Radio age (Jan 1927-Jan 1928)

32 RADIO AGE for January, 1927 considerably the local pickup of the circuits. A one mfd bypass is shown between terminal 5 and the negative filament, the 275 choke being in series with the plate section of the coil, the meter jack and the 45 volt line. The intermediate, or long wave section, of the circuit is self explanatory. Two long Wave, iron core transformers are used, the first one using 45 volt plate potential, and the second one 90 volt potential. A potentiometer is placed across the positive socket terminal and the negative of the filament battery, its center arm going to the two grid returns of the iron core transformers. The air core filter coil, 211, has 90 volts applied to the plate, while the grid return goes to the fi/g or 3 volt negative terminal of a C battery. The capacity Cx placed across the primary of the air core transformer, peaks this transformer at the desired frequency — in this case 55 kilocycles. The condenser is supplied with the transformer. OBSERVING the log shown as a result of tests on the Clough super, readers will note a slight deviation from a uniform curve for both the oscillator and antenna settings. These, we believe, are due to the changes we made during the logging, of the antenna and oscillator rotor inside of the plug-in coils. Where greatest interference from local splash was encountered, it was necessary to alter the inductive relationship of the antenna rotor to bring back sharpness. In such a case a slight irregularity shows up in the plotting of the condenser settings. The same holds true for alteration of the oscillator pickup rotor, and a difference in the positive bias applied to the oscillator will likewise bring a slightly different oscillator condenser setting. It is suggested before a permanent log is made of the receiver, all possible combinations of rotor settings be tried, especially in the vicinity of stations like WQJ against WJZ. If the rotor adjustments are made on the WQJWJZ band (separated by 10 kilocycles), and the degree of selectivity fixed, this degree will remain true for the balance of the broadcast channels. It is not advisable to be constantly changing the antenna settings since it would entail considerable bother in making up a standard set of logging figures. Particular attention should be paid to the filament setting of the tubes. With a voltmeter, adjust the filament circuit until the reading is exactly 5 volts. From this point all other adjustments may be made. However if the filament voltage is constantly shifted there will be a slight deviation in the oscillator readings. LOG OF CLOUGH SUPER 1010 1000 990 980 970 960 950 940 930 920 910 900 870 860 850 840 830 820 810 800 790 780 770 760 750 740 730 720 710 700 690 680 670 660 650 640 630 620 610 600 590 580 570 560 550 Stn KPRC WPG WGN KOIL KDKA KSBA WGES WSMB KOA KWKH WJAZ KTNT WJAX KFAB WCBD WEEI WJAD KRLV WPAP WHB WEBH KTHS WGY CNRM WTAM WOAI WHT KMMJ WCRW WCCO WLW WSB KFKB WOS WQJ WJZ WCAE KFI WBAP WOC WCFL WMC KFQB WCX WOAW KYW KSD 34 35 36 37 38 39 40 42 43 44 45 46 47 48 49 50 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 69 70 72 74 75 77 79 81 83 85 88 90 92 96 100 38 39 40 41 42 43 44 46 47 48 49 50 51 52 53 54 55 56 58 59 60 61 63 64 65 66 67 69 70 72 73 75 77 79 82 83 86 87 90 93 96 98 75* 77* 79* 82* 85* Lower beat used instead of upper. The Magazine of the Hour Supremacy/ Like the Leviathan, the Durham Metallized Resistor is the supreme achievement in its own field. Noiseless in operation, unaffected by atmospheric changes, and permanent in resistance value. 10 meg. to 500 ohms, from 50 Cts. to $1.00 ID1 RESISTORS NATIONAL RESISTANCE CO. Dept. C, Perry Bldg. Ph ladelphia, Pa Most amazing attery I u e ever offered! A gen=^^=r uine World 6-volt ====" Radio"A" Bat■ tery with 25 ampere :=r capacity for only $5! zr=r It is juBt the thing for ==■ Trickle charger. Fa mous World Quality as =r sured. Equipped with SolidRubberCase An assurance against acid and leakage. Order shipped same day— subject to your examination on arrival. Extra offer: 6% discount for cash in full with order. ACT TODAY! STORAGE RADIO "A" BATTERY .00 WolrSd Famous Now Sold on Easu Terms Both Model* Shipped Complete With All Accessories Get Agents Priee-Save 5© «. Great newel Now own a famous Marwood at th< world'eloweat ririi-'' n.r -rc;r>.( on;. hi v— und pay on ensj terms. The only Radio Bold direct oa IW termaproof that tho Marwood M FJffl bo a wooder. A ycai ahead with 4 big . ■ i\a irnpruv.-menU— Super Selectivity, Po^r-V,,,,,, < ,,fu,„,. N, w Eaay-Tunin, Principle. New Tone Quality. Save half— and Bet t Radio that can't be beat at ANY price. 30 Days Free Trial Wo trust you. Provo the Marwood tho belt buy in America. Don't buy a Radio tU yousct our Euny Terms. 30 Day.' Frco I Trial. Agent'B Confidential Low f .,!.... \| .ii \\ iii I I ; MARWOOD RADIO CORPORATION 1747-A44 Morse Avenue, Chicago, III.