Specifications

5/9/13 888-2857-001 4-15
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
Platinum VAX-C Series
The IF and local oscillator frequencies will vary somewhat to accommodate the various
modulation methods uses and the bandwidth of the output signal. Output signal
bandwidth range is 5, 6, 7, or 8 MHz. The IF frequency tolerance of +/-0.5 MHz is
needed to accommodate the various modulation methods used.
Figure 4-6 UDC Local Oscillator (2nd LO) PLL
4.4.7.3 PFRU Board Reference Oscillator Circuit
The PFRU reference oscillator circuit, shown in PFRU Board 10 MHz Reference
Oscillator Circuit, provides four outputs, which are as follows:
• A 10 or 54 MHz reference for the DAC PLL oscillator
• A 10 MHz reference for the RF Up/Downconverter PLL oscillator
• A spare 10 MHz reference, at J3
• A 54 MHz reference to Level Detector
Table 4-4 RF UDC PLL Frequencies
Band
Channel
Frequency Range Local Osc Frequency Range IF Frequency Order
BIII 168 to 242 MHz 168 to 242 MHz in 1Hz steps Inverted
Frequency
Divider
and
Phase
Detector
Low Pass
Filter
VCO
Resistive
DIvider
J1, LO-2 Output
To UDC Board
10 MHz
Reference Input
From Ref. Osc.
Switch
Divide
By 2
Resistive
Divider
Divide
By 2
Resistive
Divider
Divide
By 2
Resistive
DIvider
800 To 1600 MHz
200 To 400 MHz
400 To 800 MHz
100 To
200 MHz
100 To
200 MHz