User's Manual

2650 Watt VHF High Band Transmitter Chapter 2, System Description,
Maintenance and Remote Interface Connections
435B, Rev. 0 2-7
upper middle facing the rear of the
cabinet. The panel contains the terminal
block TB1 to which the 220 VAC input
connects.
The AC distribution panel contains four
circuit breakers that supply the AC to the
rest of the transmitter. The input AC is
connected to the main AC circuit breaker
CB1 (40 amps) that distributes the 220
VAC to the terminal block TB2. TB2 has
three MOVs, VR1, VR2, and VR3,
mounted to the terminal block: VR1
across Line 1, VR3 across Line 2 and VR2
connected across the two legs. The input
AC is wired from TB2 through three
circuit breakers, CB2, CB3, and CB4, to
the rest of the transmitter. CB2 is a 10-
amp circuit breaker that supplies the AC
voltage to the IEC outlet strip (A2-A1)
that is connected into the VHF exciter,
the (optional) receiver tray, and any
other optional accessories. CB3 is a 20-
amp circuit breaker that supplies AC
through J5 to the (A6) VHF amplifier tray
#1. CB4 is a 20-amp circuit breaker that
supplies AC through J6 to the (A7) VHF
amplifier tray #2. When the VHF exciter
circuit breaker is switched on, +12 VDC
is supplied to the VHF amplifier trays for
the operation of the LED status indicators
in the tray.
2.5 Maintenance
The 435B is designed with components
that require little or no periodic
maintenance except for the routine
cleaning of the fans and the front panels
of the trays.
The amount of time between cleanings
depends on the conditions within the
transmitter room. While the electronics
have been designed to function even if
covered with dust, a heavy buildup of
dust, dirt, or insects will affect the
cooling of the components. This could
lead to a thermal shutdown or premature
failure of the affected trays.
When the front panels of the trays
become dust covered, the top covers
should be removed and any accumulated
foreign material should be removed. A
vacuum cleaner, utilizing a small wand-
type attachment, is an excellent way to
suction out the dirt. Alcohol and other
cleaning agents should not be used
unless you are certain that the solvents
will not damage components or the silk-
screened markings on the trays and
boards. Water-based cleaners can be
used, but do not saturate the
components. The fans and heatsinks
should be cleaned of all dust or dirt to
permit the free flow of air for cooling
purposes.
It is recommended that the operating
parameters of the transmitter be
recorded from the meters on the trays
and the system metering control panel at
least once a month. It is suggested that
this data be retained in a rugged folder
or envelope. A sample format for a log
sheet is provided in Appendix B.
Photocopies of the log sheet should be
made to allow you to make continued
data entries.
2.6 Remote Interface Connections
The remote interface connections listed in
Table 2-10 are made to the (A12) A/V
input and remote interface assembly,
mounted facing the rear near the top of
the cabinet. The remote connections are
made to jack J9, 37 pos “D” Conn., and
jack J10, 25 pos “D” Conn., on the
assembly. Refer to the transmitter
interconnect drawing (1303857) for
verification of the remote connections.