DRAKE VM1550 사용 설명서 - 페이지 6

{카테고리_이름} DRAKE VM1550에 대한 사용 설명서을 온라인으로 검색하거나 PDF를 다운로드하세요. DRAKE VM1550 14 페이지. Commercial video modulator (for use in ntsc systems)

페이지 인쇄

Front Panel Controls and Indicators

F1 - POWER Indicator

Lights when the unit is connected to a source of AC

power.

F2 - AUDIO LEVEL Control

The setting of this screwdriver adjustment determines the

peak aural carrier deviation. Clockwise rotation increases

the carrier deviation. Set this control to a level which

causes the LED Over Modulation indicator (See Item 'F3')

to just begin lighting (25 kHz deviation).

F3 - AUDIO OVER MODULATION Indicator

Lights when the audio amplitude is greater than the

25 kHz deviation level.

F4 - VIDEO OVER MODULATION Indicator

Lights when the video amplitude is greater than the 87.5%

depth of modulation.

F5 - VIDEO LEVEL Control

The setting of this screwdriver adjustment determines the

video modulation level. Clockwise rotation increases the

modulation depth. Set this control to a level which causes

the LED Over Modulation indicator (See Item 'F4') to just

begin lighting (87.5% depth of modulation).

F6 - A/V RATIO Control

This screwdriver adjustment varies the level of the aural

carrier over a range from 12 to 20 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.

A U D I O L E V E L

V I D E O L E V E L

OVER

POWER

MODULATION

F4 F5

CHANNEL

A / V R A T I O

F7 - CHANNEL Designation

The label indicates the fixed channel output for your

particular model. The VM1550 is capable of fixed channel

output within the following ranges: VHF, 2-13; Lowband 1

(A8): Midband, 14-22 (A-I) and 95-99 (A5-A1); Superband,

23-36 (J-W); Hyperband, 37-44 (AA-HH);

F8 - RF OUTPUT LEVEL

This screwdriver adjustment permits decreasing the RF

output level a minimum of 12 dB below its specified output

level as the control is rotated counterclockwise. The

maximum output level of +45 dBmV is set with the

adjustment fully clockwise.

NOTE: If an output level of less than +35 dBmV is

required, add an attenuator of the appropriate value at the

modulator output.

Example: For an output level of +30 dBmV, add a 10 dB

attenuator pad to the modulator output.

VM1550 VIDEO MODULATOR

RF LEVEL