Nautel GV5, Operation & Maintenance Manual, Page: 9 / 251

GV5/GV3.5 OPERATIONS & MAINTENANCE MANUAL DESCRIPTION
VERSION 0.2 2014-07-23 PAGE 3.1.1
SECTION 3.1: DESCRIPTION
This section provides a high-level description of the transmitter’s key sections. The transmitter circuitry
is subdivided into four basic stages:
 Ac-Dc Power Stage
 Control/Monitor Stage - see page 3.1.3
 RF Drive Stage - see page 3.1.4
 RF Power Stage - see page 3.1.5
Refer to the functional block diagrams: Figure 3.1.1 on page 3.1.9 (GV5/GV3.5 transmitter) and Figure
3.1.2 on page 3.1.10 (audio path).
GV5/GV3.5 Electrical Schematics
Some descriptions in this section refer to electrical schematics (SD-#s) . These are located in Section 4 of
the GV5/GV3.5 Troubleshooting Manual.
Ac-Dc Power Stage
See electrical schematic Figure SD-1. The ac-dc power stage provides power to operate the low voltage
power supplies, which generate the 40 to 48 V dc voltage that is converted to the low level dc voltages
(±15 V and +5 V) used throughout the transmitter. This voltage is also conditioned to operate cooling
fans in the RF power module and reject load assemblies. The ac-dc power stage also converts the ac
power source to a positive dc voltage (PA volts) for the transmitter's RF power amplifiers and exciter(s).
The transmitter accepts a wide range of ac input voltage options:
 3-phase, 180 - 264 V ac (208 V ac nominal)
 3-phase, 312 - 457 V ac (380 V ac nominal)
 1-phase, 180 - 264 V ac (240 V ac nominal)
The ac-dc power stage comprises ac input terminal block TB1, power supply interface PWB (A1), low
voltage power supply (LVPS) modules A (U2), B (U3), and power supply modules (U4 through U7), two
for each of the two RF power modules. There are three amber LED pilot lamps (DS1 through DS3),
located in the bottom, rear of the cabinet, that indicate the presence of each ac phase.