User's Manual

ManualsBrandsUBS-Axcera ManualsElectronics3000-Watt UHF DTV Transmitter

Digital UHF Transmitter Chapter 2, System Description and

Customer Remote Connections

DT835A, Rev. 1 2-7

Table 2-10: UHF Amplifier Tray Status Indicators

INDICATOR FUNCTION

Enable (DS4 green) Indicates that an Enable, Operate command, is

applied to the UHF amplifier tray from the selected

UHF exciter tray

Overdrive (DS2 red) Indicates that the level of the drive is too high. The

protection circuit will limit the drive to the set

threshold. The fault is generated on the amplifier

control board.

VSWR cutback (DS1 red) Indicates that the reflected power level of the tray has

increased above 50%. This will automatically cut back

the output power level to 50%. The fault is generated

on the amplifier control board.

Overtemp (DS3 red) Indicates that the temperature of (A5-A6- A3 and A5-

A6-A4), one or both of two thermal switches mounted

on the heatsink assembly for the output amplifiers, is

above 175° F. When this fault occurs, the Enable to

the switching power supply in the affected amplifier

tray is immediately removed and it will shut down.

Input fault (DS5 red) Indicates that the input RF level to the amplifier trays

dropped below the 0 dBm range

Table 2-11: UHF Amplifier Tray Control Adjustments

ADJUSTMENT FUNCTION

Phase (A10-R5) Adjusts the phase of the RF output by approximately

70°

Gain (A11-R6) Adjusts the gain of the RF output when the amplifier

control board is in the AGC mode

Table 2-12: UHF Amplifier Tray Sample

SAMPLE DESCRIPTION

Module O/P (0 dBm) A sample of the combined output of the four dual-

stage amplifier boards taken from the dual-peak

detector board

2.1.11 DM8-R Modulator Front Panel LED Indicators

The front panel LEDs are described in Table 2-13.

Table 2-13: Modulator Front Panel LEDs

LED Indicator Function

PWR Indicates that the DC power supply is operating

MPEG

LED

Indicates the presence of a valid MPEG stream at the

J1-2B input

PLL A

LED

Indicates that the DM8 symbol clock is locked to the

frequency of the 10 MHz reference.

PLL B

LED

Indicates that the pilot frequency is locked to the

incoming 10 MHz reference.