Chapter 9
369
Assembly Descriptions and Block Diagrams
RF and LO Section for 8592L, 8593E, 8594E, 8594L, 8594Q, 8595E, and 8596E Analyzers
The buffered 21.4 MHz IF signal is amplified in the IF calibration
amplifier (IF Cal Amp). The gain of the calibration amplifier is
controlled by a DAC on the A7 analog interface assembly via the
REF_LVL_CAL control line. During the
CAL AMPTD
routine, the gain of
the calibration amplifier is adjusted so that the reference level at
top-screen is calibrated. The amplitude reference for the routine is
provided by the
−
20 dBm CAL OUT signal with 10 dB of input
attenuation in band 0. Refer to
in
for more information about the 21.4 MHz output from the
A9 third converter assembly.
A25 Counterlock Assembly
The A25 counterlock assembly performs four main functions:
• Phase-locks the 600 MHz SAW oscillator on the A9 third converter to
the 10 MHz reference.
• Counts the first LO frequency.
• Provides discriminator output, DISCRIM, to the A7 analog interface
assembly.
• Counts the 21.4 MHz IF.
Refer to
, at the end of this chapter for details about the
operation of the A25 counterlock assembly.
On the A9 third converter, the output of the 600 MHz oscillator is
divided by two and the resulting 300 MHz signal is routed to the A25
counterlock assembly. The A25 counterlock assembly divides the
300 MHz signal by 40 to generate a 7.5 MHz reference for the sampling
oscillator, stabilizer, and frequency counter. The 7.5 MHz reference and
the 10 MHz reference are divided further and compared in a
phase-frequency detector. The output of the phase-frequency detector,
VTO_TUNE, is fed back to A9 to tune the 600 MHz oscillator.
The sampling oscillator provides a 279 to 298 MHz driving signal to the
A25A1 sampler. The first LO signal is also applied to A25A1 sampler.
The first LO signal is mixed with a harmonic of the sampling oscillator
signal to generate the sampler IF. This IF is divided by 10 and fed to
one input of the frequency counter. The equation used to produce the
first LO frequency is:
Ist LO Frequency =N x F
SO
+ Sampler IF
N
represents the harmonic of the sampling oscillator.
F
SO
represents the sampling oscillator frequency
.
Sampler IF
represents the counted sampler IF (may be negative).
Summary of Contents for 8590L
Page 29: ...30 Chapter1 Introduction If You Replace or Repair an Assembly ...
Page 175: ...176 Chapter2 Making Adjustments 28 Correcting for Absolute Amplitude Accuracy for Option 051 ...
Page 279: ...280 Chapter5 Troubleshooting the IF Section Troubleshooting the A15 Motherboard Assembly ...
Page 347: ...348 Chapter7 Replacing Major Assemblies Rear Frame Assembly ...
Page 355: ...356 Chapter8 If You Have A Problem Returning Your Analyzer for Service ...
Page 379: ...380 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
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Page 381: ...382 Chapter9 Assembly Descriptions and Block Diagrams IF Section ...
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Page 392: ...393 10 Analyzer Options and Block Diagrams ...
Page 443: ...444 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
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Page 451: ...452 Chapter10 Analyzer Options and Block Diagrams Option 190 DVB C Service Menus ...
Page 483: ...484 Chapter11 Major Assembly and Cable Locations Major Assembly and Cable Locations ...
Page 537: ...538 Chapter12 Replaceable Parts Component Level Information Packets ...
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Page 541: ...542 Chapter12 Replaceable Parts Component Level Information Packets ...
Page 542: ...FOLDOUT 12 3 8590L AND 8591E RF ASSEMBLY ...
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Page 665: ...666 Chapter15 Service Equipment and Tools Service Equipment and Tools ...
Page 666: ...667 16 Safety and Regulatory Information ...
Page 673: ...674 Chapter16 Safety and Regulatory Information Protection from Electrostatic Discharge ...