500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page 5-12
15 January 2005
(n) If requirement of step (m) is met, go to step (v);
if not, complete steps (o) through (u).
(o) Adjust
TONE LEVEL
potentiometer A4A2R19
(A5A2R19) for a modulation envelope, on
oscilloscope waveform, that is precisely the
modulation depth for the modulation depth fault
threshold determined in step (b).
(p) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(q) If
SET THRSH
lamp A10DS1 is full on (not
flashing), adjust
MOD THRSH
potentiometer
A10R7 until
SET THRSH
lamp A10DS1 is
flashing.
(r) Adjust
MOD THRSH
potentiometer A10R7 until
SET THRSH
lamp A10DS1 just turns full on and
remains on.
(s) Set
KEYING
switch A4S1 (A5S1) to
OFF
.
(t) Adjust
TONE LEVEL
potentiometer A4A2R19
(A5A2R19) for a modulation envelope, on
oscilloscope waveform, that is the intended
modulation depth.
(u) Repeat steps (i) through (m).
(v) Adjust
TONE LEVEL
potentiometer A4A2R19
(A5A2R19) for a modulation envelope, on
oscilloscope waveform, that is the intended
modulation depth.
(w) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(x)
SET THRSH
lamp A10DS1 shall be flashing on
and off.
5.3.15.4 Changeover/Shutdown Check:
Check
auto changeover from side
A
to side
B
and/or the
shutdown of the transmitter when; the RF output falls
below a predetermined minimum carrier level;
modulation envelope falls below a predetermined
percentage or when keying is not present; for a
predetermined period of time, as follows:
NOTE
The changeover delay period, once set, is applicable
to both sides of the transmitter. If either side 'A' or 'B'
of the transmitter shuts down, the pre-selected delay
will occur before
STANDBY ALARM
lamp or, if
applicable,
SHUTDOWN ALARM
lamp turns on.
(a) Verify requirements of paragraphs 5.3.15.1 and
5.3.15.3 are completed and being met.
(b) Set switches as tabulated for
Test Setting
in
table 4-1.
(c) Refer to table 5-2 and determine the time
recorded as the changeover time delay in
Established References
section.
NOTE
If a changeover time delay has not been established
or is to be changed, determine the delay to be used
and record this time as the changeover time delay in
Established References
section of table 5-2.
(d) Set
MOD
switch A4S2 (A5S2) to
ON
.
(e) Set
RF
switch to
ON
.
(f) Verify transmitter is operating at the intended
carrier level and the intended modulation depth.
(g) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(h) Set
MONITOR
switch to
NORMAL
.
(i)
MONITOR-BYPASS
lamp A1A1DS8 shall turn
off and selected side
A
or
B
shall remain on.
(j) Simultaneously start stopwatch, monitor
STANDBY ALARM
lamp and set
KEYING
switch
A4S1 (A5S1) to
OFF
.
(k) After the delay determined in step (c), the
selected side (main) transmitter will turn off and
STANDBY-ALARM
lamp shall turn on.
NOTE
RF CURRENT-ALARM
lamp,
RF DRIVE-ALARM
lamp
A5DS2 (A4DS2) and
AUDIO LIMITER
lamp A5DS1
(A4DS1) shall also turn on. After a nominal five
second delay, these lamps shall turn off and the
standby transmitter shall turn on; provided it is
switched on and is serviceable.
