R.V.R. Elettronica SDC20 User manual

Manufactured by R.V.R. Elettronica -Italy
TECHNICAL MANUAL
SDC20

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 2
SDC20
STEREO DIGITAL CODER
Technical Manual

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 3
INDEX
Preliminary Instructions &Warranty InformationPag. 4
Safety RegulationsPag. 6
SECTION 1
SDC20 Stereo Digital Coder DescriptionPag. 9
Technical Specifications (Table A)Pag.10
Dimensional and Enviromental Specifications (Table B)Pag.11
Front Panel View DescriptionPag.12
Front Panel View (Fig.1)Pag.13
Rear Panel View Description (Version n°1)Pag.14
Rear Panel View (Fig.2)Pag.15
Rear Panel View Description (Version n°2)Pag.16
Rear Panel View (Fig.3)Pag.17
SECTION 2
Electrical DescriptionPag.18
SECTION 3
Installation proceduresPag.19
Top View DescriptionPag.21
Top View (Fig.4)Pag.22
Connectors Specifications (Fig.5)Pag. 23
Balanced Inputs Connection (Fig.6)Pag. 24
APPENDIX A
Circuit Diagram, Bills of Material and LayoutsPag.25
Main CardPag.26
Panel CardPag.35
Limiter Card (Optional)Pag.39

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 4
PRELIMINARY INSTRUCTIONS AND WARRANTY INFORMATION
WARNING:This is a"CLASS A" equipment. In aresidential place this
equipment can cause hash. In this case can be requested to user take
necessary measures.
Please observe safety precautions when handling this unit. This equipment
contains dangerous currents and high voltages.
This manual is written as ageneral guide for those having previous
knowledge and experience with this kind of equipment. It is not intended
to contain acomplete statement of all safety warnings which should be
observed by personnel in using this or other elettronic equipment.
R.V.R. doesn't assume responsability for injury or damage resulting from
improper procedures or practices by untrained/unqualified personnel in
the handling of this unit.
Please observe all local codes and fire protection standards in the
operations of this unit.
CAUTION: always disconnect power before opening covers or removing any
part of this unit. Use appropriate grounding procedures to short out
capacitors and high voltage points before servicing.
Any damage to the goods must be reported to the carrier in writing on
the shipment receipt. Any discrepancy or damage discovered subsequent
to delivery, shall be reported to R.V.R. within five (5) days from its
receipt.
R.V.R. extends to the original end-user purchaser all original
manufacturers warranties which are transferable and all claims are to
be made directly to R.V.R. per indicated procedures.
All manufacturers warranties will be supported by R.V.R. to ensure
precise and speedy service where possible.
R.V.R. shall not be liable for any damage of whatsoever nature, arising
out of or in connection with the product or its use thereof.
R.V.R.'s warranty shall not include:
1)Re-shipment of the unit to R.V.R. for repair purposes
2)Any unauthorized repair/modification
3)Incidental/consequential damages as a result of any defect
4)Nominal non-incidental defects
5)Re-shipment costs or insurance of the unit or replacement
units/parts
Warranty shall come into force from invoice date and for the period of
the manufactures warranty.

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 5
The warranty for aperiod of 12 months is referred to any R.V.R. product,
while for products as Transistors, Mos-Fet and Tubes of the final stages
is applied the manufacture's warranty of these devices.
To claim your rights under this warranty:
a.Contact the dealer or distributor where you prchased the unit.
Describe the problem and ask if he has an easy solution. Dealers
and Distributors are supplied with all the information about
problems that may occur and usually they can repair the unit quicker
than what the manufacturer could do. Very often installing errors
are discovered by dealers.
b.If your dealer cannot help you, contact R.V.R. in Bologna and explain
the problem. If it is decided to return the unit to the factory,
R.V.R. will mail you aregular authorization with all the necessary
instructions to send back the goods.
c.When you receive the authorization, you can return the unit. Pack
it carefully for the shipment, preferably using the original packing
and seal the package perfectly. The customer always assumes the
risks of loss (i.e., R.V.R. is never responsible for damage or loss),
until the package reaches R.V.R. premises. For this reason, we
suggest you to insure the goods for the whole value. Shipment must
be effected C.I.F. (PREPAID) to the address specified by R.V.R.'s
service manager on the authorization.
DO NOT RETURN UNITS WITHOUT OUR AUTHORIZATION AS THEY WILL BE
REFUSED
Be sure to enclose awritten technical report where mention all the
problems found and acopy of your original invoice establishing the
starting date of the warranty.
Replacement and warranty parts may be order from the following address.
Be sure to include the equipment model and serial number as well as part
description and part number.
R.V.R. Elettronica S.r.l.- Broadcasting Equipment -
Via del Fonditore, 2/2c
Zona Roveri
40138 Bologna - Italy
Telephone [phone]
Fax [phone]
R.V.R. reserves the right to modify the design and specifications of the
equipment in this manual without previous notice.

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 6
WARNING!
The currents and voltages in this equipment are dangerous!
Personnel must at all times observe safety regulation!
This manual is intended as ageneral guide for trained and qualified
personnel who are aware of the dangers inherent in handling potentially
hazardous electrical and electronic circuits.
It is not intended to contain acomplete statement of all safety
precautions which should be observed by personnel in using this or other
electronic equipment.
The installation, operation, maintenance and service of this equipment
involves risks both to personnel and equipment, and must be performed
only by qualified personnel exercising due care.
R.V.R. ELETTRONICA s.r.l. shall not be responsible for injury or damage
resulting from improper procedures or from the use of improperly trained
or inexperienced personnel performing such tasks.
During installation and operation of this equipment, local building codes
and fire protection standards must be observed.
WARNING!
Always disconnect power before opening covers,
doors, enclosures, gates, panels or shields.
Always use grounding sticks and short out high
voltage points before servicing. never make
internal adjustments, perform maintenance or
service when alone or when fatigued.
Do not remove, short-circuit or tamper with interlock switches on access
covers, doors, enclosures, gates, panels or shields.
Keep away from live circuits, know your equipment and don’t take chances.
WARNING!
In case of emergency ensure that power has been disconnected

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 7
TreatmentofelectricalShock
1) If victim is not responsive follow the A-B-C's of basic life support.
PLACE VICTIM FLAT ON HIS BACK ON A HARD SURFACE
AAIRWAYBBREATHING
IF UNCONSCIOUS,IF NOT BREATHING,
OPEN AIRWAYBEGIN ARTIFICIAL
BREATHING
LIFT UP NECK,TILT HEAD,
PUSH FOREHEAD BACK,PINCH NOSTRILS,
CLEAR OUT MOUTH IF NECESSARY,MAKE AIRTIGHT SEAL,
OBSERVE FOR BREATHING.4 QUICK FULL BREATHS.
REMEMBER MOUTH TO MOUTH
RESUSCITATION MUST BE
COMMENCED AS SOON AS
POSSIBLE.
CCIRCULATION
CHECK CAROTID PULSEDEPRESS STERNUM 11/2" TO 2"
IF PULSE ABSENT,APPROX. 80 SEC. : ONE RESCUER, 15 COMPRESSIONS,
BEGIN ARTIFICIAL2 QUICK BREATHS.
CIRCULATION APPROX. 60 SEC. :TWO RESCUERS, 5 COMPRESSIONS,
1BREATH
NOTE: DONOTINTERRUPT RHYTHMOF COMPRESSIONS
WHEN SECOND PERSONIS GIVING BREATH.
Call for medicalassistanceassoonaspossible.
2) If victim is responsive.
a. Keep them warm.
b. Keep them as quiet as possible.
c. Loosen their clothing (a reclining position is recommended).

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 8
FIRST-AID
Personnelengagedintheinstallation,operation,maintenanceor
servicingofthisequipmentareurgedtobecomefamiliarwithfirst-aid
theoryandpractices.Thefollowinginformationisnotintendedtobe
acompletefirst-aidprocedure,itisbriefandisonlytobeusedas
areference.Itisthedutyofallpersonnelusingtheequipmenttobe
preparedtogiveadequateEmergencyFirstAidandtherebyprevent
avoidablelossoflife.
TreatmentofelectricalBurns
1) Extensive burned and broken skin.
a. Cover area with clean sheet or cloth.
(Cleanest available cloth article).
b. Do not break blisters, remove tissue, remove adhered particles
ofclothing, or apply any salve or ointment.
c. Treat victim for shock as required.
d. Arrange transportation to ahospital as quickly as possible
e. If arms or legs are affected keep them elevated.
NOTE
If medical help will not be available within an hour and the victim
is conscious and not vomiting, give him aweak solution of salt and
soda: 1 level teaspoonful of salt and 1/2 level teaspoonful of baking
soda to each quart of water (neither hot or cold).
Allow victim to sip slowly about 4ounces (half aglass) over aperiod
of 15 minutes.
Discontinue fluid if vomiting occurs (Do not give alcohol).
2) Less severe burns - (1st & 2nd degree)
a. Apply cool (not ice cold) compresses using the cleanest available
cloth article.
b. Do not break blisters, remove tissue, remove adhered
particles of clothing, or apply salve or ointment.
c. Apply clean dry dressing if necessary.
d. Treat victim for shock as required.
e. Arrange transportation to a hospital as quickly as possible.
f. If arms or legs are affected keep them elevated.

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 9
SECTION1
SDC20 STEREO DIGITAL CODER
DESCRIPTION
1.1EXTERNAL DESCRIPTION
The SDC20 is contained in 19" 1U rack. This stereo digital coder
is engineered for high performance stereo FM broadcasting.
It's an equipment that integrates in acheap model, but without quality
compromises, all technical characteristics of the expansive Coders.
On the front panel there are: the Power ON/OFF luminous switch (8 Fig.1),
the two led bars for left and right channels (1-2 Fig.1) and atrimmer
for phase adjustment (14 Fig.1).
Moreover, there is acommands section with relative led indicators
composed of: a preenphasis command switch (3-9 Fig.1), a left channel
switch (4-10 Fig.1), acommand to put in phase left and right channels
(5-11 Fig.1), aright channel switch (6-12 Fig.1), a19 KHz tone selector
(7-13 Fig.1) and a trimmer for fine tuning of the phase.
On the rear panel there are: the mains voltage inlet (1 Fig.2), a MPX
output connector with its level selector (2-3 Fig.2), aRDS input
connector (4 Fig.2), aSCA input connector (5 Fig.2), aRIGHT input
connector with its level selector (8-9 Fig.2) and aLEFT input connector
with its level selector (6-7 Fig.2).
1.2ELECTRICAL DESCRIPTION
This Stereo Coder uses afrequency sinthesized internal digital
circuitry that allows very linear modulation, high stereo separation,
high input level capability.
The input/output analog section of good quality integrates oneself with
digital system answering for high input dynamics, high signal/noise rate
and very low distorsion.
1.3TECHNICAL SPECIFICATIONS
Refer to Table (A) for electrical specs and to Table (B) for
dimensional and environmental specs.

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 10
TABLE A
TECHNICAL SPECIFICATION
AUDIO INPUT (L &R)
Input LevelAdjustable from 0to 12 dB
Input Sensitivity194 mVrms (-12 dBm)
Input Impedance>6Kohm (balanced)
Frequency Responsefrom 20 Hz to 15 KHz
19 KHz Suppression-70 dB
38 KHz Suppression-72 dB
Pre-emphasis50 microsec, 75 microsec, off
SCA INPUT
Input Level0dB
Input Impedance>10 Kohm (unbalanced)
Frequency Response (20 Hz to 100 KHz)<±0.5 dB
RDS INPUT
Input Level0dB
Input Impedance>150 Kohm
Frequency Response (20 Hz to 100 KHz)<±0.5 dB
STEREO GENERATOR
Pilot Tone Frequency19 KHz ±0.1 Hz
Pilot Tone Level-20 dBm (adjustable 2dBm)
Output Impedance (Multiplex)50 Ohm (unbalanced)
Output Level (Multiplex)0dBm to +12 dBm
(with 0dBm, 1KHz input signal)
Separation (20 Hz to 15 KHz)>60 dB
Subcarrier Suppression (38 KHz)>70 dB
THD (1 KHz, output =+12 dBm)<0.03%
Signal/Noise Ratio-80 dB (DIN audio)
Power Requirements117/230 Vac, 50/60 Hz, 8W

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 11
TABLE B
DIMENSIONAL AND
ENVIRONMENTAL SPECIFICATIONS
Operating Temperature-10°C to +50°C
Humidity95% Max, Non Condensing
Weight3.2 Kg (7 Lbs)
Panel Size483 mm (19") W
44 mm (1.7") H
164 mm (6.45") D

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 12
FRONT PANEL (FIG.1)
1LEFT Left channel peak level meter by "Led Diode
Bar"
2RIGHT Rightchannel peaklevelmeterby"LedDiode
Bar"
3PREEMPHASIS Pre-emphasisON/OFF selector
4L LeftchannelON/OFFselector
5L=R/L=-R Channels phaseselector
6R RightchannelON/OFFselector
719KHz 19KHz pilottoneselector
8POWER ON/OFFpowerswitch
9PRE-EMPHASISLED Pre-emphasis ON/OFF led indicator
10LCHANNEL LED LeftchannelON/OFF led indicator
11L=R/L=-R LED Channelsphaseled indicator
12RCHANNEL LED Right channel ON/OFF led indicator
1319KHzLED 19KHz toneledindicator
14PHASE Fine tuningtrimmer

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 13
FIG.1

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 14
REAR PANEL (FIG.2)
XLR VERSION
1A.C. IN A.C. Lineinlet
2MPX MPXoutput channelconnector(XLRmale)
3MPXLEV MPX channel level selector
4RDS RDSinputchannel(XLRfemale)
5SCA SCAinputchannel(XLRfemale)
6LEFT LEFTinput channel (XLR female)
7LEFTLEV LEFT channel levelselector
8RIGHT RIGHTinput channel (XLR female)
9RIGHT LEV RIGHTchannellevelselector

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 15
FIG.2 (XLR VERSION)

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 16
REAR PANEL (FIG.3)
SOCKET VERSION
1A.C. IN A.C. Lineinlet
2MPX MPXoutputchannelconnector (Socket)
3MPXLEV MPX channel level selector
4RDS RDS input channel (Socket)
5SCA SCA input channel (Socket)
6LEFT LEFT inputchannel(Socket)
7LEFTLEV LEFT channel levelselector
8RIGHT RIGHTinput channel(Socket)
9RIGHT LEV RIGHTchannellevelselector

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 17
FIG.3 (SOCKET VERSION)

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 18
SECTION2
ELECTRICAL DESCRIPTION
2.1PANELCARD
This card is fixed on the left side of the front panel (1 Fig.4).
The Panel card allows to display the Left and Right input signals level
through a level meter on a scale from -20 dBm to + 15 dBm.
It's reliable to adjust the level until 0dBm and not more (yellow led
ON). This led meter can display peak level before or after limiter
(optional).
The value before limiter can be obtained inserting flat cable of the led
meter in J5 connector, after limiter in J4 connector.
2.2MAIN CARD
This card is fixed on the bottom in central position (2 Fig.4).
The Main card receives input signals (LEFT, RIGHT, RDS and SCA) from a
Mixer or a transmitter.
These signals are amplified and filtered through 19KHz filters and
preemphasis circuits.
Through PR1 and PR2 jumpers is possible to set 50µs or 75µs preemphasis.
Then, the signal is processed by adigital circuit and then is sent to
MPX output.
Here, this signal is mixed, if present, with RDS or SCA input.
Pilot level can be changed adjusting P5 trimmer. The variation dynamics
is of ± 2 dBm.
2.3LIMITERCARD (Optional)
This optional board is fixed on the left of the rack bottom in central
position.
This card is used to check too high level capability of input signals.
The limiter is inserted on J7 and J8 connectors through aflat cable and
it's necessary to remove PR3 and PR4 jumpers.

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 19
SECTION3
INSTALLATION PROCEDURES
3.1CONNECTIONS
Verify that SDC20 coder is switch off. Connect the output connector
of the mixer or of the last transmitter to Rand Linput connectors. The
SDC20 coder input is balanced and can be of XLR type or socket type.
Respect pins position showed in technical specifications of the
connectors (Fig.5). SDC20 has SCA and RDS inputs; the technical
caracteristics of these inputs are mentioned in Table A.
It's important don't connect any audio signals not codified because will
be mixed with MPX signal on the MPX output.
3.2INSTALLATION
The SDC20 coder is setted ex factory to obtain max stereo separation
through ameasuring professional decoder. This setting is just sufficient
for the most part of the FM station.
However it's possible, to obtain max. performance for each transmitting
system, adjust again on pilot tone phase to compensate possible FM
transmitter phase delays.
So that this adjustment is precise, it's necessary to use ameasureing
professional decoder.
In absence of measuring instruments, an approximative adjustment can be
executed in the following way:
1)Put into L and R inputs of the coder a 1 KHz sinusoidal signal.
2)Switch off the Preenphasis command.
3)Adjust input level to read on led meter asignal of 0dBm (yellow
led).
4)Adjust output level for alevel that entails adeviation of 75 KHz
(100%) on the tranmsitter meter.
5)Connect an oscilloscope to low frequency output of left channel of
a good quality tuner.
6)Switch off left channel on the coder and adjust the phase on the
oscilloscope to obtain a minimum residual of signal.
7)Now, connect the oscilloscope on low frequency output of the tuner
right channel and disconnect coder right channel inserting again
left channel.

SDC20 Stereo Digital Coder
R.V.R. Elettronica S.r.l. (Bo)Pag. 20
8)Adjust again the phase to obtain a minimum residual of signal.
9)Repeat to the bitter end the operations at points 5), 6), 7) and
8) until to obtaim maximum symmetrical separation.
Now the coder is perfectly interfaced to your FM transmitting system.
NOTE: However the tuner used for the adjustments can be of good quality,
the performances as separation of this equipment and of all transmitting
system, improbably can be compared with SDC20 ones, therefore the results
don't reflect quantitatively SDC20 characteristics.
3.2MAINSVOLTAGE CHANGE
SW6 switch allows to select the correct mains voltage that it's
necessary to coincide with A.C. line.
With selector in "A" position is selected amains voltage of 220/230V;
with selector in "B" position is selected amains voltage of 110/115V.