Vertex Standard VXA-210 Service Manual page 14

Alignment
PLL Reference Frequency
r Connect the wattmeter, dummy load and frequency
counter connected to the antenna jack, and tune the
transceiver to 120.000 MHz.
r Transmit, and adjust TC1001 on the RF Unit, if nec-
essary, so the counter frequency is 120.000 MHz (±100
Hz).
TX Power Adjustment
r Connect the wattmeter and dummy load to the anten-
na jack, and tune the transceiver to 128.000 MHz.
r Transmit, and adjust VR1004 to obtain 1.5 W RF (car-
rier) power indicated on the wattmeter (without audio
modulation input).
TX Modulation Adjustment
r Connect the Radio Tester to the antenna jack, then
adjust the AF generator output level for injection of
200 mV rms @ 1 kHz to the MIC jack. Leave the trans-
ceiver tuned to 127.500 MHz.
r Transmit, and adjust VR1002 to obtain 85 % modula-
tion (±5 %) as indicated on the Radio Tester.
r Reduce the AF generator output level to 20 mV rms,
then adjust VR1001 to obtain 30 % modulation (±3
%) on the Radio Tester.
TX Power Adjustment
PLL Reference Frequency
14
VR1004
TC1001
Alignment Point
VOR Phase Adjustment
r Set the transceiver to 108.000 MHz, set up the "FROM"
mode (press [ F ] + [ 3 ( FROM )] key, if necessary), and
set the Avionics Radio Tester as shown below.
Frequency
Output Level
30 Hz VAR.
9.96 kHz Carrier
9.96 kHz MOD
DIRECT
PHASE
r Adjust VR1003 for 90° (±1°) on the transceiver dis-
play.
VR1002
TX Modulation Adjustment
VR1001
TX Modulation Adjustment
VR1003
VOR Phase Adjustment
108.000 MHz
+40 dBµ
30 %
30 %
480 Hz
FROM
90°