MAIN/STANDBY 125 WATT RADIOBEACON TRANSMITTERS WITH CRCU and NDDS/T
(USER SUPPLIED ENCLOSURE/CABINET)
IS02007 (Page 3)
15 February 2002
(g) The system's
changeover alarm
output at
3TB1-10 (
CHG OV ALM
) of the remote control
interface assembly will be a ground potential,
indicating a changeover to the
standby
transmitter has occurred.
3.3 REMOTE (CRCU) CONTROL/
MONITORING:
A computer remote control unit
(CRCU) provides the control/monitoring interface
between the main/standby transmitter system and the
host (master) system.
3.3.1
Remote On/Off Control:
A
transmitter
off command
is applied to TB2-6 (
ON
/
OFF
) of each
transmitter from the computer remote control unit
(CRCU). If a transmitter's
CONTROL
switch has
been set to
REMOTE
, this command will turn off the
(both) transmitter(s) when it is an open circuit and it
will turn on the (both) transmitter(s) when it is a
current-sink-to-ground. If a transmitter's
CONTROL
switch has been set to
LOCAL
,
this command will
have no influence.
NOTE
The
CONTROL
switch, on the front panel of each
transmitter must be in the
REMOTE
position in order
for the CRCU to have on/off control.
3.3.2
Standby Transmitter Check:
When the
standby
transmitter is to be turned on from a remote
location to check its operational availability and the
main
transmitter is to be restored as the on-air
transmitter on completion of the check, the following
must occur:
(a) The remote control interface assembly's
RMT
XFR
switch must be set to
ENABLE
.
(b) A ground potential
transfer command
must be
applied to 3TB2-6 (
XFR CMD
) of the remote
control interface assembly from the computer
remote control unit (CRCU) for the duration of
the check.
(c) While a ground potential is being applied to
3TB2-6, the
standby
transmitter will be
enabled as detailed in paragraph 3.2.3.
(d) When the ground potential is removed from
3TB2-6 or the
REMOTE TRANSFER
switch is
set to
DISABLE
,
the
standby
transmitter will be
turned off and the selected
main
transmitter
will be restored as the operational transmitter
as detailed in paragraph 3.2.2.
THEORY OF OPERATION
4
The remote control interface circuits,
which provide the main/standby transmitter control
and main/standby related remote monitoring outputs
are described in the following. Refer to figure SD-1
for the system electrical schematic and then to figure
SD-2 for the remote control interface assembly's
electrical schematic.
NOTE
Remote control/monitoring of the main/standby
transmitter system is accomplished via the computer
remote control unit (unit 4) in conjunction with the
remote control interface assembly (unit 3). The
theory contained in this document pertains to the
remote interfacing provided by the remote control
interface assembly. Refer to the CRCU instruction
manual for its theory of operation.
4.1 ND500II
TRANSMITTERS
: Refer to
the ND500II - 125 radio beacon technical instruction
manual for a detailed theory of operation for the
transmitters. The theory for both transmitters is
identical with one major exception. The '
A
'
transmitter's harmonic filter contains a main/standby
relay which routes the output of the on-air transmitter
to the antenna.
4.1.1
Transmitter Standby Control:
The
stby on/off
control input at TB1-6 of each transmitter
is provided by the main/standby circuitry in the
remote control interface assembly (unit 3).
4.1.1.1
When a transmitter is to be inhibited (its
RF output is turned off) because it is being held in
reserve as the
standby
transmitter, its
stby on/off
input will be +15vdc. The following will be true:
(a) The
+24VDC
output at A7TB6-6 of the
transmitter will be 0.0VDC.
(b) The
+15VDC
output at TB2-1 of the
transmitter will be 0.0VDC.
