Drake VM2860A Agile Modulator – 860 MHz - Manual (Page 4)

4 Table of Contents / Description / Specifications
2 Caution Statements
2 Important Safety Instructions
4 Table of Contents / Description / Specifications
5 Front/Rear Panel Controls and Indicators
6 Operation
7 Adjustments
8
10
Channel Assignments
11
Service / If You Need To Call For Help
Warranty
SPECIFICATIONS - VM2860 / VM2862
TABLE OF CONTENTS
MONO AUDIO (VM2860)
Connector: RCA
Input Impedance: Greater than 10k ohms, unbalanced.
Input Level: 0.5 to 4.0 volt Peak-to-Peak
Frequency Range: 50 Hz to 15 kHz
Frequency Response: ± 0.5 dB
Total Harmonic Distortion: 1% @ 25 kHz deviation
Signal-to-Noise Ratio: 59 dB
Over-modulation Threshold: 25 ± 2 kHz peak deviation
A manual or auto-switching alternate IF input, labeled EAS input,
is provided for connection of an Emergency Alert System 44 MHz
IF signal. When the EAS IF signal appears at the EAS input, the
main video and audio modulated IF is replaced by the EAS input
signal.
The EAS/Alternate IF feature allows a choice between manual
and automatic selection of the EAS/ALT IF input signal. This
is done through a 3 position terminal strip on the rear of the unit.
In the manual mode the EAS/ALT IF feature is activated by a contact
closure switch, which completes a ground connection. In the
automatic mode, two positions on the terminal strip are jumpered
together enabling an automatic detection circuit in the unit. When an
EAS/ALT IF signal is routed to the EAS/ALT port the unit automatically
switches to that alternate signal.
(VM2862 only)
117 VAC ± 10%, 60 Hz,
29 Watts max
32° to 122° F
7 lbs.
DESCRIPTION
The R.L Drake VM2860 and VM2862 Video Modulators are high
quality, vestigial sideband units with synthesized visual and aural
carriers. They are designed to accept NTSC video and audio
baseband signals from a satellite receiver or similar equipment.
Front panel video and audio level controls with accompanying
modulation indicators permit easy setup of the proper modulation
levels. The A/V ratio and RF output level controls are also provided
on the front panel. A rear panel EAS alternate IF input is also
provided. The VM2860 model is for applications with mono audio
and the VM2862 model provides BTSC stereo encoded audio.
Synthesized operation provides complete frequency agility, allowing
front panel selection of any standard CATV channel from 2 to 135
(54 to 862 MHz band). FCC required offsets for aeronautical
channels are automatically provided for each channel that requires
an offset. For special applications, IRC or HRC CATV frequencies
or off-air broadcast frequencies can be selected from the front panel.
A high quality IF SAW filter with FCC predistortion eliminates
adjacent channel interference and provides optimum delay
characteristics.
STEREO AUDIO
GENERAL
AC Power:
Fuse: Fuse: 0.4A Type T 250 V
Temperature Range:
Size: 19.0 x 14.25 x 1.75 in
Weight:
VIDEO INPUT
Connector: “F” Female
Impedance: 75 ohms
Return Loss: 18 dB
Video Input Level: 0.7 volt Peak-to-Peak
Signal-to-Noise Ratio: 58 dB
Differential Gain: 2.0%
Differental Phase: 1.0 degree
Over-modulation Indicator: 87 to 92%
L/C Delay: Per FCC Requirements
RF OUTPUT
Connector: “F” Female
Impedance: 75 ohms
Return Loss: 12 dB
Channel Modes: CATV (STD,IRC,HRC) UHF, VHF
Power Level Range: +50 to +60 dBmV
Video Flatness: fv-0.5 to fv+4.2 MHz : 1.5 dB p/v
Carrier-to-Noise: -63 dB
Broadband Noise: -77 dBc
Spurious Outputs: -63 dBc
Aural/Visual Carrier Ratio: -15 ± 5 dB
Connector: RCA
Input Impedance: Greater than 10k ohms unblanced
Input sensitivity: 0.7 volt Peak-to-Peak
Frequency Response: ± 0.75 dB
Separation: 20 dB
Harmonic Distortion: Less than 1%
IF
Input/Output Connector: “F” Female
Aural Frequency: 41.25 MHz
Visual Frequency: 45.75 MHz
Composite IF Output:
Aural: +20 dBmV
Visual: +35 dBmV
Input/Output Impedance: 75 ohms
Input/Output Return Loss: 16/15 dB
EAS/Alternative IF:
Connector: “F” Female
Input Level: +35 dBmV @ 45.75 MHz
Switch Isolation: Greater than 60 dB
VM SERIES VIDEO MODULATOR