500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page 5-9
15 January 2005
(l) Oscilloscope
waveform's modulation envelope
(external voice audio) shall be 60% of intended
modulation depth.
(m) If necessary, adjust
VOICE MOD %
potentiometer
A4A2R21 (A5A2R21) until oscilloscope
waveform's modulation envelope is 60% of
intended modulation depth.
(n) Switch off signal generator's output.
(o) Oscilloscope
waveform's modulation envelope
(tone audio) should be 35% of intended
modulation depth.
(p) If necessary, adjust
TONE MOD%
potentiometer
A4A2R20 (A5A2R20) until oscilloscope
waveform's modulation envelope is 35% of
intended modulation depth.
(q) Switch on audio signal generator and set its
output to 1000 Hz at 0 dBm (0.77 V RMS).
(r) Oscilloscope
waveform's modulation envelope
shall be the composite of the external voice
audio and the tone audio (A3E). Maximum
modulation peaks shall not exceed the intended
modulation depth.
(s) Disconnect audio signal generator.
(t)
Remove shorting jumper from TB4-19.
5.3.13 IDENTIFICATION
CODE
CHECK:
Check station identification code 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 carrier and modulation depth are
set to their intended levels.
(e) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(f) Set
SPEAKER
switch to
ON
.
(g) Adjust
SPEAKER VOLUME
potentiometer for a
clear audible keyed beacon identification tone.
(h) The deciphered coded portion of the
identification message shall be the station
identification characters as assigned in
paragraph 3.9.3.1.
Refer to table 5-3 for a list of
Morse code characters.
(i) Using a stopwatch, measure and record the time
for one frame length (from the start of the code
of one frame to the start of the code of the next
frame).
(j) The time recorded in step (i) shall be between 5
and 16 seconds (typically 8 seconds; see
paragraph 3.9.3.1).
5.3.14 STANDBY '1' AND STANDBY '2'
CODE CHECKS:
Check for generation of the
standby 1 and standby 2 code variations as follows:
(a) Verify requirements of paragraphs 5.3.2 through
5.3.12 have been completed.
(b) Set switches as tabulated for
Test Settings
in
table 4-1.
(c) Set
RF
switch to
ON
.
(d) Set
MOD
switch A4S2 (A5S2) to
ON
.
(e) Verify the RF carrier output and modulation
depth are set to their intended levels.
(f) Set
KEYING
switch A4S1 (A5S1) to
ON
.
(g) Set
SPEAKER
switch to
ON
and verify an
audible keyed beacon tone can be heard from
the speaker.
(h) Connect a shorting jumper (standby 1) between
TB3-7 (TB3-11) and ground.
(i) Standby 1 code variation, as assigned in
paragraph 3.9.3.1 and recorded in table 5-2,
shall be included in the identification portion of
the ident code.
(j)
Disconnect jumper from TB3-7 (TB3-11).
(k) Connect a shorting jumper (standby 2) between
TB3-8 (TB3-12) and ground.
