Nautel XL12, Technical Instructions

Page: 80 / 238

12 000 WATT AM BROADCAST TRANSMITTER
XL12
Page 3-19
01 January 2002
Table 3-2 Exciter Panel Controls and Indicators
PANEL MARKING/
REF FIG NOMENCLATURE FUNCTION
DES NO. USED IN TEXT
A2A1S1 MD-7
AUDIO SOURCE
Three position switch (
STEREO
,
DUAL
, or
SINGLE
), with its
setting determined by the number of audio inputs being
applied and/or the exciter RF drive configuration.
Set to
STEREO
when a C-QUAM AM stereo exciter is
installed as exciter A's RF drive source.
Set to
DUAL
when two modulating audio inputs (one for
each exciter) are being applied and a monaural RF drive
PWB is installed as the RF drive source for both exciters.
Set to
SINGLE
when one audio input (common to both
exciters) is being applied and a monaural RF drive PWB is
installed as the RF drive source for both exciters.
A2A1R3 MD-7
IPM GAIN 1
Adjusted in conjunction with the active RF drive PWB's
IPM CORRECTION
(
IPM BALANCE
in C-QUAM AM Stereo
exciter PWB) potentiometer for minimal incidental phase
modulation (IPM) when the forward power level is 12 000
watts and it is being 95% modulated by a 1000Hz sine
wave.
A2A1R4 MD-7
IPM GAIN 2
Adjusted to set the reference voltage for the IPM
compensation circuit to obtain an
IPM compensation
output that represents the voltage present at the most
negative going excursion of the
PA Volts
audio component
when the RF output is 12kW and it is being 95% modulated
by a 1000Hz sine wave.
A2A1
♦
R5 MD-6
SYMMETRY
Adjusted to set the duty cycle of the RF drive voltage at
the RF amplifier in the RF power modules.
A2A1
♦
R20 MD-6
IPM CORRECTION
Adjusted in conjunction with the exciter interface PWB's
IPM GAIN 1
potentiometer for minimal incidental phase
modulation (IPM) when forward power level is 12kW and it
is being 95% modulated by a 1000Hz sine wave.
A2A1
♦
E1 MD-6
RF Drive Source
Bi-position selector circuit that allows the user to configure
the RF drive PWB to use either the output of an integral
crystal controlled oscillator or an external RF generator as
the RF drive source.
The integral crystal controlled oscillator is selected as the
RF drive source when shorting shunt post E1 is installed
on 3-pin header XE1's
MONO
position (pins 1/2 shorted).
The external RF generator is selected as the RF drive
source when shorting shunt post E1 is installed on 3-pin
header XE1's
STEREO
position (pins 2/3 shorted).