L-BAND TETRODES.
Abstract:
Three tetrodes have been assembled. Two were suitable for d-c tests, and one was available for r-f tests. Studies were conducted that produced suitable means for bonding grids to a boron nitride insulator. This technique can lead to composite grid structures where a rigid, high-conductivity control grid can support and cool a thinner, less rigid screen grid. It was found, also, that boron nitride can likewise be bonded to the cathode surface. This approach could lead to tubes having exceedingly rugged grid-cathode structures. A triode with a grid thermally bonded to the cathode was assembled and preliminary d-c tests were conducted. A broad-band input circuit for the L-67 tetrode has been built and tested. The bandwidth of the circuit has been found to be adequately wide and in good agreement with the computed value. A circuit has been built and tested that provides automatic control of the cathode temperature of these tubes. This circuit can adjust the heater power to compensate for r-f back bombardment heating of the cathode or other mechanisms that affect the cathode temperature. Author