500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page 5-20
15 January 2005
(g) Set
POWER-AC LINE
switch A6S1 to
ON
.
(h) Verify
DC SUPPLY
lamp A7DS2 (A8DS2) and
B- lamp A2A9DS1 (A3A9DS1) are on.
(i) Set
RF
switch to
ON
.
(j) Adjust
O/P POWER
potentiometer A4A2R48
(A5A2R48) for a 10.0 ampere indication on the
clip-on dc current meter.
(k)
TEST-Volts/Current
meter's indication shall be
10.0 amperes.
(l) If necessary, adjust
Current Cal
potentiometer
R2 (R3) for a 10.0 indication on
TEST-Volts/
Current
meter.
(m) Remove clip-on dc current meter.
(n) Set
TEST-Power/Mod
switch to
FWD PWR
.
(o) Set
O/P POWER
potentiometer A4A2R48
(A5A2R48) for 500 watts of forward power, as
indicated by
TEST-Power/Mod
meter.
(p)
TEST-Volts/Current
meter's indication shall be
between 10.7 and 14.7 amperes.
(q) Set
MOD
switch A4S2 (A5S2) to
ON
and note
TEST-Power/Mod
meter's modulation depth
(percentage) reading.
NOTE
When using
TEST-Power/Mod
meter for an indication
of the RF outputs modulation percentage, always set
TEST-Power/Mod
switch to
MOD-SET
and adjust
SET
100 %
potentiometer for a 100% modulation depth
indication on
TEST-Power/Mod
meter. Set switch to
MOD-READ
for actual reading.
(r) If necessary, adjust
TONE LEVEL
potentiometer
A4A2R19 (A5A2R19) for a 95% modulation
depth indication on
TEST-Power/Mod
meter.
(s) Dc current indication on
TEST-Volts/Current
meter shall be 18.0 ± 2.0 amperes.
(t) Adjust
O/P POWER
potentiometer A4A2R48
(A5A2R48) for the intended carrier level, as
indicated on
TEST-Power/Mod
meter.
(u) Adjust
TONE LEVEL
potentiometer A4A2R19
(A5A2R19) for the intended modulation depth
as indicated on
TEST-Power/Mod
meter.
(v) Record
TEST-Volts/Current
meter's current
indication, when the RF output is the intended
carrier level at the intended modulation depth,
for comparison with future test results.
(w) Set
POWER-AC LINE
switch A6S1 to
OFF
.
(x) Install panel on transmitter upon completion of
tests.
5.4.2
TEST METER ADJUSTMENT:
Check
the accuracy of the forward power and reflected
power indications of
TEST-Power/Mod
meter and if
necessary, adjust as follows:
NOTE
Test-Power/Mod
meter's accuracy was set during
manufacture. Its accuracy will affect the quality of
routine adjustments; therefore, it should not be
disturbed unless its accuracy is suspect or repairs
dictate that adjustments are necessary.
5.4.2.1 Forward
Power
Reading:
Check the
accuracy of the forward power indication of
TEST-
Power/Mod
meter as follows:
(a) Set switches as tabulated for Test Setting in
table 4-1.
(b) Verify dummy load has provision to accurately
measure the power output of the transmitter to
within 2%.
(c) Set
RF
switch to
ON
.
(d) Adjust
O/P POWER
potentiometer A4A2R48
(A5A2R48) for precisely 500 watts (by dummy
load's forward power indication).
(e) Set
TEST-Power/Mod
switch to
REFL PWR
.
(f) Indication
on
TEST-Power/Mod
meter shall be
near zero.
(g) Set
O/P POWER
potentiometer A4 (A5) A2R48
for the intended carrier level, as displayed by
dummy load's forward power indication.
