MIL-PRF-1/1427G
TABLE I. Testing and inspection - Continued.
2/
Applies to carrier only conditions.
3/
In all electrical tests involving application of filament voltage, the use of an EIMAC air-system socket, type SK-300 or SK-300A, or
equivalent, and air chimney SK-306, or equivalents, will be permissible. Unless otherwise specified under the listed test
conditions, forced-air cooling (in a base-to-anode direction) is permitted at a rate of 50 cfm (maximum at sea level, with air at 20°C)
for the base and anode; a separate source may be used for the base and anode but neither shall exceed 50 cfm.
4/
This test shall be performed yearly. An accept on zero defect sampling plan shall be used, with sample of three tubes with an
acceptance number of zero. In the event of failure, the test will be made as a part of conformance inspection, part 2, acceptance
level 6.5 (see 11/). The yearly sampling plan may be reinstated after three consecutive samples have been accepted.
5/
Each tube under test shall be subjected to one sweep cycle in each of the three axes X, Y, and Z. One sweep cycle (14 to 500 and
back to 14 Hz) shall be covered in 6 to 12 minutes.
6/
Any change in filament current resulting from the vibration or shock testing (considered individually) shall not exceed the specified
limit for ĆIf.
7/
It shall be allowable to measure Cg1g2 and Cg1k separately, with all unused elements grounded in each case, and consider the
sum to be equal to Cin.
8/
If an oscillator circuit is used, the screen voltage shall be set to Ec2 = 670 V dc, and a grid-leak resistance (Rg1) in the control-grid
circuit is permissible, with the value of Rg1 adjusted to produce the specified average anode current. If an amplifier circuit is used,
protective bias or a grid-leak resistance may be used, with a fixed screen-grid voltage of Ec2 = 500 V dc, and driving power
adjusted to produce the specified average anode current.
9/
The tube manufacturer warrants the tube for 1 year from date of shipment, or 1,000 hours of filament life, whichever first elapses.
This warranty applies only when the tube is operated within the maximum ratings (see "Absolute ratings" of MIL-PRF-1). A
defective tube shall either be replaced, or at the option of the manufacturer, a credit shall be made in the amount of the original
purchase price pro-rated on the basis of 1,000 hours of "filament-on" time.
10/
This test shall be the first test performed after the holding period.
11/
This specification sheet uses accept on zero sampling in accordance with MIL-PRF-1, table III.
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