Nautel GV5, Руководство по эксплуатации и техническому обслуживанию, Страница: 12 / 251

GV5/GV3.5 OPERATIONS & MAINTENANCE MANUAL DESCRIPTION
PAGE 3.1.4 VERSION 0.2 2014-07-23
RF Drive Stage
See electrical schematic Figure SD-3. The RF drive stage converts the exciter's RF output to the
intermediate RF level needed to drive the RF power modules. It consists of exciter A (A5), optional
exciter B (A6) and RF drive splitter/changeover assembly (A7).
Exciter(s)
Exciter A (A5) and B (A6, optional) are the RF drive sources for the transmitter. They accept the external
audio program information (see the GV5/GV3.5 Pre-installation Manual for details on various program
input types). For dual exciter applications, the exciters’ main/standby operation is controlled using the
local (or remote) AUI or the controller UI. The exciter outputs are applied to the RF drive splitter/
changeover assembly (A7). The exciter provides a nominal RF drive signal of 11 W (in analog mode).
RF Drive Splitter/Changeover Assembly
See also electrical schematic Figure SD-33. The RF drive splitter/changeover assembly (A7) controls the
routing of the main exciter and, if applicable, the standby exciter and provides the RF drive signals for
the two RF power modules. The assembly is comprised of the splitter/changeover PWB (A7A1) and the
2-way RF drive splitter/attenuator PWB (A7A2).
Exciter Relay Control - Dual Exciters Only
The RF drive outputs from exciters A and B are applied to the RF drive splitter/changeover assembly at
A7A1J1 and A7A1J2 respectively. The Exciter Relay Control input (A7A1J3-4) is a signal applied from
the control/monitor stage that controls relay A7A1K1.
 When exciter A is selected as the main RF drive source, the Exciter Relay Control input is open
circuit and relay A7A1K1 will be de-energized. Exciter A's output will be applied to 3 dB
hybrid coupler A7A1U1.
 When exciter B is selected as the main RF drive source, the Exciter Relay Control input is near
ground potential (0 V) and relay A7A1K1 will be energized. Exciter B's output will be applied
to 3 dB hybrid coupler A7A1U1.
Exciter Drive Splitter
The splitter/changeover PWB’s 3 dB hybrid coupler (A7A1U1) is connected as a splitter. The RF drive
source (A or B) selected by relay A7A1K1 is applied to A7A1U1’s input. The signal is split into two equal
amplitude signals that are 90° out-of-phase. These split signals are applied to 2-way RF drive splitter/
attenuator PWB A7A2.