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As long as these qualifications are met, and the software does not indicate any
difficulty in establishing its calibration criteria, an increase in PTR will not
degrade the system's measurement accuracy.
The following methods may be considered for increasing or decreasing the
PTR.
Voltage controlled oscillators
1
2
Be careful not to exceed the input voltage limitations of the Tune Port on the VCO
C A UTI ON
source
Increasing the tune range of the VCO is only valid as long as the VCO source is able to
NO T E
continuously meet the previously mentioned tuning qualifications.
Signal generators
1
2
3
Agilent E5505A User's Guide
Select a different VCO source that has the tuning capabilities needed for the
measurement.
Increase the tune range of the VCO source.
If you are using a signal generator with a calibrated 1 Vpk DC FM Input
(such as the Agilent 8640B, 8642A/B, 8656B, or 8662/3), the Voltage tuning
Range can be increased to 10 V as long as you select Computed from the
expected T. Constant in the Calibration Process display. These signal
generators continue to meet all of the previously mentioned tuning
qualifications across a 10 V tuning range.
Increase the signal generator's frequency deviation setting and set the
software to measure the new tuning constant or enter the increased
deviation if it is known. (Note that increasing the deviation setting often
increases the source's noise level as well.)
If you are using a synthesizer with Electronic-Frequency-Control (EFC)
capability such as the Agilent 8662A or Agilent 8663A, it is possible to
increase the tuning range of these sources using a VCO as an external time
base. When a compatible VCO source is connected to the EXT INPUT on the
8662/3, the tuning capability of the VCO source is transferred to the
synthesizer.
Absolute Measurement Fundamentals
5
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