506 Chapter10
Synthesizer Section
Introduction
Introduction
The synthesizer section includes the A7 first LO distribution amplifier,
A11 YTO, and parts of the A14 frequency control and A15 RF
assemblies. Simplified and detailed block diagrams for each assembly
are located at the end of this chapter.
Synthesizer Troubleshooting Section................................. page 508
Test Setup Troubleshooting................................................ page 514
Troubleshooting Using the TAM........................................ page 515
General PLL Troubleshooting............................................ page 520
PLL Locked at Wrong Frequency..................................... page 520
Unlocked PLL.................................................................... page 521
Unlocked Reference PLL (100 MHz VCXO) ...................... page 524
Operation (100 MHz VCXO)............................................. page 524
Troubleshooting (100 MHz VCXO)................................... page 524
Third LO Driver Amplifier (100 MHz VCXO) ................. page 528
Unlocked Reference PLL (600 MHz SAWR)...................... page 529
Operation (600 MHz SAWR)............................................. page 529
Troubleshooting (600 MHz SAWR) .................................. page 529
Third LO Driver Amplifier (600 MHz SAWR)................. page 533
Unlocked Offset Lock Loop (Sampling Oscillator) ............ page 534
Operation........................................................................... page 534
Troubleshooting................................................................. page 534
Unlocked YTO PLL............................................................. page 538
Operation........................................................................... page 538
Troubleshooting an Unlocked YTO PLL.......................... page 540
Unlocked Fractional N PLL................................................ page 547
Operation........................................................................... page 547
Confirming an Unlocked Condition.................................. page 547
Fractional N PLL.............................................................. page 548
Frequency Span Accuracy Problems.................................. page 555
Determining the First LO Span....................................... page 555
Confirming Span Problems............................................... page 556
YTO Main Coil Span Problems (LO Spans >20 MHz) ...... page 556
YTO FM Coil Span Problems (LO Spans 2.01 MHz to 20 MHz)page 557
Fractional N Span Problems (LO Spans ≤2 MHz) .......... page 559
First LO Span Problems (All Spans)................................ page 559
Phase Noise Problems......................................................... page 561
Phase Noise in Locked versus Lock-and-Roll Spans....... page 561
Reference versus Reference PLL Phase Noise ................ page 562
Fractional N versus Offset PLL or YTO PLL Phase Noise page 562
Fractional N PLL Phase Noise......................................... page 562
Sampler and Sampler IF .................................................... page 563
Sweep Generator Circuit .................................................... page 565
A21 OCXO ........................................................................... page 574
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