RADIOBEACON TRANSMITTER
ND500II (125 WATTS) DOUBLE SIDEBAND - NO VOICE
Page 4-4
15 September 2003
Table 4-2 Front Panel Controls and Indicators
PANEL MARKING/
REF
FIG
NOMENCLATURE
FUNCTION
DES
NO.
USED IN TEXT
DS1
MD-1
REMOTE CONTROL
Indicates
CONTROL
switch S4 is set to
REMOTE
and
control of the on/off function has been extended to a
remote location when on.
DS2
MD-1
MONITOR - BYPASS
Indicates
MONITOR
switch S5 is set to
BYPASS
and
shutdown circuits are inhibited when on.
DS3
MD-1
MOD DRIVE ALARM
Indicates the variable pulse width mod drive (PWM)
has been inhibited when on. PWM output is inhibited
by a variable pulse width that would cause excessive
RF output or when the RF drive is below the pre-set
minimum levels.
DS4
MD-1
RF DRIVE ALARM
Indicates the RF drive level has fallen below the
minimum RF drive threshold when on.
DS5
MD-1
OVERMOD ALARM
Indicates troughs of modulation envelope, as sensed
by an RF current probe at the harmonic filter's input
are exceeding the pre-set overmod threshold when on.
Normally turns on when the antenna impedance is
less than 50 ohms at the sideband frequency and the
antenna current is exceeding the current that would be
present if the antenna impedance was 50 ohms.
DS6
MD-1
SWR ALARM
Indicates a reflected power in excess of 14 watts has
been sensed at the output of the harmonic filter, and
the RF output is being cutback when on.
DS7
MD-1
SHUTDOWN ALARM
Indicates transmitter has been shut down when on.
DS8
MD-1
ATU STALL
Indicates antenna tuning unit's tuning motor is
drawing excessive current (normally stalled) when on.
DS9
MD-1
BATTERY ALARM
Indicates operating voltage for transmitter is being
provided by the external DC (battery) power source
when on.
DS10
MD-1
AC POWER
Indicates operating voltage for transmitter is being
provided by the AC power source when on.
F1
MD-1
BATTERY
Fuses positive voltage side of external DC power
supply, on output of DC filter U3, at 12 amperes (+48
VDC source) or 20 amperes (+24 VDC source).
