Orban OPTIMOD 8200ST User manual

Operating Manual
OPTIMOD-Studio Chassis
Automatic Gain Controller
8200ST

IMPORTANT NOTE: Refer to the unit’s rear panel for your Model #.
Model Number: Description:
8200ST/U
8200ST/E OPTIMOD-Studio Chassis, 2channel, 115V
OPTIMOD-Studio Chassis, 2channel, 230V
CAUTION AVIS
RISK OF ELECTRIC SHOCK
DO NOT OPEN
RISQUE DE CHOC
ELECTRIQUE
NE PAS OUVRIR
DO NOT EXPOSE TO RAIN OR MOISTURE
CAUTION: TO reduce the risk of electrical shock, do NOT REMOVE COVER (OR BACK).
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO QUALIFIED SERVICE PERSONNEL.
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRICAL SHOCK,
DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE.
This symbol, wherever it appears,
alerts you to the presence of uninsulated
dangerous voltage inside the enclosure —voltage
that may be sufficient to constitute arisk of shock.
This symbol, wherever it appears,
alerts you to important operating and
maintenance instructions in the accompanying
literature. Read the manual.

IMPORTANT SAFETY INSTRUCTIONS
All the safety and operating instructions should be read before the appliance is operated.
Retain Instructions: The safety and operation instructions should be retained for future reference.
Heed Warnings: All warnings on the appliance and in the operating instructions should be adhered to.
Follow Instructions: All operation and user instructions should be followed.
Water and Moisture: The appliance should not be used near water (e.g., near abathtub, washbowl, kitchen sink, laundry tub, in awet
basement, or near aswimming pool, etc.).
Ventilation: The appliance should be situated so that its location or position does not interfere with its proper ventilation. For example, the
appliance should not be situated on abed, sofa, rug, or similar surface that may block the ventilation openings; or, placed in abuilt-in
installation, such as abookcase or cabinet that may impede the flow of air through the ventilation openings.
Heat: The appliance should be situated away from heat sources such as radiators, heat registers, stoves, or other appliances (including
amplifiers) that produce heat.
Power Sources: The appliance should be connected to apower supply only of the type described in the operating instructions or as
marked on the appliance.
Grounding or Polarization: Precautions should be taken so that the grounding or polarization means of an appliance is not defeated.
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 appliance.
Cleaning: The appliance should be cleaned only as recommended by the manufacturer.
Non-Use Periods: The power cord of the appliance should be unplugged from the outlet when left unused for along period of time.
Object and Liquid Entry: Care should be taken so that objects do not fall and liquids are not spilled into the enclosure through
openings.
Damage Requiring Service: The appliance should be serviced by qualified service personnel when:
The power supply cord or the plug has been damaged; or
Objects have fallen, or liquid has been spilled into the appliance; or
The appliance has been exposed to rain; or
The appliance does not appear to operate normally or exhibits amarked change in performance; or
The appliance has been dropped, or the enclosure damaged.
Servicing: The user should not attempt to service the appliance beyond that described in the operating instructions. All other servicing
should be referred to qualified service personnel.
The Appliance should be used only with acart or stand that is recommended by the manufacturer.
Safety Instructions (European)
Notice For U.K. Customers If Your Unit Is Equipped With APower Cord.
WARNING: THIS APPLIANCE MUST BE EARTHED.
The cores in the mains lead are coloured in accordance with the following code:
GREEN and YELLOW -Earth BLUE -Neutral BROWN -Live
As colours of the cores in the mains lead of this appliance may not correspond with the coloured markings identifying the terminals in your
plug, proceed as follows:
The core which is coloured green and yellow must be connected to the terminal in the plug marked with the letter E, or with the earth symbol,
(A), or coloured green, or green and yellow.
The core which is coloured blue must be connected to the terminal marked Nor coloured black.
The core which is coloured brown must be connected to the terminal marked Lor coloured red.
The power cord is terminated in aCEE7/7 plug (Continental Europe). The green/yellow wire is connected directly to the unit’s chassis. If
you need to change the plug and if you are qualified to do so. refer to the table below.
WARNING: If the ground is defeated, certain fault conditions in the unit or in the system to which it is connected can result in full line
voltage between chassis and earth ground. Severe injury or death can then result if the chassis and earth ground are touched simultaneously.
A
CONDUCTOR WIRE COLOR
Normal Alt 1
LLIVE BROWN BLACK
NNEUTRAL BLUE WHITE
EEARTH GND GREEN-YELLOW GREEN
AC Power Cord Color Coding

Safety Instructions (German)
Ger&t nur an der am Leistungsschild vermerkten Spannung und Stromart betreiben.
Sicherungen nur durch solche, gleicher Stromstarke und gleichen Abschaltverhaltens ersetzen. Sicherungen nie uberbrucken.
Jedwede Beschadigung des Netzkabels vermeiden. Netzkabel nicht knicken Oder quetschen. Beim Abziehen des Netzkabels den
Stecker und nicht das Kabel enfassen. Beschadigte Netzkabel sofort auswechseln.
Gerat und Netzkabel keinen ubertriebenen mechanischen Beaspruchungen aussetzen.
Um Beruhrung gefahrlicher elektrischer Spannungen zu vermeiden, dart das Gerat nicht geoffnet werden, Im Fall von Betriebsstorun-
gen dart das Gerat nur Von befugten Servicestellen instandgesetzt werden. Im Gerat befinden sich keine, durch den Benutzer
reparierbare Teile.
Zur Vermeidung von elektrischen Schlagen und Feuer ist das Gerat vor Nasse zu schutzen. Eindringen von Feuchtigkeit und
Flussigkeiten in das Gerat vermeiden.
Bei Betriebsstorungen bzw. nach Eindringen von Flussigkeiten Oder anderen Gegenstanden, das Gerat sofort vom Netztrennen und
eine qualifizierte Servicestelle kontaktieren.
Safety Instructions (French)
On s'assurera toujours que la tension et la nature du courant utilise correspondent bien aceux indiqubs sur la plaque de I’appareil.
N'utiliser que des fusibles de meme intensity et du meme principe de mise hors circuit que les fusibles dorigine. Ne jamais shunter les
fusibles.
Eviter tout ce qui risque d'endommager le cable seceur. On ne devra ni le plier, ni I’aplatir. Lorsqu’on dbbranche I’appareil, tirer la fiche
et non le cable. Si un cable est endommage, le remplacer immSdiatement.
Ne jamais exposer I’appareil ou le cable aune contrainte mecaniq ue excessive.
Pour aviter tout contact averc une tension blectrique dangereuse, on n'oouvrira jamais I'appareil. En cas de dysfonctionnement,
I’appareil ne peut etre rdpare que dans un atelier autorise. Aucun element de cet appareil ne peut etre r6par§ par I’utilisateur.
Pour 6viter les risques de ddcharge aiectrique et d’incendie, protager I'appareil de I'humidita. Eviter toute panatration d'humidita ou fr
liquide dans I'appareil.
En cas de dysfonctionnement ou si un liquide ou tout autre objet apbn6tre dans I'appareil couper aussitot I'appareil de son alimentation
et s’adresser aun point de service aprdsvente autorisa.
Safety Instructions (Spanish)
Hacer funcionar el aparato s6lo con la tension yclase de corriente senaladas en la placa indicadora de caracteristicas.
Reemplazar los fusibles s6lo por otros de la misma intensidad de corriente ysistema de desconexibn. No poner nunca los fusibles en
puente.
Proteger el cable de alimentacidn contra toda dase de dafios. No doblar oapretar el cable. Al desenchufar, asir el enchufe yno el
cable. Sustituir inmediatamente cables danados.
No someter el aparato yel cable de alimentaci6n aesfuerzo mecanico excesivo.
Para evitar el contacto con tensiones elbctricas peligrosas, el aparato no debe abrirse. En caso de producirse fallos de funcionamiento,
debe ser reparado sblo por talleres de servicio autorizados. En el aparato no se encuentra ninguna pieza que pudiera ser reparada por
el usuario.
Para evitar descargas elbctricas eincendios, el aparato debe protegerse contra la humedad, impidiendo que penetren bsta oliquidos
en el mismo.
En caso de producirse fallas de funcionamiento como consecuencia de la penetracion de liquidos uotros objetos en el aparato, hay
que desconectarlo inmediatamente de la red yponerse en contacto con un taller de servicio autorizado.
Safety Instructions (Italian)
Far funzionare I’apparecchio solo con la tensione eil tipo di corrente indicati sulla targa riportante idati sulle prestazioni.
Sostituire idispositivi di protezione (valvole, fusibili ecc.) solo con dispositivi aventi lo stesso amperaggio elo stesso comportamento di
interruzione. Non cavallottare mai idispositivi di protezione.
Evitare qualsiasi danno al cavo di collegamento alia rete. Non piegare oschiacciare il cavo. Per staccare il cavo, tirare la presa emai
il cavo. Sostituire subito icavi danneggiati.
Non esporre I'apparecchio eil cavo ad esagerate sollecitazioni meccaniche.
Per evitare il contatto con le tensioni elettriche pericolose, I'apparecchio non deve venir aperto. in caso di anomalie di funzionamento
I'apparecchio deve venir riparato solo da centri di servizio autonzzati. Nell'apparecchio non si trovano parti che possano essere riparate
dalldtente.
Per evitare scosse elettriche oincendi, I’apparecchio va protetto dall'umidita. Evitare che umidita oliquidi entrino nell'apparecchio.
In caso di anomalie di funzionamento rispettivamente dopo la penetrazione di liquidi ooggetti nell'apparecchio, staccare immedi-
atamente I'apparecchio dalla rete econtattare un centra di servizio qualificato.

Operating Manual
OPTIMOD-Studio Chassis
Automatic Gain Controller
8200ST

Orban 8200ST
OPTIMOD-Studio Chassis
Operating Manual
page contents
1-
1Section 1:Introduction
Orban OPTIMOD-STUDIO CHASSIS 8200ST
2-
1Section 2:Installation
Installation
3-
1Section 3:Operation
8200ST Controls and Meters
Example Control Settings
More About 8200ST Audio Processing
4-
iSection 4:Maintenance
Getting Inside the Chassis
Performance Evaluation
5-
1Section 5 :Troubleshooting
Problems and Possible Causes
Technical Support
Factory Service
Shipping Instructions
6
-
iSection 6 :Technical Data
Specifications
Circuit Description
Parts List
Schematics, Assembly Drawings
Abbreviations
INDEX on next page

Index
A
abbreviations 6-33
accessories 6-2
AGC button 3-7
applications 1-3
assembly drawings 6-23
audible distortion 3-7, 5-3
audio
connections 2-6 -2-8
input/output 2-6 -2-8
tape recorder 3-8
automatic gain control (AGC) 3-7
B
balanced inputs 2-9
bargraph driver 6-8,6-12
block diagram 6-23
buzzes 5-2
C
cable shielding 2-7, 2-9
chassis ground 2-9
chassis, getting inside 4-2
circuit boards
access to 4-2
front panel 4-2
circuit description 6-4
circuit ground 2-9
clicks 5-2
clipper-defeat jumpers 2-5
clipping
bias 3-5, 6-9
distortion 5-3
transient 3-7
common-mode rejection 2-9
component
numbering system 6-4
vendors 6-22
compression 3-7, 6-6
connectors, audio 2-7
control settings 3-4
broadcast transmission 2-2, 3-5
FM subcarriers 3-5
controls 3-2
COUPLE switch
loss of memory on power-down
covers, removing/replacing 4-2
customer support 5-4
D
dBu (defined) 4-4,6-33
de-essing 3-7
density 6-4
distortion 5-3, 6-6
F
factory service 5-4
front panel 3-2
fuse 2-6, 6-2
G
gain reduction 3-7
meter 3-7, 6-6
gate, detector 6-7
gating 3-7, 5-3, 6-6
control circuits 4-3
grounding 2-9, 5-2
difficult situations 2-10
ground loop 2-9,2-10
H
harshness 5-3
high-frequency
limiter 3-7, 4-3, 6-9
pre-emphasis 3-8
hum 5-2
I
impedance 2-8
input 6-6
attenuators 3-7, 6-5
balanced 2-9
buffer 6-5
impedance 2-7
level 2-7
overload point 2-7
stages 4-3
installation 2-1
J
jumpers
access to 4-2
positions 2-4
K
keep-alive circuit 6-12
L
level calibration 2-11
leveling 3-7, 6-6
logic circuit 6-12
loudness 3-5
M
meter calibration 6-11
meters 3-2, 4-3, 6-2
red zone 3-7
MODULATION meter 3-9
N
noise rush-up, pumping 3-7, 5-3
O
operation 3-1
options 6-2
ordering parts 6-1 4-6-15
output
impedance 2-8
level 2-7
stages 4-3
unbalanced load 2-8
overshoot 5-2
P
packing for shipment 5-5
parts, ordering 6-15
parts list 6-14
peak
clippers 5-2
control 5-2, 6-9
level 3-7, 3-9
output level meter 6-1
1
performance evaluation 4-3
physical dimensions 6-2
power 2-3
cord 2-3, 2-6
supplies 4-3,5-2,6-13
power requirements 6-2
pre-emphasis 3-8, 5-3, 6-9
pre-emphasis jumper 2-5
product features 1-3
R
rack-mounting unit 2-6
registration card (first page)
regulated dropout 6-1
3
regulated voltage 6-13
release shape 3-7, 6-6
release time 3-7, 6-6
RF suppression 5-2, 6-5
RFI 2-3
filter 2-3
ringing 5-2
S
schematics 6-23
security cover 6-2
service 5-4
shipping
instructions 5-5
shipping damage 2-2
shrillness 5-3
specifications 6-2
stereo mode 3-9
swept sine wave measurements 3-8
swept sine wave tests 6-9
T
tape 3-8
technical support 5-4
thumps 6-6
tilt 5-2
timing module 6-6
transmitter pre-emphasis 2-3
troubleshooting 5-1
U
unbalanced load 2-8
unregulated voltage 6-13
V
VCAs 4-3, 6-6
VOICE 6-4
VOICE button 3-7
VOICE switch
loss of memory on power-down 5-3
voltage regulators 5-2,6-13
W
warranty (inside back cover)
XLR connectors 2-7

OPTIMOD-STUDIO CHASSIS 8200ST INTRODUCTION
Section 1
Introduction
page contents
1-3 Orban OPTIMOD-STUDIO CHASSIS 8200ST

OPTIMOD-STUDIO CHASSIS 8200ST INTRODUCTION 1-3
Orban OPTIMOD-STUDIO CHASSIS 8200ST
The 8200ST provides transparent gain riding, adjustable compression, high-frequency
limiting and absolute peak control —all in aspace -saving, rugged, 1-rack unit high package
.
The flexibility and natural sound of the 8200ST is ideally suited to many broadcast
applications; in particular, protecting discrete studio-to-transmitter links when using OPTI-
MOD audio processing.
Barely adequate signal-to-noise ratio often makes the land line or microw’ave studio-to-
transmitter link the weakest part ofthe broadcast chain. The 8200ST stransparent gain
control translates to improved effective dynamic range for the link and improved signal
quality at the receiver. Switch-selectable pre-emphasis limiting and peak control ensure
proper matching the 8200ST to any standard transmission medium.
Features include:
•Up to 25dB ofgain reduction for two channels of audio.
•Defeatable “Silence Gate” —not aconventional noise gate, but acircuit that
freezes the level controller’s gain when signals drop below threshold. This gate
prevents rush-up of background noise during quieter passages and exaggeration
ofbreathing during pauses in spoken voice.
•Flexible level controls: Asmooth leveler, activated when the agc button is on,
provides slow gain riding. Asecond, much faster level controller (one that works
in conjunction with the smooth leveler) can be activated with the voice button.
•Five switchable HF Limiter pre-emphasis curves (25|ts to 15Op.s): These pre-em-
phasis curves allow the HF limiting to complement the medium being protected.
•Built-in 400Hz line-up tone generators for easy system alignment.
•Two LED bargraphs per channel simultaneously displaying gain reduction and
peak operating levels.
•Independent or stereo operation, controlled via front panel couple button.
•Class-A VCAs with inherently low noise and distortion.
•Broadcast-quality interfacing with EMI-suppressed, balanced and floating inputs
and outputs.
•Defeatable clipper: follows the HF limiter for absolute peak protection.

INTRODUCTION Orban
This Page Intentionally Left Blank.

OPTIMOD-STUDIO CHASSIS 8200ST
Section 2
Installation
Installation
Figure 2-1 :AC Line Cord Wiring
Figure 2-2: Jumper Settings
Figure 2-3: Suggested Ground Scheme
CAUTION
The installation and servicing instructions in this manual are for
use by qualified personnel only. To avoid electric shock, do not
perform any servicing other than that contained in the Operating
Instructions unless you are qualified to do so. Refer all servicing
to qualified service personnel.

2-2 INSTALLATION Orban
Installation
Allow about 45 minutes for installation.
Installation consists of unpacking and inspecting the 8200ST, optional defeating of trans-
mitter’s pre-emphasis, optional resetting of clipper, output pre-emphasis and tone level
jumpers, mounting the unit in arack, connecting audio and power, calibrating the 8200ST s
modulation meters and clipping level, and setting its controls for normal operation.
The 8200ST simultaneously provides level control and protects against overmodulation.
When Orban’s OPTIMOD-AM, OPTIMOD-HF, or OPTIMOD-FM 8200 is used at the
transmitter, the 8200ST replaces the OPTIMOD's internal AGC, which should be defeated
according to instructions found in the OPTIMOD manual.
For OPTIMOD-FM 8100A or 8101, and OPTIMOD-TV 8180A or 8182A, the Orban
Studio Chassis designed for that model can also be used, although the high frequency
limiting ofthe 8200ST allows better modulation control for pre-emphasized STLs.
1. Unpack and inspect.
If you note obvious physical damage, contact the carrier immediately to make adamage
claim.
Packed with the 8200ST are: AC Power Cord
Operating Manual
Warranty/Registration Card
Safety Sheet
ad Save all packing materials! If you should ever have to ship the 8200ST (e.g., for
servicing), it is best to ship it in the original packing materials because both the
carton and packing material have been carefully designed to protect the unit.
bComplete the Registration Card and return it to Orban. (please)
The Registration Card enables us to inform you of new applications,
performance improvements, and service aids that may be developed, and it
helps us respond promptly to claims under warranty without having to
request acopy of your bill of sale or other proof of purchase. Please fill in
the Registration Card and send it to us today. (If it is lost, photocopy the
duplicate on page 1-6). We do not sell our customer’s names to anyone.
2. Check the line voltage, fuse and power cord.
aDO NOTconnectpower to the unit yet!
bCheck the VOLTAGE SELECTOR. This is on the rear panel.
The 8200ST is shipped configured for either 90-130V or 180-260V, 50Hz
or 60Hz operation, as indicated on the rear panel. Refer to the unit’s rear

OPTIMOD-STUDIO CHASSIS 8200ST INSTALLATION
panel for your Model #and the inside of the front cover of this manual for
your Model #'s line voltage setting. To change the operating voltage, set
the VOLTAGE SELECTOR to 115V (for 90-130V) or 230V (for 180-260V)
as appropriate.
cCheck the value ofthe fuse and change the fuse if the value is incorrect.
Use aVi-amp 3AG 250V Slow -Blow for 115V operation, or 14-amp “T”
type (250mA) Slow-Blow fuse for 230V operation.
dCheck power cord.
AC power passes through an IEC-standard mains connector and an RF
filter designed to meet the standards of all international safety authorities.
The power cord is terminated in a'‘U-ground” plug (USA standard), or
CEE7/7 plug (Continental Europe), as appropriate to your 8200ST’s
Model #. The green/yellow wire is connected directly to the 8200ST
chassis.
Ifyou need to change the plug to meet your country’s standard and you are
qualified to do so, see Figure 2-1. Otherwise, purchase anew mains cord
with the correct line plug attached.
CONDUCTOR WIRE COLOR
NORMAL ALT
LLINE BROWN BLACK
NNEUTRAL BLUE WHITE
EEARTH GND GREEN-YELLOW GREEN
PLUG FOR
230 VAC
(EUROPEAN)
CONDUCTOR WIRE COLOR
nLINE BROWN
NNEUTRAL BLUE
EEARTH GND GREEN-YELLOW
Figure 2-1: AC Line Cord Wiring
3. Defeat your STL transmitter’s pre-emphasis, (optional)
The STL transmitter’s pre-emphasis network may introduce overshoots that will in-
crease peak modulation without any increase in average modulation. We therefore
strongly recommend that you defeat the transmitter’s pre-emphasis (freeing the trans-
mitter from such potential overshoot), and use the 8200ST to provide the necessary
pre-emphasis.

2-4 INSTALLATION Orban
Clipper Jumpers Output Pre-Emphasis Jumpers
‘FLAT PRE-EMPHASIZED
‘CLIPPER ON CLIPPER OFF LEFT RIGHT LEFT RIGHT
OUTPUT OUTPUT OUTPUT OUTPUT
p1pin pO
in on 1In o
JA JA JE JF JE JF
Line-up Level Jumpers
*PEAK AVG
LEFT RIGHT LEFT RIGHT
OUTPUT OUTPUT OUTPUT OUTPUT
pa On PP
OIda alol
JB JC JB JC
Figure 2-2: Jumper Settings (‘Factory Configuration)
-linn
iffoi

OPTIMOD-STUDIO CHASSIS 8200ST INSTALLATION
Ifthe transmitter’s pre-emphasis cannot be defeated, then configure the 8200ST for flat
output (see step 4, below). In this case average modulation levels may have to be reduced
to accommodate the overshoots, reducing the signal-to-noise ratio achieved in the link.
4. Internal jumper configuration.
For transmission applications, we recommend you reset the 8200ST’s jumpers, as
follows:
CLIPPER on*
OUTPUT PRE-EMPHASIS pre-emphasized (see step 3,
immediately above)
TONE LEVEL peak*
*As Shipped From the Factory
aTo change any jumpers you must remove the top cover ofthe 8200ST to access the
main circuit board. (Make sure power is not connected.) Remove all screws holding
the cover in place, then lift it off. When replacing the cover, replace all screws
snugly. (Be careful not to strip the threads by fastening the screws too tightly.)
bReferto Figure 2-2 to find thejumpers on the main circuit board and to position them
according to your application.
Hie following information is provided to explain each jumper and its settings in detail.
CLIPPER jumper (JA) on; this setting enables the 8200ST's peak clippers, achieving
absolute peak control prior to the 8200ST's de-emphasis.
If the 8200ST’s de-emphasis is disabled, then the 8200ST’s peak level will
be absolutely limited. Otherwise, the maximum peak output level will
approximately follow the chosen de-emphasis curve as afunction of
frequency.
OUTPUT PRE-EMPHASIS jumpers (JE, JF) pre-emphasized; this setting disables
the 8200ST‘s de-emphasis and feeds pre-emphasized audio to an STL or other broadcast
device that does not have pre-emphasis.
The FLAT setting applies ade-emphasis filter (complementary to the pre-
emphasis chosen with the 8200ST?sfront panel HF Limiter control) to the
8200ST’s output to yield an overall “flat” response. Use the FLAT setting if
you are feeding audio to an STL that has internal pre-emphasis.
TONE LEVEL jumpers (JB, JC) peak; this setting enables the 8200ST’s built-in tone
oscillator to produce a400Hz peak reference level tone at 100% peak modulation.
“100% peak modulation” is the threshold of the 8200ST's peak clippers: peaks will
never exceed this level when the peak clippers are activated. Use peak reference level
in broadcast systems to align the 8200ST’s output level to the 100% modulation level of
the studio-to-transmitter link. You can also use peak reference level to align the
8200ST’s output level to the maximum level of adigital link.

INSTALLATION Orban
The peak reference level is only valid when the 8200ST’s peak clippers are
enabled and when the 8200ST is jumpered for pre-emphasized output. If
the 8200ST’s peak clippers are defeated, some peaks will exceed the peak
reference level. If the output of the 8200ST is “flat,’' this will substantially
(but inconsistently) reduce peak levels.
The tone level is set before de-emphasis. So ifthe 8200ST is strapped FLAT,
the output will be slightly lower than 100% modulation with reference to
very low frequencies unaffected by pre-emphasis. However, please note
that any pre-emphasis in the equipment receiving the 8200ST’s output will
restore the tone to the correct level. In almost all cases, the modulation
metering of such driven equipment occurs after its internal pre-emphasis,
and the 8200ST’s tone will therefore be at the appropriate level to set the
modulation level of the driven equipment correctly.
When TONE LEVEL jumpers are set to AVERAGE, the tone level is
approximately 18dB below 100% modulation. This level corresponds
approximately to OVU (when you use a VU meter to monitor line levels).
We do not anticipate that many users will use the tone oscillator in this
mode, but it is available for special line-up requirements.
5. Mount the 8200ST in arack, (optional)
The 8200ST requires one standard rack unit (l3
/
4inches, 4.4 cm).
There should be agood ground connection between the rack and the 8200ST chassis —
check this with an ohmmeter.
Mounting the unit near large heat-producing devices may shorten component life and is
not recommended. Ambient temperature should not exceed 113°F (45°C) when equip-
ment is powered.
6. Connect audio input and output.
See the hook-up and grounding information on the following pages.
7. Connect power cord.
Be sure you have checked the voltage setting and fuse according to step 2above.
aConnect power.
The green power light on the lower right of the front panel should light.

OPTIMOD-STUDIO CHASSIS 8200ST INSTALLATION
Audio input and Output Connections
Wire:
We recommend using two-conductor shielded cable (such as Belden 845 1or equiva-
lent), because signal current flows through the two conductors only. The shield does
not carry signal, is used only for shielding, and is ordinarily connected to ground at one
end only.
Because use of single-conductor cables virtually eliminates any possibility
of carefully controlling the system grounding scheme, it is NOTRECOM-
MENDED! Even so, it often does work adequately in low-RF environ-
ments.
Sometimes, particularly if you are using the 8200ST with musical instru-
ments or home-type equipment, single-conductor shielded cable may be
the only practical alternative. In this case, connect the inner conductors of
the shielded cables to the (+) sides (pin 2) of the 8200ST input and output
XLR connectors respectively. Connect the shield of the 8200ST input
cable to pin 3of the 8200ST’s input XLR, and connect the shield of the
8200ST output cable to pin 3of the 8200ST’s output XLR. Internally
connect pins 1and 3ofboth input and output XLRs within the connectors.
Connectors:
Input and output connectors are XLR connectors.
In the XLR connectors, pin 1is CHASSIS GROUND, while pin 2 and pin
3are abalanced, floating pair. This wiring scheme is compatible with any
studio wiring standard: If one pin is considered LO, the other pin is
automatically HI.
Input:
Nominal input level is between —10 and +8dBu. The absolute overload point is
+26dBu.
(OdBu =0.775V RMS; for this application, the dBm @600Q scale on
voltmeters can be read as if were calibrated in dBu.)
•The electronically-balanced input of each channel is compatible with most pro-
fessional and semi-professional sound equipment, balanced or unbalanced, with
asource impedance of 600Q or less.
•Input connections are the same whether the driving source is balanced or unbal-
anced.

INSTALLATION Orban
Audio Input and Output Connections (Continued)
Input (Continued):
•Connect the red (or white) wire to the pin on the XLR connector (#2 or #3) that
is considered HI by the standards ofyour organization. Connect the black wire to
the pin on the XLRconnector (#2 or #3) that is considered LO by the standards of
your organization.
•In low RF fields (like astudio site), do not connect the cable shield at the 8200ST
input —it should be connected at the source end only. In high RF fields (like a
transmitter site), also connect the shield to pin 1ofthe male XLRconnector at the
8200ST input.
•Ifthe output ofthe driving unit is imbalanced and does not have separate CHASSIS
GROUND and (-) (or LO) output terminals, connect both the shield and the black
wire to the common (-) or ground terminal ofthe driving unit.
Output
The two electronically-balanced and floating outputs of each channel simulate atrue
transformer output. The source impedance is 300. In addition, there is alOOOpF
capacitor between each output (HI and LO) to the chassis for RFI suppression. The
output is capable ofdriving loads of 6000 or higher.
If an unbalanced output is required (to drive unbalanced inputs of other equipment),
it should be taken between pin 2and pin 3ofthe XLR connector. Connect the LO pin
of the XLR connector (pin 2or 3, depending on your organization’s standards) to
ground, and take the HI output from the remaining pin. No special precautions are
required even though one side of the output is grounded.
•Use two-conductor foil-shielded cable (Belden 8451, or equivalent).
•At the 8200ST’s output (and at the output of other equipment in the system),
connect the cable’s shield to the CHASSIS GROUND (pin 1) on the XLRconnector.
Connect the red (or white) wire to the pin on the XLR connector (#2 or #3) that
is considered HI by the standards ofyour organization. Connect the black wire to
the pin on the XLR connector (#3 or #2) that is considered LO by the standards of
your organization.

OPTIMOD-STUDIO CHASSIS 8200ST INSTALLATION
Grounding
Very often, grounding is approached in a‘‘hit or miss manner. But with care it is
possible to wire an audio studio so that it is free from ground loops (which induce hum
and can cause oscillation) and provides maximum protection from power faults.
•All units in the system must have balanced inputs. In amodem system with low
output impedances and high input impedances, abalanced input will provide
common-mode rejection and prevent ground loops —regardless of whether it is
driven from abalanced or unbalanced source. (The 8200ST has balanced inputs.)
•All equipment circuit grounds must be connected to each other; all equipment
chassis grounds must be connected together.
•In low RF fields, cable shields must be connected at one end only —preferably
the source (output) end.
•In high RF fields (such as transmitter sites), cable shields must be connected to a
solid earth ground at both ends to maximize their RF shielding. This means that
all equipment in such environments must have balanced inputs to prevent the
ground loops that could otherwise be introduced.
Power:
•Ground the 8200ST chassis through the third wire in the power cord. Proper
grounding techniques never leave equipment chassis unconnected to power/earth
ground. Aproper power ground is essential to safe operation. Lifting achassis
from power ground is asafety' hazard .Ifthere is apower fault to the chassis, death
could result!