User's Manual

Model 1150A DVOR
6-14 Rev. - November, 2008
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to others for any purposes without written permission from SELEX Sistemi Integrati Inc.
n. Turn on power, turn on the Transmitter and place in bypass.
o. Connect a DVM to 1A4A1 TP5. Adjust 1A4A1R1 for 0.89 to .91 Vdc.
p. Connect DVM to 1A4A1TP4. Verify that the voltage is between 2 and 9 Vdc.
q. Refer to Figure 3-66. Connect a DVM to 1A4A1 TP7. Adjust 1A4A1R4 for 0.9 to 0.95 Vdc.
r. Connect a DVM to 1A4A1 TP11. Adjust 1A4A1R1 for 0.89 to .91 Vdc.
s. Connect DVM to 1A4A1TP10. Verify that the voltage is between 2 and 9 Vdc. If not repeat steps n and o
to select a different point of adjustment.
t. Connect a DVM to 1A4A1 TP6.
u. Adjust Transmitters>>Configuration>>Tx 1 SB1 or SB2 Phase offset to achieve 0.0 +/- 0.1 volts on TP6.
Set the value so that difference is centered about 0 degrees phase shift. For example if 10 degrees
difference between Sideband 1 and Sideband 2 is required then set Sideband 1 to -5 degrees and Sideband 2
to +5 degrees.
v. Select RMS>> Data>> Maintenance Alerts/Alarms Screen. The SB1/2 Phase, SB3/4 Phase should be clear
(not alert indication).
w. Select RMS>> Data>> Maintenance Alerts/Alarms Screen. The SB1/2 Phase, SB3/4 Phase should be clear
(not alert indication).
Table 6-2 Typical Mean Phaser Settings vs Frequency
Frequency (MHz)
Mean Phase Voltage
TP4/TP10 (Vdc)
Jumper Setting for J11
108 3.0 1 to 2
109 3.4 1 to 2
110 3.9 1 to 2
111 4.5 1 to 2
112 5.0 3 to 4
113 2.8 3 to 4
114 3.1 3 to 4
115 3.6 3 to 4
116 4.0 3 to 4
117 4.5 3 to 4
118 5.0 3 to 4
6.4.16 Antenna VSWR Check for New Frequency
All of the radiating antennas in the DVOR antenna system were installed with an initial VSWR that was less than
1.10:1 (Table 4-1a). DVOR antennas are narrow-band devices that are critically tuned using mechanical
components (stubs, positioning pieces, and capacitors) to produce a resonant antenna that is matched to a 50 ohm
impedance feed cable. Any significant change in the operating frequency of the DVOR will change the resonant
point of operation of the antenna and that will affect the VSWR of the antenna and the signal in space of the DVOR
system. Perform the following procedures to determine of there is a need to retune the antenna system.
a. Remove power from the DVOR.
b. Install a power meter (Bird model 43 or equivalent) in the carrier antenna feed cable.
c. Install a 100 W or 250 Watt detecting element in the wattmeter to measure forward power.
d. Turn on the DVOR and record the DVOR carrier forward power.
e. Install a 1 W or 5 W detecting element in the wattmeter to measure reflected power.
f. Record the DVOR reflected power.
g. Calculate the VSWR of the Carrier Antenna using the formula:
PowerREFLPowerFWD
PowerREFLPowerFWD
VSWR
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