Nautel NV7.5, Operation And Maintenance Manual

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NV10/NV7.5 Operations and Maintenance Manual Description
Page 1-6 Issue 3.4 2016-08-03
RF power stage
See Figures
SD-7
,
SD-8
and
SD-9
. The RF power stage accepts the intermediate RF drive inputs
from the RF drive stage and generates the final RF output. It consists of four RF power
modules, a module backplane PWB (A17), a combiner/filter (A16), an output power probe
(A13), a 4-input reject load assembly (A14) and a reject load interface PWB (A15).
RF power module
See Figure
SD-7
(see the NV10/NV7.5 Troubleshooting Manual for a detailed RF power module
description) and “RF Power Module Block Diagram” on page 1-11 .
Each of the four RF power modules provides up to 2750 W (for NV10) or 2062.5 W (for
NV 7.5 ) of RF output power and is comprised of an IPA power amplifier PWB, eight power
amplifier PWBs, power module interface PWB, combiner PWB, splitter PWB and six cooling
fans. The intermediate RF drive outputs from the RF drive stage are applied to the RF power
modules via module backplane PWB 1-4 (A17). Within each RF power module, the
intermediate RF drive signal is sampled and then drives the IPA amplifier. The IPA output is
sampled then split to drive the module's eight PAs. The IPA Volts and PA Volts inputs from the
associated switching power supply modules control the RF output of the IPA and eight PAs,
respectively. The RF power module receives alarm and status signals ( PS Temp , PS Fail , PS AC
Fail , and PS Module Present ) from the ac-dc power stage. The RF power module also provides a
Pwr Supply Inhibit signal (one for each of the power module’s dual supplies) to the ac-dc power
stage, which, when active, inhibits the associated switching power supply. A PA V Sample and
IPA V sample from each RF power module is applied to the control/monitor stage. The
control/monitor stage supplies a PA Volts Inhibit signal, which controls the PA outputs of the
RF power module.
Module backplane PWB
See Figure
SD-7
. The four RF power modules have an associated module backplane PWB
which interfaces with all module inputs and outputs, except for the RF output. It also provides
the fan volts connections for the module's cooling fans. The setting of dipswitches S1 through
S4 assign a four-bit address for each specific module based on module position. Jumper E1 is set
to
TERM
on RF power module 4 (the last module) to terminate the RS-485 serial
communication cable.
Combiner/filter
See Figure
SD-8
.