User's Manual

UHF Analog Driver/Transmitter/ Chapter 2, System Description,
Translator Maintenance & Remote Control Connections
LX Series, Rev. 3 2-4
NOTE: If both the Receiver and
Modulator are present in your system
the Modulated IF output from the
Receiver or Modulator must be selected.
This is accomplished by connecting a low
or removing the low to TB31-Pin 3
located on the rear of the exciter/driver
assembly. By connecting the low, the
Modulator IF output is used by the IF
Processor module. By removing the low,
the IF from the internal or external
Receiver is used. (NOTE: The IF
Processor board must be configured for
external switching by placing jumper
W11 on J29 between pins 1 & 2).
The UHF/VHF Receiver converts a low
level RF input signal to an IF frequency
of 44 MHz, filters off any unwanted out
of band energy, and normalizes the level
so that it can be applied to the IF
processor assembly. It consists of three
boards. The RF input is applied first to
the UHF/VHF preamplifier board, which
filters off out of channel energy and
amplifies the input signal. The RF output
is applied to the Mixer/PLL board, which
converts the signal down to an IF
frequency of 44 MHz. The IF output is
applied to the IF ALC board, which
amplifies the signal, filters off any
unwanted out of band energy and
controls its own IF gain to make sure
that the IF output level is constant.
There is also a provision to apply +12V
to the RF input center conductor to
power an external preamplifier.
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.
Table 2-2. Receiver Front Panel Switch
SWITCH FUNCTION
MAN/AUTO ALC
SW1
When Manual ALC is selected, the level is set by the
Manual ALC Pot R57 located on the mixer/PLL board.
(NOTE: The pot is factory set and needs no adjustment
by the customer).
When Auto ALC is selected, the level control circuit will
automatically increase or decrease the ALC to maintain
the desired output level.