HP 8924E, Assembly

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Chapter 11, Block Diagrams
Section Details
N:\mkt\MANUALS\HP8924C\ALR\blkdia.fb
RF Generator
Section
Frequency Reference Generation
The A38 Oven Oscillator provides a 10 MHz reference that is connected by an
external jumper to the rear panel REF INPUT connector. This signal goes to the
A29 CDMA Reference to generate the CDMA clock signals and provide the 10
MHz reference for the A27 Reference. All generated frequencies are derived from
the A27 Reference assembly. The A27 Reference assembly also has its own
temperature compensated crystal oscillator (TCXO) that is switched in if the
signal from the A29 CMDA Reference is not present (however, this condition
would not permit CDMA operation). The A27 Reference assembly develops the
local oscillator (LO) and reference signals needed by the assemblies that make up
the RF Generator, RF Analyzer, Spectrum Analyzer, and the A37 Measurement
assembly.
The A24 Signal Generator Synthesizer develops a 500 MHz to 1000 MHz signal
which is phase-locked to the 200 kHz reference from the A27 Reference
Assembly. When FM is needed, the modulating signal from the A34 Modulation
Distribution assembly is summed into the tune voltage of the voltage controlled
oscillator in the synthesizer. An out-of-lock indicator LED lights if the phase-
lock-loop is out-of-lock. When you turn the Test Set’s power on the LED lights
for a few seconds then goes out. If it stays on or comes on again, the loop is out-
of-lock.
The 500-1000 MHz signal then goes to the A25 I/Q Modulator assembly. The
signal is I/Q modulated when creating a CDMA signal, or is routed past the I/Q
modulators for non-CDMA signals. The signal is then sent to the A26 Output
assembly.
The A26 Output assembly develops the RF Generator’s full frequency range by
mixing, dividing, or passing the 500 MHz to 1000 MHz from the A24 assembly.
The frequencies are derived as follows:
Output Frequency Derivation
250 kHz - 250 MHz mix
250 MHz - 500 MHz divide
500 MHz - 1 GHz pass