Radio mirror (Jan-Oct 1923)

March 17, 1923 RADIO DIGEST FLEWELLING BASIS OF R.D. 76 .0O0Z5 g.P.76{ 6 6V.0 90V I MANY attempts have been made to adapt the Flewelling condenser bank to other circuits, some of which have given very good reception while others show but doubtful performance. One of the new developments of this circuit is given here as Hook-Up R.D. 76. For some time .006 mfd. condensers were rather scarce on the market so the more standard capacity of .005 mfd. was substituted. A 50-turn honeycomb coil is used in the antenna circuit with a .001-mfd. vernier variable condenser in series on the ground side. Regeneration has been increased by the use of a 250-turn honeycomb coil in the plate circuit. In addition a .00025 mfd. variable condenser is placed in series between the antenna and plate. A variable grid leak with a .00025 mfd. grid condenser is used as in the original Flewelling. A fixed condenser of .001 mfd. capacity is shunted across the telephone receivers. A hard tube is used in combination with about 90 volts of B battery in the plate circuit. The resistance of the variable grid leak should be kept high and the filament rheostat, which should be of the vernier type, is turned on about three-quarters of full current. The plate condenser is kept low while the condenser in the ground circuit is adjusted for wave length. The coupling between the two coils is adjusted for best results in conjunction with variations of the plate condenser. Often the grid leak and the rheostat can be readjusted for improvements in reception. The controls for tuning are numerous and require a little practice and some skill in operation, but the circuit is very selective and will amply repay the experimenter in results. Book Reviews The Radio Amateur's Handbook. By A. Frederick Collins. A new revised edition of this book is just out. It is a complete authentic and informative work on Radio. Fully_illustrated. Price, $1.50. Home Radio — How to Slake It. By A. Hyatt Verrill. This book is particularly adapted for the amateur who desires to know how to make Radiophones. Twelve full page illustrations and diagrams. Price, 75c. The Armstrong Super-Begenerative Circuit. By George J. Eltz, Jr., E. E. This is a De Luxe edition of this famous circuit. Profusely illustrated and fully explained. Fifty-two pages. Price, $1.00. How to Retail Radio. A new book telling of tested plans and methods and policies for the dealer in Radio. Financing, location, store equipment and arrangement. Price, $2.00. Revolutionary Theories in Wireless. By Frank E. Summers. A treatise in the how and why of Radio and science. A practical result of years of careful study and research by the author. Non-technical, written so you can understand it. Price, $2.50. Radio for the Amateur. By A. H. Packer and R. R. Haugh. The underlying principles of Radio thoroughly explained in simple language and understandable illustrations. This book will teach you how to construct and operate a receiving set successfully. Price, $1.50. Radio Reception. By Harry J. Marx, Technical Editor Radio Digest Illustrated, and Adrian Van Muffling. A simple treatise on Radio reception. Beginning with the elementary principles of electricity it carries the reader on into the essentials of Radio telephony. The most successful methods of Radio reception are explained and special reference given to practical tuning. 230 pages, with 130 illustrations. Price, $2.00. The book department of the Radio Digest is prepared to send you any of the books on Radio published, whether listed in our Book Review or not. Let us know what book you want, send us your check and we will see that the book is mailed to you. Postage stamps in payment for books not accepted. Send money order or check. Radio Book Department, Radio Digest, 133 W. Madison St., Chicago, HI. Never operate a receiving set in the cellar or other damp place. • ALL AMERICAN AUDIO TRANSFORMERS 10-1 for 1st stage $4.75 5-1 for 2nd stage 4.75 3-1 for 3rd stage 4.50 REAL DEALER DISCOUNTS DUNGAN RADIO CO. 68 WEST WASHINGTON ST., CHICAGO Gold Plated Aerials Gold-plated wire for the antenna is the latest for the utmost efficiency. R. H. G. Mathews, of Chicago, central division manager of the American Radio Relay League and one of the best known amateurs in America, uses gold-plated wire to avoid corrosion, wb4ch increases skin resistance and so lowers efficiency. Never use oilcloth as a cover for the table on which a Radio is placed. It acts as a conductor. ."5RMICS Jl laminated Phmolic ton dtnsation Product . SHEETS TUBES RODS RADIO PANELS POLISHED BLACK FINISH CUT PERFECTLY SQUARE TO ANY 51 ZE Vzi THICK /2« PER SO. INCH V\6" THICK y4< PER SO. INCH 3/32" THICK l< PER SQ. INCH YQ" THICK V/z< PER SQ. INCH 3/i6" THICK 2< PER SQ. INCH VA " THICK 2y2c PER SQ. INCH ye" THICK A< PER SQ. INCH Vz" THICK 5l/& PER SQ INCH .SEND FOR COMPLETE PRICE LIST PROMPT ATTENTION TO MAIL ORDERS DEALERS PRICES ON APPLICATION STAR RETT MFG. CO. 519 SOUTH GREEN ST. CHICAGO INCREASE YOUR RANGE BY ADDING A PERFECTLY CONSTRUCTED VARIABLE CONDENSER TO YOUR SET 1 1 PLATE $1.25 23 PLATE 1.40 43 PLATE 1.75 Mail Orders Filled Same Day Postage Extra No Personal Checks Accepted B.K.Ford&Co.4343crAGFo:h.Lre Largest Radio Store in America RADIO BUY HERE FOR LESS Largest Radio Store in America Radio Supplies purchased here are sold under a positive guarantee of satisfaction. We carry the largest new stock of first quality merchandise Complete Parts for Reinartz Circuit Includes 1 7x18 Formica Panel, 1 Bakelite Socket, 1 Howard Vernier Rheostat, 23 Plate Condenser, 11 Plate Condenser, 3 Switch Levers, 2 Dozen Switch Points, 1 Reinartz Wound Coil, 1 Variable Grid Leak, 8 Binding Posts, 25 Feet Tinned Wire, 1 Base for Coil, 1 Mounting Base Board, and 1 Diagram to Construct This Set. ct* "I 1 A IT Complete «J> 1 1 •TT«3 Complete Parts for 2 Step Amplifier Can be used to amplify Reinartz, Flewelling, Crystal or any receiving set so that loud speaker or phonograph can be used in place of head-set. These parts consist of 1 Formica Panel 7x10 (or other suitable size), 1 High Ratio Thordarson Transformer, 1 Low Ratio Thordarson Transformer, 2 Howard Rheostats, 2 Bakelite Sockets, 3 Jacks, 13 Binding Posts, 1 Baseboard for mounting, and 1 Wiring Diagram with complete instructions for assembling, with template for drilling panel. ^ 1 O >i C Complete A X ^.'"X'O Moulded Variometers $3.45 180° Moulded Varicouplers $3.4S Mahogany Variometers $1.95 180° Bakelite Varicouplers $1.75 Freshman Variable Grid Leak and Condenser 75c CRL Adjustable Grid Leak and Dubilier Condenser $1.35 Master Baldwin Type C Units with Cord $3.95 Master Baldwin Type C Head Sets $6.95 Brandes Superior Headset $5.75 Phone Connectors (take 4 sets of phones). 35c Antenella Aerial Plug $1.15 3 Coil Honeycomb Mounting $3.45 2 Coil Honeycomb Mounting $2.60 WD-11 Bakelite Sockets 50c 4 (Four) Way Plug $1.35 Barchass Coils $1.95 Firth Cord Tip Plugs 60c Thordarson Amplifying Transformers. .$2.45 Complete Knockdown Receiving Set This includes 2 Variometers, 1 Coupler, 3 Dials, 1 Rheostat, 1 Cunningham Detector Tube, 1 Bakelite Socket, 1 Mahogany Cabinet, 7x18 Formica Panel, 6 Binding Posts, 1 Switch Lever, 12 Switch Points, 2 Stops and 1 Diagram to construct this set. Set is capable of receiving 1,000 miles dl 1 *7 Q C if installed with outdoor aerial «P X I •t/O Complete Parts for Flewelling Circuit Includes 6x14 Formica Panel, 23 Plate Condenser, 3 Micon .006 Condensers, 1 Freshman Variable Grid Leak, 1 Remler Leak, 2 Coil Mount, 2 Honeycomb Coils, 2 Coil Plugs, 1 Socket, 1 Howard Vernier Rheostat, 8 Binding Posts and 1 Diagram to Wire and Construct This Set. djl <J A C Complete «P 1 4&»TtO VARIABLE CONDENSERS now. now. .SI .25 .$1.15 $4.30 Value, 43 PLATE-, now $1.75 $3.10 Value, 5 PLATE, $3.70 Value, 23 PLATE, now $1.45 $2.70 Value, 3 PLATE, $3.30 Value, 11 PLATE, now $1.35 U. S. A. Signal Corps Av^4°Vype Western Electric Phones, $7.95 Each Phone Cap is covered with large soft rubber ear cushions, and an aviation leather helmet goes with each set! These are the only phones to pass the Government specifications for sensitiveness and loudness, the requirements called for in aircraft reception. ORIGINAL BALDWIN PHONES These are the Genuine Nathaniel Baldwin "Mica Diaphragm" Phones, complete with silk cord and headband. Special at Genuine Baldwin "Mica Diaphragm" Type "C" Loud Speaking Units. Special $9.95 $4.65 3000 Ohm GUARANTEED HEADSETS, $8.50 Value $3.65 FEDERAL JACKS Filament Control Single Circuit .... Filament Control Double Circuit. . . .35c 50c MAGNAVOX LOUD SPEAKER, Type R3 $34.95 HONEYCOMB COILS 1,500 Turns $1.50 1,250 Turns 1.50 1,000 Turns 1.25 750 Turns 1.00 250 Turns 75c 150 Turns 60c 100 Turns 50c 75 Turns 40c 50 Turns 40c 35 and 25 Turns 40c Rheostats 45c Sponge Rubber Ear Caps, Pair 50c Dials, 2, 3 and 3l/2 inch. 25c Grewol Detectors $1.65 Signal Corps Super Sensitive Microphone Transmitters $2.45 Solid Copper Aerial Wire, 100 ft 35c Spaghetti Tubing, yard. 10c Lightning Arresters 95c 2-Slide Tuning Coils, at $1.95 Phone Caps, for mostly all phones 25c Signal Cps, Hot Wire Ammeters, at $5.45 Anti-Capacity Switches $1.50 Lightning Switches. . .$2.65 Hydrometers, now at 45c FORMICA PANEL, y6" thick. Black or Brown, Square Inch l^c WE GUARANTEE ALL MERCHANDISE PURCHASED OF US Mail orders receive immediate attention BUY HERE FOR LESS CHICAGO SALVAGE STOCK STORE 509 South State Street, Chicago, 111.