DRAKE VMM860AS Manuel - Sayfa 2

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FRONT PANEL CONTROLS and INDICATORS

VMM860AG

POWER/

ERROR

AUDIO

VIDEO

C A T V

CATV

B C

+100

T V

A / V

R F

F1 - POWER/ERROR Indicator

Lights when the unit is connected to the

required source of DC power via the rear panel

DC INPUT connector. A flashing condition

indicates an invalid channel setting or other

conditions that would cause the unit to operate

on an invalid channel. The RF output is

switched off for flashing (ERROR) conditions.

F2 - AUDIO Level Control

The setting of this screwdriver adjustment

determines the aural carrier deviation. Clock-

wise rotation increases the carrier deviation.

F3 - VIDEO Level Control

The setting of this screwdriver adjustment

determines the video modulation level. CW

rotation increases the modulation depth.

F4 - Channel Number Switch

Sets the desired operating channel for standard

CATV channels 02 through 135 or Broadcast

TV channels 02 through 69. See also Item F5

which sets the type of channel (CATV or

Broadcast TV) and sets the leading "1" for

CATV channels 100 through 135.

F5 - Mode Switch

Sets the type of channel, CATV or Broadcast

TV ("BC TV"). The first position of the switch

("+100") sets a leading "1" for CATV channels

100 through 135. See also Item F4 for setting

the channel. Here are two examples:

VMM860AS

Figure 1

Setting for CATV

channel "125"-

channel "25"-

CATV

+100

F6 - A/V Ratio Control

This screwdriver adjustment varies the level of

the aural carrier over a range from 12 to 22 dB

below the visual carrier. Typically, the aural

carrier should be adjusted to approximately 15

dB below the visual carrier. Clockwise rotation

increases the aural carrier level.

F7 - RF Output Level

This screwdriver adjustment permits adjustment

of the RF output level over a minimum of 10 dB

range. Maximum output is at full CW.

F8 - P. LK (Pilot Lock)

This LED indicates that the BTSC circuitry in

the VMM860AS has locked to the video sync

reference.

F9 - Audio Overmodulation

This LED illuminates when the audio input level

reaches full modulation. Set F2 for just an

occasional flicker. (VMM860AS)

F10 - Video Overmodulation

This LED illuminates at 87.5% video modula-

tion. Advance F3 CW until F10 just lights then

back off until F10 just goes out. (VMM860AS)

FCC Frequency Offsets:

F10

Output Amplitude Stability:

Intercarrier Frequency:

Spurious Outputs (5 to 900 MHz):

Input Level for 87.5% Modulation:

Video Over-modulation LED:

CATV

Input Level for +/- 25 kHz Deviation:

Total Harmonic Distortion:

Over Modulation Indicator:

Operating Temperature:

Frequency Range:

54 to 864 MHz; Standard, HRC, or IRC CATV channels 2 to

135, Broadcast TV channels 2 to 69.

Automatic (+12.5 kHz, +25 kHz, or none as required).

Output level:

+45 dBmV minimum (10 dB adjustment range).

Output Impedance:

75 Ohms, 8 dB return loss.

A/V Ratio:

Audio carrier level, adjustable from -22 to -12 dB

referenced to video carrier level.

Frequency Stability:

Within ±5 kHz

Output Flatness:

From 54 to 864 MHz, less than 3 dB change.

±1 dB

4.5 MHz

-60 dBc, (-15 dB A/V ratio and output level of +45 dBmV).

In-Channel C/N:

65 dB typical, 4 MHz bandwidth.

Broadband Noise:

-78 dBc typicial, 4 MHz bandwidth @ +45 dBmV output.

VIDEO

0.65 Vp-p to 1.5 Vp-p. Gain adjust with front panel control.

Trips at 87.5 % depth of modulation. (VMM860AS only)

Input Impedance:

75 Ohms, return loss of 26 dB minimum.

Frequency Response:

20 Hz to 4.2 MHz, ±1 dB.

C/L Delay:

Within 50 nSec. of FCC predistortion.

Differential Gain:

3% maximum (10 to 90% APL).

Differential Phase:

maximum (10 to 90% APL).

AUDIO, VMM860AG

125 mV rms to 2.5 V rms. Manual gain adjust with

front panel control.

Input Impedance:

Greater than 10 K Ohms, unbalanced.

Pre-emphasis:

75 Sec. normal, defeatable (flat) by rear panel switch for

BTSC baseband stereo compatibility.

Frequency Response:

40 Hz to 15 kHz, ±1.0 dB referenced to 75 Sec.

pre-emphasis curve.

40 Hz to 100 kHz, ±0.5 dB if pre-emphasis is defeated.

S/N ratio:

65 dB.

Less than 0.5 %.

AUDIO, VMM860AS

Input Level:

250 mV to 2.5 V rms for 25 kHz L+R deviation.

Trips at ±25 kHz L+R deviation.

Input Impedance:

Greater than 10 K Ohms, unbalanced.

Channel Separation:

> 30 dB from 100 Hz to 10 kHz.

> 25 dB from 10 kHz to 14 kHz.

Frequency Response:

±1 dB of 75 Sec pre-emphasis curve, 50 Hz to 14 kHz.

S/N Ratio:

> 60 dB

THD:

Less than 0.5 %

GENERAL

DC Power Input:

+12 V ±5% at 200 mA (AG) or 220 mA (AS).

+5 V ±5% at 350 mA (AG) or 400 mA (AS).

C to +50

C ambient.

Size:

1" W x 3.5" H x 7.5" D (AG) or 8" D (AS)

Weight:

12 oz. (AG) or 13.5 oz. (AS)

Specifications subject to change without notice or obligation.

SPECIFICATIONS