Circuit Ground; Studio Level Controller Installation (Optional); If You Are Using Orban 8200St External Agc - Orban OPTIMOD-FM 5500 Operation Manual

OPTIMOD-FM DIGITAL
power/earth ground. A proper power ground is essential for safe operation. Lift-
ing a chassis from power ground creates a potential safety hazard.

Circuit Ground

To maintain the same potential in all equipment, the circuit (audio) grounds must be
connected together:

When the 5500'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 5500 does not have a ground lift
switch. If you cannot reconfigure your grounding scheme to eliminate such a
loop, an alternative strategy is to balance and float the exciter input with the
Orban CIT25 Composite Isolation Transformer — see page 2-9.

In high RF fields, the system is usually grounded through the equipment rack in
which the 5500 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)

[This section does not apply to a 5500 being used as a stand-alone stereo encoder. In
this mode, the 5500 must be driven by a full–featured FM audio processor (like
Orban's 8500), usually via an STL].
[Skip this section if you are not using a studio level controller ahead of the 5500.
Continue with "Quick Setup" on page 2-14.]

If you are using an Orban 8100AST (or 8100A/ST) external AGC, refer to page 1-
18.

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.
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INSTALLATION