User's Manual

Digital UHF Transmitter Chapter 5, Detailed Alignment Procedures
DT835A, Rev. 1 5-1
Chapter 5
Detailed Alignment Procedures
This transmitter was aligned at the
factory and should not require
additional alignments to achieve
normal operation.
This transmitter operates using a MPEG
digital input. Check that the RF output at
J2 of (A11) the coupler is terminated into
a dummy load of at least the rated
output power of the transmitter. While
performing the alignment, 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. The readings should be very
similar. If a reading is way off, the
problem is likely to be in that tray.
Switch on the main AC and the UHF
exciter circuit breakers on the AC
distribution panel behind the rear door of
the exciter cabinet.
5.1 (A11) DM8-R Digital Modulator
(1306978; Appendix C)
The connections to the DM8-R
modulator are made through the rear
panel except for the IF sample output,
which is made through the front panel.
These connections are shown in Table 5-
1.
Table 5-1: DM8-R Modulator Connections
Description
Reference
Designator
Function
IF Output J4
Provides a 44 MHz IF Output with a 50
ohm output impedance
10 MHz Input J3
10 MHz input to the DM8-R modulator.
Provides the reference frequency to the
pilot VCXO.
SMPTE-310M Input J2
SMPTE-310 input that provides the MPEG
stream to the modulator.
110/220 VAC J1 Input Power to the Modulator
5.1.1 DM8-R Modulator Board Configuration
The Digital Modulator Board in the DM8-R is setup through a configuration header
located on the board. The configuration header contains 8 jumper positions between
pins on J26 and J27. The functions of these positions are given in Table 5-2.
Table 5-2 J26/J27 Configuration Header Definition
Function when
Jumper Position
Jumper Is Present Jumper Not Present
1 Header Enabled RS485 Enabled
2 CW Zero Normal Mode
3 Internal PRBS External Source
4 Linear Equalizer On Linear Equalizer Off
5 Nonlinear Off Nonlinear On
6 Preset Table 1 Preset Table 2
7 AGC Tracking AGC Fixed
8 Spare