Harris Maxiva ULX, Техническое руководство

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10/6/10 888-2629-200 4-33
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
Maxiva ULX COFDM Series
4.6.3 IPA (driver) and PA Module
The purpose of Maxiva ULX PA and IPA (driver) module is to amplify modulated RF
signal providing approximately 19dB gain over the TV frequency bands IV/V. The
module includes its own power supply section that generates drain bias for RF power
generating section of the module. The PA module is designed to be used within
terrestrial television standards G, H, I, K, KI, L, M, N with color systems PAL, SECAM
or NTSC. The PA module can operate in common amplification mode with single or
dual aural sub-carrier present along with the visual amplitude modulated carrier. The PA
and IPA (driver) modules can be used to amplify digitally modulated RF signals, such
as COFDM and 8-VSB. The modulation bandwidth is not to exceed 8MHz.
The PA and IPA (driver) Modules are the same, hereafter, they will be referred to as the
PA module. A schematic orientated block diagram of the PA module is shown in Figure
4-13 on page 4-34. The Connector I/O board is the connecting link to the PA or IPA
backplane board for all connectors except for the RF output connector. See the module
photo in Figure 1-6 on page 1-10 to aid in IPA/PA module component identification.
The RF input, signal enters the Connector I/O board through the blind-mate connector
J1. It enters the Splitter board through J2, where it is split into four signals, which are
the drive signals for the four PA pallets, A13 through A16. The RF signal enters each
PA pallet through E1 and the amplifier signal leaves the pallet through E2. From the PA
pallets, the four RF signals enter the combiner board via ports 1 through 4. The
combined output leaves the combiner board and the PA module through a blind mate
RF connector.
Blind mate connector J1 is a combination RF and control connector. A discussion of the
connector pinout is included in Section 4 “Section 4 Theory of Operation” on page 4-39
a drawing of the connector is shown in Figure 4-16 on page 4-40.
Three phase AC power enters the Connector I/O board at J1 pins E1-8 through K1-8,
then via TB1, TB2, and TB3 to the AC Distribution board J10, J11, and J12. In the AC
Distribution board, a single phase of the three phases of AC input power is applied to
each power supply in an arrangement which balances the load between the phases.
Three phase AC in 208 to 240 volt delta or 380 to 415 volt wye can be used in these
transmitters. Additional information concerning the three phase AC connections is
given in Section 4.6.3.1 on page 4-35.
Each power supply provides a DC output voltage which is controlled by the
PA_Voltage_Select signal from the MCM (main control module in the TCU) via the
Cabinet Control Bus pin 7, see Figure 4-14 on page 4-37 for signal path. This DC
voltage, on pin 7 of the Cabinet Control Bus, determines the output voltage of the eight
PA module power supplies as indicated in Table 4-15 on page 4-36. Within the PA
module, the PA_Voltage_Select signal path is via J1-B5 to J2-8 on the Connector I/O
board, J4-8 to J1-8 on the Splitter board, J1-8 to J2-1 on the Monitor board, J9-1 to J1-8
through J8-8 on the AC Distribution board, to J1-8 on each power supply board.