User Manual

PINEAPPLE TECHNOLOGY, INC. V. THEORY OF OPERATION
DTXPRO-1.2KU OPERATING AND SERVICE MANUAL
THE INFORMATION PROVIDED HEREIN IS PINEAPPLE TECHNOLOGY INCORPORATED PROPRIETARY INFORMATION AND
CANNOT BE COPIED OR DISTRIBUTED WITHOUT PRIOR AUTHORIZATION
V - 5
V. THEORY OF OPERATION (Continued)
E. DXDPRO-10U DIGITAL MODULATOR AND EXCITTER
The heart of any TV Transmitter is the Modulator. This equipment receives the ASI or SMPTE digital
stream from the program source. The modulator generates the ATSC/8VSB signal and up converts it
to the desired Television Channel.
The modulator performs several additional important function as listed below;
1. Manages the linear and non linear correction of the output signal.
2. Provides a platform for all alarms and monitoring functions via Ethernet.
3. Manages TS inputs
REFER TO INSTRUCTION MANUAL PROVIDED WITH THIS PACKAGE FOR MORE DETAILS ON
OPERATING AND USING THE DXDPRO-10U MODULATOR..
F. PA1KU-50 FINAL AMPLIFIER
The DTXPRO-1.2KU transmitter uses three (3) PA1KU-50 integrated power amplifiers. See section VI
PA1KU-50 for block diagram and parts list. This integrated final amplifier assembly is built using 50
VDC power transistors and includes a full power isolator with an 800 watt dump load
G. DRIVER AND ALC CIRCUITS ARE INCLUDED IN THE DXDPRO-10U MODULATOR/DRIVER.
1. The ALC and output power level adjustments are integrated into the DXDPRO-10U modulator.
These controls perform the same as the previous driver with ALC (DR50U). Additional information is
also available in the DTXPRO-10U MODULATOR MANUAL.
The ALC function when active is designed to keep the transmitter output power at a predetermined
level, typically 100%. The output power is sampled with a directional coupler located after the digital
mask filter. The power sampled is detected in the modulator and a DC voltage proportional to the
power level is provided to the processor for display on the front panel and on the Ethernet Web
Page.
2.0 VDC = 120% Output Power
1.8 VDC = 100% Output Power
1.3 VDC = 50% Output Power
Note: % FWD Power = 30V²
% RFLD Power = 12.5V²
The ALC is adjusted to maintain the output power you have selected at a constant level.