MIL-PRF-49118B(CR)
calibration error, stability versus service conditions and aging. The initial calibration error
(frequency error measured at time of Group A acceptance) shall be less than ± 0.3 ppm
referenced to the TCXO offset frequency at 30° C (see 4.5.23). (Radio must be temperature
stabilized before "A" test can be run).
3.5.24 Frequency stability.
3.5.24.1 Long term stability. The frequency drift due to aging of the reference 4.5 MHz
frequency standard shall not exceed 0.6 ppm per year when tested in accordance with 4.5.24.
3.5.24.1.1 Aging preconditioning requirement. This requirement is a prerequisite for
paragraph 3.5.24.1.2 and shall measure the absolute frequency error after a full 24 hour soak in
accordance with 4.5.24.1. The frequency shall be within ± 1.0 ppm of the dial frequency after
the 24 hour interval.
3.5.24.1.2 Aging, long term aging. A prerequisite for this check shall be the successful
completion of 3.5.24.1.1. When tested in accordance with 4.5.24.2, the frequency drift due to
aging of the TCXO shall be less than ±0.3 ppm at any time during the 30 day period of the test.
3.5.24.2 Stability vs service conditions. The frequency of the Radio Set (3 minute transmit
and 27 minute receive) shall remain within ± 1.0 ppm of the dial frequency when subjected to the
combined effects of temperature, humidity and voltage variation. Tests such as humidity, which
are performed at elevated temperature over prolonged periods of time, shall also consider the
effects of TCXO aging to determine compliance with this requirement (the aging effect for the 20
day humidity requirement shall be less than or equal to ± 0.2 ppm). This requirement shall also
be met when the Radio Set is operated in a continuous 24 hour key down condition at rated
power output at ambient temperatures up to 160° F when a means of external forced air cooling
is applied to the heat sink (see 4.5.24.3).
3.5.24.3 Warm-up. The frequency accuracy of 3.5.23 shall be met within five seconds
after the radio set has been turned on over the entire operating temperature range of the radio set
(see 4.5.24.4).
3.5.25 Phase and frequency jitter. The difference of the phase averaged over a
10 millisecond or a 13.33 millisecond period to the phase averaged over the successive
10 millisecond or 13.33 millisecond period shall not exceed five degrees when measured
between the signal input and output terminals of the transmitter or receiver. Phase and frequency
variation produced during bounce shall not degrade the maximum signal-plus-noise-plus-
distortion to noise-plus-distortion ratio of either the receiver of transmitter by more than 1dB
(see 4.5.25).
3.5.26 Input power. The input power to the receiver shall not exceed 7 watts in any mode
of operation. In the high power transmit mode, the maximum input power requirements shall be:
Mode
2-7.999 MHz
8-9.999 MHz
10-76 MHz
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