MIL-DTL-55288E
d.
The casting after impregnation, shall be air tight, and no leakage shall be allowed when tested in
e.
Flatness shall be as specified in Government-furnished drawings.
f.
Dimensions shall be as specified in the Government-furnished drawings.
3.4.2 Impregnation of aluminum castings. All exterior aluminum castings shall be impregnated in accordance with
MIL-STD-276, using class 3 impregnation material in accordance with MIL-I-17563. Castings which have been
impregnated shall be marked "IMP". The impregnation shall be to correct general seepage only and shall not be
used to correct poor foundry techniques or significant porosity (see 4.4).
3.5 Plastic material and parts. When not machined, plastic material and parts shall have the original smooth or
polished surfaces. Surfaces that have been sawed, cut, punched, or otherwise machined shall be as smooth as
practicable in accordance with good manufacturing practice for the intended application. Plastic material and parts
shall conform to the following, except that plastic material used for arc resistance shall be limited to the type
specified. During the selection of plastic materials, consideration shall be given to tropicalization requirements.
3.5.1 Thermosetting. Unless in hermetically sealed enclosures, the thermosetting plastic material shall be treated.
3.5.2 Thermoplastic. Plastic molding material used in the construction of SM-D-542070 shall be unfilled, virgin,
polycarbonate molding compound in accordance with ASTM-D3935. These materials shall not be treated and shall
be masked, if necessary, during any treatment of equipment which might result in degradation of the electrical and
physical characteristics of the material. Only fungistatic compositions shall be used or compounds modified with
fungicides as an ingredient and capable of passing the fungus test, method 508, of MIL-STD-810.
3.6 Marking.
3.6.1 General. Marking shall conform to MIL-STD-13231 (see 4.4). Front panel marking shall be group I as
described in that specification.
3.6.2 Visibility. Wherever practicable, parts shall be so mounted that their identification marking will be readily
visible with minimum disassembly of the equipment.
3.6.3 Serial numbers. The Matching Unit-Base, MX6707/VRC shall be serial numbered.
3.6.4 National Stock Number (NSN). The Matching Unit-Base MX-6707/VRC, the Antenna Element AS-1730/VRC
(Lower Whip Section) and the Antenna Element AT-1095/VRC (Upper Whip Section) shall be marked with their
applicable National Stock Numbers.
3.7 Service conditions. The equipment shall meet the following service conditions.
3.7.1 Temperature (see 4.7.1).
Operating. Ambient temperature in the range of +160°F, to -60°F. (The 160°F temperature includes effect
a.
of sun load). Exposure at the high temperature extreme not to exceed 4 hours, and at the low temperature
extreme not to exceed 72 hours, at any one time. The antenna shall comply with 3.8.3 except that power
handling capability shall be performed for only 15 minutes and at one frequency in each sub-band.
Non-operating. Exposure in the range of +160°F, to -60°F; exposure at the higher temperature extreme not
b.
to exceed 4 hours, and at the low temperature extreme not to exceed 24 hours, at one time. When
returned to room temperature, the antenna shall comply with 3.8.1 and 3.8.2.1 and 3.8.3 with the exception
of "a." above.
3.7.2 Relative humidity (see 4.7.2). Antenna shall meet the requirements of 3.8.1, 3.8.2, and 3.8.4 when tested in
accordance with 4.7.2.
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