Harris Atlas DVL1100, Technical Manual

Page: 115 / 180

2/25/03 888-2473-001 4-15
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
ATLAS Series™
4.4 Transmitter RF System
4.4.1 V-XCAST Exciter(s)
The Atlas transmitter comes standard with a single ITIS V-XCAST exciter. A
second standby exciter is available as an option along with an exciter changeover
switch in the Drive Control Unit (DCU). Operation and information about the V-
XCAST exciter is contained in the ITIS instruction manual shipped with the exciter.
The output of the exciter(s) are connected into the DCU.
4.4.2 Drive Control Unit (DCU)
The Drive Control Unit or DCU is a configurable unit which will have different
components and uses depending on the transmitter power level and the number of
exciters. It is a single rack unit mounted in the front of the transmitter just below the
exciters. Its basic function is to house the exciter changeover switch when required
and for exciter power metering. The following examples cover the different
configurations which are shown on the DCU Wiring Diagram, 843-5550-078:
Configuration 1: DVL 400 - DVL 3000 with Single Exciter
•
For this configuration the DCU consists of a sample coupler for
monitoring of the exciter power output.
Configuration 2: DVL 400 up to DVL 3000 with Dual Exciters
•
For this configuration the DCU will include the DCU controller, an RF
drive switch with a dummy load for the off-air exciter and two sample
couplers. This allows for RF monitoring of both exciters and automatic
(or manual) changeover in case the output of the on-air exciter fails.
Configuration 3: DVL 4300 and DVL 5700 with Single Exciter
•
For this configuration the DCU consists of a sample coupler for
monitoring of the exciter power output and a 3dB hybrid used as a drive
splitter to feed RF to both cabinets.
Configuration 4: DVL 4300 and DVL 5700 with Dual Exciters
•
For this configuration the DCU will include the DCU controller, an RF
drive switch with a dummy load for the off-air exciter, two directional
couplers and a 3dB hybrid used as a drive splitter to feed RF to both
cabinets.
The RF outputs of the DCU connect to the Backplane Interface Boards for
distribution to the PA Modules in each cabinet.