User's Manual

PINEAPPLE TECHNOLOGY, INC.
LTX100U/VL/VH Operating and Service Manual
V -- THEORY OF OPERATION
V
--- THEORY OF OPERATION (Page 1 of 2)
A
. INTRODUCTION
The LTX100U/VL/VH series transmitters were designed to meet or exceed all FCC applicable specifications for
TV broadcast equipment. Special attention was given to the selection of sub-assemblies and components
to achieve maximum reliability and minimum down time. The construction of the LTX100U/VL/VH is
BASIC and MODULAR with most components are field replaceable. Special emphasis was placed on
"KEEPING IT SIMPLE" and returning to more traditional transmitter layouts and instrumentation.
Refer to the LTX100U/VL/VH block diagram for an overview of the transmitter architecture. This will
give the technician basic information needed to understand the operation of the transmitter and the function
of each subassembly.
SEE SECTION Vl.A FOR PARTS LIST AND BLOCK DIAGRAM.
B. MA1000 Modulator/Exciter
The modulator/exciter is set up at the factory for the operating frequency (Channel) specified by the
customer as shown on the appropriate FCC document including any appropriate offset.
Refer to the Cadco user manual at the end of this manual for information on the modulator.
C. LTX100( ) Mainframe Power Amplifier
Cabinet - The cabinet is constructed of heavy gauge steel and is very durable. This enclosure is
painted black and is resistive to harsh environment. Standard 19 inch rack mounting.
The LTX100( ) Mainframe is the power amplifier assembly that accepts the video and audio signal
from the modulator/exciter and raises it up to the required output power which will be sent to th
e
antenna.
LTX100( ) Mainframe Assembly's internal sub-assemblies include the following:
1. DC Power Suppl
y
2. RF Deck
3. Status Monitoring (1A0035)
4. Output Power Detector Board (1A0027)
5. Reflected Power Detector (1A0029) and Shutdown Switch
6. Metering and Monitoring Assembly (1A0300
)
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