MIL-PRF-1/1669A(CR)
TABLE I. Testing and inspection - Continued.
13/
The electron tube shall be subjected to a relative humidity of 90 to 95 percent for 96 hours in accordance with MIL-STD-202,
method 103, test condition B. Upon completion of this test, the tube shall meet the requirements for cathode current and power
output (2) herein.
14/
The electron tube shall be capable of being tuned smoothly and without discontinuities over the frequency range including the limits
specified. The number of turns of the tuner required to tune the tube over the frequency range shall be as specified herein. From
lowest to highest frequency, tuning shall be in a clockwise direction.
15/
The acceptance level for the combined defectives for attributes in conformance inspection, part 1, exclusive of "visual-mechanical
examination", shall be 1.0 percent. A tube having more than one defect shall be counted as one defective.
16/
With tube synchronously tuned, cavity #3 shall be set approximately one turn high in frequency. Drive power shall be increased to
indicated drive power, and then cavity #3 shall be retuned to maximum power output. Minor adjustments of other cavities may be
made in order to maximize power output.
17/
The minimum power output condition for power output (1) and (2) shall be available continuously without exceeding the maximum
operating temperatures specified under "Absolute ratings" herein, while providing air cooling with an ambient inlet temperature, at
sea level, of 45 C - 55 C, and an approximate air flow of 380 pound/hour against a back pressure of 0.45 inches of water,
maximum.
18/
A frequency swept driver shall be used to view the power output response during the bandwidth test (see 16/ 17/).
19/
The tuning mechanism of each individual cavity shall withstand the maximum specified stop torque at the extreme ends of the
tuning range, without damage.
20/
For periodic tests, sample tubes are be selected at random intervals so that during any twelve month period a minimum of two
tubes shall have been successfully tested. In the event of failure of one or more tubes in a sample, these tests are to become a
part of conformance inspection, part 2, until two successive lots have successfully completed these tests. After two successive
lots have been successfully completed, the periodic tests shall then be eligible to be resumed on a twelve month basis.
21/
The tube shall be subjected (non-operating) to shock test in accordance with MIL-STD-202, test method 213, test condition A
except:
Peak value (g's) = 20
Velocity change (VI) = 140.01
After this test, the tube(s) shall meet the power output (2) and cathode current requirements herein.
22/
The tube shall be mounted rigidly on the vibration table, and subjected to vibration, as follows:
a. The tube shall be vibrated under simple harmonic motion through 10 complete scan cycles in each of 3 mutually perpendicular
axes, one of which shall be parallel to the beam axis. Each scan cycle shall be of ten minutes duration consisting of a
continuously varying vibration frequency between the limits of 10 to 500 to 10 Hz. The vibration frequency shall be divided
into 3 steps with peak acceleration as shown below:
G = 10, between 10 and 100 Hz, except a limited displacement of 0.06-inch double amplitude.
G = 5, between 100 and 150 Hz.
G = 2, between 150 and 500 Hz.
b.
The waveguide and collector may be supported by a suitable fixture or fixtures such that, when the tube is subject to
vibration, the ratio of the peak acceleration, as measured on the flange of the waveguide or on the top center of the collector,
with respect to the peak acceleration on the base plate, has a minimum value of 1:1.
c.
It is also permissible to secure the tuner shafts to prevent rotation during the vibration test.
After this test, the tube(s) shall meet the power output (2) requirement.
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