MAIN/STANDBY 125 WATT RADIOBEACON TRANSMITTERS WITH CRCU and NDDS/T
(USER SUPPLIED ENCLOSURE/CABINET)
IS02007 (Page 2)
15 February 2002
3.2 MAIN/STANDBY
OPERATION:
Main/standby operation requires the '
A
' and '
B
'
transmitters to be in-circuit and functional. The
main/standby control circuitry on the remote control
interface assembly will dictate which transmitter is
selected as the
main
transmitter and which one is
operational (on-air). The operational (on-air)
transmitter will provide 24VDC source voltage to the
NDDS/T which will then provide a RF signal at the
transmitter’s operating frequency to J3 (Ext RF
Drive) of the operational transmitter.
3.2.1
Selection of Main Transmitter:
The
setting of the remote control interface assembly's
SELECT MAIN TX
switch (3S1) determines which
transmitter is designated and selected as the
main
transmitter, when the '
A
' and '
B
' transmitters are
operational.
3.2.2
Main Transmitter Operational:
When
the transmitter selected by the
SELECT MAIN TX
switch is turned on and producing a satisfactory RF
output, the following will occur:
(a) The source voltage for NDDS/T’s 24VDC
inputs will be provided by the selected main
transmitter. The NDDS/T will provide a RF
signal at the transmitter’s operating frequency
to J3 (Ext RF Drive) of the selected main
transmitter.
(b) The
24VDC
and
15VDC
voltages required by
the remote control interface assembly will be
provided by the selected
main
transmitter.
(c) The
standby
transmitter will be turned off
(inhibited). 15VDC will be applied to TB1-6
of the
standby
transmitter as its
stby on/off
input from the remote control interface
assembly.
(d) The RF output from the selected
main
transmitter will be routed to the antenna by the
main/standby relay in transmitter
A
's harmonic
filter.
(e) The antenna tuning unit operating voltage and
controls (TB2-3/4/5/8) will be provided by the
selected
main
transmitter.
(f) The
system's
remote audio
output at 3TB1-9
(
RMT AUD
) of the remote control interface
assembly will be provided by the selected
main
transmitter.
(g) The system's
changeover alarm
output at
3TB1-10 (
CHG OV ALM
) of the remote control
interface assembly will be a positive DC
voltage, indicating the selected
main
transmitter is operational and a changeover to
the
standby
transmitter has not occurred.
3.2.3
Standby
Transmitter
Operational:
When the transmitter selected by the
SELECT MAIN
TX
switch shuts down because of a malfunction or is
intentionally turned off, the main/standby circuitry
will automatically enable the
standby
transmitter (in-
circuit transmitter not selected as the
main
transmitter) and route its RF output to the antenna.
When the
standby
transmitter is on-air, the following
will occur:
(a) The
24VDC
and
15VDC
voltages required by
the remote control interface assembly will be
provided by the
standby
transmitter.
(b) The
main
transmitter will be off (inhibited).
15VDC will be applied to TB1-6 of the
main
transmitter as its
stby on/off
input from the
remote control interface assembly.
(c) The RF output from the selected
standby
transmitter will be routed to the antenna by the
main/standby relay in transmitter
A
's harmonic
filter.
(d) The source voltage for NDDS/T’s 24VDC
inputs will be provided by the selected standby
transmitter. The NDDS/T will provide a RF
signal at the transmitter’s operating frequency
to J3 (Ext RF Drive) of the selected standby
transmitter.
(e) The antenna tuning unit operating voltage and
controls (TB2-3/4/5/8) will be provided by the
standby
transmitter.
(f) The
remote audio
output at 3TB1-9 (
RMT AUD
)
of the remote control interface assembly will
be provided by the
standby
transmitter.
