Data Sheet Chapter 5

10-kW UHF Transmitter with Chapter 5, Detailed Alignment Procedures
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840A, Rev. 0 5-1
Chapter 5
Detailed Alignment Procedures
This transmitter was aligned at the
factory and should not require additional
alignments to achieve normal operation.
Before beginning the alignment
procedures, check that the RF output at
J2 of (A18) the output coupler assembly
of the transmitter is terminated into a
dummy load or is connected to the
antenna. While performing any
alignments, refer to the Test Data Sheet
for the transmitter and compare the final
readings from the factory with the
readings on each of the trays. They
should be very similar. If a reading is off
by a substantial amount, the problem is
likely to be in that tray.
5.1 (A1-A4) UHF Exciter Tray
(1063301; Appendix A)
If the (optional) 4.5-MHz composite input
kit has been purchased, the UHF exciter
tray is capable of operating using either
the 4.5-MHz composite input or the
baseband audio and video inputs. The kit
adds (A24) the composite 4.5-MHz filter
board and (A25) the 4.5-MHz bandpass
filter board to the UHF exciter. The 4.5
MHz generated by the aural IF
synthesizer board is not used when the
4.5-MHz composite input kit has selected
the 4.5-MHz intercarrier signal generated
by the 4.5-MHz composite input. The
composite 4.5-MHz filter board and the
4.5-MHz bandpass filter board are not
used when the 4.5-MHz composite input
kit uses the 4.5-MHz intercarrier signal
generated by the baseband video and
audio inputs with baseband select.
The exciter tray has been factory tuned
and should not need to be aligned to
achieve normal operation. To align the
UHF exciter for 4.5-MHz composite input,
apply the 4.5-MHz composite input, with
the test signals used as needed, to video
input jack J1 on the rear of the tray.
Select the 4.5-MHz composite input by
removing the baseband select from J7-6
and J7-7 on the rear of the tray, if
applied.
To align the UHF exciter using baseband
video and audio inputs, connect the
baseband video, with the test signals
used as needed, to video input jack J2 on
the remote interface panel. For balanced
audio input, connect the baseband audio
to TB1-1(+), TB1-2(-), and TB1-3 (GND)
on the remote interface panel. For
composite/stereo audio, connect the
stereo source to J6 on the remote
interface panel.
5.1.1 (A6) (Optional) Delay Equalizer
Board (1227-1204; Appendix B)
This board has been factory tuned and
should not be retuned without the proper
equipment. If it is necessary to tune the
board:
1. Select a sinX/X test signal as the
video source to the delay equalizer
board.
2. Monitor the video output of the
board at video sample jack J2 with
a video measuring set (VM700) that
has been adjusted to measure
group delay.
3. Tune the four stages of the board
using the variable inductors (L1-L4)
and potentiometers (R7, R12, R17,
and R22) until the signal attains the
FCC group delay curve. The stages
are arranged in order of increasing
frequency. Adjust R29 as needed to
attain the same level coming out of
the board as is going into the
board.