DRAKE VM2551 Instruction Manual
VM2551
Commercial Video Modulator
(For use in NTSC systems)
Instruction Manual
© Copyright 2005 R.L. Drake Company P/N: 3852551B-12-2005
is a registered trademark of the R.L. Drake Company
2 Caution Statements
WARNING: TO PREVENT FIRE OR
ELECTRICAL SHOCK DO NOT
EXPOSE TO RAIN OR MOISTURE
!WARNING!
RISK OF ELECTRIC SHOCK
DO NOT OPEN
WARNING:
CAUTION:
ATTENTION:
CAUTION: TO REDUCE THE RISK OF ELECTRIC SHOCK,
REFER SERVICING TO QUALIFIED PERSONNEL
A product and cart combination should be moved with care. Quick stops,
excessive force and uneven surfaces may cause the product and cart
combination to overturn.
The lightning flash with arrow head symbol, within an equilateral triangle,
is intended to alert the user to the presence of uninsulated "dangerous
voltage" within the product's enclosure that may be of sufficient
magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert
the user to the presence of important operating and maintenance
(servicing) instructions in the literature accompanying the product.
TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS
PRODUCT TO RAIN OR MOISTURE. DO NOT OPEN THE CABINET, REFER
SERVICING TO QUALIFIED PERSONNEL ONLY.
TO PREVENT ELECTRIC SHOCK, DO NOT USE THIS (POLARIZED) PLUG WITH AN
EXTENSION CORD RECEPTACLE OR OTHER OUTLET UNLESS THE BLADES
CAN BE FULLY INSERTED TO PREVENT BLADE EXPOSURE.
POUR PREVENIR LES CHOCS ELECTRIQUES, NE PAS UTILISER CETTE FICHE
POLARISEE AVEC UN PROLONGATEUR, UNE PRISE DE COURANT OU UNE
AUTRE SORTIE DE COURANT, SAUF SI LES LAMES PEUVENT ETRE INSEREES
A FOND SANS EN LAISSER AUCUNE PARTIE A DECOUVERT.
DO NOT REMOVE COVER
NO USER-SERVICEABLE PARTS INSIDE
Important Safety Instructions
1. Read Instructions—All the safety and operating instructions should be read before the product is
operated.
2. Retain Instructions—The safety and operating instructions should be retained for future reference.
3. Heed Warnings—All warnings on the product and in the operating instructions should be adhered to.
4. Follow Instructions—All operating and use instructions should be followed.
5. Cleaning—Unplug this product from the wall outlet before cleaning. Do not use liquid cleaners or
aerosol cleansers. Use a damp cloth for cleaning.
6. Attachments—Do not use attachments that are not recommended by the product manufacturer as they
may cause hazards.
7. Water and Moisture—Do not use this product near water—for example, near a bathtub, wash bowl,
kitchen sink or laundry tub; in a wet basement; or near a swimming pool; and the like.
8. Accessories—Do not place this product on an unstable cart, stand, tripod, bracket, or table. The
product may fall, causing serious injury to a child or adult, and serious damage to the product. Use only
with a cart, stand, tripod, bracket, or table recommended by the manufacturer, or sold with the product.
Any mounting of the product should follow the manufacturer's instructions, and should use a mounting
accessory recommended by the manufacturer.
9. A product and cart combination should be moved with care. Quick stops, excessive force, and uneven
surfaces may cause the product and cart combination to overturn.
10. Ventilation—Slots and openings in the cabinet are provided for ventilation and to ensure reliable
operation of the product and to protect it from overheating, and these openings must not be blocked or
covered. The openings should never be blocked by placing the product on a bed, sofa, rug, or similar
surface. This product should not be placed in a built-in installation such as bookcase or rack unless
proper ventilation is provided or the manufacturer's instructions have been adhered to.
11. Power Sources—This product should be operated only from the type of power source indicated on
the marking label. If you are not sure of the type of power supplied to your home, consult your product
dealer or local power company. For products intended to operate from battery power, or other sources,
refer to the operating instructions.
12. Grounding or Polarization—This product may be equipped with a polarized alternating-current line
plug (a plug having one blade wider than the other). This plug will fit into the power outlet only one way.
This is a safety feature. If you are unable to insert the plug fully into the outlet, try reversing the plug.
If the plug should still fail to fit, contact your electrician to replace your obsolete outlet. Do not defeat
the safety purpose of the polarized plug.
Alternate Warnings—If this product is equipped with a three-wire grounding-type plug, a plug having a
third (grounding) pin, the plug will only fit into a grounding-type power outlet. This is a safety feature. If
you are unable to insert the plug into the outlet, contact your electrician to replace your obsolete outlet.
Do not defeat the safety purpose of the grounding-type plug.
12 a. Mise à la terre ou Polarisation—Cet appareil est équipé avec un cordon d'alimentation à trois fils.
Il est a brancher sur une prise ayant un connecteur a la terre. Assurez-vous que la connection a la terre
ne manque pas.
13. Power-Cord Protection—Power-supply cords should be routed so that they are not likely to be
walked on or pinched by items placed upon or against them, paying particular attention to cords at plugs,
convenience receptacles, and the point where they exit from the product.
14. Outdoor Antenna Grounding—If an outside antenna or cable system is connected to the product, be
sure the antenna or cable system is grounded so as to provide some protection against voltage surges
and built-up static charges. Article 810 of the National Electrical Code, ANSI/NFPA 70, provides
information with regard to proper grounding of the mast and supporting structure, grounding of the leadin wire to an antenna discharge unit, size of grounding conductors, location of antenna-discharge unit,
connection to grounding electrodes, and requirements for the grounding electrode. See Figure A.
15. Lightning—For added protection for this product during a lightning storm, or when it is left unattended
and unused for long periods of time, unplug it from the wall outlet and disconnect the antenna or cable
system. This will prevent damage to the product due to lightning and power-line surges.
16. Power Lines—An outside antenna system should not be located in the vicinity of overhead power
lines, other electric light or power circuits, where it can fall into such power lines or circuits. When
installing an outside antenna system, extreme care should be taken to keep from touching such power
lines or circuits as contact with them may be fatal.
17. Overloading—Do not overload wall outlets, extension cords, or integral convenience receptacles
as this can result in a risk of fire or electric shock.
18. Object and Liquid Entry—Never push objects of any kind into this product through openings as they
may touch dangerous voltage points or short-out parts that could result in a fire or electric shock. Never
spill liquid of any kind on the product.
19. Servicing—Do not attempt to service this product yourself as opening or removing covers may
expose you to dangerous voltage or other hazards. Refer all servicing to qualified service personnel.
20. Damage Requiring Service—Unplug this product from the wall outlet and refer servicing to qualified
service personnel under the following conditions:
a. When the power-supply cord or plug is damaged,
b. If liquid has been spilled, or objects have fallen into the product,
c. If the product has been exposed to rain or water,
d. If the product does not operate normally by following the operating instructions. Adjust only those
controls that are covered by the operating instructions as an improper adjustment of other controls may
result in damage and will often require extensive work by a qualified technician to restore the product
to its normal operation,
e. If the product has been dropped or damaged in any way, and
f. When the product exhibits a distinct change in performance—this indicates a need for service.
21. Replacement Parts—When replacement parts are required, be sure the service technician has used
replacement parts specified by the manufacturer or have the same characteristics as the original part.
Unauthorized substitutes may result in fire, electric shock or other hazards.
22. Safety Check—Upon completion of any service or repairs to this product, ask the service technician
to perform safety checks to determine that the product is in proper operating condition.
23. Wall or Ceiling Mounting—The product should be mounted to a wall or ceiling only as recommended
by the manufacturer.
24. Heat—The product should be situated away from heat sources such as radiators, heat registers,
stoves, or other products (including amplifiers) that produce heat.
NOTE TO CATV SYSTEM INSTALLERS:
THIS REMINDER IS PROVIDED TO CALL THE CATV SYSTEM INSTALLER'S ATTENTION TO
ARTICLE 820 - 40 OF THE NEC THAT PROVIDES GUIDELINES FOR PROPER GROUNDING
AND, IN PARTICULAR, SPECIFIES THAT THE CABLE GROUND SHALL BE CONNECTED TO
THE GROUNDING SYSTEM OF THE BUILDING, AS CLOSE TO THE POINT OF CABLE
ENTRY AS PRACTICAL.
EXAMPLE OF ANTENNA GROUNDING
ANTENNA
LEAD IN
WIRE
GROUND CLAMP
ELECTRIC
SERVICE
EQUIPMENT
POWER SERVICE GROUNDING
ELECTRODE SYSTEM
(NEC ART 250, PART H)
GROUND
CLAMPS
ANTENNA
DISCHARGE
UNIT (NEC
SECTION 810-20)
GROUNDING
CONDUCTORS
(NEC SECTION
810-21)
Table of Contents / General Description 3
TABLE OF CONTENTS
Caution Statements /
2
Important Safety Instructions
Table of Contents / General Descrption
3
Front Panel Controls and Indicators
4
Rear Panel Connections
5
GENERAL DESCRIPTION
Installation
6
Specifications
7
Service / If You Need To Call For Help
8
Warranty
9
A / V
AUDIO
RATIO
LEVEL
OVER DEV
The Drake VM2551 Video Modulator is a vestigial
sideband unit with synthesized visual and audio carriers.
The VM2551 is designed to accept video and audio
baseband signals from a satellite receiver, video server,
VCR, camera, or similar equipment. Front panel video
and audio level controls and overmodulation indicators
permit setting the proper modulation levels. Synthesized
operation provides complete frequency agility, allowing
front panel selection of any standard, HRC, or IRC, CATV
channel from 2 to 78 and channels 95-99 or OFF AIR TV
channels 2-27. FCC required channel frequency offsets,
for aeronautical channels of zero, +12.5 kHz, or +25 kHz
are selected automatically and offset positive when
offsets are required.
AUDIO
VIDEO
VIDEO
LEVEL
OVER MOD
CHANNEL
ANT /
STD
CATV
HRC
SEL
IRC
RF OUT
OUTPUT
LEVEL
CH
TEST
The modulator accepts standard (sync negative) polarity
video at a 0.7 -1.5 Vpp level. A high quality IF SAW filter
eliminates adjacent channel interference.
IF loop-through capability in the VM2551 supplies an IF
output prior to channel conversion. This feature provides
the capability to replace the standard internally generated
IF output with an alternate source of composite IF, or
allows insertion of IF scrambling equipment.
The internally generated aural carrier may be disabled by
moving an internal jumper and an external 4.5 MHz
carrier can can be inserted via the rear panel 4.5 MHz
input.
These features, combined with a carefully designed low
intermodulation output stage, provide reliable operation
in a densely crowded SMATV or cable environment.
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