Nautel XR6, Operation And Maintenance Manual

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XR6/XR3 Operations and Maintenance Manual Description
Issue 3.1 2013-03-14 Page 1-3
Figure 1.1: Exciter Stage
Distribution PWB
The distribution PWB (A11) provides inputs to the exciter stage and accepts voltage and control
signals from the exciter stage for distribution to the RF power modules, RF drive buffer PWB, and
control/monitor PWB.
RF Synthesizer PWBs
The RF synthesizer PWBs A (A2A2) and B (A2A4) contain microprocessor-controlled synthesizers
which use direct digital synthesis (DDS) techniques to generate the required RF carrier frequency
signals F
c
(A) and F
c
(B). The F
c
(A) and F
c
(B) signals are provided to the RF drive buffer PWB, via
the exciter interface PWB.
The RF synthesizer PWBs also provide signals at twice the pulse duration switching frequency,
2F
pdm
(A) and 2F
pdm
(B). Rotary DIP switches allow for the selection of any frequency in the
broadcast band. The 2F
pdm
outputs are applied to the associated interphase PDM driver PWBs
through the exciter interface PWB, and are used to drive the PDM ramp integrator circuits on the
interphase PDM driver PWBs.
Exciter
Interface
RF
Drive
RF
Drive
PDM
Driver
PDM
Driver
A
B
A
B
RF
Power Supply
+24 V dc
+15 V dc
+5 V dc
-5 V dc
Power Supplies
To Power Modules
& System Control
PDM 1
PDM 2
F PDM
Alarms
Remote
Interface
Audio
RF Drive
Buffer
To Power
Modules
RF Drive