Orban OPTIMOD-FM 8700, Operating Manual

Page: 78 / 390

2-16
INSTALLATION ORBAN MODEL 8700i
preemphasis be defeated (freeing the STL from such potential overshoot) and that
the 8200ST be used to provide the necessary preemphasis.
If the STL transmitter’s preemphasis 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 2-17.
B) Place jumper JA in the C
LIPPER
O
N
position.
C) If you have defeated the STL transmitter’s preemphasis, place jumpers JE and
JF in the
P
RE
-E
MPHASIZED
position.
D) If you cannot defeat the STL transmitter’s preemphasis, place jumpers JE and
JF in the
F
LAT
position.
E) Replace the top cover and then replace all screws snugly. (Be careful not to
strip the threads by fastening the screws too tightly.)
2. Install the 8200ST in the rack. Connect the 8200ST’s audio input and output.
Refer to the 8200ST Operating Manual if you require information about installa-
tion, audio input, and audio output connections to the 8200ST.
3. Set 8200ST Output Level with tone.
A) Press the TONE button on the 8200ST.
The TONE lamp should light and the modulation meters should indicate
“0.” If they do not, re-strap jumpers JB and JC to “peak.” (Refer to Figure
2-4 on page 2-17.)
The 8200ST is now producing a 400Hz sine wave at each output. The peak
level of this tone corresponds to 100% modulation.
B) Adjust the 8200ST’s
L O
UT
and
R O
UT
controls so that the STL transmitter is be-
ing driven to 100% modulation.
The L O
UT
and R O
UT
controls are now correctly calibrated to the trans-
mitter. If no significant overshoot occurs in the transmitter, the
MODULATION meter will now give an accurate indication of peak modu-
lation of the STL.
C) Turn off the tone by pressing the T
ONE
button.
If the STL transmitter suffers from bounce or overshoot, you may have to
reduce the
L O
UT
and R O
UT
control settings to avoid peak over-
modulation caused by overshoots on certain audio signals.