MIL-DTL-28778A
Table II. Materials inspection
Materials
Requirement
Applicable specification
paragraph
Insulating material:
Laminated phenolic
MIL-I-24768/1, or MIL-I-24768/9
Molded phenolic or melamine
Wire:
Magnet wire
Solder and soldering flux
J-STD-005, and J-STD-006
4.3 Inspection conditions. Unless otherwise specified herein, all inspections shall be performed in
accordance with the test conditions specified in the general requirements of MIL-STD-202.
4.3.1 Test frequency. When a test frequency is specified herein, the frequency used shall be within ±
2 percent of nominal value.
4.3.2 Test voltage. The rated RMS voltage at the minimum frequency of the specified frequency
range shall be applied at the rated duty cycle (that is, transformers rated at 50/60 Hz shall be tested at 50 Hz). When
rated primary voltages are specified with a tolerance, the test voltage shall be the rated voltage. For multitap primary
windings where a range of voltages is specified, the test voltage shall be applied to the highest voltage in the range
and applied to the appropriate terminals (that is, 105 to 125 volts shall be tested at 125 volts). For dielectric
withstanding voltage tests, the peak of the voltage applied shall not exceed, by more than 5 percent, the peak of the
pure sine voltage.
4.4 First article inspection. Unless otherwise specified (see 6.2), the first unit shall be required for
first article inspection. First article inspection shall consist of all examination and testing necessary to determine
compliance with the requirements of this specification. First article inspection shall be performed by the supplier,
after award of contract and prior to production, at a location acceptable to the Government. First article inspection
shall be performed on a unit which has been produced with equipment and procedures normally used in production.
First article inspection shall include the tests specified in table III.
TABLE III First article inspection
Examination or test
Requirement
Method
paragraph
paragraph
Visual and mechanical examination
(external)
Fungus 1/
Dielectric withstanding voltage
Induced voltage
Insulation resistance
Electrical characteristics
DC resistance and resistive unbalance
Inductance and inductive unbalance
Center-tap balance at low levels (-20 to 80 dBm
balance)
Corona discharge
Turns ratio
Polarity
10
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