sides, expands to a minimum mating surface 90 mm 3.5 inches wide around the
periphery of the door. Mating surfaces of the door's expandable shields
and the door frame shall be a conductive material. Provide the door with
an air system that maintains a nominal sealing pressure of [240 kPa] [35
psi] [_____]. In the RF sealed position, the shielded door shall provide
the same minimum attenuation as the class of shielding specified without
derating.
a.
Design: The door shall be designed for long life and reliability
without the use of RF gaskets, RF finger stock, or other sealing
devices other than the direct metal-to-metal contact as specified
above. The RF sealing device shall be fail-safe upon loss of air
pressure and shall readily allow manual opening of the door. For
either normal operation or fail-safe operation, the maximum time
to reach the open condition shall be no more than 7 seconds. The
enclosure design shall include provision for removing the door for
routine maintenance without disturbing the door alignment and RF
sealing properties.
b.
Control Panel: The inside and outside of the shielded enclosure
shall contain a control panel to include the necessary opening and
closing air valves. The outside control panel shall also have a
pressure regulator and filter. Provide for quick opening of door
air supply from inside the enclosure to allow escape when
opening-air valves fail or malfunction.
2.4
LINE FILTERS
2.4.1
Power Line Filters
Shall conform to the requirements of Section 16280N RADIO FREQUENCY
INTERFERENCE POWER LINE FILTERS and shall have current and voltage ratings
as [indicated] [specified].
2.4.2
Telephone and Signal Line Filters
MIL-F-15733. Filters shall have an
insertion loss of 100 dB in the
frequency range of 14 KHz to 10 GHz
measured according to MIL-STD-220, full
load condition. Filters shall have
a pass band of [_____] KHz to [_____]
KHz with a characteristic impedance
of [_____] ohms.
2.5
WAVEGUIDE-TYPE AIR VENTS
Provide honeycomb type with cores fabricated of brass or steel. Each
waveguide shall be electrically and mechanically bonded to adjacent
waveguides. Air vents shall be a permanent part of the shielded enclosure
and shall have a shielding effectiveness equal to that of the total
enclosure. Static pressure drop through the vents shall not exceed 5 Pa
0.02 inch water gage at an air velocity of 3 m/s 600 feet per minute.
2.6
GROUNDING STUD
Enclosure shall have a permanently installed, solid brass or bronze
grounding stud complete with hardware and jamb nuts located in the entrance
plate [unless otherwise specified or indicated]. The stud shall be 12 mm
1/2 inch diameter double-threaded bolt which allows a full 50 mm 2 inch
running thread inside and outside of the shielded enclosure.
SECTION 13094N
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