DRAKE VM2862 Manuale di istruzioni - Pagina 4

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Front Panel Controls and Indicators

F1 - POWER Indicator

This LED lights when the unit is connected to a source of

AC power. The LED flashes when on an invalid channel or

if there is a synthesizer error.

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 modulation 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 the 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).

VIDEO

LEVEL

POWER

NORMAL

OVER-MOD

NORMAL

Figure 1 - FRONT PANEL

F6 - A/V RATIO Control

This screwdriver adjustment varies the level of the aural

carrier over a range from 12 to 25 dB below the visual

carrier. The aural carrier should be adjusted to

approximately 15 dB below the visual carrier (normal

operation). Clockwise rotation increases the aural carrier

level and thus decreases the A/V ratio.

F7 - EAS ACTIVE Indicator

This indicator lights when a signal is present at the EAS

input (R2) indicating that the modulator has switched to the

EAS signal.

F8 - CATV, CATV +100 CHANNEL Switch

This two position switch allows selection of the desired

operating channel from 02 to 99 (when the switch is in the

CATV position) and channels 100 to 135 (when the switch

is in the CATV +100 position). See the CHANNEL

ASSIGNMENTS section for a list of the corresponding

operating frequency, and offset, if any, for each channel

number.

F9 - CHANNEL Switch

These pushwheel switches allow the selection of the

desired operating channel from 01 to 135. See the

CHANNEL ASSIGNMENTS section for a list of the

corresponding operating frequency, and offset, if any, for

each channel number.

F10 - RF OUTPUT LEVEL Control

This screwdriver adjustment varies the RF OUTPUT level.

Clockwise rotation increases the level.

F6 F7

AUDIO

A / V RATIO

CHANNEL

LEVEL

CATV CATV +

100

OVER-MOD

EAS ACTIVE

F10

VM2860 VIDEO MODULATOR

RF OUTPUT