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2-12
INSTALLATION
Circuit Ground
Studio Level Controller Installation (optional)
If you are using Orban 8200ST external AGC
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.
[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 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
C) If you have defeated the STL transmitter's pre-emphasis, place jumpers JE and
JF in the P
-E
RE
MPHASIZED
O
position.
LIPPER
N
position.
ORBAN MODEL
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Troubleshooting
