RADIOBEACON TRANSMITTER
ND500II (125 WATTS) DOUBLE SIDEBAND - NO VOICE
Page 5-3
15 September 2003
(g)
Connect the transmitter's RF output to a
precision, 50-ohm, resistive dummy load that
has provision to accurately display the RF
power being applied to it and is rated at a
minimum of 250 watts.
(h)
Verify the main power source (AC or DC) is
switched on.
(i)
If using an AC power source, verify it is within
five percent of voltage used to select the
primary and secondary winding taps of power
transformer A1T1 (see paragraph 3.8.3).
(j)
If using a DC power source, verify it is within
±
2V of its nominal DC voltage.
(k)
Set
POWER
switch S3 to
ON
.
(l)
MONITOR BYPASS
lamp DS2,
RF DRIVE
ALARM
lamp DS4,
SHUTDOWN ALARM
lamp
DS7 and
AC POWER
lamp DS10 shall turn on.
(m) All remaining lamps will be off.
(n)
After approximately five seconds,
RF DRIVE
ALARM
lamp DS4 should turn off.
5.3.2.3
B+ DC Voltage (No Load) Check
: Check
the no-load voltage of the unregulated B+ DC power
supply, as follows:
NOTE
TB3 is located on the ATU power supply assembly
which is mounted on the side and is accessible from
the bottom of the transmitter.
(a)
Connect a digital voltmeter between TB3-4 (+)
and ground.
(b)
Digital voltmeter indication shall be between
46.0 and 62.0 VDC.
(c)
Set
TEST
switch S6 to
B+ VOLTS
.
(d)
TEST
meter M1's indication shall be within five
percent of digital voltmeter reading obtained in
step (b).
(e)
Record difference between
TEST
meter M1
reading obtained in step (d) and digital
voltmeter reading obtained in step (b) as
TEST
meter M1's correction factor for
B+ VOLTS
in
Established References
section of table 5-2.
5.3.2.4
+24 Volt DC Check
: Check the output
voltage of the unreg24 VDC power supply,
as follows:
(a)
Connect a digital voltmeter between TB3-1 (+)
and ground.
(b)
Digital voltmeter indication shall be between
22.0 and 26.0V.
(c)
Set
TEST
switch S6 to
+24 VOLTS
.
(d)
TEST
meter M1's indication shall be within five
percent of digital voltmeter reading obtained in
step (b).
(e)
Record difference between
TEST
meter M1
reading obtained in step (d) and digital
voltmeter reading obtained in step (b) as
TEST
meter M1's correction factor for
+24 VOLTS
in
Established References
section of table 5-2.
5.3.2.5
+15V Check
: Check the output voltage of
the reg15V power supply, as follows:
NOTE
A11TB1 is located on the remote interface PWB
(A11) at the rear of the transmitter (see figure MD-
5).
(a)
Connect a digital voltmeter between
A11TB1-24 (+) and ground.
(b)
Digital voltmeter indication shall be between
14.0 and 16.0V.
(c)
Set
TEST
switch S6 to
+15 VOLTS
.
(d)
TEST
meter M1's indication shall be within five
percent of digital voltmeter reading obtained in
step (b).
