A-A-50728A
3.1 Safety. The equipment shall be UL (Underwriters Laboratories) listed and approved and/or shall comply with the type III safety requirements of Mil-PRF-2880.
a. Leakage current protection. Protection shall be provided from leakage current in excess of 3.5 mA rms (AC and DC) from any accessible conductive parts of equipment (including control shafts with knobs broken or removed and recessed calibration or adjustment controls) to either pole of the power source for any position of the power switch(es).
b. Radio frequency interference (RFI) capacitors. Any capacitor used in RFI filters shall be rated for at least four ($) times the operation voltage.
c. Type III ventilation openings.
1. Ventilation openings shall be designed to prevent accidental contact with live electrical circuits and mechanical moving parts.
2. Top ventilation openings shall incorporate small mesh screening or similar design to prevent the expulsion of hot electronic particles due to failure of electronic devices such as capacitors.
3.2 Parts, materials, and processes. Except for marking, the FSLSD shall comply with the type III parts, materials, and process requirements of Mil-PRF-28800. Nonstandard parts approval requests shall be in accordance with MIL-PRF-28800. Front panel marking shall be in accordance with MIL-PRF-28800.
a. Restricted material. The equipment shall comply with the restricted material requirements of Mil-PRF-
28800, including the requirement for mercury and radioactive materials, and shall contain no combination of materials which cause deterioration of any material contained in the equipment due to the effects of outgassing.
3.3 Design and construction. Unless otherwise specified herein, the equipment shall comply with the type III design and construction requirements of Mil-PRF-28800. The equipment shall be of solid-state construction. Encapsulation and embedment (potting) of subassemblies may be used only for high voltage circuits where construction is
susceptible to leakage or corona, indicators and associated controls shall be in close proximity to each other, all
potentiometer controls shall have at least a 270 degree rotation range (4.71 radians).
a. Type of construction. Construction of the FSLSD shall be of a monolithic or a separate component design.
b. Modular design restrictions. The modular design concept for the FSLSD is acceptable with the following restrictions:
1. The FLSD shall consist of a single unit with one or more separate modules.
2. Each module shall contain a power circuit protection fuse.
3. Each module plug-in card shall be keyed and mated with the back plane receptacle so that modules may not be randomly placed into the mainframe.
4. Modules shall not be removable by access through the front or rear of the mainframe with the unaided hand.
5. The FSLSD shall come with one (1) blank space cover and one (1) extender board.
6. A package part number shall be assigned to the FSLSD as a whole system. This system part number shall be marked on the mainframe identification plate and all plug-in(s).
c. Signal input and output connectors. Unless otherwise specified, all signal input and output connectors shall be Type BNC female.
d. Internal cooling. The equipment shall be capable of operating continuously for twenty four (24) hours at 55°C if forced air is used, it shall be as specified in Mil-Prf-28800.
1. Forced air cooling motor. DC brushless motors shall be utilized for the forced air cooling motor in the equipment.
2. Air filter. Equipment utilizing a cooling scheme which exhausts air from the equipment through the cooling fan shall not require an externally accessible air filter.
3. Thermal switch. A thermal switch shall be provided which will interrupt circuit power to the
FSLSD when the internal temperature rises to the degree of possible damage to the electronic
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