voltage insuring an unusually flax automatic volume control charateristic with the desirvd time delay. The dual volume control 110 comprises the 350,000-ohm audio control potentiometer and the 20,000-ohm bias control potentiometer. The audio volume control functions only with switch 169 in the a-v-c position and in this position it permits the desired adjustment of the audio level to the output tube and load. See Figure 6. The bias volume control also varies to some extent the r-f and i-f tube bias. For manual volume control with switch 169 in the m-v-c position the bias volume control becomes the active control operating on the cathode bias of the first and second r-f and the first and second i-f .Implifier tubes. These potentio-meters provide a smooth variation or sensitivity.
b. CONSTANT INTERNAL RECEIVER NOISE.—
The flat gain characteristics of the r-f and detector coils insures a uniform noise level over the bands. This is obtained by a combination of inductive and capacitive coupling in the coils.
27. DYNAMOTOR DM-28.(*).
The dynamotor and associated r-f filter circuits are assembled in one unit (Ref. 400) which supplies all of the high voltage direct current required for the operation of the receiver. In addition a maximum of 20 milliamperes at approximately 200 volts d-c is available at contacts 2 and 5 on the connector plug at the rear of the receiver for the operation of external accessory equipment.