We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
40
RADIO BROADCAST
NOVEMBER, 1926
front approximately in line with the 500,000ohm volume control on the panel.
At this point the base board assembly may be laid aside and further work on the panel continued.
First examine the Marco dials; two types are available on the market. The new style is recognized by the fact that the lamp receptacle holding the pilot light is completely isolated from the metal frame of the dial whereas, in the old style, one side of the lamp receptacle was connected to the frame. The new style dials can be used without any alterations, but it will be necessary to change slightly the construction if the old dials have been purchased.
In this latter instance, it is necessary to cut away the upper part of the frame supporting the dial light, removing a 3^-inch section. By means of a small piece of fibre, rubber, or other insulating material, these two parts are joined together again. The insulating strip insures against short circuits, etc., and, in the circuit employed, prevents blown out tubes. Detailed sketches showing how these changes are made, are contained in Fig. 10.
After the dials have been satisfactorily altered, the condensers are mounted on them, and the whole assembly is mounted on the panel. When this is completed, the panel may be fast
Radio Broadcast Photograph
THE TUNING CONTROLS
Are clearly shown in this side view of the R. B. "Lab" Receiver. The two nearest tubes are the r. f. and detector ones, and not the audio stages, B+ as one would be apt to suppose
FIG. 6
To the right a plan of the battery connections to the binding post strip is given. A Belden cable is employed for all but the C battery leads
C Battery
C Battery
C4V;
SECOND AUDIO STAGE
DETECTOR
RADIO FREQUENCY AMPLIFIER
FIG. 7
Here is given the circuit diagram of the four-tube Radio Broadcast "Lab" Receiver. Note that the progress of the incoming signals is from left to right, and not vice versa, as is usually the case. The coil unit at the extreme left, between the terminal numerals 44-46 is a Samson type O audio output impedance coil designed to protect the windings of the loud speaker. Its impedance is variable in two steps which approximately match existing types of loud speakers