Radio mirror (Jan-Oct 1923)

mm RADIO DIGEST Juhj 7, 1923 Flewelling Super with Loop Aerial Need Make Few Changes to Convert Flivver Set I have tried out the Flewelling hook-up and found it satisfactory and tried to adapt it to a loop antenna and the results have been more than satisfactory. For WORKSHOP KINKS? EARN A DOLLAR— THERE are many little kinks worked out at home that would aid your fellow Radio worker if he only knew about them. There are new hook-ups, new ways of making parts and various unique ways of operating sets that are discovered every day. Radio Digest is very much interested in securing such material. Send them in with full details, including stamped envelope so rejected copy may be returned. The work must be entirely original, not copied. RADIO KINKS DEPARTMENT, Radio Digest 123 West Madison St., Chicago, 111. anyone desiring to take along their portable Flewelling for that camping trip or vacation this summer, they will be wise to ''se a loop, as the results are practically the same as when I used a regular antenna and also has the usual additional advantages of the loop antenna. By following the hook-up, the method of arrangement is readily seen and the additional cost is quite negligible. With this super hook-up I have logged 46 stations in one month, none less than 600 miles and the most distant was "WSB at Atlanta, Georgia. The airline distance being approximately 1,437 miles from Sydney, N. S. I claim my super hook-up to be original with me, although it does incorporate an idea from Flewelling and uses tuned plate regeneration. I also claim that it is the simplest form of a super set with a loop or regular antenna. I used the Canadian dry cell tube (Northern Electric 215A) with 90 volts on the plate. — Allison D. Trumbull, Sydney, N. S. Variable Grid Leak A variable grid leak can be made from the parts shown in the illustration. Three holes large enough for binding posts are made in a piece of celluloid 1% by 3i inches^ Other parts required are two BAKEUTG PIECE o o o 3HOLtS FORSCREViS 2r — BRASS CURVED SLIGHTLY TO BE .SOLDERED ON THE SCtlCW HEAD OF BINDING POST WITH INSULATEO KNOB brass bolts with nuts, one binding post with insulated knob, one piece of brass or copper, like the one shown in the sketch, long enough to reach from the center hole and to follow in the ink line on the celluloid. The piece of brass or copper is soldered to the head of the screw and the insulated Premier m. Products Are all their name implies Why not begin standardizing now? Variocouplers Transformers Rheostats Potentiometers Head Sets Resistances "Microstats" Dials and Knobs Condensers Jacks Plugs Correspondence solicited from responsible distributors Write today for Radio "Parts" Bulletin. $r?mter fatlrlr fccmpany Established 1905 3810 RAVENSWOOD AVENUE CHICAGO, ILL. CIRCUIT GOOD FOR CAMP OUTFIT —If— binding post and the metal index pointer is screwed on the end. The assembled parts can be either mounted on the panel or on a piece of bakelite a little larger in size than the celluloid. If a condenser is desired the screw heads can be raised above the celluloid with brass pieces or nuts and the condenser mounted above. The line or mark should be made with India ink, and the two points when straight across should almost touch the binding posts at the ends. — Ira N. Faurot, Smith Center, Kansas. R. R. Spike Good for Portable Scorn not the lowly railroad spike. It has the makings of a crackerjack antenna or ground and may be a valuable adjunct to the summer Radio kit of any "bug" who would rather swing a few healthy heaves of the hammer than climb a tree to string an aerial. Take a railroad spike and file it off clean. Then drive it deep into the trunk of a good-sized tree. Use a common ground clamp for making a connection, and you'll find you have a ground of unusual quality. Drive a spike like the first one in another tree and hook it up to your antenna binding post. The tree will do the rest. What could be sweeter? Old and New B Batteries It is not advisable to connect old and new plate batteries of the dry cell types in the same circuit. The reason for this is that the internal resistance of the battery increases with the age and a large amount of the energy of the new dry battery is consumed in forcing the current through the high resistance of the old battery. A block of B battery having a potential of 22.5 volts when first put in service may be used until the potential has fallen to 15 volts. Then it should be discarded and replaced by a new battery. REFLEX Erla Reflex Transformers DEALERS: SEND FOR LITERATURE NOTE: We are the Largest Exclusive Radio Jobbers in the Middle West IH»H»Kflrf')H 123 WMadixon Jt.Chicaqo Finding Battery Noises Interfering noises in a Radio receiver employing a vacuum tube may be due to current irregularities in the filament battery or in the plate battery. To locate the source of the noises, these batteries may be tested in turn by touching the cord tips of the telephone receivers across the terminals of the batteries. If a click and no further noises are heard when the filament battery is tested in this manner the trouble is elsewhere, but if a hissing sound is heard in the receivers the battery needs charging. If a crackling or snapping sound is heard when the plcte battery is tested it should be discarded and a new battery placed in service. Regenerative Interference A regenerative receiver, when operated beyond the oscillating point, causes considerable interference with nearby receiving stations. This is due to the fact that oscillations of small power are produced by the set and radiated from the antenna. These oscillations when combined with oscillations transmitted from a Radiophone station, produce a beat of audible frequency which seriously interferes with the reception of broadcast music or speech. This interference, due to re-radiation, may be prevented by combining Radio frequency amplification with the regenerative set, thus effectually preventing the radiation of oscillations from the antenna system. We Will JlailVbu One IF COMPARE IT WITH WHAT YOU ARE NOW USING OURS IS BETTER MAIL US 3 0 CENTS NOT Return it at Our Expense [ZobelStein laboratories 822 9T_HST. BROOKLYN,N.Y.Souih2650 WILLMD RADIO COMPANY 291 Broadway New York City FLEWELLING CIRCUIT Every part complete, including drilled panel and book of diagrams and instruc til QC tions «pll.S/0 REINARTZ CIRCUIT Every part complete, including drilled panel and book of diagrams and instruc $10.95 Two-stage Audio-Frequency Amplifier. Every part complete for above d»1 1 nf\ circuits at , «P 1 1 .UU Two-inch Dials, same design, for rheostats and potentiometer; special at $0.25 Audio Frequency Transformer. Designed for use with W. D. II tubes; list, $4.50; price.. 2.75 Variocoupler — Litz Wire Wound Secondary; value, $4.50; special 2.25 Ball Bearing Inductance Switch; value, 75c; special 30 V. T. Sockets, nickeled, brass, sleeve, composition base; value, $1.00; special at 40 Aluminum Loud Speaking Horn, nickel plated, highly polished; $8.00 list 3.75 Filament Rheostat, 6 ohm .65 Filament Rheostat, 20 ohm 80 Filament Rheostat, 50 ohm 90 With 2" Dial, 15c extra. CONDENSERS $1.05 13 Plate Variable; value, 2.50 23 Plate Variable; value, 3.50 .... 1.20 1.35 1 .95 3.75 4.00 4.25 Honeycomb Coils, 50 turns mounted 95 Honeycomb Coils, 75 turns mounted 1.00 Double Ceil Mountings 2.45 Triple Coil Mountings 3.35 Reinartz Coils, increased wave length and mounting 1.45 Jacks, Single Circuit; value, 65c, special at... .30 Double Circuit; value, 90c; special at 45 Multiple Point Inductance Switch with Knob and. Dial (15 Switch Points) 1.75 Lightning Arresters, approved 90 Three-inch Dials, unbreakable, heat resisting composition, high finish; special 30 Every article advertised above is guaranteed by the manufacturer and by us. Mail orders filled immediately. Transportation PREPAID on all orders of $5.00 or over, east of the Mississippi River. All others Include postage. Back of Panel Mounting for Two Honeycombs The accompanying illustration shows a method of mounting two honeycomb coils back of a panel. The main rod or shaft may be of No. 6 wire or %-inch brass rod, 8 to 10 inches long. The lead may be a piece of No. 8 or 10 wire of suitable length. A washer must be placed between the dial and panel to keep the dial from rubbing. The spring at the end of the rod is to keep a strain on the rod and coil to prevent its moving of its own accord. The loop in the main rod equals one-third of the diameter of the movable coil (outside diameter). — E. A. Boepple, Rocky River, Ohio. HOOK-UP BLUE PRINTS WITH ALL PARTS' VALUES GIVEN FOR— 1 — Hazeltine Neutrodyne 2— Gibbons Ultra Audion 3— Coekaday Four-Circuit 4 — Single Tube Keflex 5— Three Tube Reflex 6 — Flewelling Flivver 7 — Armstrong Super Regenerative 8 — Armstrong Super Heterodyne 9 — New Ultra Reinartz 10 — Kaufman Circuit These helpful prints designed by a Member of the Institute of Radio Engineers. All ten mailed prepaid for Ave dollars ($5) or single prints at 75c apiece. Send money order or check (no stamps). HOME WORKSHOP CO.. P.O. Box 1062, CHICAGO t&ttla&e J&ceiA&M. BLUE PRINTS for the construction of a Flewelling Receiving Unit and two step amplifier. ALL DETAILS FOR ASSEMBLY Description of apparatus and accessories and details of tuning. CABINET DIMENSIONS PANEL LAYOUTS LIST OF PARTS Send only money orders — no checks or stamps. Coins at mmm