Abstract: An electric potential is applied to first and second electrodes on opposite sides of a gap between an electronic component and a heat spreader. At least one of a thermal interface material in the gap, the electronic component and the heat spreader is subjected to a changing physical condition. The capacitance is monitored. Such a method can be practiced using an array of components sharing a common heat spreader. An assembly for testing thermal interfaces includes a printed circuit board, a plurality of electronic components mounted to and operatively associated with the printed circuit board, a heat spreader positioned for absorbing heat generated by the electronic components, a first electrode associated with the heat spreader, a plurality of second electrodes associated, respectively, with the electronic component, and a device for monitoring electrical capacitances. The technique may be employed for monitoring physical changes in electronic devices.

Abstract: A resonant circuit arrangement for anode resonant circuits in radio frequency output amplifiers. A transmitter tube is formed with a cylindrical grid electrode and, coaxial therewith, a hollow cylindrical anode member encircling the grid electrode. A first circular metal disk extends perpendicularly from the grid electrode beyond the anode member. A second circular metal disk, with a smaller external diameter than the first, extends perpendicularly from the outer surface of the anode member. A hollow metal cylinder extends from the peripheral edge of the first circular metal disk past the second circular metal disk. A third circular metal disk extends from the hollow metal cylinder parallel with the first and second circular metal disks and on the side of the second disk opposite the first disk. A fourth circular metal disk is positioned between and parallel to the third and fourth disks.