Nautel ND500II Manual

MAIN/STANDBY 125 WATT RADIOBEACON WITH NDDS/T
IN NARB07 CABINET)
INTRODUCTION
1.
When two ND500II 125 watt radiobeacon
transmitters and an NDDS/T Dual Direct Digital
Synthesizer (DDS) are installed in an NARB07
cabinet, some mechanical information in the
transmitter's instruction manual must be changed and
the cabinet's electrical information is required. This
document identifies the mechanical differences. It
also provides an electrical parts list and point-to-point
wiring information for the cabinet. It is recommended
that, where replacement pages are not provided,
affected areas of the transmitter instruction manual be
highlighted using a suitable marker, or changed using
pen and ink, to ensure users of the manual are aware
of the differences.
MECHANICAL DIFFERENCES
2.
The drawer slide depicted in figure MD-17
of the transmitter instruction manual has been
replaced with a different type of slide.
possible to swivel the transmitter when using this
slide. All references to rotating the transmitter when
it is extended on its drawer slide must be ignored. If it
is not possible to access a specific area of a transmitter
when it is extended on its drawer slide, the transmitter
must be lifted off its slides and placed on a work
surface.
CABINET DESCRIPTION (see figure 1):
3.
The cabinet is 30 inches high, 21 inches
wide and 24.5 inches deep. It houses two ND500II
radiobeacon transmitters and an NDDS/T. The upper
transmitter is designated as the A transmitter, while
the lower transmitter is designated as the B
transmitter. The cabinet also contains a type N RF
coaxial connector (J1), which is the RF output
connection point for the RF feed cable; two AC power
duplex receptacles; a two-pole, double-throw switch
(S1) that selects which transmitter will be the main
transmitter; three barrier strips (TB1, TB2 and TB3),
which are used as the external wiring interface; and
the interconnecting wiring. Refer to figure 3 for an
electrical schematic of the cabinet.
THEORY OF OPERATION
4.
ND500II instruction manual describes the operation
of both transmitters. The following provides a brief
description for when they are connected in a
main/standby dual installation. See figure 3 of this
information sheet for system interconnection.
The upper transmitter (ND500II-113-x20) is identified
as the A transmitter and the lower transmitter
(ND500II-013-x20) is the B transmitter.
transmitter's harmonic filter contains a relay that
routes the RF output of the active transmitter to the
antenna system.
4.1
main transmitter, as selected by the (S1)
switch, is turned on and producing a satisfactory
TX
It is not RF output; the following will occur:
(a) The source voltage for the NDDS/T's 24VDC
inputs will be provided by the selected main
transmitter. The NDDS/T will provide a RF
signal at the transmitter's operating frequency to
J3 (Ext RF Drive) of the selected main
transmitter.
(b) 15VDC, from TB2-1 of the main transmitter,
will be applied to TB1-6 of the standby
transmitter as its standby off control signal.
(c) If the A transmitter is the main transmitter, the
main/standby relay in its harmonic filter will be
energized.
transmitter, the main/standby relay in the A
transmitter's harmonic filter will be de-
energized. The selected main transmitter's RF
output will be routed to the cabinet's
coaxial connector (J1).
(d) The source for the antenna tuning unit controls,
at TB3-6 thru TB3-10 (
cabinet's customer interface assembly, will be
the selected main transmitter.
(e) The selected main transmitter will be providing
the 'audio out' (RMT AUD) sample.
IS02001 (Page 1)
29 January 2002
The theory of operation presented in the
NOTE
MAIN TX OPERATION:
If the B transmitter is the main
ATU CONT
(INSTALLED
The A
When the
SELECT MAIN
RF OUT
) of the