UHF Analog Driver/Transmitter/
Chapter 5, Detailed Alignment Procedures
Translator
LX Series, Rev. 3
5-2
factory with the readings on each of the
modules. The readings should be very
similar. If a reading is way off, the
problem is likely to be in that module.
Switch On the main AC for the system.
5.2 LX Series Exciter/Amplifier
Chassis Assembly
The transmitter operates using baseband
audio and video inputs. The translator
uses the on channel UHF input.
NOTE:
In systems that contain two
exciters with an exciter switcher, both
exciters must have audio and video
inputs. Each exciter should be operated
one at a time using the following
procedure by first selecting Exciter A as
the On Air exciter then selecting Exciter B
as the On Air exciter. The Exciter
Switcher must be in the manual mode.
On the LCD Display, located on the
Controller/Power Supply Module, in
Transmitter Set-Up, push the right
button to switch the transmitter to
Operate, STB will be displayed. The
check of and the setup of the Audio and
Video input levels are completed using
the LCD Display and the front panel
adjustments on the Modulator assembly.
The level of the RF output includes
adjustments of the drive level to the
Power Amplifier and the adjustment of
the linearity and phase predistortion to
compensate for any nonlinear response
of the Power Amplifier. The adjustments
are located on the front panel of the IF
Processor module.
5.2.1 (Optional) Receiver Module
Assembly
NOTE:
Not present in a Transmitter
system.
Connect an on channel RF input to J12
the receiver RF input jack on the rear of
exciter/driver assembly.
Verify that all LEDs located on the front
panel of the Receiver are Green. The
following details the meaning of each
LED:
PLL 1 Fault (DS6)
- Displays the status
of the Local oscillator PLL
PLL 2 Fault (DS8) -
Displays status of
optional input frequency correcting PLL
DC on center conductor (DS4) -
Displays whether or not DC is applied to
the RF input center conductor*
*Caution: Do not hook up the RF
input to any test equipment with the
DC bias applied. Always move the
jumper W1 on J2 on the UHF
Preamplifier board to the Bias off
position,
between pins 2 & 3,
to
prevent possible damage to the test
equipment.
5.2.2 Modulator Module Assembly
NOTE:
May not present in a Translator
system.
The Modulator Assembly has adjustments
for video levels and audio modulation
levels, and other related parameters.
Connect an NTSC baseband video test
signal input (1 Vpk-pk) to the transmitter
video input jack J7 on the rear of the
exciter. Jacks J7 and J17 are loop-
through connected; the J17 jack can be
used as a video source for another
transmitter. Connect a baseband audio
input (+10 dBm) to the balanced audio
input terminal block TB02-1 [+], TB02-2
[-], and TB02-3 [ground] or, if
stereo/composite audio is provided,
connect it to BNC jack J3, the composite
audio input jack. Verify that all LEDs
located on the front panel of the
Modulator are Green. The following
details the meaning of each LED:
AURAL UNLOCK (DS5)
– Red Indicates
that 4.5 MHz Aural IF is unlocked from
the Nominal 45.75 MHz visual IF.
