECTION I Industrial Tube Characteristics.. 52 SECTION II Tubes and their Functions 61 SECTION III Tubes at Work 70 SDINOILIDaTA — ZP6I aunt CLASSIFICATION OF ELECTRON TUBES INPUT OUTPUT SOURCE OF ELECTRONS Thermionic Cathode ELECTRICAL ENERGY ELECTRICAL ENERGY Pool Cathode METHOD OF CONTROL None Electrostatic CHARACTER OF CONTROLLED REGION OR SPACE High Pressure Gas Low Pressure Gas or Vapor Vacuum Gas or Vapor Vacuum Electromagnetic Gas or Vapor None Cold Cathode RADIANT ENERGY (light) RADIANT ENERGY Right I Thermionic Cathode ELECTRICAL ENERGY Photoelectric Cathode Metallic Contact Electro- Igniter static Electrode None Electro- static Electro- static Electra- magnetic Radiant Energy Right) Vacuum Vapor Vapor Vapor Gas Gas Vacuum Vacuum Gas Vacuum Metallic TUBE NAME Tungar or Phonotron Rectigon Kenotron Thyratron Pliotron Permatron Magnetron Pool Tube Grid Pool Ignitron Tube Glow Tube Grid Glow Tube Cathode Ray Tube Cathode Ray Tube Phototube Phototube Barrier Layer Cell FUNCTION RECTIFIER OR SWITCH CONTROLLED RECTIFIER AMPLIFIER OSCILLATOR, GENERATOR OR INVERTER VOLTAGE REGULATOR WAVE FORM ANALYSIS LIGHT DETECTION AND MEASUREMENT In this tabular classification of •lectron tubes suitable for industrial purposes the graph:cal symbol for the type of tube in question is used to designate the customary or possible uses to which the tube is put. Tubes having electrical energy in both input and output circuits may be regarded as impedances. while those in which the input or output is radiant energy may be regarded as energy converters Industrial Tube Characteristics OF all methods of controlling energy, that afforded by the use of electron tubes is one of the most convenient and effective. The advantages of control through the use of electron tubes may be summarized as follows: (1) There is a wide variety of energy trans- forming devices whose output is ca- pable of being associated with elec- tron tubes. (2) The electrical power output of an electron tube is ca- pable of minute and complete control through the employment of a control element usually called a grid. (3) By coupling the appropriate energy converter to a tube, one form of energy may be transformed into an electrical voltage or current which can then be very easily and con- veniently modified in almost any con- ceivable manner. (4) Through use of the electron tube the expenditure of aminute amount of control power may effect the control of a very con- siderable amount of power in the output circuit because of the ampli- fying properties of the tube. (5) Through the appropriate energy con- verting device in the output circuit of an electron tube, the controlled electrical energy may be reconverted into other forms of energy for the measurement, detection, indication, or control of certain physical, chemi- cal, or other properties. (6) The control afforded through the use of a vacuum tube is of a flexibility and convenience not approached by any other control mechanism. (7) For many applications and in many fields of endeavor, the availability of tubes with extremely high input impedance is a decided advantage. (8) The availability of tubes to handle pow- ers from the smallest up to hundreds of kilowatts, enables the advantages of electron tube control equipment to be applied to the power, industrial, or communications fields with equal facility. (9) With proper design, installation, and maintenance, elec- tron tubes make a stable, rugged, flexible and convenient device of long useful life. (10) Certain types of tubes are available in which one form of energy may be directly converted into another form. Thus, phototubes convert light into an electrical cur- rent and conversely cathode-ray tubes convert electrical current into varia- tions of light. Through the use of such tubes, vast opportunities are opened up for the industrial uses of electron tubes. (11) Finally, the unique properties of the electron tube enable it to perform a wide variety of functions, all of which are extremely useful. For example, the tube may operate in the follow- ing manner: (a) As an amplifier, over a wide range of frequency and power. (b) As an oscillator or generator of voltage over a wide range of fre- quency, power and waveform. (c) As a trigger or relay circuit or switch. (d) As a modulator or demodula- tor to combine or to separate two or more frequencies. (e) As a measuring instrument, indicator, or comparator. (f) As a rectifier or inverter over a very wide range of frequencies, currents, or power. (g) As a frequency converter to change from one frequency to an- other. (h) As avisual indicator or image- forming device as in the electron microscope or the television camera or projecting tube. All of these advantages and opera- tions cannot be obtained in a single tube. Instead, a very great number of tube types in various classifica- tions according to mode of opera- tion are commercially available. Fur- therfore, to make an appropriate selection from the tubes already available, and to utilize the tubes advantageously, some knowledge of the method of operation and the characteristics of the most suitable tubes is necessary. Types of Electron Tubes The many types of tubes available for industrial service may be classi- fied according to: (1) the type of control stimulus which causes them to perform the industrial job to which they are assigned, (2) the phenomena occurring within the tube itself, (3) the method of operation, or (4) the number of internal ele- ments or electrodes. Under the first method of classifi- cation, most tubes may be regarded simply as electrical impedances in which a voltage and current are ap- plied to the input terminals and a voltage and current are obtained from the output. Another common type of tube is that which also acts as an energy converter. The photo- tube, for example, converts radiant energy into electrical energy, while the cathode-ray tube converts electri- cal energy into light. In the second classification, we may have vacuum tubes providing smooth instantaneous control of out- put, or gaseous tubes providing con- trol of the average (but not instan- taneous) value of the output power. We may have two electrode tubes or rectifiers in which the useful power output is always less than the input. We may also have control tubes or multi-element tubes, in which the useful output is greater than the input control power, the power sources connected to the tube ac- counting for the difference. The classification according to method of operation is largely as- sociated with the use of the tube and will be treated in Section II. Tubes are commonly classified ac- cording to the number of electrodes. Depending upon whether they have two, three, four, or five electrodes they are known as diodes, triodes, tetrodes or pentodes. Two element tubes may be regarded as two ter- minal networks. All commonly used multi-element tubes in which a vary- ing signal is impressed on only one grid, may be thought of as equivalent to a rather special kind of four ter- minal T or Y network, which can be analyzed by studying the input and output current and voltage rela- tionships. To obtain a picture of the funda- ELECTRONICS — June 1942 53 mentais of operation, it is desirable to classify tubes according to the phenomena which makes them work. Fundamental Operations of Control Tubes All control tubes consist of at least three elements: (1) A source of the electrons (or ions), usually produced by the cathode, which per- mits conduction of an electric cur- rent through the tube; (2) an elec- trode (plate .;ir anode) to collect the electrons .(or ions) within the evacuated space of the tube; and (3) control elements or modifying arrangements (grid) almost alway^s located in the space lietween the sourcé•orélectrons and the collector and whose purpose is to modify the flow of current in some manner in accordance with the voltage on this control element. The cathode (which supplies the electrons) and the con- trol element form the input ter- minals whereas the cathode and the collector form the output terminals of the tube, as usually' .used. Two- element tubes do not have the con- trol element. Let us assume that we have the most common type of control vac- uum tube securely locked up in a black box with a number of ter- minals marked on it. Beyond the markings on these three pairs of terminals, we do not care at all, for the moment, as to the nature of the contents of the box. Our primary Fig. 2 Output and transfer characteristics of electron tube having characterictics of a triode. Graphical methods of deter- mining plate resistance, r , transconductance, g , and amplification. u. are given at A. B. and C respectively 111111111p Fig. 1 Schematic wiring diagram for determining the input, oUtput, and transfer characteristics of electron tube contained in the black box purpose is to investigate the proper- ties of the device in this box in terms of external conditions which we can easily measure with electrical in- struments. The three sets of terminals are labelled input, output and heater. The heater terminals must be connected to abattery of proper voltage. The in- struction book with the black box states that a battery must be placed in series with the output circuit and another in series with the input circuit. If the box is connected as shown in Fig. 1 and we attach to it certain meters as indicated we are in a posi- tion to learn all we want to know about its d-c or static characteristics. All we have to do is to vary the polarity and magnitude of the vp_t- ages E,. and E,, and measure the resulting input and output currents. We shall find that: (1) For all voltages E, for which terminal A, is negative with respect to A2,the input current (and therefore the input power) is negligible. Therefore we can state that the input impedance of the box is very high. (2) Some current flows in the output circuit if terminal B, is positive with re- spect to B.2. No current flows if this polarity is reversed. (3) For agiven resistor R., and 'battery voltage E., the plate current, I., is a function of input voltage, E,. Over a certain range, this relationship is more or less linear but in general, the re- lationship is not linear. (4) For a given input voltage, E„ and load resistor R., the output current de- pends upon the voltage E.. The volt- age between B, and 132 is not E. but E.-1,,R,, since a voltage drop oc- curs across Rb. The plot of current, against voltage, E,„ is an S-shaped curve in the majority of cases. (5) For constant values of Er:and Eb, the current in the output, /4 is a 5• June 1942 — ELECTRONICS function of the load resistance, R„. (6) Even acasual examination shows that the output current I,„ is tre- mendously greater than the input current, and from this we infer that the box may be used as a current amplifier. (7) Voltage variations applied to the input result in a very much larger variation in voltage in the output and measured by E,,. From this, we conclude that the tube in the box may be used 'as a voltage amplifier. (8) From the last two statements, we conclude that the tube may be used as a power amplifier, since the input voltage and current of minute quantities are capable of controlling a very much larger amount of voltage and current in the output circuit. (9) We note, however, that the polarity of the output voltage across the resistor is opposite from that of the polarity of the input voltages and accordingly, we conclude that the tube operates as a 180 deg. phase shifting network for resistive loads. (10) Electrically we can regard the black box as an impedance, but we note that we must supply sources of power to this im- pedance for otherwise it will not function properly. In this respect the black box differs from a trans- former in which sources of power external to that being transferred are not required to effect the neces- sary control or transformation. (11) By careful examination of our data, we conclude that the box is, in g2n- Fig. 3—Output and transfer characteristics of electron determining plate resistance, r,. transconductance, g , tube having characteristics of a pentode. Graphical methods of and amplification facto:, p., are given at A. B. and C respeclively ELECTRONICS - Junk, .1942 eral, a non-linear device, but that under certain conditions of opera- tion, the relationship between input and output may be made linear. (12) If we were to add an alternat- ing voltage in series with th 2steady or d-c input voltage, we would meas- ure alternating currents and voltages in the output circuit which are mag- nified replicas of their input. If we make a graphical plot of the d-c voltages and currents in the in- put and output circuits, with the plate resistor short circuited, we ob- tain the d-e or static characteris- tics of the tube. The shape of these curves will depend upon the type of tube contained in the box, but the essential concepts of tube operation apply no matter what the curve Fig. 4—Bridge circuit for measuring plate resistance for selected grid and plate op- erating voltages. E and E, shape. Typical characteristics for a triode and for a pentode are shown in Figs. 2 and 3. These static char- acteristics suffice to give us all the important information we need to know concerning tube operation, for from them we can obtain knowl- edge of: (1) the important tube parameters, amplification factor, plate resistance, r,,, and transconduc- tance, g„,, (2) the required d-c op- erating voltages for desired opera— tion of the tube, (3) the mode of op- eration of the tube with any kind of load in its output circuit, and (4) the mode of operation of the tube with any kind of time-varying input signal applied to the grid or input. Operating Coefficients for Vacuum' Tubes Since the plate current is a func- tion of the plate voltage, even if the load resistance, R,, of Fig. 1, is short circuited, the plate circuit must have sc me internal .resistance. Its d-c re- sistance may be determined from Ohm's law, but this value is seldom cf any use to the designer and will nit be found in manufacturers' literature. The resistance for small changes of plate voltàge, and with .the grid voltage maintained con- stant, is very important. It may be measured by the circuit of Fig. 4, for the operating voltages E, and E,„ since the cathode-plate circuit takes the place of the unknown re- Fig. 5-Circuit for measuring transcon• ductance for grid and plate operating voltages. E, and E,, respectively sistor in one arm of the a-c Wheat- stone bridge. In general, a different value of plate resistance is obtained for each new value of E,, and E., so these operating voltages should be specified when the plate resistance, r,, is measured. The plate resistance is defined as the ratio of the change in plate volt- age to the corresponding change in plate current produced, all other volt- ages being maintained constant. The mathematical definition is given in Fig. 2A and 3A which also shows that the plate resistance at any oper- ating point specified by the dashed lines, may be determined from the inverse slope of the Ee l, character- istic at this point. (This is, of course, measured in terms of voltage and current changes as measured on the graph, and not by measuring angles with a protractor.) For a fixed value of plate voltage, the plate current is a function of the grid voltage, and it is convenient to have a tube factor, which designates the ability of the grid to control the plate current. This term, called the transconductance (formerly called mutual conductance) may be meas- ured by the circuit of Fig. 5. It is defined as the ratio of the change in plate current to the change in grid voltage causing it, under the condi- tion that all other electrode voltages remain constant. As shown in Figs. 2B and 3B, the transconductance is measured by the inverse slope of the Eel, curve, at the point of the char- acteristic determined by the operat- ing voltages (shown by the dashed lines). The unit of transconductance is the mho or reciprocal ohm, al- though the terms milliamperes-per- volt and micromho are also employed, since they are more convenient sub- multiples of the mho. Finally, we may determine the relative effect of the grid and plate voltages upon the plate current. This is the slope of the constant-current curves of Figs. 2C and 3C, is called the amplification factor, and is des- ignated by the Greek letter its. The amplification factor may be meas- ured with the circuit of Fig. 6, or it may be determined graphically, as indicated in Figs. 2C and 3C. The amplification factor is a numeric, having no dimensions; it is merely a voltage ratio. rg. 6-Simple bridge circuit for measur- ing amplification factor for grid and plate -,perating voltages, E. and E, An interesting relation connecta these three tube coefficients, for ji = g,„ = μJr, r, Consequently, if we know the values of any two at the same operating voltages, we can easily calculate the value of the third at the same oper- ating conditions. Tubes may have values of p. from 3 to several thous- and (values of 10 for triodes and 800 for pentodes are typical) ;values of transconductance from 500 to 10,000 micromhos, with 1,500 mi- cromhos a typical value; and values of plate resistance from 500 ohms to 100,000 ohms for triodes and up to several megohms for pentodes. Table Ishows operating characteristics for a few typical vacuum tubes. TABLE Type No. Description Diodes 6H6 Full Wave Rect. 12Z3 Half Wave Rect. 219 F103A WL-660 Triodes PJ10 Det. Amp. Ose. 5.0 0.25 -9.0 135 6C5 a a a 6.3 0.30 -8.0 250 6F5 a a a 6.3 0.30 -2.0 250 89 Amp. Ose. 6.3 0.40 -31.0 250 841 te te 7.5 1.25 -9.0 425 842 a 7.5 1.25 -96.0 425 849 ‘‘ 11.0 5.0 • 2,500 818 le le 22.0 52.0 * 15,000 862 u a 30.0 325.0 * 20,000 I- OPERATING CHARACTERISTICS OF TYPICAL VACUUM TUBES Heater Screen Grid Anode Grid Voltage Current Voltage Voltage Voltage E (Volts) (Volts) (Volt») 117' 250 50,000 50,000 230,000 IR (Volts) (Amps) 6.3 0.3 12.6 0.3 22.0 24.5 28.0 51.0 10.0 10.5 FP-54 6D6 25A6 6L6 813 Tetrodes and Pentodes Low Grid Cur. Voltage Amp. Beam Tetrode Amp. 2.5 6.3 25.0 6.3 10.0 *Depends upon method of operation 0.09 6 0.30 -3.0 250 0.30 -18.0 160 0.90 -18.0 350 5.0 2,000 100 120 250 400 Ampli- Plate Trans- Plate Anode fication Resist- Conduct- Dissi- Current Factor ance ance pation lb r, 41. Pt (Ma.) (Ohms) (μ mhos) (Watts) 4 60 2,500 9,000 30 3 8 10,000 1,250 8 20 10,000 2,000 0.9 100 66,000 1,500 32 4.7 26,000 1,800 8 2.2 30. 40,000 750 12 28. 3. 2,500 1,200 12 350 19. * * 400 1,000 8. • . 10,000 1,500 10. s • 125,000 8.2 1,280. 48. 100. 54. 170. 100 • 1.0 40 800,000 1,600 42,000 2,375 33,000 5,200 • 1.0 5.3 19. 100. 56 June 1942 - ELECTRONICS Characteristics of Gaseous Tubes If we proceed in the manner al- ready outlined to study the charac- teristics of gas tubes, we shall obtain results which at first appear to be somewhat erratic but which are, none the less, subject to an orderly and systematic classification. If we have a two-element tube (i.e. not a control tube) in a blue box the input terminals can be short cir- cuited and we can obtain all of the information we desire from a study of the output voltage and current. For low values of plate voltage E,, any current which flows at all is measured in microamperes or at most a very few milliamperes. As E. is increased, acritical value is ob- tained at perhaps 10 to 25 volts be- yond which the current suddenly rises to a rather high and constant value determined by the external re- sistance R. and the voltage E., ac- cording to Ohm's law. Increasing the voltage beyond the critical value will increase th 2 current as calcu- lated on the basis of Ohm's law, tak- ing account only of the resistor Rb and neglecting the tube resistance. On the basis of this operation we conclude that, aft-2r the critical volt- age has been reached or exceeded, the internal resistance of the gas tube had suddenly decreased to an ex- tremely small value from its previous value of several hundred or several thousands of ohms. The relatively large current will continue to flow in R. until E. is reduced to a fairly low value, when the current will sud- denly decrease to a negligible value. This operation of a two-element tube indicates that it can be used as a voltage control switch. The smooth type of voltage-current control pos- sible with vacuum tubes has now been lost and for most practical purposes the tube can be used to conduct cur- rent on an all-or-nothing basis. If we place a control type of gas tube in a blue box with the grid and cathode connected to the input terminals and the plate or anode and cathode connected to the output terminals, the operation becomes more complicated. Let us apply steady voltages to the input and out- put circuits and measure the input and output currents as these voltages are varied. Again, at a given grid voltage the tube suddenly conducts at some critical value of positive plate voltage. Likewise, for a given positive plate voltage, the tube sud- denly conducts at some critical grid voltage. The breakdown now de- pends not only upon the magnitude of the plate voltage but also upon the magnitude of the grid or input voltage. Over a considerable range of values the critical grid voltage which initiates conduction is some fairly definite fraction o