Axcera-430A FCC Type Acceptance Report Operational Description
February 2004
8-3
8.4. System Overview
The 430B (1303854) is made up of the trays and assemblies listed in Table 8-1.
Table 8-1. 430B Major Trays and Assemblies
MAJOR ASSEMBLY
DESIGNATOR
TRAY/ASSEMBLY NAME
DRAWING NUMBER
A2
AC distribution panel
1265-1600
A4
VHF exciter
1070901
A6 and A7
Two VHF amplifier trays
1301169
A8
VHF combiner assembly
1219-1006
A9
Bandpass filter assembly
1067297
A12
Remote interface assembly
1083510
The (A4) VHF exciter can operate using either the baseband audio and video inputs
alone or, if the (optional) 4.5-MHz composite input kit is purchased, the 4.5-MHz
composite input or the baseband video and audio inputs to produce a diplexed,
modulated, and on-channel frequency aural RF output. The switching is
accomplished by a relay on the sync tip clamp/modulator board that uses a baseband
select to control a relay that chooses either the 4.5 MHz generated from the baseband
inputs or from the 4.5-MHz composite input.
To operate the transmitter with the (optional) 4.5-MHz composite input kit using
baseband inputs, the baseband video must be connected to J1 or J2; the baseband
audio must be connected to the proper input jack; and a baseband select must be
connected from J7-6 and J7-7. To operate the transmitter with the (optional) 4.5-MHz
composite input kit using the 4.5-MHz composite input, the 4.5-MHz composite input
must be connected to J1 or J2 and the baseband select must be removed from J7-6
and J7-7.
The RF output of the VHF exciter is split two ways in (A5) the 2-way power splitter
assembly (ZFSC-2-2). The outputs of the splitter feed the two (A6 and A7) VHF
amplifier trays that amplify the RF signals to approximately 300 watts each. The
outputs of the two VHF amplifier trays are combined in (A8) the VHF combiner that
provides approximately 600 watts peak of sync output. The 600-watt output is
connected to (A9) a bandpass filter assembly. The bandpass filter is tuned to provide
the high out-of-band rejection of unwanted products. The filtered signal is connected
to A9-A5, a coupler assembly that provides a forward and a reflected power sample to
the visual/aural metering board in the VHF exciter. The forward sample is processed to
provide peak detected visual and aural power output samples to the transmitter
control board in the VHF exciter. The reflected power sample is also peak detected and
wired to the transmitter control board. The transmitter control board connects the
visual, aural, and reflected power output samples to the front panel meter to monitor
the system.
In the VHF amplifier tray, a forward power sample and a reflected power sample from
the 4-way combiner board are connected to the dual peak detector board, single
supply. This board provides peak-detected forward samples to the amplifier control
board and supplies the samples to the front panel meter of the tray.