500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page 5-22
15 January 2005
(k) Set
MOD
switch A4S2 (A5S2) to
ON
.
(l) Set
Test-Power/Mod
switch to
MOD-SET
.
(m) Adjust
SET 100 % MOD
potentiometer for a
100% modulation depth indication on
TEST-
Power/Mod
meter.
(n) Set
TEST-Power/Mod
switch to
MOD-READ
.
(o) Adjust
TONE LEVEL
potentiometer A4A2R19
(A5A2R19) for the intended modulation depth,
as indicated by
TEST-Power/Mod
meter.
(p) Slowly decrease variac's output until
BATTERY-
ALARM
lamp just turns on when dc option is
installed or
SWR-ALARM
lamp just turns on
when dc option is not installed.
(q) Ac voltmeter's indication shall be 15.5 ± 0.5%
(10.5 ± 0.5% if low end of ac supply voltage is
180 V RMS) less than the voltage determined in
step (e).
(r) If necessary, slowly adjust
Low AC Voltage
Threshold
potentiometer A7A3R3 (A8A3R3)
until the appropriate
ALARM
lamp (
BATTERY
or
SWR
) just turns on.
(s) Slowly increase variac's output until the
ALARM
lamp (
BATTERY
or
SWR
) just turns off.
(t) Ac voltmeter's indication shall be 10.5 ± 0.5%
(5.5 ± 0.5% if low end of ac supply voltage is
180 V RMS) less than the voltage determined in
step (e).
(u) Repeat steps (p) through (t) until their
requirements are met without further adjustment
of
Low AC Voltage Threshold
potentiometer
A7A3R3 (A8A3R3).
(v) Disconnect variac and connect transmitter
directly to the ac power supply source.
5.4.4
LOW
BATTERY
VOLTAGE
THRESHOLD ADJUSTMENT (DC OPTION
INSTALLED):
Verify the low battery voltage
threshold is set to the level that will initiate a
transmitter shutdown when the battery bank has
discharged to the battery manufacturer's
recommended discharge cut-off voltage, as follows:
NOTE
The low battery threshold level is set to -42.0 V dc
during factory tests. If the battery manufacturer's
recommended discharge cut-off voltage is less
negative than -42.0 V dc, the recommended cut-off
voltage may be used to determine the low battery
voltage threshold level. The low battery threshold
level must not be more negative than -42.0 V dc.
5.4.4.1 Low Battery Voltage Threshold
Adjustment Pre-requisites:
Complete the following
pre-requisites prior to attempting to determine the low
battery voltage threshold or finalizing the adjustment.
(a) Verify battery panel related links are removed
from between terminals TB3-1/TB3-2 and
TB3-3/TB3-4 (see note on figure SD-1).
(b) Set
Low Battery Threshold
potentiometers
A11A1R7 side
A
and A11A1R8 side
B
fully
clockwise.
(c) Set switches as tabulated for
Test Setting
in
table 4-1.
(d) Set
POWER - BATTERY
switch A6S2 to
ON
.
(e) Set
RF
switch to
ON
.
(f) Set
MOD
switch A4S2 (A5S2) to
ON
.
(g) Verify transmitter's RF output is the intended
carrier level and its modulation envelope is the
intended modulation depth.
(h) Set
POWER-AC LINE
switch A6S1 to
OFF
.
(i)
BATTERY ALARM
lamp shall turn on.
(j) Verify the transmitter's RF output is the
intended carrier level and its modulation
envelope is the intended modulation depth.
