OPTIMOD-AM DIGITAL
INSTALLATION
2-31
11.
Test the equipment downstream from OPTIMOD-AM.
Test the RF envelope at the transmitter’s output to determine if it exhibits tilt,
overshoot, or ringing. If you observe these problems, you can often adequately
equalize it them with the 9400’s transmitter equalizer, whose settings are de-
termined by the on-air Transmission Preset.
Dealing with tilt and overshoot may seem fussy, but every dB of tilt or overshoot
is a dB of loudness lost!
Use the 9400's built-in square wave generator to make this test:
A)
Navigate to
S
ETUP
>
T
EST
.
B)
Set the
T
ONE
M
OD
to 0%.
C)
Set the
M
ODE
to
S
QUARE
.
D)
You may now turn the final amplifier on. Observe the RF envelope at the
common point with a DC-coupled oscilloscope and advance the
T
ONE
M
OD
control until you can easily see the shape of the square wave.
Sweep the
T
ONE
F
REQ
control from 125 to 1000 Hz and observe the shape
of the square wave as you do so. If you are driving more than one trans-
mitter and/or your antenna load changes between day and night, test all
combinations that you will be using.
If the square wave is free from tilt and ringing at all frequencies in the
sweep, you do not need to set up the transmitter equalizer in steps 12
through (13.H)a) below. Otherwise, you must do so to achieve the high-
est loudness and coverage that your facility can produce.
If you observe problems with some combinations of transmitter and load
but not others, record which combinations cause problems. You will only
need to set up set up the Transmitter Equalizer for these combinations.
You will dedicate one Transmission Preset for each problematic combina-
tion so that each combination can be equalized independently.
Figure 2-9
on page 2-33 shows tilt and
Figure 2-11
on page 2-35 shows
ringing.
Caution
: To avoid damaging the transmitter, do not exceed 50% modulation
with square waves.
Important
: Do not place additional clipping devices after OPTIMOD-AM! The
additional distortion introduced by these devices will totally nullify the advan-
tages of OPTIMOD-AM's distortion-canceling clipper and will cause the out-of-
band energy induced by clipping to violate FCC or ITU-R standards.
12.
Equalize the transmitter’s low frequency square wave response.
[Skip the Transmitter Equalizer adjustment steps [(steps 12 though (13.H)a)] if
the RF envelope square wave test you preformed in step 11 above showed no
sign of tilt, overshoot, or ringing.]
Summary of Contents for Optimod-AM 9400
Page 1: ...Operating Manual OPTIMOD AM 9400 Digital Audio Processor Version 1 2 Software...
Page 7: ...Operating Manual OPTIMOD AM 9400 Digital Audio Processor Version 1 2 Software...
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Page 260: ......
Page 261: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 29...
Page 267: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 35 CPU Module...
Page 273: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 41 RS232 BOARD PARTS LOCATOR...
Page 275: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 43 8300 POWER SUPPLY PARTS LOCATOR...
Page 284: ...6 52 TECHNICAL DATA ORBAN MODEL 9400 DSP BOARD PARTS LOCATOR DRAWING 32170 000 14...
Page 292: ...6 60 TECHNICAL DATA ORBAN MODEL 9400 DISPLAY BOARD PARTS LOCATOR...
Page 293: ...OPTIMOD AM DIGITAL TECHNICAL DATA 6 61 DISPLAY BOARD...