Chapter 9
455
IF Section
A5 IF Assembly
A5 IF Assembly
The input switch connects the IF to either the cal oscillator on the A4
assembly or the 10.7 MHz IF output from the A15 RF assembly. The
automatic IF adjustment uses the cal oscillator on A4 at instrument
turn-on and between sweeps to align the IF filters and step-gain
amplifiers. During sweeps the input switch selects the 10.7 MHz IF
output from A15. The LC filters are variable-bandwidth filters that
provide resolution bandwidths from 30 kHz to 2 MHz. The automatic IF
adjustment sets the bandwidths and center frequencies of each filter
stage.
The crystal filters are variable-bandwidth filters that provide resolution
bandwidths from 300 Hz to 10 kHz. The automatic IF adjustment sets
the filter bandwidths and symmetry.
The step-gain amplifiers consist of the first step-gain stage, second
step-gain stage, and third step-gain stage. These amplifiers provide
gain when the 8564EC or 8565EC spectrum analyzer reference
level is changed. The amplifiers also provide gain range to compensate
for variations in the IF filter gains, which change with bandwidth and
environmental conditions, and band conversion loss in the front end.
Fixed-gain amplifiers shift the signal levels to lower the noise of the IF
chain.
The assembly has two variable attenuators. The fine attenuator
provides the 0.1 dB reference level steps. The reference 15 dB
attenuator provides a reference for automatic adjustment of the
step-gain amplifiers and the log amplifier. The reference 15 dB
attenuator also provides gain for changes in spectrum analyzer
reference level.
Various buffer amplifiers provide a high-input impedance to prevent
loading of the previous filter pole and a low-output impedance to drive
the next filter pole.
Digital control signals from the W2 control cable, the "analog bus,"
drive the control circuitry. At the beginning of each sweep the analog
bus sets each control line for instrument operation. At the end of each
sweep the analog bus sets each control line for the next portion of the
automatic IF adjustment routine. IF adjustments continuously remove
the effects of component drift as the spectrum analyzer temperature
changes.
The assembly contains a reference limiting amplifier. This amplifier
provides a known amount of limiting for the automatic IF adjustment
routines. (Limiting occurs only during the automatic IF adjustment
routines.) The LC34_Short switches are open during sweeps. The
current in the reference limiter is increased during sweeps to prevent
limiting.
Содержание 8564EC
Страница 17: ...25 1 General Information ...
Страница 37: ...47 2 Adjustment Diagnostic Software ...
Страница 55: ...Chapter 2 65 Adjustment Diagnostic Software 2 LO Frequency Figure 2 2 LO Frequency Adjustment Locations ...
Страница 57: ...Chapter 2 67 Adjustment Diagnostic Software 3 YTO FM Coil Figure 2 3 YTO FM Coil Adjustment Locations ...
Страница 77: ...89 3 Manual Adjustment Procedures ...
Страница 129: ...161 3a Manual Adjustment Procedures 3335A Source not Available ...
Страница 142: ...175 4 Assembly Replacement ...
Страница 151: ...184 Chapter4 Assembly Replacement Procedure 2 A1 Front Frame A18 LCD Figure 4 2 LCD Assembly Exploded View ...
Страница 163: ...Chapter 4 205 Assembly Replacement Procedure 5 A2 A3 A4 and A5 Assemblies Figure 4 10 Assembly Cables 2 of 3 ...
Страница 166: ...208 Chapter4 Assembly Replacement Procedure 5 A2 A3 A4 and A5 Assemblies Figure 4 14 GPIB and A1A1 W1 Cable Placement ...
Страница 168: ...210 Chapter4 Assembly Replacement Procedure 6 A6 Power Supply Assembly Figure 4 15 Power Supply Cover ...
Страница 176: ...226 Chapter4 Assembly Replacement A9 Input Attenuator Figure 4 22 A9 and A10 A12 Mounting Screws ...
Страница 179: ...Chapter 4 229 Assembly Replacement A11 YTO Figure 4 23 A11 Mounting Screws at Right Side Frame ...
Страница 183: ...Chapter 4 233 Assembly Replacement Procedure 8 A14 and A15 Assemblies Figure 4 25 A14 and A15 Assembly Cables ...
Страница 190: ...Chapter 4 243 Assembly Replacement Procedure 11 Rear Frame Rear Dress Panel Figure 4 29 A6 Power Supply Cover ...
Страница 194: ...Chapter 4 257 Assembly Replacement Procedure 13 A21 OCXO Figure 4 34 A21 OCXO Mounting Screws ...
Страница 196: ...259 5 Replaceable Parts ...
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Страница 224: ...303 6 Major Assembly and Cable Locations ...
Страница 228: ...Chapter 6 307 Major Assembly and Cable Locations Introduction Figure 6 2 Top View A2 and A3 Unfolded ...
Страница 229: ...308 Chapter6 Major Assembly and Cable Locations Introduction Figure 6 3 Top View A2 A3 A4 and A5 Unfolded ...
Страница 230: ...310 Chapter6 Major Assembly and Cable Locations Introduction Figure 6 5 Bottom View A15 Unfolded ...
Страница 231: ...Chapter 6 311 Major Assembly and Cable Locations Introduction Figure 6 6 Bottom View A15 and A14 Unfolded ...
Страница 233: ...314 Chapter6 Major Assembly and Cable Locations Introduction Figure 6 9 Rear View FL4 B1 BT1 A20 VGA Connector ...
Страница 234: ...315 7 General Troubleshooting ...
Страница 238: ...Chapter 7 319 General Troubleshooting Introduction Figure 7 2 Ribbon Cable Connections 1 of 3 ...
Страница 239: ...320 Chapter7 General Troubleshooting Introduction Figure 7 3 Ribbon Cable Connections 2 of 3 ...
Страница 242: ...Chapter 7 323 General Troubleshooting Introduction Figure 7 5 Service Cal Data Menu ...
Страница 271: ...352 Chapter7 General Troubleshooting Block Diagram Description Figure 7 6 Functional Sections ...
Страница 283: ...364 Chapter7 General Troubleshooting Block Diagram Description ...
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Страница 287: ...377 8 ADC Interface Section ...
Страница 291: ...Chapter 8 381 ADC Interface Section Introduction Figure 8 2 A3 Test Connector Pin Locations ...
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Страница 322: ...427 9 IF Section ...
Страница 356: ...Chapter 9 461 IF Section A5 IF Assembly Figure 9 13 Detailed IF Adjust Signature 5 ...
Страница 358: ...Chapter 9 463 IF Section A5 IF Assembly Figure 9 14 Noisy Signature Figure 9 15 Noise with Correct Shape ...
Страница 359: ...464 Chapter9 IF Section A5 IF Assembly Figure 9 16 Region B Amplitude Variation Figure 9 17 Region B Amplitude Offset ...
Страница 369: ...474 Chapter9 IF Section Cal Oscillator P O A4 Assembly Figure 9 21 Output Waveform 10 kHz Resolution Bandwidth ...
Страница 370: ...Chapter 9 475 IF Section Cal Oscillator P O A4 Assembly Figure 9 22 Output Waveform 3 kHz Resolution Bandwidth ...
Страница 371: ...476 Chapter9 IF Section Cal Oscillator P O A4 Assembly Figure 9 23 Output Waveform 1 kHz Resolution Bandwidth ...
Страница 372: ...Chapter 9 477 IF Section Cal Oscillator P O A4 Assembly Figure 9 24 Output Waveform 300 Hz Resolution Bandwidth ...
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Страница 379: ...487 10 Controller Section ...
Страница 394: ...521 11 Synthesizer Section ...
Страница 431: ...564 Chapter11 Synthesizer Section Unlocked Fractional N PLL Figure 11 8 VCO Bias Voltages for A14 Assemblies ...
Страница 447: ...Chapter 11 581 Synthesizer Section Sweep Generator Circuit Figure 11 11 Simplified Synthesizer Section ...
Страница 448: ...582 Chapter11 Synthesizer Section Sweep Generator Circuit Figure 11 12 Simplified A14 Assembly Block Diagram ...
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Страница 454: ...593 12 RF Section ...
Страница 475: ...614 Chapter12 RF Section A14 Frequency Control Assembly Figure 12 4 A7 LO Multiplier Amplifier Drive ...
Страница 489: ...628 Chapter12 RF Section A15 RF Assembly Figure 12 10 10 MHz TTL Reference at U304 Pin 13 ...
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Страница 492: ...633 13 Display Power Supply Section ...
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Страница 505: ...671 14 Component Level Information Packets ...
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