Radio Digest (July 1924-Apr 1925)

16 RADIO DIGEST -Illustrated August 2, 1924 THIRTY-MINUTE ABC (Continued from page 13) Figure 191 shows a reversed feedback which may be adjusted to overcome oscillation in the Radio amplifier and permit use of a tuned plate circuit output. Figure 192 shows another form of stabilization in which non-tuned input coils number 1, and number 2 are coupled to tuned circuits number 3 and number 4. By using very few turns of wire on the input coils the tendency for self oscillation is avoided. Keflex Circuits Reflex circuits are of various forms; a simple type is shown in Figure 193. The audio output from the rectifier or detector is fed back as input to the amplifying tube which also has a Radio frequency input and output circuit. Combinations are possible in which two stages of amplification at both audio and Radio frequency are practicable with economy of tubes. Such circuits will cause difficulties if not properly matched up to secure cor Guaranteed Head-Sets RED-HEADS" are guaranteed radio phones. You run no risk when you buy them. Money back if, after 7 days' trial, you're not satisfied that they're the best receivers on the market at the price. "Why not act right now and get a pair? It'll mean getting the maximum from broadcasting from the day you put them into use. eseovehs NOW READY The new 1924 Model F | The new "Red-Head" Jr. Cfc en Per Pair «C (\(\ Per Pair JPD.OU Compiete I «P*»'V»U Complete "Red-Heads" sent prepaid on receipt of price if you are unable to get them at your dealers. THE NEWMAN-STERN COMPANY DEFT. R. D., NEWMAN-STERN BUILDING, CLEVELAND, OHIO VARIOMETER VARIOCOUPLER Pat.Pending A compact No-Loss inductance for that summer portable Ffanstiehl Variometer, P-301 $4.75 Pfanstiehl Variocoupler, P-300 5.00 Stagger-wound coils for every circuit PFANSTIEHL RADIO COMPANY Highland Park, 111. Chicago: 1001 W. Washington St. Haymarket 8010 S. HAMMER RADIO CO. 303 Atkins Ave., Brooklyn, N. Y. $2450 PHOENIX ULTRADYNE LIST PBICE $26.00, SPECIAL PHONES 8.50 X. & K.. 4000 ohms S 5.85 12.00 Western Electric 8.75 8.00 Brandes Superior 4.70 12.00 Baldwin Type C 7.85 7.00 Federal 4.85 rlson 4.50 12.00 Dr. Selbt 6000 ohms 5.75 LOUD SPEAKERS 30.00 Music Master $24.00 S.'i.OO Maenavai, New Type 28.50 25.00 Baldwin Original 21.50 10.00 Brandes Table Talker 8.50 Baldwin Unit _.. 4.65 TRANSFORMERS 7.00 Federal No. 6J $ 5.25 5.00 Acme 3.75 ill-American *. 3.80 mertran 5.50 12.50 Como Duplex P. P _ 9.75 12.50 Modern Push-Pull 9.75 5.00 Erla 4.15 5.00 Erla Sekctoformer 4.25 12.00 All-Amerlcan P. P 9.75 MISCELLANEOUS Pathe Phusifornu-r $7.95 $5.50 Amsco 28-P1 (4" dial) 4.10 1.00 Amsco 6 ohm .85 1.25 Amsco 20 ohm 1.00 Amsco 30 ohm 1. 10 Amsco Potentiometer 400 ohm 1.25 Ambassador foils 4.95 Cockaday Colls, Pre n. 4.50 Cockaday Coils, Eastern 3.35 $2.00 Rclnartz Coll 1.40 Erla Crystals 90 Brach Lightning Ar rcslors 1.75 Genuine Lavite Resistance 1. 10 Ample* Grid Denser .80 Sunerdyne Colls 4.95 Orders over $5.00 will be shipped prepaid. Money or C. 0. D. Not insured unless insurance charges included. Write for Price List rect phase or time value of the input and output energies. Figure 194 illustrates the general plan of both input and output with the Radio AUDIO INPUTl Figure 194 m § h m * I • 1 r ty///////jfr////////M///MW///MW///^ Prices Effective to August 16th Mention second choice to be shipped if article ordered is out of stock; Orders amounting to over $2.50 Insured Free Radiola Type 1 Crosley 51 Crosley Trirdyne SETS Tube ..$ 7.48 .. 14.00 .. 48.75 PHONES Frost 2000 Ohm.. Baldwin, C ..$ 2.85 .. 8.43 CONDENSERS 23 Plate — Standard , Vernier, with dial „ ..$ 1.12 .. 1.98 LOUD SPEAKERS Magnavox — B3 and Ml Magna vox — M4 , Western Electric 10D ..$24.80 .. 18.75 .. 39.50 TRANSFORMERS Acme Transformers A2, R2, R3, R4 $ 3.55 All American Transformer 5 to 1, 10 to 1 3.45 Ametram 5.10 VALLEY RADIO SUPPLY CO. 2206a Locust St. ST. LOUIS, MO. Write for Agent's Confidential Price List. Always include Parcel Post. Tiri JACK TRI-JACK is a dustproof, solderless, super-compact jack with practically zero capacity — the greatest improvement in jacks so far. Solid bakelite! It costs only $1.25. TRI-COILi Radio Frequency Transformer has done wonders in the one tube reflex circuit. Sells for $2. Write for the FREE construction booklet. BROOKLYN META.I STAMPING Corp. M8 Atlantic Ave., Brooklun.N.Y. frequencies separated. Units of this kind can be connected to similar units or other circuits. Suppose two tubes are used to afford two Radio and two audio stages. Ordinarily this will not quite equal the operation as if four tubes were used, and with poor design, there will be much energy loss through the capacity in the audio circuits. (Discussion of the neutrodyne and the super-heterodyne will be the topic of the next article by Mr. Edelman. Diagrams will be given descriptive of these circuits. — Editor's note.) SIX-TUBE SUPERDYNE (Continued from page 15) ber is to hold the Radio frequency tube from oscillating when both tuned circuits are brought to absolute resonance. With the tickler winding on the rotor described above both halves are connected in series so that the windings are in the same direction on the halves. It does not really matter which direction the rotor CONNEU/EY ELECTRIC LABORATORIES 3Q9 Fifth Avenue NEW YORK CITY JL "THE ACCENT IS ON SERVICE. " 14-16 Vesey St. NEW YORK VARIOCOUPLEE3 $3.50 Workrite 180° Silk Wound $2.95 3.50 Fisher, Large, 90° 2.75 2.75 Fisher. 180° 2.25 4.25 Special Bank Wound Coupler for Haynes Circuit (with diagram) 3.25 7.00 Ambassador Coil (with diagram) 5.50 VARIOMETERS $3. 50 Workrite $2.9 5 5.00 Pathe Moulded 2.25 3.50 Fisher, Large 2.85 CONDENSERS $2.00 R. C. 11 plate $1.05 2.25 E. C. 23 plate 1.35 2.75 R. C. 43 plate 1.65 VERNIER CONDENSERS $4.00 R. C. 23 plate $2.25 5.00 R. C. 43 plate 2.95 PHONES $18.00 DR. SEIBT IMPORTED "SUPER fl?/» nn HEADSET" 3>0.»U $12.00 N. & K., Imported $6.90 The above items are just a few of our numerous attractive priced articles, which are contained in our BULLETIN OF RADIO PARTS. Gladly sent to you upon request. We are headquarters for "Radion" and "Bakelite Dilecto" Panels. The best panel material available. Mail orders promptly attended to. Will ship C. O. D. unless remittance accompanies order. tl»st&-Kj<j6..< or stator is wound as they can be shifted by turning rotor over. Reversing the coil in the plate circuit will sometimes change audibility of signals. (In the next part of the article by Mr. Williams he will tell how to operate the superdyne receiver. — Editor's note.) Care of the Battery Watch the water level of the battery. Do not allow the water to reach as low as the tops of the plates. Add distilled water until the electrolyte is well above the plates. Never use tap water in a storage battery. The chemicals in the water will destroy the battery. If the battery leaks, do not try to fix it at home, but take the battery to a reliable battery service station. Keep the top of the battery clean. Any water allowed to remain on top of the battery will cause a small amount of leakage, which is a slow discharge of the battery. Use old cloths when cleaning any part of the battery because the acid in time will destroy the fiber of the material. Build a FADA 5 tube Neutrodyne Receiver Yon can assenible one in a few honrs. For distance, selectivity and loud speaker volume there's nothing better. The PADA 5-tube Neutrodyne out-' fit No. 167-A contains everything needed — the finest Neutrodyne parts that can be purchased. The FADA "How to Build It" hook makes everything as simple as A, B, C. Buy the original FADA No. 167-A in the sealed package, $65.60. F. A. D. ANDREA, INC. 1581 Jerome Ave. New York FLa d i o © Save at Modell's Some of Our Many Bargains LOOP AERIAL D76. Can be assembled by anyone in five minutes; all wood parts, wire and binding posts included, complete, 69c RADIO SOLDERING IRON Indispensable for the man who builds his own sets D 109 $1 -95 D 1 33— Soldering Paste, tube 25 PLATE CIRCIUT "B" BATTERIES D80— 22% Volt Small $1.15 D8I— 22y2 Volt Medium 1.45 D82— 22% Volt Large 1.95 The highest grade of battery made at prices lower than they ever were sold before. D83 — 45 Volt Medium 1.95 D84 — 45 Volt Large 2.50 D85— 45 Volt Extra Large 3.50 D86— 360 Hour 1% Volt Twin Double Duty "A" Battery 75 WOOD CABINETS Highest grade Mahogany finish Cabinets. Hinged top. These cabinets are being sold at less than one-half regular value. D57— Wood Cabinet; panel size 7"xl0", each....$2.50 D58 — Wood Cabinet; panel size 7"xl2" 2.75 D59— Wood Cabinet; panel size 7"xl4" 3.00 D60 — Wood Cabinet; panel size 7"xl8" 3.50 DC I — Wood Cabinet; panel size 7"x21" 3.75 D62 — Wood Cabinet; panel size 7"x24" 4.00 Baseboards (Mahogany Stained) for use with above cabinets 7x10 25c 7x14 35c 7x21 45c 7x12 30c 7x18 40c 7x24 50c America's Greatest Radio Retailers •191 FULTON *7I CORTLANDT BROOKLYN Cor. Church Near Washington ""81 Flatbush Ave. •14 CHURCH ST. 15 Whitehall St. Post Radio Elec. Cor. Cortl. Cor. Stone St. Corp. '•Open Sat. Ev'gs)**24l W. 42d St. (**Open Ev'g) Bet. 7th & 8th Aves. MAIL ORDER DEPT. 58 Church St. NEW YORK CITY