500 WATT RADIOBEACON TRANSMITTER
ND2000A-02x-xx0
Page
4-15
15 January 2005
Table 4-8
Monitor PWB
Controls and Indicators
PANEL MARKING/
REF
FIG
NOMENCLATURE
FUNCTION
DES
NO.
USED IN TEXT
A10DS1
MD-34
SET THRSH
Flashes between tone periods during keyed MCW
operation. Continuously on when RF carrier level falls
below preset carrier fault threshold (normally -3.0 dB)
or when modulation level falls below preset
modulation fault threshold (normally -4.0 dB) or
keying fails.
A10LS1
MD-34
SPEAKER
Provides an audible signal for local monitoring of the
detected modulation.
A10R7
MD-34
MOD THRSH
Adjusted to produce a modulation fault signal when
modulation level falls below the desired percentage
(must be at least 1.0 dB below the carrier fault
threshold). Ultimately will cause the transmitter to
shut down if the modulation percentage does not
exceed this minimum threshold level within the time
delay period of the shutdown circuit.
A10R18
MD-34
CARR THRSH
Adjusted to produce a carrier fault signal when the
carrier level falls below the desired level (usually -3.0
dB). Ultimately will cause transmitter shut down if the
carrier level does not exceed this minimum threshold
level within the time delay period of the shutdown
circuit.
A10R23
MD-34
RF CURRENT
Adjusted, when operating into a 50.0 ohm resistive
load, for a modulation threshold (normally 95%) that
represents the maximum permissible before peak RF
current thresholds are exceeded. When the modulation
envelope exceeds 95%, the peak detected RF current
sample will cause the
RF CURRENT ALARM
lamp to
turn on.
A10R48
MD-34
CHANGEOVER DELAY
Adjusted for a delay of between 20 and 80 seconds
before transmitter changeover/shutdown occurs.
A10R79
MD-34
FWD PWR CAL
Adjusted, during adjustment procedures, to precisely
set the forward power indication on the
TEST
meter,
when the
TEST
switch is set to
FWD PWR
.
A10R95
MD-34
SWR CUTBACK THRESHOLD
Adjusted for
SWR
fault threshold that represents the
maximum acceptable reflected power before an
SWR
cutback output will be produced. When an
SWR
cutback output is produced, the RF output will be
cutback to a level that will ensure the reflected power
does not exceed the threshold level.
