2-12
INSTALLATION
ORBAN MODEL
Circuit Ground
To maintain the same potential in all equipment, the circuit (audio) grounds must be
connected together:
•
When the 8500S’s stereo encoder is driving an
unbalanced exciter input
, you
may encounter a ground loop. (Some older exciters have unbalanced inputs.)
Unlike some older Orban FM processors, the 8500S does not have a ground lift
switch. If you cannot reconfigure your grounding scheme to eliminate such a
loop, you can balance and float the exciter input with a Jensen JT-123-BMCF
transformer (see page 2-16).
•
In high RF fields, the system is usually grounded through the equipment rack in
which the 8500S is mounted. The rack should be connected to a solid earth
ground by a wide copper strap — wire is completely ineffective at VHF because
of the wire’s self-inductance.
Studio Level Controller Installation (optional)
[Skip this section if you are not using a studio level controller ahead of the 8500S.
Continue with “Quick Setup” on page 2-15.]
•
If you are using an Orban 6300 as a studio level controller, refer to its Operating
Manual.
If you are using Orban 8200ST external AGC
If the STL uses pre-emphasis, its input pre-emphasis network will probably introduce
overshoots that will increase peak modulation without any increase in average
modulation. We therefore strongly recommend that the STL transmitter’s pre-
emphasis be defeated (freeing the STL from such potential overshoot), and that the
8200ST be used to provide the necessary pre-emphasis.
If the STL transmitter’s pre-emphasis cannot be defeated, then configure the 8200ST
for flat output. In this case average modulation levels of the STL may have to be re-
duced to accommodate the overshoots.
1.
Configure the 8200ST’s internal jumpers.
A)
Remove all screws holding the 8200ST’s cover in place; then lift it off.
Refer to Figure 2-4 on page 2-13.
B)
Place jumper JA in the
C
LIPPER
O
N
position.
C)
If you have defeated the STL transmitter’s pre-emphasis, place jumpers JE and
JF in the
P
RE
-E
MPHASIZED
position.
Summary of Contents for OPTIMOD-FM 8500S
Page 1: ...Operating Manual OPTIMOD FM 8500S Digital Audio Processor Version 1 0 Software...
Page 7: ...Operating Manual OPTIMOD FM 8500S Digital Audio Processor Version 1 0 Software...
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Page 310: ...6 28 TECHNICAL DATA ORBAN MODEL 8500S CONTROL BOARD PARTS LOCATOR...
