DRAKE VM2862 Manual de instruções - Página 3

Procurar online ou descarregar pdf Manual de instruções para Modulador DRAKE VM2862. DRAKE VM2862 12 páginas. Commercial video modulator
Também para DRAKE VM2862: Manual de instruções (12 páginas)

Imprimir página
DRAKE VM2862 Manual de instruções
Table of Contents / Description / Specifications
TABLE OF CONTENTS
2
Caution Statements
2
Important Safety Instructions
3
Table of Contents / Description / Specifications
4
Front Panel Controls and Indicators
5
Rear Panel Controls and Connections
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. If
SAP is required, this option is available for the VM2862 model, and
is field installable.
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 after moving an
internal jumper.
A high quality IF SAW filter with FCC predistortion eliminates
adjacent channel interference and provides optimum delay
characteristics.
SPECIFICATIONS - VM2860 / VM2862
RF
Frequency Range:
54 MHz to 864 MHz.
Standard CATV channels 2 to 135.
Broadcast, HRC, and IRC channel plans available by
internal jumper.
FCC Offsets:
Automatic, positive.
Output Level:
+60 dBmV minimum, 12 dB minimum adjustment
range.
Amplitude Stability:
± 1 dB.
Output Impedance:
75 Ohms, 12 dB return loss within output filter
passband.
A/V Ratio:
-12 dB to -25 dB.
Frequency Stability:
± 5 ppm. All oscillators locked to the same internal
reference.
Spurious Outputs:
-60 dBc at +60 dBmV output level, 5 MHz to
1000 MHz, 15 dB A/V ratio.
Phase Noise:
-85 dBc at 10 kHz offset.
Output Filter Bands:
54 MHz to 258 MHz, 258 MHz to 462 MHz, 462 MHz
to 660 MHz, 660 MHz to 864 MHz.
Broadband Noise:
-80 dBc, 4 MHz bandwidth, +60 dBmV output level,
±18 MHz offset within output filter passband, -90 dBc
outside of output filter passband, output filtered into 4
approximately 200 MHz wide bands.
VIDEO
Input Level:
1 Vp-p ± 3 dB, manual gain adjustment with
modulation indicators.
Input Impedance:
75 Ohms, 25 dB return loss.
Frequency Response:
20 Hz to 4.2 MHz, ± 1 dB with 4.5 MHz trap off,
20 Hz to 4.1 MHz, ±1 dB with 4.5 MHz trap on.
In-channel C/N:
65 dB.
L/C Delay:
±50 nS of FCC predistortion with 4.5 MHz trap off,
-20 +80 nS of FCC predistortion with 4.5 MHz trap on.
Differential Gain:
± 3%.
Differential Phase:
± 3
0
.
MONO AUDIO
Input Level:
250 mVrms to 2.5 Vrms, manual gain adjustment with
LED modulation indicators.
Input Impedance:
10K Ohms, unbalanced.
6
7
9
10 Service / If You Need To Call For Help
11 Warranty
VIDEO
LEVEL
POWER
NORMAL
OVER-MOD
NORMAL
An 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.
A 4.5 MHz video trap may be selected via an internal jumper
(VM2862 has 4.5 MHz trap on as factory setting). This may be used
to filter off a 4.5 MHz sound subcarrier or undesired video
components to prevent interference to the stereo or SAP channels.
The RF section of the modulator contains bandpass filtering that
divides the 54 to 862 MHz output range into four bands, each
approximately 200 MHz wide. This filtering, in conjunction with the
use of high level, low noise floor mixing, ensures very low
broadband noise at the output. Thus a full complement of up to all
134 available channels from VM2860 or VM2862 modulators may
be combined while maintaining an excellent C/N of each channel.
All of the mentioned features, combined with a carefully designed
low noise and low distortion output stage, provide reliable operation
in a densely crowded SMATV or CATV environment.
The inclusion of a fan in the VM2860 and VM2862 permits rack
mounting of this equipment without leaving the typical 1U air space
between modulators.
MONO AUDIO, cont'd.
Frequency Response :
BTSC STEREO AUDIO
Frequency Response:
Frequency Response:
Auto Switching Level:
Installation / Installation Diagram
Channel Assignments
Internal Jumper Settings
A / V RATIO
AUDIO
CHANNEL
LEVEL
CATV CATV +
100
OVER-MOD
EAS ACTIVE
Pre-emphasis:
75 S.
50 Hz to 15 kHz, ±1 dB.
THD:
0.5% maximum.
S/N:
65 dB.
(VM2862 only)
Input Level:
250 mVrms to 2.5 Vrms, manual gain adjustment with
LED modulation indicators.
Input Impedance:
10K Ohms, unbalanced.
Separation:
30 db, 50 Hz to 12.5 kHz; 25 dB, 12.5 kHz to 14 kHz.
± 0.5 dB, 50 Hz to 14 kHz.
THD:
0.5% maximum.
S/N:
65 dB.
SAP AUDIO Option
(VM2862 only)
Input Level:
250 mVrms to 2.5 Vrms, manual gain adjustment with
over-modulation indicator.
Input Impedance:
10K Ohm, unbalanced.
±2 dB, 50 Hz to 10 kHz.
THD:
1% maximum.
S/N:
80 dB.
EAS INPUT
Level :
+30 dBmV, ±1 dB (visual carrier).
Impedance:
75 Ohm, 20 dB return loss.
Isolation:
60 dB.
+20 dBmV.
GENERAL
AC Power:
115 VAC ± 10%, 60 Hz,
23 Watts (VM2860), 28 Watts (VM2862).
Fuse:
1/2 Amp Slo-Blo 5 X 20 mm.
Temperature Range:
0° to 50° C.
Cooling:
Internal 1.85 CFM fan allows operation in the rack
without air spaces between units.
Radiated Emissions:
FCC Part 15.
Size:
11.25" D x 1.75" H x 19" W
Weight:
8 lbs. 8 oz.
3
VM2860 VIDEO MODULATOR
RF OUTPUT
2
5