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
PowerSupply Regulation
CLKI
+10 V
+5 V
−11 V
DATAI
DATA0
RFLATCH
CLK0
100MHz
Oscillator
CALEnable
Distribution UP
CALEnable
+5V
100MHz
@--22dBm
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 regulationto minimize power
supply ripple. Otherwise, both the Oscillator andthe Amplitude Calibrator
would produce FM sidebands proportional to power supply ripple amplitude and
frequency.
Crystal Heater. The Crystal Heater maintains the oscillator crystal’scase
temperature within a 3°window of the crystal’soperatin g temperature (near
70°C) over the instrument’soperating temperature range. The crystal leads sink
heat such that the crystal inside the case operat es at temperatures below the case
temperature.