Downloaded from https://www.everyspec.com MIL-STD-1311D 4.11.1 Cathode-ray tubes. In addition to the requirements of 4.11 , cathode-ray tubes shall be tested with a raster covering not less than 25 percent nor more than 75 percent of the tube-screen area. The light output or beam current shall be initially adjusted to the specified value measured in accordance with the pertinent portions of method 5221. Life tests shall be interrupted at approximately 10 and 50 percent of the specified life-test duration for measurement of the pertinent characteristics and any necessary readjustment of the test conditions. 4.11.2 Gas-switching tubes.
These tubes shall have the rf line power measured immediately before the last tube preceding the load. Periodically during the life test, the TUTs may be interchanged in their positions on the life-test rack. When an ignitor structure is used, the ignitor current shall not be adjusted during the life test. Life-test end points shall be measured using the voltage and resistor specified on the TSS. 4.12 Definitions and instructions for pulse modulators and pulse diodes. 4.12.1 Definitions. a. Charging diode (hold-off diode). A tube inserted between the supply and the pulse forming network (PFN) to prevent any power from the network flowing back into the dc supply (see figure 1 ). b.
Clipper diode (line clipper or shunt diode). A diode in series with a resistor is placed in parallel with the modulator tube to dissipate the negative charge of the PFN after it has discharged through the thyratron (see figure 1 ). c. Transformer back-swing diode (clamper diode). A diode placed across the primary winding of the load transformer which dissipates the back-swing energy from the pulse transformer. (See figure 1 .) This diode aids in resetting the transformer core, and changes the dc voltages. For pulse applications, the rms current Ip is calculated as Ib x ib or Du ib . transformer BS diode and thyratron modulator. FIGURE 1.
Modulator circuit showing charging diode, clipper diode, 7