Reference Versus Reference Pll Phase Noise; Fractional N Versus Offset Pll Or Yto Pll Phase Noise - Agilent Technologies 8564EC Service Manual

Spectrum analyzers

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Synthesizer Section

Phase Noise Problems

Reference versus Reference PLL Phase Noise

If the problem seems to be in the frequency reference or reference PLL

circuitry, measure the noise with internal and external references. If

there is no difference, suspect the circuitry associated with the

100 MHz VCXO

Fractional N versus Offset PLL or YTO PLL Phase

If the spectrum analyzer has excessive noise at >1 kHz offset, measure

the noise with center frequencies of 100 MHz and 2.5 GHz.

If the measurements are equal, suspect the fractional N circuitry and

the YTO loop circuitry on the A14 frequency control assembly.

If the measurements differ by 2 dB to 5 dB, with the 2.5 GHz

measurement at a higher noise level, suspect the offset lock loop

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