Nautel NX15, Operation And Maintenance Manual

Page: 15 / 178

NX15/NX25 Operations and Maintenance Manual Description
Issue 6.0 2019-01-31 Page 1-7
Control/Monitor Stage
See electrical schematic
SD-3
.
The control/monitor stage monitors critical signal samples and status/alarm signals from the
exciter stage, RF power stage, and ac/dc power stage. It also provides customer interfaces for
monitoring transmitter status and accepts customer inputs for distribution to other system
components. The control/interface PWB (A4) is the primary component of the control/
monitor stage. It provides various functions, including:
• Accepts all analog and digital modulation inputs and synchronization signals (10 MHz,
1 PPS, 1 kHz) and distributes them, along with RF voltage and current samples, to the
exciter stage.
• A15 V, +5V and -15V from the rack interface to generate on-board power
supply requirements.
• Monitors the forward and reflected power samples from the directional coupler and
initiates a shutback when the reflected power exceeds the factory set threshold.
• Amplifies the forward and reflected power samples for the RF monitor output.
• Monitors shutback requests from the rack interface for arc detector and low B+ shut-
down events.
• In conjunction with the remote interface PWB, accepts customer connections for digi-
tal remote inputs, digital remote outputs and analog outputs.
• Accepts customer connections to complete the external interlock and transmitter
(PDM) inhibit circuits.
• Contains a microcontroller that: manages presets, scheduler and exciter changeover;
controls RF on/off status, controls RF symmetry, controls RF monitor level, stores
network settings; manages the transmitter’s response to certain alarm/fault conditions.
• Contains push-button switches that provide backup control for the RF on/off and
local/remote functions.