Abstract: In an electron gun assembly comprising at least one oxide coated cathode and a G1 grid, a method of spacing the cathode a predetermined distance from the G1 grid includes the following steps. First, the cathode oxide coating is moistened with water causing it to become electrically conductive. Next an ohmmeter is connected to indicate the electrical resistance between the electrically conductive oxide coating and the G1 grid. The spacing between the cathode and the G1 grid is then reduced until the ohmmeter indicates that there is electrical conductivity therebetween. At this point there is zero spacing between the cathode and the G1 grid. The spacing between the cathode and the G1 grid is then increased by an amount equal to the predetermined spacing. The cathode is then permanently fixed at the predetermined spacing with respect to the G1 grid.