Radio age (Jan 1927-Jan 1928)

RADIO AGE for January, 1927 Detail of Coupler A GREAT many of the requests received in this office were for the details of the coupling unit on which in this issue, on page 19, are given the number of turns for the plate, grid and pickup windings. The wire used is No. 26, DCC, and the stator form is 3 inches in diameter, with the rotor being 2l/2 inches in diameter. The connections are shown in detail at the left of the coupler sketch, while the proper method of wiring them in is shown in the pictorial representation on page 21. For the more advanced experimenters we are again showing the schematic circuit of the receiver, with slight changes made in it since its first appearance in November. One departure from the original one is the insertion of a C battery in series with the center tap of the loop which will have a tendency to further sharpen up that circuit. This is only suggested for those living under the shadow of a broadcasting station in some of the metropolitan areas. Tendency of the intermediates to oscillate is suppressed by means of the C battery tap going to the filament terminal of all of the RF transformers, and the first audio. Grid bias is given the last audio where a UX112 is used, this bias being the full voltage of the C battery, 71/2 volts. Two ten ohm rheostats are The Magazine of the Hour 19 EVERY NIGHT LOG Kc Stn. Loop Osc. 1010 KPRC 61 60 1000 WPG 62 62 990 WGN 64 63 980 KOIL 65 64 970 KDKA 66 65 960 KSBA 67 66 950 WGES 69 68 940 WSMB 70 69 930 KOA 71 70 920 KWKH 73 72 910 WJAZ 74 73 1 900 WBZ 75 74 890 WJAX 77 75 880 KFAB 78 76 870 WCBD 79 79 860 WEEI 81 80 850 WWJ 83 81 840 KRLV 85 84 830 WPAP 86 85 820 WDAF 88 87 810 WEBH 90 88 800 KTHS 92 90 790 WGY 93 91 780 CKY 94 93 770 WTAM 95 93 760 WO A I 98 96 750 WHT 100 98 740 KMMJ 103 101 730 None heard 720 wcco 106 104 710 WLW 109 107 700 WSB 111 109 690 None heard 680 WOS 113 112 670 WQJ 117 115 660 WJZ 120 118 650 KMA 121 120 640 KFI 124 123 630 WBAP 126 124 620 woe 131 129 610 WCFL 136 134 600 KFRU 139 137 590 WIP 141 140 580 WCX 143 141 570 WHO 151 149 560 KYW 158 156 550 KSD 163 160 Detail of the oscillator coupler No. 26 DCC wire is used in all windings. The turns are shown in sketch provided, one for the filament control of three of the intermediate stages while the second one is used for the filament control of the first and second detectors. The tubes to be used are noted in the pictorial representation and this scheme should be followed for best results. While the midget condenser used for balancing the loop is placed on the panel where it may be easily reached, in actual practice it has been found possible to place it back of the panel and once adjusted for a certain tube in the first detector stage, it can be left alone. Perhaps the average set builder will like it on the panel so it is shown in that position. By means of it the loop may be made either sharp or broad. Switching around the two outside loop terminals may make a difference on the tuning of this midget condenser, and it is rec RHEOSTAT VAR. RESISTANCE RHEQSTi* This sketch shows how the parts should be laid out on the baseboard