Chapter 7
359
General Troubleshooting
Block Diagram Description
Fractional N PLL (part of A14)
The fractional N PLL produces an output of 60 MHz to 96 MHz. This
PLL output serves as the reference frequency for the YTO PLL. A
one-to-one relationship in frequency tracking exists between the
fractional N PLL and the YTO. A change of 1 MHz in the fractional
N PLL will produce a 1 MHz change in the YTO frequency.
IF Section
The IF section processes the 10.7 MHz output of the RF section and
sends the detected video to the ADC/interface section. The following
major assemblies are included in this section:
A3 interface assembly
A4 log amplifier/calibration oscillator assembly
A5 IF assembly
The spectrum analyzer uses trace-data manipulation to generate the
5 dB/DIV scale from the 10 dB/DIV scale. The A3 interface assembly
amplifies and offsets the 10 dB/DIV video to generate the 2 dB/DIV
scale. The 1 dB/DIV scale is generated from the 2 dB/DIV scale through
trace data manipulation. The first 50 dB of IF gain (log and linear
mode) is achieved using the linear step-gain amplifiers on the A5
assembly. The video-offset circuit on the A4 assembly provides the
remaining 60 dB of log mode IF gain. The linear amplifiers on the A4
assembly provide 40 dB of linear mode gain. IF gain steps of less than
10 dB (regardless of the reference level) are accomplished on the A5
assembly.
A4 Log Amplifier/Cal Oscillator Assembly
The A4 log amplifier has separate log and linear amplifier paths. After
amplification, the signal path consists of a linear detector, video log
amp, buffer amplifier, video offset, and video buffer amplifier. Other
auxiliary functions include the frequency counter prescaler/conditioner,
the AM/FM demodulator, and down-conversion to 4.8 kHz for digital
resolution bandwidths of 1 Hz through 100 Hz.
The cal oscillator, which is part of A4, supplies the stimulus signal for
automatic IF adjustments. Normally, the oscillator operates only during
retrace (for a few milliseconds) to adjust part of the IF. (All IF
parameters will be re-adjusted approximately every five minutes.) With
continuous IF adjust on, a group of IF parameters are adjusted during
each retrace period (non-disruptive). If continuous IF adjust is off, the
most recent IF calibration data will be used.
The IF parameters adjusted include step gains, log amplifier gain and
offset, bandwidth centering, 3 dB bandwidth, bandwidth amplitude,
crystal-filter symmetry, and oscillator frequency used in 1 Hz through
100 Hz resolution bandwidths.
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 ...
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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 ...
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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 ...
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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 ...
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