System Description Chapter 2

3-kW UHF Transmitter Chapter 2, System Description
835-3, Rev. 0 2-4
Note: If the transmitter does not switch to Operate when S1 is switched to
Operate, check that a dummy jumper plug, with a jumper between pins 23 and
24, is connected to jack J11 on the rear of the UHF exciter tray. This jumper
provides the interlock needed for the operation of the transmitter. If the
interlock is present, the green LED DS5 on the transmitter control board should
be lit.
The operation of the transmitter is controlled by the front panel switches on the UHF
exciter tray. During the normal operation of the transmitter, switch S2 should be in the
Auto position. The front panel of the UHF exciter also has LEDs that indicate a video
fault (loss) (red LED DS9) and a VSWR cutback (amber LED DS7).
2.4 Baseband Input and Remote Connections
The baseband video and audio inputs to the transmitter connect to the rear of the UHF
exciter assembly. The baseband video input connects to jack J1. The baseband audio
input connects to J5 for balanced audio or to jack J3 for composite, stereo, audio.
Remote monitoring and operation of the transmitter is provided through jacks J10 and
J11 on the rear of the UHF exciter tray. Jack J11 should have a dummy plug connected
to it, with a jumper connected between pins 23 and 24, that provides the interlock to
the exciter which is needed to operate the transmitter. If this jumper is missing, the
transmitter will not switch to Operate. If remote connections are made to the
transmitter, they should be made through the plug provided in the installation material
to jack J11 or J10 on the rear of the UHF exciter tray as shown in the transmitter
interconnect drawing.
2.5 Main AC Input
The transmitter needs an AC input of 220 VAC at 100 amps for the amplifier assembly
and 80 amps for the UHF exciter and the 1-kW transmitter assembly.
The 220-VAC input to the amplifier assembly connects to (A10) the AC distribution
assembly, amplifier array (1245-1300), on the right side, center rear of the cabinet. The
assembly contains TB1, which is connected to the 220 VAC (line 1 to TB1-1, ground to
TB1-2, and line 2 to TB1-3).
The AC distribution panel contains seven circuit breakers that supply the AC to the rest
of the exciter assembly. The input AC from TB1 is connected to CB1, the main AC circuit
breaker (100 amps), that distributes the 220 VAC to the other six circuit breakers. The
output of CB1 has three MOVs (VR1, VR2, and VR3) mounted to it, one connected from
each leg of the input AC to ground and one across the two legs. The switched input AC is
wired through the six circuit breakers, CB2 to CB7, to the six 600-watt amplifier trays in
the amplifier cabinets. CB2 is a 20-amp circuit breaker that supplies the AC voltage to
(A1) the 600-watt amplifier tray. CB3 is a 20-amp circuit breaker that supplies the AC
voltage to (A2) the 600-watt amplifier tray. CB4 is a 20-amp circuit breaker that
supplies the AC voltage to (A3) the 600-watt amplifier tray. CB5 is a 20-amp circuit
breaker that supplies the AC voltage to (A4) the 600-watt amplifier tray. CB6 is a 20-
amp circuit breaker that supplies the AC voltage to (A5) the 600-watt amplifier tray.
CB7 is a 20-amp circuit breaker that supplies the AC voltage to (A6) the 600-watt
amplifier tray.
The 220 VAC input to the UHF exciter assembly and 1-kW transmitter connects to (A8)