Nautel ND2000A-02x-xx0 Series, Технические инструкции

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500 WATT RADIOBEACON TRANSMITTER
ND2000A-02X-xx0
Page 3-15
15 January 2005
NOTE
If the intended modulation depth is less than 95%, it
will be necessary to adjust the modulation depth fault
threshold level, while operating into the antenna
system, as detailed in paragraph 5.3.15.3 and the
combined voice/tone (A3E mode) modulation depth as
detailed in paragraph 5.3.12.
3.13.3.1 Set RF output's modulation envelope to the
intended modulation depth as follows:
(a) Verify the intended carrier level has been
determined as detailed in paragraph 3.13.1 and
the transmitter's unmodulated RF output is the
intended carrier level.
(b) Verify
setting of
RF MON
switch A9A2S1 has
been determined as detailed in paragraph 3.13.2
and it is set to the established setting.
(c) Set switches as tabulated for
Test Setting in
table 4-1.
(d) Set
TONE LEVEL
potentiometers A4A2R19 and
A5A2R19 fully counter clockwise.
(e) Set
the
RF
switch to
ON
.
(f) Set
MOD
switch A4S2 (A5S2) to
ON
.
(g) Monitor oscilloscope waveform and slowly
increase modulation depth by adjusting
TONE
LEVEL
potentiometer A4A2R19 clockwise until
95% modulation is attained or the
SWR-ALARM
lamp turns on or until modulation envelope is
excessively distorted.
(h) Set
TONE LEVEL
potentiometer to the setting
that will provide 95% modulation or the best
compromise of depth and distortion when the
SWR-ALARM
lamp is not turned on.
(i) Set
TEST-Power/Mod
switch to
MOD-SET
.
(j) Adjust
the
SET 100 % MOD
potentiometer for
100% indication on the lower scale of the
TEST-
Power/Mod
meter.
(k) Set
the
TEST-Power/Mod
switch to
MOD-READ .
(l) Record
TEST-Power/Mod
meter's lower scale
indication as the intended modulation depth in
Established References section of table 5-2.
(m) Set
TEST-Power/Mod
switch to
REFL PWR
.
(n)
TEST-Power/Mod
meter's reflected power
indication shall be less than 50 W.
(o)
SWR-ALARM
lamp shall be off.
(p) Set
SELECT MAIN TX
switch to
B
.
(q) Verify the transmitter's unmodulated RF output
is the intended carrier level.
(r) Set
TEST-Power/Mod
switch to
MOD-SET
.
(s) Adjust
SET 100 % MOD
potentiometer for 100%
indication on the lower scale of the
TEST-
Power/Mod
meter.
(t) Set
TEST-Power/Mod
switch to
MOD-READ
.
(u) Adjust
TONE LEVEL
potentiometer A5A2R19
for modulation depth recorded in step (l).
(v) Set
TEST-Power/Mod
switch to
REFL PWR
.
(w)
TEST-Power/Mod
meter's reflected power
indication shall be less than 50 W.
(x)
SWR-ALARM
lamp shall be off.