User's Manual

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300-Watt Digital UHF Transmitter Chapter 2, System Description

DT830A, Rev. 1 2-4

Table 2-3. Digital Modulator Control Pushbuttons

PUSHBUTTON FUNCTION

Menu

Controls which menu is displayed on the

LCD readout

Up Arrow (↑)

Moves the active line up one position on the

LCD display

Down Arrow (↓)

Moves the active line down one position on

the LCD display

There are four front panel status indicator LEDs.

Table 2-4. Digital Modulator Status Indicators

LED FUNCTION

MPEG (Green)

Indicates the presence of an MPEG-2 signal;

can be internal or external depending on

menu selection

REF (Green)

Indicates the presence of an external 10

MHz reference source

PLL Locked (Green)

Indicates that the phase-locked loop circuit

is functioning and locked

Power (Green)

Indicates that the DC power supply is

functioning

Table 2-5. Digital Modulator Sample

SAMPLE DESCRIPTION

Front panel sample Sample of the 44 MHz IF output

2.2.2 (A4) UHF Digital Exciter Tray (1294-1111; Appendix C)

Table 2-6. UHF Exciter Tray Meters

METER FUNCTION

Meter (A4-A18)

Reads power in terms of a percentage of

the calibrated output power level on the

upper scale. The voltage level is read on

one of the bottom two scales. A full scale

reading on the top scale is 0-120%, which

is equivalent to the full-rated 300 watts or

1000 watts in the upgradeable version,

average power. Also reads % Exciter

Power, % Reflected Power, and ALC

reading.

Switch (S3), meter

Selects the desired ALC voltage reading, %

Exciter Power, % Output Power, and %

Reflected Power

ALC

(0-1 V)

Reads the ALC voltage level, .8 VDC, on

the 0-10 scale