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Theory of Operation
2715 Spectrum Analyzer Service Manual
3-17
Figure 3--8 is a block diagram of the Reference Oscillator section.
Amplitude
Calibrator
>
Heater
Microprocessor
Interface
Output
Buffer
Output
Buffer
Input
Buffer
Power Supply Regulation
CLKI
+10 V
+5 V
−11 V
DATAI
DATA0
RFLAT CH
CLK0
100 MHz
Oscillator
CAL Enable
Distribution
UP
CAL Enable
+5 V
100 MHz
@--22 dBm
RF
Spare
CFC
~
Figure 3- 8: Reference Oscillator Diagram
Power Supply Regulation. The Oscillator and the Amplitude Calibrator are
furnished with stringent, on board, power supply regulation to minimize power
supply ripple. Otherwise, both the Oscillator and the Amplitude Calibrator
would produce FM sidebands proportional to power supply ripple amplitude and
frequency.
Crystal Heater. The Crystal Heater maintains the oscillator crystal’s case
temperature within a 3° window of the crystal’s operating temperature (near
70° C) over the instrument’s operating temperature range. The crystal leads sink
heat such that the crystal inside the case operates at temperatures below the case
temperature.