TABLE 1. Testing and inspection - Continued.
inspection, part 3
Life-test end point:
1. Overall anode to cathode dc supply voltage.
2. Anode to 9 dynode dc supply voltage.
3. An anode load resistance of at least 10,000 ohms is recommended for a protective resistance.
4. Vibration test is to be performed prior to other qualification inspection tests.
5. Adjust tube position to give maximum sensitivity. The light during test, except during life test, shall be incident
upon the aperture approximately 0.8 inch x 0.2 inch (20.32 mm x 5.08 mm) located to center of the cathode.
6. Apply 100 volts between the cathode and all other pins tied together.
7. Apply Ebb according to the range of lb in the following table:
45 to 63
63 to 88
88 to 120
374 and greater
8. Capacitance between anode and dy9, all other elements grounded.
9. Capacitance between anode and all other elements.
10. Life test.
(a) Life test shall be made during a cycle of 6 hours on and 18 hours off. The life test duration of 500 hours shall consist of
21 cycles. The luminous flux at the cathode shall be adjusted initially and at the end of 15 minutes operation daily to
give an anode current of 2.5 mA dc. Color temperature shall be greater than 2,000K.
(b) Longer tube life may be expected when operating conditions require lower anode current.
11. Omit immersion in water and test dry. Apply torque test with 20.0 pound-inches minimum.
12. Test circuit and test equipment requirements.
A bleeder network to provide equal voltage per stage; 8-MegΩ series resistance for cathode, and all dynodes excluding the
last dynode (9 ); 1-MegΩ series resistance for last dynode (9 ) and anode; a regulated (0.1 percent) power supply with low-
ripple (0.05 volts peak-to-peak maximum) as a voltage source; a sensitive dc microammeter to determine anode current; an
oscilloscope, with a low-capacity divider, is connected across the anode load resistance (1-MegΩ) to monitor noise and
breakdown; base pins of photomultiplier under test connected so that the degradation of breakdown characteristic is
minimized; a vacuum pump, low-pressure chamber and manometer; a light source with an adjustable iris and sand-blasted
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