RADIOBEACON TRANSMITTER
ND500II (125 WATTS) DOUBLE SIDEBAND - NO VOICE
Page 4-8
15 September 2003
Table 4-4 Modulator Driver PWB (A4) Controls
PANEL MARKING/
REF
FIG
NOMENCLATURE
FUNCTION
DES
NO.
USED IN TEXT
C11
MD-9
PWM Freq
Adjusted to fine tune the PWM square wave
generator's output to 70kHz.
R2
MD-9
MOD %
Adjusted for the keyed tone audio level that will
provide the desired modulation depth.
R26
MD-9
RAMP ADJ
Adjusted for the reference voltage that will position
the negative going peaks of PWM ramp integrator's
triangle waveform output, measured at TP3, at zero
VDC (ground).
R31
MD-9
O/P PWR
Adjusted for the desired RF output carrier level. Set,
when there is no modulation present, for the DC
voltage that will cause the variable pulse width
generator to produce a mod drive (PWM) output with
the required on/off ratio.
