RADIOBEACON TRANSMITTER
ND500II (125 WATTS) DOUBLE SIDEBAND - NO VOICE
Page 5-17
15 September 2003
(i)
Set
MOD %
potentiometer A4R2 fully counter
clockwise.
5.5.3
TRANSMITTER TURN-ON
: Apply
main power to the transmitter and verify the indicator
indications are normal at turn-on, as follows:
(a)
Verify the requirements of paragraph 5.5.2
have been completed.
(b)
Verify main power source is switched on at its
source.
(c)
Set
POWER
switch S3 to
ON
.
(d)
MONITOR BYPASS
lamp DS2,
RF DRIVE
ALARM
lamp DS4,
SHUTDOWN ALARM
lamp
DS7 and
AC POWER
lamp DS10 should turn
on.
(e)
After approximately five seconds,
RF DRIVE
ALARM
lamp DS4 should turn off.
(f)
REMOTE CONTROL
lamp DS1,
MOD DRIVE
ALARM
lamp DS3 and
SWR ALARM
lamp DS6
should be off.
5.5.4
CARRIER LEVEL ADJUSTMENT
:
Set the carrier portion of the RF output to the
'intended' carrier level, as follows:
(a)
Verify the requirements of paragraph 5.5.2
through 5.5.3 have been met.
(b)
Verify switches are set as tabulated for
Calibration Setting
in table 4-1.
(c)
Set
TEST
switch S6 to
FWD PWR
.
(d)
Adjust
O/P PWR
potentiometer A4R31, on
modulator driver PWB assembly, for a forward
power indication, on
TEST
meter M1, that is the
'intended' carrier level (maximum 125 watts).
(e)
Set
TEST
switch S6 to
REFL PWR
.
(f)
Reflected power indication on
TEST
meter M1
shall be near zero watts.
(g)
SWR ALARM
lamp DS6 shall be off.
5.5.5
MODULATION DEPTH (MCW
TONE ONLY) ADJUSTMENT
: Set the
modulation percentage to the 'intended' modulation
depth, as follows:
NOTE
If a high 'Q' antenna is used, it may not be possible
to obtain the desired modulation depth and remain
within RF stress current limits. Refer to section 4
paragraph 4.7 for a more detailed explanation.
(a)
Verify the requirements of paragraph 5.5.2
through 5.5.4 have been met.
(b)
Verify switches are set as tabulated for
Calibration Setting
in table 4-1.
(c)
Set
VOLUME
potentiometer R1 fully counter
clockwise (turned off).
(d)
Set
MOD
switch S2 to
ON
.
(e)
Set
TEST
switch S6 to
MOD % REF
.
(f)
Adjust
SET 100 % REF
potentiometer R2 for a
MOD %
indication of 100 on lower scale of
TEST
meter M1.
(g)
Set
TEST
switch S6 to
MOD % READ
.
NOTE
The 'intended' modulation depth is the 'maximum'
modulation depth a specific antenna system will
accommodate before excessive reflected sideband
and/or distortion is produced. It must not exceed 95
percent.
(h)
Adjust
MOD %
potentiometer A4R2, on
modulator driver PWB, for an indication on the
lower scale of
TEST
meter M1, that is the
'intended' modulation depth.
(i)
Set
RF MON
switch S1, on harmonic filter A7,
to monitor either the RF output’s voltage
(
VOLT
) or current (
CUR
) waveform.
(i)
Adjust
VOLUME
potentiometer R1 clockwise
for a comfortable audio level from
SPEAKER
LS1.
