Radio broadcast .. (1922-30)

Record Details:

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726 Radio Broadcast From the binding post marked " +A" run a wire to each socket terminal marked " + F". From the binding post marked " — A" run a wire to one terminal of the filament switch. From the other switch terminal run a wire to one terminal of each rheostat. The other three terminals of the rheostats are connected respectively to each socket terminal marked " — F". The filament circuit is now completed. As each wire is put in place it is well to mark it off on the circuit diagram with a red or blue pencil. The antenna-grid circuit is wired as follows: Run a wire from the tuner terminal marked F&B WINDING STYLE WOODEN SPOOL FORM FOR RADIO FREQUENCY TRANSFORMER FIG. 3 Constructional and winding details o. the special radio-frequency transformer "LA" to the left hand binding post which should also be marked "LA" (long antenna.) Run a wire from the terminal "SA" to the binding post to the right of the one marked "LA." This binding post should be marked "SA" (short antenna.) Then connect the terminal marked "GND" to the binding post to the right of the one marked "SA." This binding post should be marked "GND" (ground). This completes the antenna-ground connections. The grid circuit is wired as follows. Connect the tuner terminal "C2" to the stationary plates of your thirteen or seventeen plate condenser, and connect the terminal "Ci " to the rotor plates. Then run a wire from "C2" terminal to the first socket terminal marked "G". Connect the tuner terminal marked " — -A" to the secondary terminal of the high ratio audio transformer marked "G." The "F" terminal of this transformer secondary is joined to the wire from the " — A" binding post. A small fixed mica condenser (.00025 or -0005 mfd.) should be connected across the secondary terminals of this audio transformer. There remains only the compensating condenser, the rotating plate of which is connected to the first socket terminal marked "P" while the stationary plate is connected to the tuner terminal "Ci ". This completes the grid circuit. All these connections are clearly shown in Fig. 2 together with the general shape of the wires, and by following the drawing the problem becomes fairly simple. The reflex circuit is wired as follows. Connect the first socket terminal marked "P" to the "P" terminal of the radio-frequency transformer. The " B " terminal of this transformer is connected to the upper terminal of the double circuit jack. The bottom terminal of the double circuit jack goes to the binding post at the extreme right and should be marked "+B". A fixed mica condenser C^ of .005 mfd. capacity should be connected across the two outside terminals of the double circuit jack. From the "G" terminal of the radiofrequency transformer, run a wire to one end of the fixed detector. The other terminal of the fixed detector is connected to the primary terminal of the high ratio audio transformer marked " P." The " B " terminal of this audio transformer is connected to the "F" terminal of the radio-frequency transformer. The reflex circuit is now completed, From the double circuit jack terminal next to the top, run a wire to the low ratio audio transformer terminal marked "P." The remaining double jack terminal is connected to the " B" terminal of the low ratio transformer. Join the "G" terminal of this transformer to the second socket "G" terminal and connect the "F" terminal of the transformer to the wire coming from the " — A" binding post. Connect the "P" socket terminal to the bottom terminal of the next double circuit jack. The top terminal of the second jack goes to the :'+B" binding post. The wiring is completed by connecting together the binding posts marked " — B" and " +A." ADDING A PUSH-PULL AMPLIFIER COONER or later, into the life of every real ^ radio fan comes the desire for more volume and then comes the hunt for a means of amplification. Though both the one-tube and the two-tube units of this reflex circuit afford good volume on all average reception, there are many who want more. But how to get this additional volume has been more of a problem than would at first glance appear.