Radio mirror (Jan-Oct 1923)

FIHUniM 12 RADIO DI GEST June 16, 1923 Variations in Flewelling Circuit Maker Claims Set Gets More Music, Less Noise The two circuits shown are modifications of the Flewelling that have given the writer excellent results. The diagrams are self-explanatory. The top hook-up is 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 clay. 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. the Flewelling variation with one step of audio frequency amplification. The bottom hook-up is the same variation practically with the exception that the stage of audio frequency has been removed. The binding posts are" shown in the top diagram to explain how the step of amplification can be cut out. The upper diagram shows a .006 mfd. condenser with a variable grid leak across it. Those who have had trouble with the critical Flewelling whistle can use this hook-up. It has volume galore, but for the person who has found the whistle a stumbling block let him use the second diagram. The volume produced by this hook-up is almost as good, with the added •advantage of having the critical whistle eliminated. The lower hook-up is my favorite set, sometimes using one stage ONE AND TWO TUBE CIRCUITS j has been a pleasure to tune in with the ten levers attached to the knobs. It is also quite necessary to keep the grid condenser and the 1%-volt bias battery as far back in the set as possible. — O. P. Klein. Leduc, Alta. Effective Height of Antenna The element of the antenna which determines its ability to pick up or give off signals is its effective height. The term of effective height does not mean the height from the ground connection to its topmost point, but is more nearly the average height from ground connection to the center of its exposed area. For an antenna consisting only of a straight vertical wire the effective height is almost two-thirds its actual height, while for an antenna having a large horizontal top FEET PER POUND OF COPPER WIRE HAVING VARIOUS INSTALLATIONS B. &• S. Single Double Single Double Cotton Silk Gauge Enamel Cotton Cotton Silk Silk Enamel Enamel 18 200 196 189 201 199 196 202 19 253 246 237 255 252 242 248 20 320 311 298 324 319 307 315 21 404 387 370 400 389 380 394 22 509 488 401 501 493 479 497 23 642 612 584 632 631 600 622 24 810 763 745 799 779 750 781 25 1019 953 903 1008 966 933 982 26 1286 1201 1118 1263 1202 1166 1232 27 1620 1500 1422 1534 1543 1457 1548 28 2042 1860 1759 1988 1917 1824 1946 29 2570 2370 . 2207 2520 2485 2288 2433 30 3218 2860 2529 3165 3009 2810 3031 31 4082 3482 2768 3933 3683 3473 3793 32 5132 4234 3737 4913 4654 4267 4737 33 6445 5141 4697 6129 5689 5267 5956 34 8093 6317 6168 7646 7111 6461 7427 35 10197 7755 6737 9680 S856 7835 9207 36 12890 9511 7S77 12162 10S69 9437 114S5 of amplification. However, it gives wonderful results with the detector tube only as shown. It is important not to use plate voltage above the amount stated in each case, except where 45 volts is indicated. This may be increased to 67% volts, but I find 45 volts quite sufficient. In fact it will give results on one stage of amplification with 22% volts. Allow me to emphasize that connecting the variocoupler in this way saves one variable condenser. I have tried several variocoupler hook-ups and they will work, but when it comes to loud signals, mine seems to be best. The 1%-volt grid bias battery on the detector tube is not an absolute necessity, but it helps to increase signals. Stress should be laid on the little rubber covered levers that I attach to my dials. These are better than tinfoil and other methods of shielding from body capacity. It is often impossible to tune without some means to turn the dial at a distance. It structure the effective height is very nearly the actual height. The only purpose of the horizontal top element of a receiving antenna is to give a greater effective height for a given actual height. The filament posts in 1%-volt tubes are diagonally opposite, while in the 6-volt tubes they are adjacent. PATENT ATTORNEYS PATENTS. Booklet free. Highest references, liest results. WATSON E. COLEMAN, Patent Lawyer, 624 F Street,Washington, D. C. SOMETHING NEW &vMi//^/ A real loud Talking Detector made of "B" Meu I.. 100%, superior to any crystal. I Puts n e wj life intol your set.' Guaranteed for one year. It's the cheapest in the long run. Sold by all live dealers, or can be ordered from the B-Metal Refining Co. 3134 Trumbull Ave. Detroit, Mich. 50c WITH TWO GOOD CONDENSERS AND A B-T VERNIER TUNER you can hook up the latest circuits with absolute vernier control and greatly superior results. Detailed diagrams furnished. 180-750 meters. Price $5.00 BREMER-TULLY MFG. CO. SJ2 S. Canal St Chicago Crystal Hook-up The hook-up here given has proven very selective and effective on long distance reception for a crystal set. Some of the many stations heard are WEAF, WOC, WIiAG and WSB. A two-wire 65 feet in length aerial was used on the set. — Xeill H. Martin, "Wilmette. 111. Lines for Grid Leak on Bottom of Triode Tube In operating vacuum tube receiving sets I have found that no two detector tubes are alike when it comes to the amount of current consumed and the resistance of the grid leaks which each requires. For the amateur who cannot afford to purchase several tubular grid leaks of different values, this kind which I have been using myself will prove quite a help. Trace back from the tube socket and find which filament terminal of the tube is connected to the positive side of the A battery. After determining this, draw LEAD PENCIt. mark ore. IND»A INK. BASE OF VACUUM TOBE with a soft lead pencil or a pen full of india ink, a line, or perhaps two lines, between this particular terminal and the grid terminal of the vacuum tube, as is shown in the accompanj'ing illustration. The leak may be regulated by making the lines heavy or light as the case may be, and once adjusted it will always remain the same. Thus a separate grid leak may be had for each different tube used without changing any of the apparatus within the machine. The one caution which must be observed is in determining the respective grid and positive filament terminals. — Howard R. Ackerman, Prairie City, 111. Use 2 5 -ohm rheostats on 1%-volt tubes. CARTER RESISTANCE UNIT By placing this Resistance Unit in the Rheostat circuit, regular 6 ohm Rheostats will properly operate the new No. 201-A and No. 199 rubes. Each Code No. 15-A, 15 ohm, for No. 201-A Tube..50o Code No. 25-A, 25 ohm, for No. 199 Tube 50c Write for bulletins on this and other Carter products CARTER RADIO COMPANY 209 South State Street, Chicago "SENIOR" SET I "Michigan" ^^ = Regenerative E Radio Receivers I Will Work Wonderfully All Summer Great progress has been made in Radio in the last year*. The belief that "Radio won't work in hot weather" is now largely dispelled as far as "Michigan" Regenerative Receivers are concerned. Regeneration, Amplification, Selective Tuning and other special features worked out by us during the past year largely eliminate static and other disturbances. "Michigan" Regenerative Receivers give superior results when used with any of the dry battery tubes now available. "JUNIOR" SET Take a Michigan Receiver Along With You on Your Summer Vacation Trip, Set One Up on Your Front Porch at Home. Add this long-distance wonderworker to your other summer pleasures and make the summer of '23 the happiest of your life. Send for circular describing the wonderful Michigan "Senior" and "Junior" Regenerative Receivers, licensed under Armstrongs U. S. Patent No. 1,113,149 and pending letters patent 807,388 covering the fullest development of regeneration. Give name and address of your favorite radio Dealer when you write, as we sell thru Dealers only, and want to tell your Dealer friends about our exclusive MRC Franchise. ^m»iiiiiiiiiniiiiimuiNMiiiiimnini'""ni»"iuimniiniiiniiiiiiiiiy