The plasmas of the negative glow region of a cold‐cathode discharge in helium and neon are examined for their ability to supply free electrons for operation of a ``vacuum'' amplifier tube. The plasma replaces the conventional oxide‐coated hot cathode in a tube with closely‐spaced fine‐mesh grids. At gas pressures ∼1‐mm Hg the volt‐ampere characteristics of the amplifier portion of the total discharge tube are essentially the same as found in the high‐vacuum, hot‐cathode counterpart.The noise content of the plate current of the ``glow‐cathode'' tube, defined by equivalent noise‐diode current, was examined from 50 kc to 50 Mc. At the lower frequency this equivalent current is ∼10 times the actual plate current flowing. At frequencies approaching 50 Mc the equivalent current drops to a factor ∼0.5 and may be considerably lower for unexamined frequencies above 50 Mc.