Thales DVOR 432, Technical Manual

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DVOR 432
Operation and Maintenance Installation
4-7
Ed. 01.04
4.3 MATCHING OF ANTENNAS
4.3.1 Mechanical Preadjustments
The following adjustments have to be carried out at all antennas
according to the station frequency.
4.3.1.1 Plate-Capacitor C
A
a) Remove cover of antenna.
b) Read spacing of capacitor plates C
A
(Fig. 4-2) for the station
frequency fromFig. 4-1 (e.g. 8.2 mmfor 115 MHz).
c) Manufacture an appropriate distance piece in a size equal to the
measure found above (e.g. file head of screw to fit).
d) Loosen lock nuts with spanner and set the plates to the proper
distance with the help of distance piece. The two plates should be
set approximately symmetrical to the frame.
e) Tighten capacitor plates with lock nuts. Then check their distance
once again.
4.3.1.2 Quartz Trimmer-Capacitor C
Tr
Remove antenna cover. Trimmer C
Tr
is located in the center of the
antenna feed (Fig. 4-2). For adjustment, a screwdriver with a long blade
is necessary.
a) Turn C
Tr
carefully (quartz trimmer!) counterclockwise to the stop.
b) Read the number of turns for C
Tr
to adjust station frequency from
Fig. 4-1 (e.g. 11 turns for 115 MHz) and adjust C
Tr
accordingly.
c) Replace cover and fasten it provisionally with 2 or 3 screws.
4.3.1.3 C
5
of Matcher/Decoupling Module
(for sideband antennas only)
The matcher/decoupling module and cables are accessible through an
opening in the antenna pedestal, which is closed by a slide.
a) Turn C
5
(Fig. 4-2) carefully counterclockwise to the stop.
b) Read the number of of turns for C
5
to adjust the station frequency
fromby means of Fig. 4-1 (e.g. 9.5 turns for 115 MHz) and adjust
C
5
accordingly.