500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page 5-17
15 January 2005
5.3.18.1
RF Current-Alarm Check:
RF
CURRENT-ALARM
lamp was checked in paragraph
5.3.17.
5.3.18.2 SWR-Alarm Check:
SWR-ALARM
lamp
was checked in paragraph 5.3.16.
5.3.18.3 Shutdown-Alarm Check:
Check
SHUTDOWN-ALARM
lamp as follows:
(a) Set switches as tabulated for
Test Setting
in
table 4-1.
(b) Set
RF
switch to
ON
.
(c) Set
MOD
switch A4S2 (A5S2) to
ON
.
(d) Verify the RF output is the intended carrier level
and it is being modulated by the intended
modulation depth.
(e) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(f) Set
MONITOR
switch to
NORMAL
.
(g) Verify
MONITOR-BYPASS
lamp is turned off.
(h) Set
KEYING
switch A4S1 (A5S1) to
OFF
.
(i) After the changeover time delay recorded in
Established References
section of table 5-2
(between 20 and 80 seconds), the selected side
(main transmitter) will shut down and
STANDBY-ALARM
lamp will turn on.
NOTE
When changeover occurs and the standby transmitter
fails to turn on, an additional 20 to 80 second delay
will occur plus a nominal five second delay before a
shutdown-alarm control signal is generated.
(j) After an additional changeover time delay
period (between 20 and 80 seconds),
SHUTDOWN-ALARM
lamp will turn on.
(k) Set
RF
switch to
OFF
.
(l) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(m) Set
MONITOR
switch to
BYPASS
.
(n) Set
RF
switch to
ON
.
(o)
MONITOR-BYPASS
lamp shall turn on,
STANDBY-ALARM
lamp and
SHUTDOWN-ALARM
lamp shall turn off.
(p) The selected side (main transmitter) shall turn
on and resume normal operation.
5.3.18.4 Standby-Alarm Check:
The standby
changeover and indicator circuits are checked in
paragraphs 5.3.18.3.
5.3.18.5 Battery-Alarm Check:
When the dc
option is installed,
BATTERY-ALARM
lamp function is
checked in paragraph 5.3.19. When the dc option is
not installed,
BATTERY-ALARM
lamp function is
checked in paragraph 5.4.3.
5.3.18.6 Mod
Drive-Alarm
Check:
Check mod
drive fault monitoring/indicating circuits as follows:
NOTE
Completion of these checks will alter PWM ramp
integrator circuit. On completion, the ramp
integrator circuit must be readjusted in accordance
with paragraph 5.3.7.
(a) Set switches as tabulated for
Test Setting
in
table 4-1.
(b) Set
POWER TRIM
potentiometer A4R5 (A5R5)
and
RAMP ADJUST
potentiometer A4A2R58
(A5A2R58) fully clockwise.
(c) Set
O/P POWER
potentiometer A4A2R48
(A5A2R48) fully counterclockwise.
(d) Connect a shorting clip across resistor
A4A2R59 (A5A2R59).
(e) Connect an oscilloscope between test point
A4A2TP6 (A5A2TP6) and ground.
(f) Disconnect connector P6 from A4J1 (A5J1).
(g) Set
RF
switch to
ON
.
(h) Adjust
O/P POWER
potentiometer A4A2R48
(A5A2R48) clockwise until
MOD DRIVE-ALARM
lamp A4DS3 (A5DS3) turns on.
