Receiver Design for Minimun Fluctuation Noise

The effects of various changes in both tube and circuit conditions have been investigated with regard to their influence on the limitation which fluctuation noise sets on the sensitivity of a receiver. It is concluded that for minimum noise the following conditions should obtain: The gas pressure in the tube should be less than 10
^-4
mm of mercury; the antenna-to-grid transfer circuit should be as efficient as possible; the plate-circuit load impedance should be high enough to give a gain of at least five for the first radio-frequency tube apart from the antenna coupling circuit; and the cathode emission should be high enough so that the tube is always operating under dense space-charge conditions.