Adjustments 3
Keysight E4416A/E4417A Power Meters Service Guide 77
Power Reference Oscillator Level Adjustment
Description
This test adjusts 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).
If an equivalent measurement system is employed for post-factory test, 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. This specification includes the ±0.4% setting
and also takes into account other factors that will contribute to determining the
accuracy after 2 years. The complete breakdown of the ±0.5% specification is as
follows:
– Test line limit: 0.1%.
– System uncertainty: 0.3%.
– 2 year oscillator drift: 0.04%.
– Delta environment: <0.06%.
The following adjustment procedure ensure the power reference oscillator meets
the post-factory accuracy setting of ±0.4%.
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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