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Power Reference Oscillator Level Adjustment
3-6 Agilent E4418B/E4419B Service Guide
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).
Note 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%.
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%.
Note To ensure maximum accuracy in re-adjusting the power reference
oscillator output, this procedure provides step-by-step instructions for
using Agilent test instruments of known capability. Signal acquisition
criteria may vary if alternative test instruments are used. In such
cases refer to the manufacturer’s guidelines for further information.