MIL-PRF-49204B(CR)
4.11.1 Fungus. As a pretest, the antenna system shall be subjected to
the free space VSWR test, 4.15.1. The system shall be installed in the
chamber but the radiating elements and support mast sections removed to the
extent required to accommodate the chamber size. Other parts and the bag
shall be arranged in the chamber so that the other parts are unprotected by
the bag. This test should not be conducted after a salt fog test or a sand
and dust test. A heavy concentration of salt may affect the germinating
fungal growth, and the sand and dust can provide nutrients, thus leading to a
false indication of the biosusceptibility of the test item. Twenty-eight days
is the minimum test period to allow for fungal germination, breakdown of
carbon molecules, and degradation of material. The equipment in the assembled
and ready for delivery condition or representative samples subject to approval
of the procuring agency shall be subject to the fungus test. After 28 days
based on visual examination, the equipment or samples shall show no more than
sparse micobial growth with restricted tuberal growth development in an area
10% or less of the total area and no more than six unrelated minute colonies
with mycelial development in noncritical areas. Critical areas include
terminal spacing, CCA'S, etc. The equipment shall fail if it shows more than
the growth specified herein.
After exposure, the following shall be conducted: RF power capability, 4.15.3,
Dielectric withstanding voltage, 4.15.5, Air pressure, 4.12.4, Free space
VSWR, 4.15.1, and Inspection for physical condition, 4.12.1. During
Inspection for physical condition the items of the system shall be examined
for evident of fungus growth or damage. (3.8.3)
4.11.2 Salt fog. As a pretest, the antenna system shall be subject to
the free space VSWR test, 4.15.1. The system shall be installed in the
chamber but with radiating elements and support mast section removed to the
extent required to accommodate the chamber size. Other parts and the bag
shall be arranged in the chamber so that the other parts are unprotected by
the bag. The salt fog test should be conducted after other climatic tests,
especially fungus and humidity. Sand and dust testing should following salt
fog testing. A minimum exposure period of 48 hours is recommended, followed
by a 48 hour drying period. Alternating 24 hour periods of salt fog exposure
and standard ambient (drying) conditions for a minimum of four 24 hour periods
provides a realistic exposure and a higher damage potential then continuous
exposure to a salt atmosphere. The 48 hour period shall be constant wetting.
Use gentle wash in running water not warmer than +380 C (+1000 F) and drying.
There shall be no corrosion of finishes or metals. Corrosion shall be defined
as any attributed to flaky, pitted blistered or otherwise loosened finished on
metal surfaces. There shall be no clogging or binding of moving mechanical
parts. After exposure, the following shall be conducted: RF power capability,
4.15.3; dielectric withstanding voltage, 4.15.5; Air pressure, 4.12.4,
Inspection for physical condition, 4.12.1 and free space VSWR, 4.15.1. (3.8.4)
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