78
Chapter 2
Block Diagrams
A18 Reference Assembly
A18 Reference Assembly
The purpose of the A18 reference assembly is to provide a phase locked
10 MHz signal to other boards within the instrument. The 10 MHz
reference is phase locked to either an internal reference source, or an
externally applied signal of arbitrary frequency ranging from 1 MHz to
30 MHz.
The 10 MHz signal is provided to the A19 synthesizer assembly, the
A12 analog IF assembly, the A22 CPU assembly, and the rear panel
BNC output connector. In addition, a 50 MHz signal and a 300 MHz
signal are provided to the A17 RF assembly. The 50 MHz signal is used
for calibration purposes, and is switched on when amplitude calibration
is performed. The 300 MHz signal is used as a second LO for the RF
assembly, and is always on.
The reference assembly utilizes a phase-lock loop which provides
stabilization for all the internal reference oscillators used throughout
the instrument.
The reference assembly performs the following function:
• phase locks the 100 MHz VCXO to an internal 10 MHz frequency
reference or to an externally provided standard ranging from 1 MHz
to 30 MHz.
• provides a phase-locked 300 MHz (100 MHz
×
3) second LO to the
A17 RF assembly.
• provides the reference unlock detector which, through the A22 CPU
assembly, warns the user that the reference lock loop is unlocked.
• provides a phase-locked 50 MHz (100 MHz
÷
2) internal calibrator
signal to the A17 RF assembly.
• provides the 10 MHz phase-locked reference for various assemblies
in the instrument.
100 MHz VCXO
The 100 MHz voltage controlled crystal oscillator is used as the main
reference in the instrument. It is phase-locked with either an internal
or external frequency reference. The overall frequency accuracy of the
instrument is determined by the accuracy of the frequency reference.
Summary of Contents for E4406A VSA Series
Page 4: ...4 ...
Page 10: ...10 Contents ...
Page 11: ...11 1 Troubleshooting ...
Page 66: ...66 Chapter1 Troubleshooting How to Return Your Instrument for Service ...
Page 67: ...67 2 Block Diagrams ...
Page 119: ...Chapter 2 119 Block Diagrams Block Diagrams Block Diagrams ...
Page 120: ...120 Chapter2 Block Diagrams Block Diagrams ...
Page 122: ...122 Chapter2 Block Diagrams Block Diagrams ...
Page 124: ...124 Chapter2 Block Diagrams Block Diagrams ...
Page 125: ...125 3 Parts List ...
Page 164: ...164 Chapter3 Parts List Hardware ...
Page 165: ...165 4 Assembly Replacement ...
Page 169: ......
Page 170: ...170 Chapter4 Assembly Replacement Removal and Replacement Procedures ...
Page 227: ...Chapter 4 227 Assembly Replacement Front Frame Subassemblies Figure 4 39 Keypad Parts ...
Page 231: ...231 5 Post Repair Procedures ...
Page 262: ...262 Chapter5 Post Repair Procedures Automated Adjustments ...