User's Manual Part 1

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allows to manage the Transport Stream (TS) inputs in a fully redundant configuration, thus significantly improving
the reliability of the whole broadcasting system in every operating condition.
The ATSC TRANSMITTER is totally compliant to the A/53, A/54 and A/64 ATSC recommendations with
6MHz output channel bandwidth, in VHF and UHF bands.
RF AMPLIFIER MODULE DESCRIPTION
The RF Amplifier Modules place in the TXUD1000/ATSC Transmitter station are equipment designed to
simplify transport and installation. Born to ensure high working reliability they excel also for their great
performance. Thanks to the excellent linearity of the amplifiers, achieved with the use of the state-of-the-art
LDMOS (UHF) technology, these equipment allow excellent performance both with analog and digital TV
signals. The design redundancy (a power supply for every MOS device), the oversized unbalanced power
dummy loads, the wide input range of the switching-mode power supplies, allow a NO STOP transmission
24h per day. The temperature of the amplifiers is guaranteed by a forced air cooling system extremely noiseless.
The presence of Amplifier Control that collects all measures from amplifiers and from antenna system ensure
a single control point to access to all MOSFET currents, power supplies voltages, temperature of the heat
sinks, amplifiers output powers together with the RF power reading of the output antenna system.
A multifunctional display on the Amplifier Control makes it possible to verify all the operating parameters of
the unit. The amplifiers in the series are remotable by wired telemetry connector or by serial communication,
RS232 on front panel or RS485 on rear panel of the Amplifier Control.
CHANNEL CHANGE PROCEDURE
To proceed with a channel change operation, please follow the below indications:
- Follow the channel change indications on users manual of the exciter;
- from each RF Amplifier Modules select the new closest channel frequency;
- tune the Bandpass Output Filter on new channel;
- if the difference with the two channel is less than 10 you don’t need to change the power amplifier phase
balance. Otherwise, connect a digital meter to a DC Monitor (BNC) on each dummy load and keep low the
value, by tuning the microstrip length on the input divider;
- connect a Wattmeter and a Dummy Load;
- set the rated output power and tune the right Forward Power indication on the Amplifier Control display;
- set the output at 10% of the rated ones, swap the Forward and Reflected cable on the rear of the Amplifier
Control and set the reflected indication.
The 3dB Output Coupler is a wide band type and don’t need any tuning operations.