2
Performance Tests
36
E4416A/E4417A Power Meters Service Guide
Power Reference Level Test
Description
This test verifies the power level accuracy of the internal 50 MHz
oscillator- also called the power reference oscillator. The power reference
oscillator output is factory adjusted to 1 mW ±0.4%. This accuracy includes a
performance limit of 0.1% and a system measurement uncertainty figure of
0.3% (traceable to the National Physical Laboratory (NPL), UK). Refer to
Appendix C
for the measurement uncertainty of the system.
If an equivalent measurement system is employed for post- factory test (with
ambient temperature of 23 ±3 °C), the power reference oscillator output can
again be set to 1 mW ±0.4%. This setting is sufficient to ensure that the power
reference oscillator meets the accuracy specification of ±0.5% after 2 years.
Electrical
Characteristics
Performance Limits
(maximum)
Conditions
Power reference
1 mW
Internal 50 MHz oscillator factory set to ±0.4%
traceable to National Physical Laboratory
(NPL), UK.
Power reference
accuracy setting
±0.1%
Guardbanded Test Line Limits.
Power reference
accuracy after 2 years
±0.9% (0 to 55 ºC)
Worst case power meter accuracy, taking into
account the possibility of oscillator drift and
operation at 55 º.
N O T E
The setting of the oscillator output accuracy is determined from the system
measurement uncertainty plus any chosen test line limit.
For example, if a test line limit of 1 mW ±0.2% was chosen while maintaining a system
measurement uncertainty of ±0.3%, the overall accuracy of the test setup for the 1 mW
power output becomes 0.3% + 0.2%, giving a setting accuracy of 0.5%.
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