MIL-DTL-13791G
4.10.12 Vibration resistance. To determine conformance to 3.5.7.4, the distributor shall be
electrically connected and mechanically mounted in a suitable apparatus over the test frequency range
and shall be capable of applying vibration in each of the three axes. Each distributor output lead shall be
connected to the spark gap shown on MIL-DTL-13791/16 and set at 3 mm. With 28.5 V dc input and
operating at 1200 rpm, the specimens shall be subjected to a simple harmonic motion having an
amplitude of 0.03 inch (0.06 inch maximum total excursion), the frequency being varied uniformly
between 10 and 55 hertz (Hz). The entire frequency range, from 10 to 55 Hz and return to 10 Hz, shall
be traversed in approximately 1 minute.
4.10.12.1 Pitch-filled or oil-filled coil. To determine conformance to 3.5.7.4.1, the distributors with
pitch-filled or oil-filled coil shall be subjected to 24 hours of specified vibration in each of three mutually
perpendicular axes (total 72 hours).
4.10.12.2 Molded or potted coil. To determine conformance to 3.5.7.4.2, the distributors with
molded or potted coil shall be tested in an ambient air temperature of 180 5ºF. The distributors shall be
subjected to 32 hours of specified vibration in each of three mutually perpendicular axes (total 96 hours).
Testing shall be accomplished in two phases as follows:
Phase I
The distributor shall be subjected to a simple harmonic motion having an
amplitude of 0.08 inches (0.16 inch maximum total excursion).
Frequency shall be varied uniformly between 5 and 50 Hz. Frequency
range shall be traversed in 1 minute, from 5 to 50 Hz.
Phase II
Amplitude shall be 0.02 inches (0.04 inch maximum total excursion).
Frequency shall be varied uniformly between 50 and 100 Hz. Frequency
range shall be traversed in 1 minute, from 50 to 100 to 50 Hz.
4.10.13 Coil mounting. To determine conformance to 3.5.7.4.3, mount the ignition coil in the
distributor base and secure with clamp assembly and screws. The distributor shall be assembled in the
adapter and mounted in the vibrator fixture so that vibration is in the plane of centerlines of the distributor
shaft and coil. Input vibration of 20 g shall be applied at the worst resonant frequency of the coil
(between 60 and 150 Hz).
4.10.14 Shock resistance. To determine conformance to 3.5.7.4.5, the distributor assembly shall be
subjected to the procedure as specified in condition A, method 213 of MIL-STD-202.
4.10.15 Electromagnetic interference. To determine conformance to 3.5.7.4.6, class A3 distributor
assemblies shall be subjected to test methods CE03 and RE02 as specified in MIL-STD-461. Class CI
assemblies shall be subjected to test methods CE03 and RE05 as specified in MIL-STD-461.
4.10.15.1 Resistor-suppressor. To determine conformance to 3.5.7.4.5.1, resistance values of
resistor-suppressors shall be measured and recorded. While undergoing short duration, high peak
voltage pulses in accordance with the following:
4 1 pulses per second
Pulse repetition rate
Pulse duration
100 microseconds or less
5000 V dc 250 V dc
Pulse magnitude
Pulse rise time
10 to 15 microseconds
4.10.16 High temperature operation. To determine conformance to 3.5.7.4.6, the distributor
assembly shall be installed in a chamber in which ambient air temperature is controlled at 200 10ºF.
4.10.17 Low temperature operation. To determine conformance to 3.5.7.4.8, the distributor temperature
shall be stabilized at -65 5ºF for 24 hours, removed from the cold chamber and allowed to warm in air
not more than 5 minutes. The distributor shall then be operated as specified in 3.5.1, except that only
one lead shall be checked and values obtained shall be within 25% of the lowest value obtained in the
first output test.
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