Radio age (Jan 1927-Jan 1928)

16 RADIO AGE for February, 1927 The Magazine of the Hour o o o <> O O il±f: -^"M ^X c* 00/ rrr &, 3 OHM RHEOSr/tT &+ e ff£GOHr7 GRID L£/>K Rj /SOO OHP7 F7XeD f?£S Schematic circuit by means of which the Power Six may be wired. The novice may use the pictorial representation on the opposite page for the same purpose view of the completed receiver. Circuit diagram, and the front panel view are shown on page 16 while the pictorial representation of the set (for use by those unable to read a schematic diagram) is printed on page 17, where also the list of parts used in making up this set may be found. Connections Simple OSCILLATION control in the Power Six is the well known system used by Bremer-Tully and called the "Counterphase." Wiring of the set may be done with No. 14 tinned, round bus wire. All sockets used are the cushion type while the detector socket has a snubber attachment which will eliminate microphonic action in that tube. The biasing battery should preferably be placed inside of the cabinet. In the circuit diagram on page 16 it will be seen that all connections to the filaments are very simple ones. Only one rheostat is used and this is in the negative filament lead where the filament switch is also located. Assuming that all wiring has been finished, go over the work again to make sure that no wrong connections have been made. Then put in tubes, connect loud speaker and turn on batteries, previously having adjusted all the mikro-mike condensers to about half way down. Tune in a station of moderate volume to exact resonance, this being done with the condenser dial and the trimmer. Adjust the volume control to greatest volume without oscillation. This means greatest volume secured without a whistle or beat note secured when the condenser dial is rotated back and forth across the incoming signal. Disconnect either the positive or negative filament connection to socket of tube number three. The signal will still be heard. Turn adjustment screw of mikro-mike number twenty (see pictorial representation for all numbered parts) carefully until a point is Front panel view of the Power Six found where the signal diminishes in volume or disappears entirely. Now rotate right hand dial for loudest signal, also ro-tating trimmer condenser to exact resonance. Again adjust mikro-mike to the setting which gives weakest signals or at which signal disappears. If signal remains weak or disappears over a setting of several turns of the mikro-mike screw, adjust to the middle of this weak or silent band. This will be the proper setting for mikro-mike number twenty. Replace the filament connection to tube number three and retune the set carefully using the trimmers. Remove filament connection of tube number two and determine setting of mikromike number nineteen exactly the same as before. Retune both dials carefully before making final adjustment of mikro-mike. Signal may become weak or disappear altogether over a band of one or more turns of the mikromike. The proper setting is half way between the settings where volume starts to increase. Replace filament connection to tube number two and retune the signal carefully. Remove either positive or negative filament connection on tube number one and adjust mikro-mike number eighteen exactly the same as the previous ones, first finding approximate setting, then retuning carefully as before to find the final setting.