Operating instructions

2-32
INSTALLATION ORBAN MODEL 9400
Overview of Transmitter Equalization
The
Transmitter Equalizer has a low frequency section to equalize tilt and a high
frequency section to equalize overshoot and ringing. If you are adjusting a
CQUAM AM stereo plant, you must also adjust a second set of high frequency
controls (for the L–R channel). These L–R controls do nothing in a mono facility.
The Transmitter Equalizer does not affect the 9400’s HD processed output.
The Transmitter Equalizer setup parameters are stored independently in the four
Transmission Presets (See page 1-17). If you are driving two transmitters, you will
usually
dedicate either one or two Transmission Presets to each transmitter. Us-
ing two transmission presets per transmitter allows you to equalize that trans-
mitter and its antenna load independently for day and night operation. This may
be desirable if the transmission parameters (power or antenna pattern) change
between day and night.
In addition to the Transmitter Equalizer controls, you must set the L
OWPASS,
H
IGHPASS, and POS PEAK controls in each preset you use.
If you are only driving one transmitter and the plant’s parameters do not change
between day and night, then you only need to use and adjust the default TX1
/
DAY Transmission Preset.
Description of the TX EQ Controls
LF FREQ
: Determines the frequency at which the response of the Tilt
Equalizer section of the Transmitter Equalizer is up approximately +3dB.
This control is only available for the L+R (envelope modulation) channel.
LF GAIN:
Determines the maximum amount of low frequency correction
provided by the Tilt Equalizer section of the Transmitter Equalizer. The
control is only available for the L+R channel.
HF DELAY:
Determines the frequency at which the delay equalizer sec-
tion of the Transmitter Equalizer begins to add phase shift to correct for
non-constant delay in the transmitter and antenna system. This control is
available for both the L–R and L+R channels.
The L–R channel is only of interest if you are equalizing a CQUAM AM
stereo installation. In mono installations, the L–R Transmitter Equalizer
controls have no effect.
HF GAIN: Determines the frequency at which the High Frequency Shelv-
ing Equalizer section of the Transmitter Equalizer begins to roll off the
high frequency response, compensating for overshoot in the transmitter
and antenna system. This control is available for both the L–R and L+R
channels.
Procedure for LF Equalization
You will set up one 9400 Transmission Preset at a time.
A) Connect the vertical input of the oscilloscope to
the transmitter’s sampling
loop (or other convenient source of RF).
B) Connect the sync (or external trigger) input of the oscilloscope to an available
9400 analog output.