Agilent Technologies E4418B Service Manual page 52

Performance Tests
Power Reference Level Test
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 same equipment used to measure the accuracy of the power reference
oscillator can also be used to set it to the post-factory accuracy of ±0.4%
(for further information refer to chapter 3, Adjustments).
The following procedure ensures maximum accuracy in measuring power
reference oscillator output 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.
The test is performed using Equation 2-4:
Equation 2-4: Power Level Provided By The Reference Oscillator
(
2V V
comp
P = ---------------------------------------------------------------------------------- -
(
meas
4R Calibratio
The components of this equation are defined as follows:
• V is the voltage measured between V
0
applied and after the Agilent 432A has been zeroed.
• V is the voltage measured between V
1
This power is approximately 1 mW.
• V is the voltage between the Agilent 432A V
comp
chassis ground with power applied.
• R is the resistance of the mount resistor in the Agilent 432A power
meter. For further information refer to Appendix A.
• Calibration Factor is the value of the thermistor mount at 50 MHz
2-16
2 2
)
V + V V
– –
1 0 0 1
)
Factor
n
comp
comp
Agilent E4418B/E4419B Service Guide
and V with no power
RF
and V with power applied.
RF
connector and
comp