MIL-PRF-49176B(CR)
TABLE III. Group A inspection.
Inspection
Requirement paragraph
Test paragraph
Output noise
3.5.1
4.5.1
Output voltage and output current
3.5.2
4.5.2
Current limits
3.5.3
4.5.3
4.4.2 Group B inspection. Not required.
4.4.3 Group C inspection. Group C inspections shall be conducted on regulators selected
from units which have passed the tests in 4.2.1. The sample(s) shall be tested in accordance with
the inspections specified in Table IV. Samples shall be selected in accordance with the contract
(see 6.2.c).
TABLE IV. Group C inspection.
Inspection
Requirement paragraph
Test paragraph
Line rejection
3.5.4
4.5.4
Output impedance
3.5.5
4.5.5
Vibration
3.6.5
4.6.5
4.5 Methods of inspection.
4.5.1 Output noise. Output noise voltage shall be determined by measuring wideband rms
noise voltage at the regulator output with a true-rms voltmeter using the test setup and test methods
of 4.5.2. Since the noise output of the regulator is very low, it may fall under the minimum
threshold level of the true-rms voltmeter. The measurement may then be performed using a low-
noise amplifier connected at the +5 Vdc output of the regulator. Using the voltage gain and signal
bandwidth of the amplifier, noise shall be calculated using the equation as follows:
enoise / √Hz = [eout ÷(AV x (NBW)1/2)]
enoise / √Hz = equivalent input noise seen at the regulator output
where:
eout = rms noise voltage measured at the amplifier output
AV = amplifier voltage gain, typically 6000 V/V; equivalent input noise
typically 2nV / √Hz
NBW = noise bandwidth = š/2 x signal bandwidth
signal bandwidth low 3dB point =10 Hz maximum
signal bandwidth high 3dB point = 35 kHz minimum
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