528
Chapter 11
Synthesizer Section
Confirming a Faulty Synthesizer Section
Confirming a Faulty Synthesizer Section
The A11 YTO (the 1st LO of the spectrum analyzer) is a YIG-tuned
oscillator which tunes from 2.95 to 6.8107 GHz. The A7 LO
multiplier/amplifier (LOMA) levels the A11 output and distributes the
signal to the following:
A8 low band mixer
A10 YIG-tuned mixer/filter (RYTHM)
A12 switched barium-tuned mixer (SBTX)
A15U100 sampler
1ST LO OUTPUT to the front panel
The synthesizer section includes the following PLLs (Phase Locked
Loops):
The fractional N PLL is sometimes swept backwards (higher frequency
to lower frequency). This is necessary because of the way in which the
sampler IF signal is produced.
NOTE
The frequency control board is digitally controlled. If multiple failures
appear in unrelated areas of the circuitry, the control may be at fault.
Refer to the troubleshooting procedures in this chapter for further help
on isolating those failures.
Check Sampling
Oscillator Tune
Voltage (steps
1-4)
1. Connect the positive lead of a DVM to A15J200 pin 13 and the
negative lead to A15J200 pin 6. This measures the sampling
oscillator tune voltage which is an input to the ADC MUX of the A3
interface assembly.
2. Set the spectrum analyzer to the following settings:
Span ................................................................................. 0 Hz
Center frequency .................................................. 389.5 MHz
Trigger ...................................................................... SINGLE
3. Use the data entry keys to tune the
CENTER FREQ
to the values
listed in
.
YTO PLL
A7, A11, A14 and A15
assemblies
Offset PLL (sampling
oscillator PLL)
A15 RF assembly
Fractional N PLL
A14 frequency control
assembly
Reference PLL
A15 RF assembly
Summary of Contents for 8564EC
Page 17: ...25 1 General Information ...
Page 37: ...47 2 Adjustment Diagnostic Software ...
Page 77: ...89 3 Manual Adjustment Procedures ...
Page 129: ...161 3a Manual Adjustment Procedures 3335A Source not Available ...
Page 142: ...175 4 Assembly Replacement ...
Page 194: ...Chapter 4 257 Assembly Replacement Procedure 13 A21 OCXO Figure 4 34 A21 OCXO Mounting Screws ...
Page 196: ...259 5 Replaceable Parts ...
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Page 224: ...303 6 Major Assembly and Cable Locations ...
Page 234: ...315 7 General Troubleshooting ...
Page 238: ...Chapter 7 319 General Troubleshooting Introduction Figure 7 2 Ribbon Cable Connections 1 of 3 ...
Page 239: ...320 Chapter7 General Troubleshooting Introduction Figure 7 3 Ribbon Cable Connections 2 of 3 ...
Page 242: ...Chapter 7 323 General Troubleshooting Introduction Figure 7 5 Service Cal Data Menu ...
Page 271: ...352 Chapter7 General Troubleshooting Block Diagram Description Figure 7 6 Functional Sections ...
Page 283: ...364 Chapter7 General Troubleshooting Block Diagram Description ...
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Page 286: ......
Page 287: ...377 8 ADC Interface Section ...
Page 291: ...Chapter 8 381 ADC Interface Section Introduction Figure 8 2 A3 Test Connector Pin Locations ...
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Page 322: ...427 9 IF Section ...
Page 356: ...Chapter 9 461 IF Section A5 IF Assembly Figure 9 13 Detailed IF Adjust Signature 5 ...
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Page 379: ...487 10 Controller Section ...
Page 394: ...521 11 Synthesizer Section ...
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Page 454: ...593 12 RF Section ...
Page 489: ...628 Chapter12 RF Section A15 RF Assembly Figure 12 10 10 MHz TTL Reference at U304 Pin 13 ...
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Page 492: ...633 13 Display Power Supply Section ...
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Page 505: ...671 14 Component Level Information Packets ...
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