Agilent Technologies 856290216 service manual A21 Ocxo, Synthesizer Section

Phase Noise Problems

Phase Noise in Locked versus Unlocked Spans

Reference versus Reference PLL Phase Noise

Fractional N versus Offset PLL or YTO PLL Phase Noise

Fractional N PLL Phase Noise

Sampler and Sampler IF

Sweep	Generator Circuit
A21 OCXO
Caution	All of the assemblies are extremely sensitive to electrostatic discharge (ESD).
	For further information regarding electrostatic cautions, refer to “Electrostatic
	Discharge” in Chapter 1, “General Information.”
Caution	Using an active probe, such as an HP 850248, with a spectrum analyzer is
	recommended for troubleshooting the RF circuitry. If an HP 1120A active
	probe is being used with a spectrum analyzer, such as the HP 8566A/B, or

HP 8569A/B having dc coupled inputs, either set the active probe for an ac coupled output or use a dc blocking capacitor (HP 11240B) between the active probe and the spectrum-analyzer input. Some spectrum analyzers can be set to ac coupled. Failure to do this can result in damage to the analyzer or the probe.

Troubleshooting Using the TAM

Refer to Chapter 7, “General Troubleshooting,” for information on enabling the TAM for use with the HP 85623 Spectrum Analyzer.

When using automatic fault isolation, the TAM indicates suspected circuits that need to be manually checked. Use Table 11-2 to locate the manual procedure.

Table 11-3 lists assembly test connectors associated with each manual probe troubleshooting test. Figure 11-l illustrates the location of Al4 and Al5 test connectors.

The pin locations of a 16-pin TAM connector are indicated in Figure 11-2. Table 11-l indicates the correspondence between a measured signal line and the TAM connector pin.

11-2 Synthesizer Section