Nautel XL12, Technical Instructions

Page: 43 / 238

12 000 WATT AM BROADCAST TRANSMITTER
XL12
Page 2-19
01 January 2002
2.2.9.4 Audio Wiring:
Refer to paragraph 2.1.6 to
identify the audio input options and then determine
the audio input option(s) which is/are applicable to
the exciter configuration in use.
(a) Route audio wires thru a cable entry hole in the
cabinet and through the control/monitor panel's
ferrite toroid, to the destination identified for
the exciter configuration in use.
(b) If a monaural audio input which provides 125%
positive/100% negative modulation is used,
connect the positive input to TB2-8 and the
negative input to TB2-9 of the remote interface
PWB.
(c) If a second monaural audio input is used for
exciter B, connect the positive input to TB2-11
and the negative input to TB2-12 of the remote
interface PWB.
NOTE
Connection of the audio cable's shield is
dependent on the presence or absence of ground
loops. In some installations, it may be necessary
to connect the shield at one end only. In these
cases, connect the end that provides the best
results.
(d) If Nautel's AM stereo option is installed,
connect the left and right audio to TB1 of the
C-QUAM AM stereo exciter PWB. The
phase relationship of the left and right audio is
crucial to C-QUAM AM stereo operation.
The correct polarization must be maintained
when connections are made:
- connect left audio's positive input to TB1-5,
negative input to TB1-3 and shield to TB1-4.
- connect right audio's positive input to TB1-10,
negative input to TB1-8 and shield to TB1-9.
2.2.9.5 External RF Drive Wiring:
If the RF
drive for one or both exciters is to be applied from an
external source (refer to paragraph 2.1.5), connect
its wiring as follows:
(a) Route RF drive coaxial cable thru a cable entry
hole in the cabinet and through the
control/monitor panel's ferrite toroid, to the
vicinity of the exciter interface PWB.
(b) Cut the RF drive coaxial cable to length,
terminate it with a coaxial BNC connector and
connect it to the exciter interface PWB's
EXT
RF
connector (J7).
2.2.10 REASSEMBLY:
Assemble panels and
assemblies removed in paragraph 2.2.4.
(a) Install the rear door on the cabinet:
- lift door over cabinet hinge pin.
- snap door's spring-loaded hinge pin into cabinet
retaining socket.
- connect door-to-cabinet ground wire.
(b) Install AC contactor cover inside rear cabinet
frame above A23K1.
(c) Install the connector access panels below the
RF power module trays by turning 1/4 turn
fasteners clockwise.
(d) Install RF output filter access cover using
retained hardware.
(e) Install 8-input RF combiner/filter access cover
using retained hardware.
(e) Install transmitter top cover.
2.2.11 REFERENCE GROUND INTER-
CONNECTION:
Connect a continuous, low-
impedance conductor (0 AWG copper wire, two-inch
copper strap or equivalent), as described in Nautel's
'Lightning Protection for Radio Transmitter Stations'
booklet, between the station reference ground and
the transmitter's reference ground bolt Refer to
figure MD-2 to locate the transmitter's reference
ground and to figure 2-3 for its assembly detail.