DRAKE VM2050 Руководство по эксплуатации - Страница 6

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Front Panel Controls and Indicators

VM2050 T CHANNEL MODULATOR

F1 - POWER Indicator

Lights when the unit is connected to a source of

AC power.

F2 - VIDEO LEVEL Control

The setting of this screwdriver adjustment determines the

video modulation level. Clockwise rotation increases the

depth of modulation. After installing the unit, and with a

nominal 1 Vp-p video source connected, adjust the

VIDEO LEVEL control to a point where the red LED

modulation indicator (see item F3) just remains off (87.5%

depth of modulation). It is normal for the green modula-

tion indicator to be on with only sync level video input.

F3 - MODULATION Indicators (Video)

The green LED will be turned on continuously with sync

level or higher video input. An overmodulation condition

is noted with the red LED turned on continuously. The

VIDEO LEVEL control should be set to a point where the

red LED just remains off (see item F2).

F4 - AUDIO LEVEL Control

The setting of this screwdriver adjustment determines the

audio deviation level. Clockwise rotation increases the

level. After installing the unit and with a nominal 250 mV

RMS (approximately -10 dBu) audio source connected,

adjust the AUDIO LEVEL control to a point where the

green LED is turned on continuously and the red LED just

remains off (25 kHz peak deviation).

F5 - MODULATION Indicators (Audio)

The green LED will be turned on continuously for peak

deviations of approximately 2.5 kHz (10% of 25 kHz

maximum) or greater. An overmodulation condition is

noted with the red LED turned on continuously. The

AUDIO LEVEL control should be set to a point where the

red LED just remains off (see item F4).

F6 - A/V RATIO Control

V I D E O

A U D I O

L E V E L

POWER

MODULATION

Figure 1

This screwdriver adjustment varies the level of the aural

carrier over a range from 10 to 20 dB below the visual

carrier. The aural carrier should be adjusted to approxi-

mately 15 dB below the visual carrier (normal operation).

Clockwise rotation increases the aural carrier level and

thus decreases the A/V ratio.

F7 - CHANNEL Switch

These pushwheel switches allow the selection of the

desired operating channel from T07 to T14. See Table 1 -

CHANNEL ASSIGNMENTS for the list of corresponding

operating frequency for each channel number.

F8 - OUTPUT ENABLED Indicator

Lights to indicate a valid channel is selected. The RF

output is switched off for any invalid channel settings or

other conditions that would cause the unit to operate on

an invalid frequency.

F9 - RF OUTPUT LEVEL Control

This screwdriver adjustment varies the RF OUTPUT level.

Clockwise rotation increases the level.

R F O U T P U T

A/V RATIO

LEVEL

T-

CHANNEL

OUTPUT

ENABLED