Downloaded from https://www.everyspec.com MIL-STD-1311D 4.8.5 Holding periods. After completion of all manufacturing processes through final pinch-off of the vacuum envelope, the tube shall be held non-operating for minimum periods as specified in the following category listing. (NOTE: Tube categories not listed shall be held for a minimum of 24 hours.) During this holding period, external processes may be completed that do not require the application of high voltage. These processes include the completion of painting, decals, leads, magnets, mounting flanges, connectors, tuner, and other miscellaneous external hardware.
Required testing performed after the holding period shall be designated on the TSS by a note. These tests shall be the first conducted after the holding period. Other required testing shall be conducted before or after the holding period, at the manufacturer’s option. HOLDING PERIODS Category Hours held Beam switching ................................................................................................. 48 Cathode Ray ..................................................................................................... 48 Cathode-Ray Charge Storage ...........................................................................
48 Cold Cathode .................................................................................................... 96 Crossed-Field Amplifier ..................................................................................... 108 Electron Multiplier .............................................................................................. 48 Electron-Ray Indicator ....................................................................................... 24 Gas Switching ................................................................................................... 168 Graphic Indicator ...............................................................................................
24 Ignitron .............................................................................................................. 96 Image Converter ................................................................................................ 672 Image Orthicon .................................................................................................. 48 Klystron ............................................................................................................. 168 M - Backward Wave...........................................................................................
168 Magnetron ......................................................................................................... 48 Negative Grid (Microwave) ................................................................................ 72 Noise Source ..................................................................................................... 108 O - Backward Wave ........................................................................................... 168 Phototube .......................................................................................................... 168 Power or Transmitting (except Hydrogen Diodes) ..............................................
72 Power Diode, Hydrogen ..................................................................................... 96 Pulse Modulator, Hydrogen ............................................................................... 96 Pulse Modulator, Vacuum .................................................................................. 72 Radiation Counter .............................................................................................. 720 Receiving .......................................................................................................... 24 Thyratron ...........................................................................................................
96 Traveling Wave.................................................................................................. 168 Vidicon .............................................................................................................. 48 Voltage Regulator or Reference......................................................................... 24 Voltage Regulator, Corona ................................................................................ 720 4.8.6 Preheating. Prior to testing, all tubes shall be preheated under conditions not exceeding the maximum ratings for sufficient time to obtain stabilized values of electrical characteristics.
Preheating may be done in the test set if desired by the manufacturer. 4.8.6.1 Preheating cathode-ray tubes. Cathode-ray tubes shall be preheated for not less than 60 seconds under conditions of maximum rated filament voltage (no other voltages necessary). 4.8.7 Stabilization. When stabilization is specified on the TSS, all tubes shall be stabilized prior to characteristic tests for not less than the period specified. Voltages as specified on the TSS shall be applied continuously during stabilization. After all the tubes in any lot have been stabilized once, and have met the requirements of this specification, no further stabilization of these tubes will be required.
4.8.8 Electrical connections. Wiring or bus bar connections of ample size to carry the necessary currents are permitted; however, electrode connectors designed expressly for coding purposes shall not be used unless specified on the TSS. 4.8.9 Tapped filaments. Tapped filaments designed for either series or parallel operation shall be tested in a manner which will insure proper internal and external connections. 4.8.10 Metal shields and envelopes. Any shields and metal-tube envelopes, except those of external anode tubes and metal cathode-ray tubes, shall be connected to the reference point.
For cathode-ray storage tubes, external shields shall be connected to ground potential of the test set. 4.8.11 Cathode resistor bias. When tests are to be made with cathode resistor bias, the resistor shall be bypassed with a capacitor of 3 ohms maximum reactance at the test frequency. For noise and vibration output, 1,000 µ F is sufficient. 4