DRAKE 300VMFPLUS 사용 설명서 - 페이지 4

{카테고리_이름} DRAKE 300VMFPLUS에 대한 사용 설명서을 온라인으로 검색하거나 PDF를 다운로드하세요. DRAKE 300VMFPLUS 10 페이지. Commercial video modulator (for use in ntsc systems)

페이지 인쇄

Front Panel Description

F1 - POWER Indicator

Lights when the unit is connected to a source of AC

power.

F2 - OUTPUT TEST Connector

Provides a reduced level sample of the RF output signal.

The level at this connector is approximately 30 dB lower in

level than the RF OUTPUT signal. It is used to monitor

the active signal without affecting the level or quality of the

RF output signal.

F3 - CHANNEL Designation

The label indicates the fixed channel output for your

particular model. The 300VMF+ is capable of fixed

channel output (factory tuned) within the following

ranges: Channel 2 through 78 and 95 through 99.

F4 - 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 +55 dBmV is set with the

adjustment approximately fully clockwise.

NOTE: If an output level of less than +43 dBmV is

required, add an attenuator of the appropriate value at

the modulator output.

Example: For an output level of +35 dBmV, add a 12 dB

attenuator pad to the modulator output and set the

output level to +47 dBmV.

Figure 1

F5 - 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 normally 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.

F6 - AUDIO LEVEL Control

The setting of this screwdriver adjustment determines the

peak aural carrier deviation. Clockwise rotation

increases the carrier deviation. After installing the unit,

and with an audio source connected, adjust the AUDIO

LEVEL control for 25 kHz deviation. If an audio

modulation meter is not available, use a TV set and

adjust for equal volume as compared to a known off-air

broadcast. Monitor for a few minutes to assure that

maximum volume of the audio source program does not

cause an over-modulation condition.

F7 - VIDEO LEVEL Control

The setting of this screwdriver adjustment determines the

video modulation level. Clockwise rotation increases the

modulation depth. After installing the unit, and with a

nominal 1 Volt P-P video source connected, adjust the

VIDEO LEVEL control for the correct percentage of

modulation (87.5%). If test equipment is not available for

such measurements, then adjust for proper picture

contrast when viewed on a TV set (compare with known

off-air broadcast picture quality).