MIL-PRF-1/851H
TABLE I. Testing and inspection - Continued.
17/ The tube shall be tuned to the extremes of the mechanical tuning range. The frequency limits shall be measured after the tube
reaches temperature stabilization. The upper frequency limit condition may be considered met after 20 minutes of operation at the
high-frequency mechanical limit. The lower frequency limit condition may be considered met after 5 minutes of operation at the low-
frequency mechanical limit.
18/ The frequency obtained by turning the tuning mechanism to a given setting in one direction shall be reproducible when returning to
the same setting from the opposite direction to within the specified limits.
19/ Shock test.
(a)
A resilient cushion (see figure 1, note 2) shall be interposed between hammer and anvil of table and a suitable hammer angle
shall be selected to produce a shock of approximate cubic waveform and of the specified magnitude and duration (see figure 1,
note 3). The mounting plate of the tube shall be bolted with brass bolts to either the table or the standard angle bracket,
depending upon the direction of the desired shock, using a 1.562 inch (39.67 mm) thick brass spacer between the tube
mounting plate and table or angle bracket. The shock shall be measured on the brass spacer. The tube shall be given one
shock in each of the following directions:
(1) Parallel to cathode axis, with cathode terminals pointing away from hammer.
(2) Perpendicular to cathode axis and to the output waveguide axis.
(3) Perpendicular to cathode axis and parallel to the output waveguide axis.
(b)
A resilient cushion consisting of a .281 inch (7.14 mm) thick rubber sheet of 30 shore durometer hardness, covering the entire
anvil of the table, produces the specified shock duration under the given conditions of table load and shock magnitude.
(c)
Because of the varying resilience of the tube on its mounting plate with different shock directions and the high ratio of tube to
table weight, the hammer angle will vary with the tube orientation to produce the required magnitude of shock.
(d)
Criteria for passing shock test. After the shock test, the tube shall show no mechanical failure and shall meet all initial
electrical test requirements.
20/ The tube shall be rigidly mounted by the mounting plate and vibrated perpendicular to cathode and output axis. The mounting plate
shall be bolted with nonmagnetic bolts to the table using a nonmagnetic metallic spacer to maintain the required minimum 2 inch
(50.80 mm) clearance between the magnets and other magnetic materials. After the vibration test, the tube shall show no
mechanical failure and shall conform to the test requirements of power output (1), stability (1), pulse voltage, tuning characteristics,
and tuner drive torque as these tests are specified in conformance inspection, part 1.
21/ The tuner drive torque shall not exceed the amount specified. The drive mechanism shall not be set against either stop.
22/ The acceptance level for the combined attributes in conformance inspection, part 1, shall be 1.0, inspection level II. This
specification uses an accept on zero (c = 0) sampling plan in accordance with MIL-PRF-1, Table III.
23/ Revision letters are not used in this revision to identify changes with respect to the previous issue, due to the extensiveness of the
changes.
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